Development of the musculoskeletal system of vertebrates. Tasks: to acquaint students with the structure and function of the musculoskeletal system in different groups of animals, with the direction of evolution of the musculoskeletal system. The value of the musculoskeletal system

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The evolution of the integument of the body.

In invertebrates, integuments develop from the ectoderm. The evolution of the integument followed the path of transformation of the ciliated epithelium (ciliary worms) into a flat epithelium, devoid of cilia, with the formation of a cuticular layer outside. Already in invertebrate animals, the cover performs not only the function of protection, but also many others (perception of mechanical and chemical irritations, touch, defeat of the victim, scaring off enemies).

In chordates, the cover is not a homogeneous structural formation, but consists of two parts - the epidermis and the dermis, which are closely related to each other, but differ in origin: the epidermis develops from the ectoderm, the dermis from the mesoderm. The evolution of the integument followed the path of replacing a single-layer cylindrical epithelium and a poorly developed dermis (lancelet) with a stratified squamous keratinized epithelium and a well-developed dermis (vertebrates).

Further evolution of the integument in a series of vertebrates led to the division of the epidermis into the upper protective stratum corneum and the lower germ layer. The cells of the stratum corneum, as they approach the surface, flatten, fill with fibrillar protein-keratin, die and desquamate, which is important in conditions of constant terrestrial existence.

In all higher vertebrates, specialized structures are formed due to the modified stratum corneum of the epidermis: scales, claws, horns, feathers, nails, hair. It should be noted that in the ancestors of mammals, the body was covered with scales, which is preserved on the limbs and tail of a number of modern mammals (rodents, insectivores, marsupials). In many amniotes, in which teeth are reduced, the skin along the edges of the jaws becomes keratinized, forming a beak. The nails and hooves that arose in mammals are a modification of the claws.

The appearance of hair in mammals provided thermal insulation, species-specific coloration of the skin (together with pigment cells of the epidermis and dermis), improved touch, aero- and hydrodynamic properties of the body.

Functions of the integument of the body.

1.Protection against mechanical, physical and chemical influences.

2. Barrier - a barrier to the penetration of bacteria and other microorganisms.

3. Thermal insulation (skin, hair, feathers).

4. Participation in heat exchange between the body and the environment.

5. Participation in the regulation of the body's water balance.

6. Participation in the excretion of end products of metabolism (gland).

7. Participation in respiration (O2 absorption and CO2 release).

8. Metabolic function (storage of energy material, formation of vitamin D, milk).

9. An important role in intraspecific relationships: skin and hair pigments provide species-specific skin coloration; the totality of the secrets of odorous, sebaceous, sweat glands makes it possible to distinguish individuals of one's own and other species, facilitates the meeting of a male and a female.

10. Passive protection - adaptive coloration (protective, warning, dismembering, mimicry) ensures the adaptation of the organism to the environment.

Evolutionary transformations of integument in chordates.

Expansion of the number of functions performed - in addition to protection, integuments take part in gas exchange, thermoregulation, in the removal of end products of metabolism;

Change of function - placoid scales on the jaws turned into teeth;

The intensification of the body defense function led to the differentiation of the integument: the development of the dermis due to the growth of connective tissue, the division of the epidermis into two layers (horny and growth); the formation of specialized derivatives of the skin, multicellular glands of several types;

The emergence of new structural elements skin - hairline;

The appearance of specialized derivatives of sweat glands - the mammary glands.

Onto-phylogenetically determined malformations of integument in humans.

1. Lack of sweat glands (anhidrosis dysplasia).

2. Excessive hairiness of the skin (hypertrichosis).

3. Polymammary (polythelia).

4. Increased number of mammary glands (polymast).
The evolution of the musculoskeletal motor system.

One of the main properties of animal organisms - movement (locomotion) - is carried out due to the musculoskeletal system. The supporting formations of invertebrates are varied and can be of ecto-, entho-, and mesodermal origin. So, in intestinal cavities, the supporting function is performed by the mesoglea, locomotion by the epithelial-muscular cells of the ecto- and endoderm; the skeleton of coral polyps develops from the ectoderm. Most invertebrates have an external skeleton. In chordates, the skeleton is internal (ento- and mesodermal origin). We are the basis of their body

neck-chordal complex (myochord), consisting of a chord (axial elastic cord) and metameric muscles adjacent to it. The notochord is laid in the embryonic period of all chordates and performs a morphogenetic role - under the influence of the chordo-mesodermal rudiment, the neural tube, spine develop, and the somites differentiate.

In the process of progressive evolution of chordates, the following occurred: the replacement of the notochord by the vertebral column, consisting of vertebrae; the acquisition by the vertebrae of procoelity (anterior concavity) and plasticity (anterior and posterior surfaces of the vertebrae are flat); skull formation; loss of the metameric structure of the muscles and the appearance of specialized muscle groups; change in the location of the limbs and the type of their attachment. Adaptations to different habitat conditions led to the formation of diverse types of movement, which expanded the possibilities of obtaining food, escaping from enemies, searching for optimal habitats, and settling by chordates in almost all biotopes of land, water, and the lower layers of the atmosphere.

Functions of the musculoskeletal system.

1. Preservation of a certain body shape.

2. Protection of organs from influences.

3. Support for the entire body weight, lifting it above the ground.

Division of the common atrium and common ventricle into right and left sections

Displacement of the heart from the cervical region to the chest to establish optimal relationships with the lungs (heterotopia)

Reduction of the cardinal veins and Cuvier ducts, their transformation into hollow, jugular veins and coronary sinus.
The evolution of the excretory system.

The excretory system arose in animals in connection with the need to maintain the constancy of the internal environment by removing dissimilation products from the body. In unicellular animals and sponges, the function of excretion and osmoregulation is performed by contractile vakz "olis. In intestinal cavities, special excretory organs have not been identified. In more highly organized invertebrates, due to the complication of the internal structure and the formation of dense outer covers, complex and diverse excretory organs are formed. Despite the differences in their structure, the principle of excretion of products of dissimilation in all invertebrates is similar and is carried out due to two main processes: ultrafiltration and active transport of substances.During the ultrafiltration of a liquid, proteins and other large molecules do not pass through the semipermeable membrane of the excretory organs.Active transport occurs in two opposite directions : with the help of active secretion, substances are transferred from the internal environment of the animal to the lumen of the excretory organ, and with active reabsorption, their transport occurs in the opposite direction.

The kidneys of all classes of vertebrates also work on the principle of filtration - reabsorption and secretion. At the same time, 99% of the filtrate is reabsorbed and less than one percent is excreted in the form of urine. In an evolutionary sense, this method of isolating dissimilation products turned out to be the most beneficial, since as a result of ultrafiltration, any foreign and most of the toxic substances remain in the urine and are excreted from the body. The latter enables animals to expand and change their habitat and food sources without creating a special mechanism for the elimination of each new, possibly toxic substance that has entered the body with food.

functions of the excretory system.

1 - excretory - removal of dissimilation products and toxic substances;

2 - maintenance of water-salt homeostasis;

3- maintaining acid-base balance, glucose levels, ionic composition;

4- excretion of reproductive products (gametes);

5- participation in the regulation of blood pressure.

Evolutionary transformations in the excretory system of vertebrates.

1. Substitution - replacement of the pronephros by the primary, and in higher vertebrates by the secondary kidney;

2. Polymerization of homogeneous structures - an increase in the number of nephrons from 6 - 12 in the pronephros, up to several hundred in the primary and up to one million or more in the secondary kidney;

3. Strengthening the main function of the kidneys is manifested in a significant increase in the level of glomerular filtration and tubular reabsorption. This is achieved by a number of transformations:

a) an increase in the number of nephrons;

b) the formation of the renal corpuscle and the reduction of the infundibulum, which leads to the establishment of direct contact of the excretory tubules with the circulatory system and to the loss of communication with the coelom;

c) an increase in the size of the renal corpuscles and an increase in renal blood flow;

d) elongation and differentiation of convoluted tubules, obrazo-; loop of the nephron.

4. Separation of functions.

Formation of the oviduct from the paramesonephric canal and the vas deferens from the mesonephric cord.
Onto-phylogenetically determined malformations of the excretory and reproductive systems in humans.

1. Gartner's canal - the preservation of the mesonephric canal in women - the source of cysts and malignant changes. In 30% of girls, it obliterates

2. Various anomalies in the development of the uterus and vagina (double, saddle-shaped, bicornuate, divided, asymmetric uterus; double or septated vagina)

3. Cryptorchidism - undescended testicles. Non-closure of the inguinal canal - a predisposition to hernias

4. Non-separation of the cloaca (normally in the seventh week it is divided into the urogenital sinus and rectum) - various fistulas between the rectum and the genitourinary system - rectovesical fistula; rectovaginal fistula.

5. Pelvic position of the kidney.
Kidney development in human ontogeny

In human embryogenesis, all three types of vertebrate kidneys are laid in turn: the pronephric kidney functions from the third to the sixth week, the primary kidney - from the sixth to the eighth week of embryonic development. The nephrons of the secondary kidney are laid at 7-8 weeks and complete the formation by 32-36 weeks of intrauterine development. The final formation of the kidneys occurs in postnatal development. In the regulation of water-salt metabolism in the fetus, its kidneys, placenta and amnion participate. In this case, there is a constant circulation of water and osmotically active substances: the fetus swallows the amniotic fluid, part of which is absorbed in the gastrointestinal tract, enters the bed, is removed from there through the placenta or is filtered by the kidneys of the fetus. In newborns, the nephrons are functionally immature. They are characterized by:

a) low glomerular filtration rate;

b) reduced ability to concentrate urine;

c) limited ability to remove excess water;

5. Common forebrain ventricle

6. Non-closure of the posterior suture of the neural tube of the spinal cord

7. Absence of the corpus callosum

Endocrine system.

It arose on the basis of humoral regulation inherent in all living organisms from unicellular to humans. It is associated with the ability of cells to synthesize physiologically active substances that regulate processes in the cell itself and are released into the environment through which they act on other cells.

In unicellular organisms, active substances are released for interaction with other individuals. In multicellular - they perform the function intermediaries in intercellular interactions. In the beginning, their action was limited to the nearest cells, which is why they received the name tissue or local hormones. Some of them were neurosecrets, because they were synthesized

neurons and released into the environment by their axons (adrenaline, norepinephrine, dopamine), accumulating in synapses or spreading to nearby cells. Neurosecretion is characteristic of all multicellular organisms.

In connection with the complication and differentiation of multicellular organisms, it became necessary to distant regulators that would ensure the coordinated activities of all bodies. They became true hormones, substances of various chemical nature entering the blood, transported by it and acting as chemical regulators of cellular processes.

In annelids, they first form neurohemal organs - small depots of neurosecrets, surrounded by a network of dilated blood capillaries through which neurosecretions enter the blood.

In arthropods, in the area of ​​\u200b\u200bthe “brain”, a group of cells surrounded by a membrane is distinguished, specialized for neurosecretory function -(intercerebral gland) - gland of internal secretion. At the same time, other endocrine glands (sexual) appear - the function of which is controlled by the hormones of the intercerebral gland.

Thus, in the phylogenesis of hormonal regulation in invertebrates, there is a transition from intracellular secretion of active regulatory substances to endocrine glands that synthesize neurohormones - peptides or hormones of a different chemical nature.

In vertebrates, all levels of humoral regulation are found: cellular with the help of metabolites and cAMP, tissue with the help of local hormones (prostaglandins, serotonin, dopamine, adrenaline), organ and system-organ with the help of true hormones entering the blood and acting remotely.

In vertebrates, it forms endocrine system, unifying endocrine glands, in which it occupies a special place hypothalamus. Its neurons combine the ability to conduct nerve impulses and secrete neurohormones. It connects the nervous and endocrine systems. Thanks to the hypothalamus, the endocrine system is able to respond to external and internal signals. Therefore, the hypothalamus is neurosecretory body. (Except for the hypothalamus, the ability to neurosecretion retained the pineal gland, adrenal medulla, neurons of the autonomic nervous system). The hypothalamus forms single system With pituitary gland. Nerve impulses arriving at the hypothalamus activate secretion releasing - hormones(liberins and statins), each of which regulates the synthesis in the pituitary gland tropins, with the help of which the pituitary gland controls the activity of other endocrine glands, growth processes, etc. The neurohormones of the hypothalamus are deposited in the posterior lobe of the pituitary gland, which is essentially neurohemal organ, similar to those of invertebrates.

Many endocrine glands in vertebrates were formed by specializations cells of various tissues (thymus, gonads, pancreas, thyroid), the products of which - hormones - began to enter the blood,

The endocrine glands in vertebrates were formed from different rudiments, different ways. In the process of phylogenesis, individual secretory cells merged into groups (thyroid gland), metamerically located sections of secretory tissue united into a common gland (thymus, adrenal medulla and cortex), endocrine cells were included in another organ (ultimobranchial glands, pancreas), a change in function (epiphysis, thyroid gland), displacement of the place of laying (thyroid gland).

In the process of phylogenesis, new departments were formed and new hormones appeared (pituitary gland, adrenal glands),

Some glands were formed by combining two parts originating from different primordia (pituitary gland, adrenal glands).

Major evolutionary transformations in the endocrine

chordate system.

1. The transition from a diffuse endocrine system to a highly specialized regulatory system that combines the endocrine glands.

2. Strengthening of the main regulatory and integrating function, an increase in the number of secretory cells, the appearance of new sections and new hormones in the glands (posterior pituitary gland, mineralocorticoids appeared in terrestrial vertebrates)

3. Change of function (transition of some glands from external to internal secretion, from the ability to perceive light signals to the secretion of hormones)

4. Oligomerization - connection of several rudiments into a large glandular mass (thymus, adrenal medulla, pancreas)

5. Heterotopia - mixing of the organ site (thyroid gland, pituitary gland)

6. Improving communication with the nervous system, the formation of a single neuro-humoral regulation.

Onto-phylogenetic defects of the human endocrine system.

1. Underdevelopment and hypofunction of the posterior pituitary gland.

2. Ectopia of the adenohypophysis (a group of glandular cells under the mucous membrane of the roof of the mouth).

3. Persistence of Rathke's pocket (cyst of Rathke's pocket between the anterior and middle lobes of the pituitary gland)

4. Thyroid duct - a strand of cells with a cavity inside (a trace of thyroid heterotopia)

5. Ectopia of the thyroid gland and median cervical fistulas.

6. Median cysts of the neck, located in the direction of the thyroid anlages.

7. Cryptorchidism

8. Accessory lobules of the thyroid gland, individual cells synthesizing thyroxine on the ventral side of the pharynx.

9. Heterotopia of the pancreas (islets of glandular tissue in the wall of the small intestine or stomach).

One of the main properties of animal organisms - movement (locomotion) - is carried out due to the musculoskeletal system. The supporting formations of invertebrates are varied and can be of ecto-, entho-, and mesodermal origin. So, in intestinal cavities, the supporting function is performed by the mesoglea, locomotion by the epithelial-muscular cells of the ecto- and endoderm; the skeleton of coral polyps develops from the ectoderm. Most invertebrates have an external skeleton. In chordates, the skeleton is internal (ento- and mesodermal origin). We are the basis of their body

neck-chordal complex (myochord), consisting of a chord (axial elastic cord) and metameric muscles adjacent to it. The notochord is laid in the embryonic period of all chordates and performs a morphogenetic role - under the influence of the chordo-mesodermal rudiment, the neural tube, spine develop, and the somites differentiate.

In the process of progressive evolution of chordates, the following occurred: the replacement of the notochord by the vertebral column, consisting of vertebrae; the acquisition by the vertebrae of procoelity (anterior concavity) and plasticity (anterior and posterior surfaces of the vertebrae are flat); skull formation; loss of the metameric structure of the muscles and the appearance of specialized muscle groups; change in the location of the limbs and the type of their attachment. Adaptations to different habitat conditions led to the formation of diverse types of movement, which expanded the possibilities of obtaining food, escaping from enemies, searching for optimal habitats, and settling by chordates in almost all biotopes of land, water, and the lower layers of the atmosphere.

Functions of the musculoskeletal system.

1. Preservation of a certain body shape.

2. Protection of organs from influences.

3. Support for the entire body weight, lifting it above the ground.

4. Locomotion - the skeleton serves as a place of attachment of motor muscles, when they contract, parts of the skeleton work as a lever, providing various movements.

The main evolutionary transformations of the musculoskeletal system of vertebrates.

1. Replacement of the chord with the spinal column (substitution).

2. Change of cartilaginous skeleton to bone (substitution).

3. Differentiation of the skeleton.

4. Fusion of the bones of the skull (oligomerization).

5. Reduction in the volume of segmental muscles, change in the direction of bundles of muscle fibers, isolation of all more specialized muscle groups.

6. Formation on the basis of paired fins of lobe-finned fishes of terrestrial-type limbs.

7. Reduction in the volume of the dorsal and trunk muscles, an increase and a significant complication of the muscles of the limbs.

8. Expansion of the number of functions performed (abdominal muscles with a terrestrial lifestyle are involved in maintaining the walls of the abdominal cavity, in breathing).

9. An increase in the proximal and a decrease in the distal extremities.

10.Increased mobility of bone joints (function activation); a decrease in the number of bones in the wrist, a decrease in the number of phalanges of the fingers.

Features of the human musculoskeletal system

1. Vertical arrangement of the spinal column; the presence of bends in it.

2. An increase in the size of the vertebrae (from top to bottom).

3. Moving the foramen magnum closer to the middle of the base of the skull led to the disappearance of the occipital ridges, to which the muscles were attached to hold the head.

4. The development of the mastoid process of the temporal bone, to which the muscle is attached, holding the head in a vertical position.

5. Enlargement of the brain region of the skull and a decrease in the facial region.

6. Development of differentiated muscles of the fingers; opposition of the thumb.

7. Tilt of the pelvis at an angle of 60 ° due to the movement of the center of gravity of the body.

Ontophylogenetic malformations of the human skeleton.

1. Preservation of an excess amount of chordal material (may lead to the development of tumors - chordomas).

2. Reduction or increase in the number of vertebrae (per vertebra) in each section of the spine.

3. Cleft of the arch of the vertebrae and nonunion of the spinous processes of the vertebrae (leads to the formation of spinal hernias).

4. Cervical ribs at the last cervical vertebra.

5. Violation of the heterotopia of the belt upper limbs- congenital high standing of the shoulder blades.

6. Fusion of the cervical and upper thoracic vertebrae (sharp shortening of the neck).

7. Additional ribs at the first lumbar vertebra.

8. Tail appendage (tail persistence).

9. Syndactyly (fusion of fingers).

10. Polyphalangia (increase in the number of phalanges of the fingers).

11. Polydactyly (an increase in the number of fingers).



BU VO "Surgut State University»

Methodical development

Laboratory lesson No. 9 for I-year students.

Topic of the lesson: “Evolution of the integument of the body.

The evolution of the musculoskeletal system.

Completed by (a) student (ka) of the 1st year

medical institute

_____ groups

FULL NAME._________________________

_________________________

Surgut, 2015

Purpose of the lesson: To study the main stages of the evolution of body integuments in invertebrates and chordates. Identify the main directions of evolution of integuments in animals. To substantiate the possibility of the formation of ontophylogenetic malformations of integument in humans.

To study the main stages of development of the musculoskeletal system in invertebrates and vertebrates. Highlight the main evolutionary transformations of the musculoskeletal system. Note the differences in the structure of the human skeleton and the skeleton of mammals. Substantiate the possibility of the formation of human ontophylogenetic defects of the musculoskeletal system.

Questions for self-preparation of students:

1. Derivatives of what germ layers are integuments of invertebrates and chordates?

2. What is the role of integument in the life of the organism?

3. Which way was the evolution of invertebrate covers?

4. What are the functions of derivative covers in invertebrates?

6. What are the evolutionary transformations of integuments in vertebrates?

7. What is the origin of placoid scales, bony scales of fish, horny scales of reptiles, hair of mammals?

8. What ontophylogenetic malformations of the integument can be in humans and what are they caused by?

9. From what germ layers do the skeleton of invertebrates, the notochord and the skeleton of vertebrates develop?

10. In which animals does the notochord function throughout life, in which - only in the embryonic period?

11. What is the role of the musculoskeletal system?

12. What are the characteristic features of the musculoskeletal system in invertebrates?

13. What are the main evolutionary transformations of the musculoskeletal system in chordates?

14. Into what departments is the spine of fish, amphibians, reptiles, mammals, and humans differentiated? What is the number of vertebrae in each department?

15. Vertebrae of what departments have ribs in different classes of vertebrates? Who first developed a chest and what did it mean?

16. What are the main phylogenetic stages in the development of the brain skull in vertebrates?

17. What are the principles of evolutionary transformations of the brain skull?

18. What is the origin of the fins of fish, the shoulder and pelvic girdle of terrestrial vertebrates?

19. What are the structural features of the fins of lobe-finned fish? What is the origin of terrestrial-type limbs?

20. What are the progressive transformations of limbs and somatic muscles in vertebrates?

21. What is the similarity in the structure of the human skeleton and vertebrates?

22. What are the features of the human musculoskeletal system?

23. What explains the fact that the innervation of the shoulder girdle in mammals and humans is carried out by the cervical, and not the thoracic segments of the spinal cord?

24. What ontophylogenetic defects of the musculoskeletal system are found in humans and what causes them?

body integuments

The integuments of the body are in direct contact with external environment and perform a variety of functions. In invertebrates, the evolution of the integument occurred from ciliated epithelium (ciliary worms) to epithelium devoid of cilia (flukes, tapeworms, round worms, annelids). In many invertebrates, the epithelium is covered on the outside with a multi-layered cuticle (additional support and protection). In arthropods, the chitinized cuticle functions as an exoskeleton, with the appearance of which they have lost the ability to change the shape of the body. They developed multi-knee limbs, connected to the body with joints that provide complex movements. The evolution of the muscular component of the musculoskeletal system in invertebrates was carried out from the skin-muscular sac (worms) to specialized groups of striated muscles (arthropods).

In all chordates, the body cover differentiates into the epidermis and dermis, which are closely related to each other, but differ in origin: the epidermis develops from the ectoderm, the dermis from the dermatome of the mesoderm. The evolution of the epidermis took place in the direction from a single-layer columnar epithelium (non-cranial subtype) to a stratified squamous epithelium (Vertebrate subtype). In fish and amphibians, the epidermis is formed by living cells; The development of land by vertebrates led to the keratinization of the surface layers of the epidermis, and it became possible to prevent the uncontrolled loss of water through evaporation, which is important in conditions of permanent terrestrial existence. The transition from the inner part of the epidermis to the outer in amphibians and reptiles is gradual, and in mammals there is a border (brilliant layer) between the germ layer and the horny layer. Derivatives of the epidermis are a variety of specialized structures: scales, horns, hooves, claws, nails, hair (modifications of the stratum corneum), as well as numerous exocrine glands (mucous, poisonous, ceruminous, sebaceous, sweat, milky). The evolution of the glands took place in the direction of complication from unicellular to multicellular structured structures that deepened into the dermis.

The evolution of the dermis took place along the path of an increase in the fibrous component (collagen fibers), the development of vascular networks and nerve plexuses, and the formation of subcutaneous fat. It should be noted that the fibrous structure of the dermis is secondary (primary is the presence of bone formations in it - in bony fish, the dermis consists of thick bone scales). This is evidenced by paleontological data of successive stages of reduction of bony scales and transition to the modern structure of the dermis in amphibians and reptiles.

The integuments of mammals are constructed in the most complex manner due to the expansion of the number of functions performed. In the dermis, papillary and reticular layers are formed; dermal papillae provide closer contact between the epidermis and dermis, bring blood vessels closer to the epidermis (thermoregulation intensification). A new structural element of the epidermis is formed - the hairline. It differs in different animals, in different parts of the body, at different times of the year, in individuals of different ages. The diverse coloration of animals is of great adaptive importance: protection, warning, role in mating behavior, etc.

Mammals develop specialized derivatives of the sweat glands - the mammary glands, which gave the name to the class; representatives of the previous classes of vertebrates do not have any precursors of these glands.

The ontogeny of the integuments of mammals and humans reflects their evolution according to the type of archallaxis, which does not allow recapitulation of the ancestral state of a trait (for example, horny scales), otherwise the entire course of embryogenesis changes. Violation of the early embryogenesis of the integument of the body can lead to the formation of ontophylogenetic defects, which, however, do not affect the vital functions of the body.

Musculoskeletal system

The progressive evolution of animals is largely due to the peculiarities of the structure of the musculoskeletal system and the nature of motor activity. In most invertebrates, the skeleton is external, in the form of cuticular formations. The development of the musculoskeletal system in invertebrates occurred along the path of the appearance of a solid exoskeleton (chitinized cuticle), articulated articular limbs, and striated muscles. This brought arthropods on the path of wide adaptation and made it possible to master all habitats. Currently, this is the largest group of the animal world.

In chordates, an internal skeleton is formed. It is based on the musculo-chordal complex (myochord). The notochord is laid in the embryogenesis of all chordates and performs a morphogenetic role - under the influence of the myochord, the neural tube and spine develop, and the sclerotome differentiates into cartilage or bone. Throughout life, the notochord is the axial skeleton in non-cranial, cyclostomes, and ganoid fish. In most vertebrates, it is mixed with a cartilaginous or bony spine, consisting of vertebrae; this made it possible to increase the strength of the axial skeleton while maintaining its mobility.

In the process of evolution of vertebrates, differentiation of the spine into sections, the formation of a brain skull to protect the brain and sensory organs took place. The facial skull is a derivative of the visceral skeleton and supports the anterior part of the intestinal tube in vertebrate ancestors. In aquatic forms, paired limbs arise: pectoral and ventral fins, on the basis of which terrestrial-type limbs developed. The evolution of the limbs and their girdles was accompanied by a decrease in the number of bone elements, the replacement of fixed joints by movable joints, lengthening of the proximal and shortening of the distal sections. The structure of the limbs is adapted to the living conditions and the mode of movement. A change in the structure of the vertebrae from amphicoelous - biconcave (fish) to acelous - with flat end surfaces (mammals) increased the strength of the connection of the vertebrae while maintaining the mobility of the spinal column. In higher vertebrates, the chest is formed.

The change in habitat (landfall) led to a change in the method of attaching the limbs to the body: unlike amphibians and reptiles, in mammals, the limbs are directed downward from the body, which greatly facilitated movement and increased its efficiency. In amphibians, the connection between the shoulder girdle and the skull is lost, due to which the head and forelimbs are able to move independently of each other. In terrestrial forms, the cervical ribs shorten (amphibians) or disappear (reptiles, mammals) ( Attachment 1).

The development of the muscular system correlated with an increase in the support function, which was expressed in the replacement of metameric muscles with specialized muscle groups, in an increase in the relative mass of limb muscles, and in a decrease in the mass of dorsal and trunk muscles. In higher vertebrates, metamerism is preserved in the location of part of the muscles of the spinal column, abdominals, and intercostal muscles.

Adaptations to different conditions of terrestrial existence contributed to the formation of diverse types of movement, which expanded the possibilities of obtaining food, escaping from enemies, searching for optimal habitats and settling by vertebrates in almost all biotopes of land, water, and the lower layers of the atmosphere.

In human embryogenesis, the main phylogenetic stages of the development of the musculoskeletal system are recapitulated. Violation of the mechanism of changing the ancestral state of a trait to a species-specific one leads to the development of ontophylogenetic defects of the musculoskeletal system.

Task for students

Work 1. Functions of the integument of the body.

Learn the functions and write in your workbook.

1. Protection against mechanical, physical, chemical and biological (bacteria, viruses, fungi) influences.
2. Support.
3. Receptor (tactile, pain, temperature sensitivity).
4. Touch.
5. Gas exchange.
6. Regulation of water-salt metabolism.
7. Thermoregulation (heat exchange, thermal insulation).
8. Metabolic (formation of subcutaneous fat, vitamin D, milk).
9. Excretory.
10. Adaptive (adaptive coloration; variability of hairline; variety of appendages; secretion of glands determines behavioral responses).

Work 2. Comparative characteristics of body integument in various types of invertebrates.

Using the materials of textbooks and the proposed table. 1, study the features of the structure of integuments in different types of invertebrates.

Table 1

Work 3. Evolutionary transformations of integument in chordates.

Study the transformations and write in your workbook.

1. Strengthening the main - protective function due to:

a) formation of a multilayered epidermis;

b) keratinization of the upper layers of the epidermis;

c) formation of specialized structures (scales, claws, nails);

d) adaptive coloration;

e) proliferation of connective tissue in the dermis.

2. Strengthening the function of thermoregulation due to:

a) abundant circulatory network of the dermis;

b) rapid change in the diameter of arterial vessels.

3. Expansion of the number of functions performed:

a) participation in heat exchange;

b) heat-insulating;

c) water-salt metabolism;

d) receptor;

e) signal;

e) metabolic.

4. Function change:

a) division of the epidermis into two layers: growth and horny;

b) the formation of vertebrate teeth from the placoid scales of cartilaginous fishes;

c) a special type of hair - vibrissae perform the function of touch.

5. Formation of new structural elements of the skin in mammals - hairline, subcutaneous adipose tissue, glands of a new type: sebaceous, sweat, milk .

Work 4. Comparative characteristics of the integument of the body in animals of the Chordata type.

Using the following characteristics of the epidermis and dermis, conduct a comparative analysis of the structure of the integument of non-cranial and various classes of vertebrates. Arrange your work in the form of a table. 2.

Lesson number 5.

Topic:

Class: 7 B

Goals:

To study the features of the musculoskeletal system of mammals.

To study the complication of the musculoskeletal system in the course of evolution.

Tasks:

educational:

To study the structure and functions of the musculoskeletal system of mammals.

To study the structure and functions of the musculoskeletal system during evolution.

Find out the features of complication in representatives of the musculoskeletal system of different taxa.

developing:

Formation of the ability to establish cause-and-effect relationships.

Developing the ability to work with a book and spreadsheets.

educational:

To generalize the complex of knowledge about the evolution of the musculoskeletal system.

Lesson type: explanation of new material.

Method: illustrative.

The form: group.

Must know after the lesson:

The structure and functions of the musculoskeletal system, ranging from unicellular to chordates.

Features of the complication of the structure of the musculoskeletal system in representatives of different taxa.

During the classes:

Organizational start:

Teacher: Hello guys, sit down! Please open your notebooks and write down the topic of our lesson: "The evolution of the musculoskeletal system."

Learning new material:

Teacher: During a long evolutionary path, animals mastered new territories, types of food, constantly adapted to the conditions environment. In order to survive, animals had to look for food, better hide or defend themselves from enemies, and move faster. Changing along with the body, the musculoskeletal system had to provide all these evolutionary changes.

What do you think are the most remarkable animals?

Student: The most primitive are rhizopods, which do not have a support system, move slowly, flowing with the help of pseudopods, while constantly changing shape.

Teacher: For the first time, the speed of movement changes in flagellates and ciliates. Guys, you have to remember which animals formed the outer skeleton?

Student: The external skeleton was formed in crustaceans, arachnids and insects. It is represented by a chitinous cuticle, a chitinous shell that is impregnated with lime. Muscles are attached to this cover, which allows these animals to move quite quickly. Currently, arthropods are the most common type of animal.

Teacher: And what are the disadvantages of such a skeleton?

Student: It should be noted that the external skeleton also has its drawbacks: it does not grow with the animal, and during growth it is necessary for the animal to molt several times, while the animal becomes completely defenseless and becomes easy prey for enemies.

Teacher: Guys, let's write down in the table the information that we have spoken to you:

Teacher: Guys, along with the outer one, there is an inner skeleton. Please tell me what are the advantages of the internal skeleton?

Student: The internal skeleton is devoid of such shortcomings - it grows with the animal and allows even more specialization of individual muscles and their groups, while achieving record speeds of body movement. All chordates have an internal skeleton.

Teacher: The skeleton of most vertebrates is formed by bones, cartilage, tendons. The bones of the skeleton can be connected either motionless - growing together, or movably - with the help of a joint. Muscles are attached to bones in such a way that the bones are set in motion. The skeleton has the following parts:

Axial skeleton;

limb skeleton;

Skull skeleton.

Fish, amphibians, reptiles, birds and mammals have a well-developed spine, which consists of vertebrae. Each vertebra consists of a body, upper and lower arches. The ends grow together and form a canal in which the spinal cord is located. The notochord persists throughout life in beluga and sturgeon.

Guys, what parts does the backbone of fish consist of?

Student: The spine in fish consists of the trunk and tail sections.

The spine is formed by biconcave vertebrae, between which remains of the notochord are preserved. The vertebrae of the trunk region have an upper arch and an upper process, ribs are attached to them from below. In the caudal region, the vertebrae have superior, inferior arches, and spinous processes.

The skull consists of the brain and facial sections. The facial section is represented by the jaws, the hyoid arch and the gill apparatus.

The skeleton of the fins is represented by bone rays, the girdle of the forelimbs is connected to the skull. In addition to paired fins - pectoral and ventral, there are unpaired fins - dorsal and anal.

Teacher: Guys, let's write down what we just said to you.

Systematic group	Dep. Skeleton	Departments of the skeleton	The bones that make up the skeleton
Superclass: Pisces		brain department	Consists of many bones fused immobile.
		facial department	Represented by jaws, hyoid arch and gill apparatus.
	Spine	trunk department tail section
	Skeleton free. final	Unpaired fins (dorsal, caudal, anal)	Represented by the radius bones. In the nutria of the body there are supporting bones.
		Paired fins (pectoral and ventral)	Represented by bone rays.
	Limb belts	Forelimb belt	The girdle of the forelimbs is connected to the skull. Both pectoral and ventral fins are attached to both belts by means of small bones.
		Rear limb belt

What do you think, what are the main features of the skeleton in amphibians?

Student: In amphibians, in connection with the aquatic-terrestrial lifestyle, the axial skeleton has become more complex and is represented by the cervical region, consisting of one vertebra, the trunk - from seven vertebrae with ribs that end freely. The sacral region consists of one vertebra, the pelvic bones are attached to it. Tailed amphibians have several vertebrae in the tail region. The skull is movably articulated with the cervical vertebrae.

Musculature loses its metameric structure and is represented by many individual muscles.

The skeleton of a frog, like that of all vertebrates, is divided into four sections: the axial skeleton, the skeleton of the skull, the skeleton of the limbs and the skeleton of the limb belts.

The axial skeleton is represented by the spine, which, in addition to trunk and tail departments characteristic of fish appeared cervical and sacral departments.

The skull of a frog is movably articulated with a single cervical vertebra, which ensures the movement of the head in a vertical plane (the head cannot move in a horizontal plane).

The number of vertebrae in the trunk of a frog is seven. The frog does not have ribs, but in tailed amphibians, short upper ribs develop on the vertebrae of the trunk, and legless ones have real ribs.

The sacral region includes one vertebra, bearing long transverse processes, to which the iliac bones of the pelvis are attached.

The tail section of the frog ends with a tail bone - urostyle- a bone, which is several vertebrae merged in the process of embryonic development.

The forelimbs are four-fingered (the first finger is reduced), they consist of three sections: shoulder- brachial bone, forearm- fused radius and ulna and brush, represented by bones wrist, metacarpus and phalanges of fingers.

The hind limbs consist of three sections: hips, shins and feet. The thigh consists of the femur, the lower leg is made of the fused tibia and tibia, the foot is made of bones tarsus, metatarsus and phalanges of fingers.

Shoulder girdle frog encircles the body with a wide semicircle and is fixed in the muscles. It is represented by several paired bones: the shoulder blades, ending in wide suprascapular cartilages, crow bones and clavicles, as well as one unpaired bone - the sternum.

Pelvic girdle consists of three paired bones, fused due to heavy loads: iliac, pubic and ischial. With the help of the ilium, the pelvic girdle is attached to the transverse processes of the sacral vertebrae.

Teacher: Guys, please fill in your plate with the help.

Systematic group	Dep. Skeleton	Departments of the skeleton	The bones that make up the skeleton
Class: Amphibians		brain department Facial department	The number of bones is less, as there are no gill covers.
	Spine	Cervical department (1 line) Trunk department (7 stars) Sacral department (1 line) tail section	Formed by vertebrae of different structures. (False) ribs are attached to the trunk vertebrae.
	Skeleton free. final	Forelimbs
		Hind limbs
	Limb belts	Forelimb belt
		Rear limb belt

And now, let's see what features the musculoskeletal system of reptiles has. I am listening to your answers.

Students: The spine of reptiles has five sections: cervical; chest; lumbar; sacral; tail.

In the cervical region, the vertebrae are movably connected. They provide the mobility of the head - a necessary condition for existence on earth. The thoracic and lumbar vertebrae bear the ribs. In some, the ribs connect to the sternum to form the ribcage, providing protection to the organs and better airflow to the lungs. The sacral region consists of two vertebrae. The tail section is well developed. In snakes, all parts of the spine bear ribs, except for the tail. It should be noted that the ribs end freely, which allows them to swallow large food.

Teacher: With the help of a textbook, please write down the listed features on a tablet.

Systematic group	Dep. Skeleton	Departments of the skeleton	The bones that make up the skeleton
Class: Reptiles		No difference	No difference
	Spine	Cervical department (more than 1 star) Thoracic Lumbar region Sacral region (2 stars) tail section	Formed by vertebrae of different structures. Ribs are attached to the trunk vertebrae.
	Skeleton free. final	Forelimbs	Shoulder (humerus), forearm (radius and ulna), hand (wrist, metacarpus and 4th phalanges of fingers).
		Hind limbs (There are no differences from amphibians)	Femur (femur), tibia (tibia and fibula), foot (tarsus, metatarsus and 5 phalanges of fingers)
	Limb belts	Forelimb belt (There are no differences from amphibians)	The shoulder blades to which the bones of the forelimbs are attached.
		Rear limb belt (There are no differences from amphibians)	Consists of 3 pairs of fused bones (ilium, pubis and ischium)

Let's see, what is the complication of the musculoskeletal system in birds?

Students: The spine of birds has five sections, like that of reptiles. In the cervical region, there are from 9 to 25 vertebrae connected movably. The fused thoracic vertebrae and ribs connected to the sternum form the chest. The sternum of many birds has a special protrusion - the keel. Muscles that are actively working during flight are attached to the keel. The final thoracic, lumbar, sacral and first caudal vertebrae have fused, creating a powerful sacrum that serves to support the hind limbs, which increases the strength of the skeleton - fitness for flight. The bones of birds are light, many of them are hollow inside.

Despite some differences, the skeleton performs similar functions:

body support;

protection of internal organs;

movement of the body in space.

But at the same time, the skeleton is light and strong due to the thinness of the bones and their pneumaticity.

brain department the skull is large, articulated with the spine by one condyle, as in reptiles.

AT facial region huge eye sockets and elongated jaws, modified into a beak.

The skeleton of the body consists of spine and chest. The spine includes five sections: cervical, thoracic, lumbar, sacral and caudal. Saddle joints are characteristic of the cervical vertebrae, which provides greater mobility of the neck (in owls, the angle of rotation of the head reaches 270 degrees).

The posterior thoracic, lumbar, 2 sacral and anterior caudal fused into a complex sacrum.

The middle tails remained free, the latter merged, forming the coccygeal bone.

The chest is formed by ribs, consisting of two bones connected by a joint at an angle to each other. Due to this structure of the ribs, the sternum can approach and move away in relation to the spine during respiratory movements.

On the upper part of the ribs are flat outgrowths that overlap the back ribs, which increases the strength of the chest.

Most birds have a keel on the sternum, to which the pectoral muscles are attached, which set the wings in motion.

The forelimbs consist of the humerus, the forearm is represented by the ulna and radius, the hand consists of fused bones of the wrist and metacarpus, forming a common bone - buckle, and three fingers: second, third and fourth.

Basin of birds open, ischial and pubic bones do not fuse, this is due to the laying of large eggs.

Due to the fact that the main load during walking falls on the hind limbs, the pelvic bones are massive, firmly fused with the posterior thoracic, lumbar, sacral vertebrae, as well as with part of the caudal vertebrae, forming a complex sacrum.

Teacher: Well done guys, let's fill in the remaining columns of the table using your textbook.

Systematic group	Dep. Skeleton	Departments of the skeleton	The bones that make up the skeleton
Class: Birds		Facial department brain department	Formed by fused bones. There are huge eye sockets and a horny beak without teeth.
	Spine	Cervical (from 9 to 25 vertebrae) Thoracic Lumbar sacral department tail section	Formed by vertebrae of different structures. Ribs are attached to the trunk vertebrae, which fuse with the sternum, and it forms a keel, to which the muscles are attached. In birds, the posterior thoracic, lumbar, 2 sacral and anterior caudal fused into a complex sacrum.
	Skeleton free. final	Forelimbs
		Hind limbs
	Limb belts	Forelimb belt	The shoulder blades and clavicles are fused and form a fork.
		Rear limb belt

Teacher: Now guys, let's look at the skeleton of mammals and describe it in the same way:

Systematic group	Dep. Skeleton	Departments of the skeleton	The bones that make up the skeleton
Class: Birds		Facial department brain department	There is a movable mandibular bone. Formed by fused bones.
	Spine	Cervical department (7 stars) Thoracic (From 9 to 24 stars) Lumbar (from 2 to 9 stars) Sacral department (3–4 stars) tail section	Formed by vertebrae of different structures. Ribs are attached to the trunk vertebrae, which fuse with the sternum, below there are false ribs. The sacral vertebrae fuse together to form the sacrum.
	Skeleton free. final	Forelimbs (Like reptiles)	The shoulder (humerus), forearm (radius and ulna), the hand is modified. There is a reduction of bones and 1 phalanx remains.
		Hind limbs (Like reptiles)	Femur (thigh bone), lower leg (tibia), a tarsus appears (fused bones of the tarsus and spit) and from 1 to 4 phalanxes of the fingers.
	Limb belts	Forelimb belt (Like reptiles)	There are shoulder blades and collarbones.
		Rear limb belt (Like reptiles)	The pelvic bones are fused and adhered to the lumbosacral spine.

Teacher: Well done, you worked well today, but we didn’t understand the last question, so in what direction did the evolution of the musculoskeletal system in birds go?

Students: Despite some differences, the skeleton performs similar functions: supporting the body; protection of internal organs; movement of the body in space. But at the same time, the complication of the skeleton led to an increase in the speed of movement in specific conditions for them. At the same time, some lightening of the bones contributed to this.

The complication followed the path of specialization of the structure and functions of the vertebrae.

Teacher: Well done, well, with the help of this table, we clearly looked through the line of evolution of the musculoskeletal system of animals.

Tell me, who first has a chest? (reptiles).

Who gets real limbs for the first time? (amphibians).

What are the adaptations of birds for flight?

The date: _______________20___ Class: __________

FULL NAME. ______________________________________________________________

Topic of practical work: The evolution of the musculoskeletal system in animals.

Determine which class the animal belongs to, which is characterized by the presented skeleton:

ExerciseI: Fill in the rectangles.

Name the parts of the animal's skeleton:

Name the parts of the skull:

Name the sections of the spine:

Name the bones forming the forelimbs (features, if any):

Name the bones forming the hind limbs (features, if any):

ExerciseII: Name the features of complication in the structure of this skeleton in comparison with another class.

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Exercise III: Name the features of adaptation to the way of life of animals belonging to this class.

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Development of the musculoskeletal system

The human skeleton and muscles change throughout life. In childhood, adolescence they grow and develop rapidly. The growth and ossification of the skeleton is completed by the age of 25. Bones grow in length up to 23-25 ​​years, and in thickness up to 30-35 years. The normal development of the musculoskeletal system depends on good nutrition, the presence of vitamins and minerals in food. mineral salts. The development of the skeleton is also affected by human motor activity. In people who are engaged in physical labor, sports, protrusions and tubercles form on the bones at the points of muscle attachment. This increases the contact surface of the muscle tendon with the bone, which contributes to the strength of the attachment. In addition, the periosteum is more abundantly supplied with blood, the bones grow faster. They are stronger and more durable.

The value of motor activity

Without movement it is impossible to imagine the life and work of man. Movement is necessary for its normal physical and mental development.

In our time, various machines and devices have taken on a significant part of the hard physical labor. This led to the fact that the person began to move less, his muscle load decreased.

obesity of the heart. Fat inclusions in muscle tissue (shown as numbers 1 and 2)

Lack of movement, i.e. hypodynamia (literally: decrease in strength), adversely affects human health. The work of the heart and lungs is disrupted, resistance to diseases decreases, and obesity. To maintain motor activity, a person must constantly engage in physical labor, physical education, and sports.

The Importance of Muscle Training

When working, the muscles are better supplied with blood. It brings more nutrients and oxygen to muscle cells.

Metabolic processes are constantly going on in the body. Part of the substances absorbed in the intestine goes to the construction of cell and tissue elements, to the synthesis of enzymes. The other part breaks down and oxidizes with the release of energy. These processes are closely related. The stronger the processes of decay and oxidation go, the more intensively new substances are created.

If there is a discrepancy between the intake of nutrients and energy expenditure, the excess of absorbed substances goes to the formation of fat. It is deposited not only under the skin, but also in the connective tissue, which often replaces specialized tissues (muscle, liver, etc.).

Consider what happens during intense muscular work. Intensive biological oxidation of organic substances leads to the formation of a large number of ATP molecules that are involved in the work of muscles. Muscular work occurs due to the breakdown of ATP molecules with the release of energy. After its completion, usually a significant supply of unused ATP molecules remains in the muscle fibers. Due to these molecules, the lost structures are being restored, and there are more of them than there were at the beginning of the work. This phenomenon is called training effect . It occurs after intense muscular work, subject to sufficient rest and good nutrition. But everything has its limit. If the work is too intense, and the rest after it is not enough, then there will be no restoration of the destroyed and no synthesis of the new.

Therefore, the training effect will not always appear. Too little work will not cause such a breakdown of substances that could accumulate many ATP molecules and stimulate the synthesis of new structures, and too hard work can lead to the predominance of decay over synthesis and further exhaustion of the body. The training effect is given only by the load at which the synthesis of proteins overtakes their decay. That is why for a successful workout, the effort expended must be sufficient, but not excessive. Other important rule consists in the fact that after work a mandatory rest is necessary, allowing you to restore the lost and acquire a new one.

Systematic exercise contributes to the growth and development of muscles. A person becomes physically stronger, more resilient.

Now medicine knows substances that can dramatically increase nerve and muscle strength for a short time, as well as drugs that stimulate the synthesis of muscle proteins after exercise. The first group of drugs was named doping. (For the first time, doping began to be given to horses participating in races. They really showed great agility, but after the races they never restored their previous form, most often they were shot.) In sports, the use of these substances is strictly prohibited. An athlete who has taken doping has an advantage over those who have not taken it, and his results may turn out to be better not due to the perfection of technology, skill, labor, but due to taking the drug, moreover, doping has a very harmful effect on the body. A temporary increase in working capacity may be followed by a complete disability.

Substances of the second type are used in medicine, for example, when restoring muscle activity after the plaster cast, applied after a bone fracture, has been removed. In sports, these substances are of limited use.

How to properly distribute physical activity? Is it necessary to perform strength exercises barely awake? It turns out not. Target morning exercises only to move from sleep to the state of wakefulness, to increase blood circulation and respiration, to increase efficiency. Typically, charging includes five to ten exercises for different muscle groups. Charging begins with sipping, which helps to warm up the muscles, joints and ligaments. Then exercises are performed for the shoulder girdle, arms, torso, pelvic girdle and legs. Charging ends with running in place, walking and respiratory movements that normalize blood circulation.

The complex of physical exercises usually includes static and dynamic exercises. Static exercises include such exercises as "swallow", "poses of yogis"; to dynamic - all exercises that include certain movements. Static exercises develop strength, endurance, the ability to work with a lack of oxygen, but they cannot develop speed, accuracy and purposefulness of movements. This is achieved through dynamic exercises. Thus, static and dynamic exercises complement each other and are used in the right proportion.

The same set of exercises ceases to have an effect on the human body if it becomes habitual. Therefore, once a week, a set of exercises is usually updated.

The main task of physical education lessons at school is to teach the correct economical movements when walking, running, jumping, skiing and skating, working on sports equipment. But it is not often possible to get such a load that would give a training effect in physical education classes. Therefore, sports are essential. It is of great importance for every person right choice sport. In this case, one must proceed from one's anatomical and physiological prerequisites, abilities, age, and state of health.

By developing muscles, we train and nervous system. Our movements become more precise, faster and more economical. Remember how awkward your first moves on skates, bikes were and how they became when you learned to skate well. Physical exercises develop the chest, respiratory muscles, strengthen the heart, improve the functioning of the digestive system.

Swimming is good in summer. Swimming works all muscle groups. Swimming is a great way to massage the body and harden the body. It makes a person resistant to colds. Be sure to go skiing in winter. During the ski run, the muscles of the legs, arms, back work, the circulatory, respiratory and nervous systems are strengthened.

In order to become strong, dexterous, hardy and efficient, it is necessary to regularly engage in physical labor, physical education and sports. Training increases muscle strength, improves coordination and automation of muscle actions. Training has a beneficial effect not only on the muscles themselves, but also on the state of the skeleton, on the development of the whole organism. Strengthened muscular work contributes to the training of the respiratory and cardiovascular systems, the development of the heart muscle and chest muscles, improves mood, creates a feeling of cheerfulness and ultimately leads to an increase in the vital activity of the whole organism.

Useful for muscle training and varied physical work: work in the garden and garden, cleaning the classroom and apartment.

The skeleton and muscles change throughout a person's life. They improve with training and degrade with physical inactivity. An increase in muscle strength occurs with loads close to the limit, adequate nutrition and good rest.