One of the main properties of animal organisms - movement (locomotion) - is carried out due to the musculoskeletal system. The supporting structures of invertebrates are diverse and can be of ecto-, ento- and mesodermal origin. Thus, in coelenterates, the support function is performed by the mesoglea, while locomotion is performed 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 (en-to- and mesodermal origin). The basis of their body is our
cervicochordal complex (myochord), consisting of a notochord (axial elastic cord) and metameric muscles adjacent to it. The notochord is formed in the embryonic period of all chordate animals and plays a morphogenetic role - under the influence of the chordomesodermal rudiment, the neural tube and spine develop, and somites differentiate.
In the process of progressive evolution of chordates, the following occurred: replacement of the notochord with a vertebral column consisting of vertebrae; acquisition by the vertebrae of integrity (anteroconcavity) and plasticity (the anterior and posterior surfaces of the vertebrae are flat); formation of the skull; loss of metameric muscle structure and the appearance of specialized muscle groups; change in the location of the limbs and the type of their attachment. Adaptations to different living conditions led to the formation of diverse types of movement, which expanded the possibilities of obtaining food, escaping from enemies, searching for optimal habitat zones, and the settlement of chordates in almost all biotopes of land, water, and the lower layers of the atmosphere.
Functions of the musculoskeletal system.
1. Maintaining a certain body shape.
2. Protection of organs from influences.
3. Support for the entire body weight, raising it above the ground.
4. Locomotion - the skeleton serves as a place of attachment for motor muscles; when they contract, parts of the skeleton work like a lever, providing various movements.
Basic evolutionary transformations of the musculoskeletal system of vertebrates.
1. Replacement of the notochord with the spinal column (substitution).
2. Replacement of the cartilaginous skeleton with a bone one (substitution).
3. Skeletal differentiation.
4. Fusion of the skull bones (oligomerization).
5. Reducing the volume of segmental muscles, changing the direction of muscle fiber bundles, separating an increasing number of specialized muscle groups.
6. Formation of land-type limbs based on the paired fins of lobe-finned fish.
7. Reduction in the volume of the dorsal and trunk muscles, increase and significant complication of the muscles of the limbs.
8. Expanding the number of functions performed (the abdominal muscles, during a terrestrial lifestyle, are involved in maintaining the walls of the abdominal cavity and in breathing).
9. Increase in proximal and decrease in distal parts of the limbs.
10.Increasing the mobility of bone joints (function activation); reduction in the number of bones in the wrist, reduction in the number of phalanges of the fingers.
Features of the human musculoskeletal system
1. Vertical position of the spinal column; the presence of bends in it.
2. 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 nuchal ridges, to which the muscles were attached to hold the head.
4. Development of the mastoid process of the temporal bone, to which the muscle that holds the head in an upright position is attached.
5. Enlargement of the cerebral part of the skull and reduction of the facial part.
6. Development of differentiated muscles of the fingers; opposable thumb.
7. Pelvic tilt at an angle of 60° due to the movement of the body’s center of gravity.
Onto-phylogenetic malformations of the human skeleton.
1. Preservation of an excess amount of chordal material (can lead to the development of tumors - chordomas).
2. Decrease or increase in the number of vertebrae (by one vertebra) in each part of the spine.
3. Cleft vertebral arch and non-fusion of the spinous processes of the vertebrae (leads to the formation of spina bifida).
4. Cervical ribs at the last cervical vertebra.
5. Violation of heterotopia of the upper limb girdle - congenital high position of the shoulder blades.
6. Fusion of the cervical and upper thoracic vertebrae (sharp shortening of the neck).
7. Accessory ribs at the first lumbar vertebra.
8. Caudal appendage (persistence of the tail).
9. Syndactyly (fusion of fingers).
10.Polyphalange (increase in the number of phalanges of the fingers).
11.Polydactyly (increase in the number of fingers).
BU HE "Surgut State University"
Methodological development
Laboratory lesson No. 9 for first-year students.
Topic of the lesson: “Evolution of the integument of the body.
Evolution of the musculoskeletal system."
Completed by a first year student
Medical Institute
_____ groups
FULL NAME._________________________
_________________________
Surgut, 2015
Purpose of the lesson: Study the main stages of the evolution of body integument in invertebrates and chordates. Identify the main directions of evolution of integument in animals. To substantiate the possibility of the formation of ontophylogenetic malformations of the integument in humans.
Study the main stages of development of the musculoskeletal system in invertebrates and vertebrates. Identify the main evolutionary transformations of the musculoskeletal system. Note the differences in the structure of the human skeleton and the skeleton of mammals. To substantiate the possibility of developing ontophylogenetic defects of the musculoskeletal system in humans.
Questions for self-preparation of students:
1. What germ layers are the derivatives of the integuments of invertebrates and chordates?
2. What is the role of the integument in the life of the body?
3. What path did the evolution of invertebrate integuments take?
4. What are the functions of derivative integuments in invertebrates?
6. What are the evolutionary transformations of integument in vertebrates?
7. What is the origin of placoid scales, bone scales of fish, horny scales of reptiles, and hair of mammals?
8. What ontophylogenetic malformations of the integument can a person have and what causes them?
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 animals 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. What sections is the spine of fish, amphibians, reptiles, mammals, and humans differentiated into? What is the number of vertebrae in each section?
15. Which vertebrae have ribs in different classes of vertebrates? Who first developed a chest and what significance did it have?
16. What are the main phylogenetic stages of 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 girdles of terrestrial vertebrates?
19. What are the structural features of the fins of lobe-finned fish? What is the origin of terrestrial limbs?
20. What are the progressive transformations of the limbs and somatic muscles in vertebrates?
21. What are the similarities between the skeletal structure of humans 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 occur in humans and what causes them?
Coverings of the body
The integument of the body is in direct contact with the external environment and performs various functions. In invertebrate animals, the evolution of integument occurred from ciliated epithelium (ciliated worms) to epithelium devoid of cilia (flukes, tapeworms, roundworms, annelids). In many invertebrates, the epithelium is covered on the outside with a multilayer cuticle (additional support and protection). In arthropods, the chitinized cuticle serves as an exoskeleton, with the advent of which they lost the ability to change body shape. They developed multi-legged limbs connected to the body with joints that allow complex movements. The evolution of the muscular component of the musculoskeletal system in invertebrates was carried out from the skin-muscle sac (worms) to specialized groups of striated muscles (arthropods).
In all chordates, the body cover is differentiated into epidermis and dermis, which are closely related to each other, but different in origin: the epidermis develops from the ectoderm, the dermis from the dermatome of the mesoderm. The evolution of the epidermis occurred in the direction from a single-layer cylindrical epithelium (subtype Cranial) to a multilayered squamous epithelium (subtype Vertebrates). 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, which created the opportunity to prevent uncontrolled loss of water through evaporation, which is important in conditions of constant terrestrial existence. The transition from the inner to the outer part of the epidermis in amphibians and reptiles is gradual, and in mammals there is a border between the germinal layer and the stratum corneum (stratum pellucida). 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, lacteal). The evolution of glands occurred in the direction of complication from unicellular to multicellular shaped structures, which went deeper into the dermis.
The evolution of the dermis took place along the path of increasing the fibrous component (collagen fibers), developing vascular networks and nerve plexuses, and forming 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 bone scales and the transition to the modern structure of the dermis in amphibians and reptiles.
The integument of mammals is constructed in the most complex manner due to the expansion of the number of functions performed. The papillary and reticular layers form in the dermis; dermal papillae provide closer contact between the epidermis and dermis, bringing blood vessels closer to the epidermis (intensification of thermoregulation). A new structural element of the epidermis is formed - hair. It varies in different animals, in different parts of the body, at different times of the year, in individuals of different ages. The varied colors of animals have great adaptive significance: protection, warning, role in mating behavior, etc.
Mammals develop specialized derivatives of sweat glands - mammary glands, which give the class its name; Representatives of previous classes of vertebrates do not have any predecessors of these glands.
The ontogeny of the integument of mammals and humans reflects their evolution according to the type of archallaxis, which does not allow the recapitulation of the ancestral state of a character (for example, horny scales), otherwise the entire course of embryogenesis changes. Disruption of early embryogenesis of the body integument 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 determined by the structural features of the musculoskeletal system and the nature of motor activity. Most invertebrates have an external skeleton, in the form of cuticular formations. The development of the musculoskeletal system in invertebrates occurred along the path of the appearance of a hard exoskeleton (chitinized cuticle), articulated articular limbs and striated muscles. This put arthropods on the path of widespread adaptation and allowed them to master all habitats. Currently, this is the largest group of the animal world.
In chordates, an internal skeleton is formed. Its basis is the muscular-chordal complex (myochord). The notochord is formed in the embryogenesis of all chordates and plays 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 skullless, cyclostome 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.
During the evolution of vertebrates, the spine differentiated into sections and the formation of the brain skull to protect the brain and sensory organs. The facial skull is a derivative of the visceral skeleton and supports the anterior part of the intestinal tube in the ancestors of vertebrates. In aquatic forms, paired limbs arise: pectoral and ventral fins, on the basis of which terrestrial limbs developed. The evolution of the limbs and their girdles was accompanied by a decrease in the number of bone elements, replacement of fixed joints with movable joints, lengthening of the proximal and shortening of the distal sections. The structure of the limbs is adapted to the living conditions and method of movement. The change in the structure of the vertebrae from amphicoelous - biconcave (fish) to acoelous - 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 forms.
A change in habitat (exit to land) led to a change in the way the limbs are attached to the body: unlike amphibians and reptiles, in mammals the limbs from the body are directed downward, 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) ( Annex 1).
The development of the muscular system correlated with an increase in support function, which was expressed in the replacement of metameric muscles with specialized muscle groups, in an increase in the relative mass of the muscles of the limbs and in a decrease in the mass of the dorsal and trunk muscles. In higher vertebrates, metamerism is preserved in the arrangement of part of the muscles of the spinal column, abdominal muscles 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 habitat zones, and populating almost all biotopes of land, water, and the lower layers of the atmosphere with vertebrates.
In human embryogenesis, recapitulation of the main phylogenetic stages of the formation of the musculoskeletal system occurs. Violation of the mechanism for changing the ancestral state of a trait to a species-specific one leads to the development of ontophylogenetic defects of the musculoskeletal system.
Assignment for students
Work 1. Functions of the integument of the body.
Study the functions and write them down in your workbook.
- Protection from mechanical, physical, chemical and biological (bacteria, viruses, fungi) influences.
- Support.
- Receptor (tactile, pain, temperature sensitivity).
- Touch.
- Gas exchange.
- Regulation of water-salt metabolism.
- Thermoregulation (heat exchange, thermal insulation).
- Metabolic (formation of subcutaneous fat, vitamin D, milk).
- Excretory.
- Adaptive (adaptive coloration; variability of hair cover; variety of appendages; secretion of glands determines behavioral reactions).
Work 2. Comparative characteristics of body integument in various types of invertebrate animals.
Using materials from textbooks and the proposed table. 1, study the structural features of the integument of different types of invertebrate animals.
Table 1
Work 3. Evolutionary transformations of integument in chordates.
Study the transformations and write them down in your workbook.
1. Strengthening the main protective function due to:
a) formation of a multilayer epidermis;
b) keratinization of the upper layers of the epidermis;
c) formation of specialized structures (scales, claws, nails);
d) adaptive coloring;
e) proliferation of connective tissue in the dermis.
2. Strengthening the function of thermoregulation due to:
a) an abundant blood network of the dermis;
b) rapid changes in the diameter of arterial vessels.
3. Expanding the number of functions performed:
a) participation in heat exchange;
b) thermal insulation;
c) water-salt metabolism;
d) receptor;
e) signal;
e) metabolic.
4. Change of functions:
a) division of the epidermis into two layers: germinal and horny;
b) the formation of vertebrate teeth from placoid scales of cartilaginous fish;
c) a special type of hair - vibrissae perform the function of touch.
5. Formation of new structural elements of the skin in mammals - hair, subcutaneous fatty tissue, new type of glands: sebaceous, sweat, milk .
Work 4. Comparative characteristics of body integument in animals of the Chordata type.
Using the characteristics of the epidermis and dermis given below, conduct a comparative analysis of the structure of the integument of skullless and various classes of vertebrates. Present your work in the form of a table. 2.
7-B CLASS
Lesson type
Target
Tasks:
Educational:
Educational:
Educational:
Basic concepts:
Forms p working with the student isya
Teaching methods
Materials and equipment: GoogleChrome
During the classes:
1. Students take their places at their desks, withwith the help of MANAGE MED
2.Organizational moment. Guys, hello! Let's greet each other, i.e. shoulder partner and face partner.
Who loves to dance;
Who loves spring;
4.Updating knowledge. Guys, in order to remember how animals move, let’s complete the task "We crawl, we fly, we swim..."
(
With the help of a muscular leg.
Amoeboid movement.
5.Goal setting and motivation, explanation of new material.
What section are we studying?
(skeleton)
2. invertebrates – chordates
3. skullless – vertebrates
2. invertebrates – chordates
CONCLUSION:
3. skullless – vertebrates
6. STRUCTURE OF INSIDE-OUTSIDE SECURITY (
Thank you for the warm-up, thank your given partner and take your seats.
Group 1
Group 2
Group 3.
Jaws without teeth
2.Biological task:
Exit ticket
1.A strong exoskeleton is characteristic of:
A) worms;
B) insects;
B) arachnids;
D) crustaceans.
2.The advantages of the internal skeleton are:
A) ability to grow;
B) formed by connective tissue;
B) supplements body weight;
D) has a structure that does not interfere with movement.
3. The axial skeleton of the lancelet is:
A) spine;
B) chitinous cover;
B) chord;
D) exoskeleton impregnated with lime.
4.The keel has many sternums:
A) mammals;
B) reptiles;
B) amphibians;
D) birds.
5.The skeleton of various representatives of chordates performs similar functions:
A) body support;
B) protection of internal organs;
C) better air supply to the lungs;
D) movement in space.
6. The internal skeleton is characteristic of:
A) fish;
B) crustaceans;
B) mammals;
D) amphibians.
7. Significant disadvantages of the exoskeleton are:
A) location on the surface of the body;
B) inability to grow;
B) supporting function for muscles;
D) protection of internal organs.
8. In fish, the following are attached to the spine:
A) caudal fin; B) ribs; B) pectoral fins; D) skull.
9. Reptiles can move their heads thanks to the movable connection of the vertebrae of the section:
A) sacral; B) breast; B) cervical; D) lumbar.
Teacher: Povarnitsina T.A. MBOU "Novosheshminskaya Gymnasium"
13.03.2014
‹ ›
To download the material, enter your E-mail, indicate who you are, and click the button
By clicking the button, you agree to receive email newsletters from us
If the downloading of the material has not started, click “Download Material” again.
- Biology
Description:
7-B CLASS
Lesson topic: The musculoskeletal system of animals (evolution of structure)
Lesson type: a lesson in learning new material.
Target: study the evolution of the structure of the ODS of animals.
Tasks:
Educational:
Identification of the functions of animal ODS and the causes of evolutionary changes in ODS;
Substantiation of the relationship between the structure and functions of the animal body;
Comparison of the structure of the ODS of animals of different systematic groups, identification of complications
(unicellular - multicellular, invertebrates - chordates, amorphous - vertebrates, different classes of vertebrates - cyclostomes, cartilaginous fish, bony fish, amphibians, reptiles, birds, mammals);
Explanation of the reasons for the differences and substantiation of the adaptability of the ODS of animals to various environmental conditions and habitats.
Educational:
Development of skills to work with drawings and texts (textbook, presentation slides, demonstration tables), samples of external and internal skeletons (analyze their contents, describe the structure of skeletons, compare skeletons of different organisms...)
Development of skills to give examples of animals (with different types of skeletons);
Developing the ability to understand the feasibility of evolutionary changes;
Development of thinking and communication skills.
Educational:
Fostering feelings of love for nature, admiration for its wisdom and expediency;
Fostering a sense of responsibility for the success of one’s studies, the desire for self-education and self-development.
Basic concepts:
“musculoskeletal system”, “external skeleton”, “internal skeleton”, “axial skeleton”, “spine”, “vertebra”, “limb skeleton”, “limb girdle”, “bone”, “joint”, “skull” "
Forms of work with students : lecture using presentation illustrations, frontal, workshop, group work with layouts.
Teaching methods: TAKE OFF-TOUCH DOWN; INSIDE-OUTSIDE SECL.
Materials and equipment: personal computer, multimedia projector, browser GoogleChrome for reproducing the EOR of the Unified Collection of the Central OR, models of skeletons of amphibians, birds, mammals, applications of bone types, mollusk shells, crayfish skeleton, collection of beetles.
During the classes:
1. Students take their places at their desks, with with the help of MANAGE MED(classroom management tool) are distributed in one team to organize an effective learning process.
2.Organizational moment. Guys, hello! Let's greet each other, i.e. shoulder partner and face partner.
3. TAKE OFF-TOUCH DOWN - “stand up and sit down” (learning structure for getting class information):
Stand up, guys who love sports;
Who loves to dance;
Who loves to play musical instruments;
Who loves spring;
Who has learned their homework?
4.Updating knowledge.Guys, in order to remember how animals move, let’s complete the task "We crawl, we fly, we swim..."
( The teacher asks questions, the students answer).
- Expulsion of water from the mantle cavity.
- Walking movements using suction cups.
- With the help of bristles and contraction of longitudinal and transverse muscles.
- Due to the contraction of only the longitudinal muscles.
- With the help of a muscular leg.
- Amoeboid movement.
- With the help of flagella and cilia.
- Due to the muscles of the tail and body.
- Jumping movements using the muscles of the limbs.
10. Flight movements using the muscles of the limbs
2. “We are not afraid of frost or heat!”
List all the functions of the body.
1.What substance is necessary for the formation of shells and shells?
2.What is the name of a dense non-cellular formation in arthropods?
3.What layers does the skin of vertebrates consist of?
5.Goal setting and motivation, explanation of new material.
Let's decide on the topic of today's lesson.
What “bridge” can be made from the last lesson to today’s?
What is the logic in the sequence of studying the educational material of our section?
What section are we studying?
Evolution of the structure and functions of organs and their systems.
From the study of external integuments we move on to the study of internal organ systems (figuratively speaking, we examined the animal externally, now we are trying to look deeper)
I provide support for the body, I help walk, run, and jump. (skeleton)
Since the integument is often part of the ODS (we remember the concept of “cutaneous-muscular bag”, we remember that in arthropods the muscles are usually attached to the exoskeleton...), it is logical to move on to this topic after studying them
-What is the main goal of our lesson?
(to study the evolution of the structure of the joint body of animals, systematizing knowledge about the structure of the body of animals of different systematic groups).
Prove that the body needs ODS (for movement, to protect cells, tissues, organs, for support and maintenance, maintaining a constant body shape...)
Why are the skeleton and musculature, such different structures, combined into one organ system? (for the successful operation of any organ that performs a movement, it needs support)
Explain the reasons for the evolution of ODS, changes in it over time (the development of new territories by animals, the development of new types of food, the need to survive, to actively seek food, to hide better from enemies, to constantly improve their adaptations to changing environmental conditions... thus, ODS, changing along with the organism, should have ensured all these evolutionary changes)
What stages, “steps” in achieving the main goal of the lesson (in studying the evolution of ODS from one group of animals to another) can we identify?
1. unicellular – multicellular
2. invertebrates – chordates
3. skullless – vertebrates
4. different classes of vertebrates - fish, amphibians, reptiles, birds, mammals
Let's name the main musculoskeletal structures of protozoa and multicellular invertebrates and trace evolutionary changes
1. unicellular – multicellular invertebrates
Conversation using presentation slides
What supporting and motor structures does the body of a protozoan have? (amoeba - cell membrane, pseudopods, euglena - flagellum as an outgrowth on the membrane, ciliates - cilia as outgrowths on the membrane);
What supporting and motor structures appear in coelenterates? (epithelial-muscle cells in the ectoderm);
What changes are characteristic of worms? (external extensible integument of the body, skin-muscular sac, hydroskeleton);
In mollusks? (shells of gastropods and bivalves);
In arthropods? (exoskeleton in the form of chitinous integuments of insects, arachnids, in the form of lime-soaked integuments of crustaceans, to which muscles are attached);
Are there any animals with an internal skeleton among invertebrates? (in cephalopods, the internal cartilaginous skeleton is the head capsule, which protects the brain and eyes, but this is rather an exception, since a real internal skeleton appears only in chordates);
Let's pay attention to the evolutionary possibilities of the internal skeleton that appeared in chordates
2. invertebrates – chordates
Individual-group work to identify the advantages and disadvantages of the external and internal skeletons (students A are preparing to name as many advantages of the external skeleton as possible, and students B are preparing to name the internal skeleton), followed by discussion and conclusions.
Exoskeleton – strength, muscle attachment and provision of movement, development of new methods of movement (jumping, flying), settlement.
Exoskeleton - does not grow with the animal, makes the animal defenseless during molting, limits body size (especially in land animals).
Internal skeleton - grows with the animal, increases the speed of body movement due to greater specialization of individual muscles and their groups.
CONCLUSION:the internal skeleton is more progressive.
***We remember that chordates are divided into lower and higher. What are the “cons” of the ODS of lower chordates and the “pros” of the ODS of higher chordates?
In the lower ones - the lancelet - the notochord is retained throughout life, and in the higher ones it is replaced during development by the spine, which partially or completely ossifies
In higher vertebrates, a skull appears
Vertebrates develop skeletons of limbs and their girdles
Vertebrates have more complex muscles
3. skullless – vertebrates
The skeleton of most vertebrates is formed by bones, cartilage, and tendons.
Bones are composed of organic and inorganic substances and are very strong.
Independent individual work to identify types of bone connections (last paragraph on page 194 of the textbook), followed by a conclusion about the progressive significance of joints.
Fixed (fusion of bones) and movable (using a joint) connection.
The bones of the vertebrate skeleton have special places for muscle attachment (by attaching to two skeletal bones connected through a joint, the muscle sets them in motion).
The skeleton consists of three main parts: the axial skeleton, the skeleton of the limbs and the skeleton of the head - the skull.
The axial skeleton of skullless animals is represented by a notochord, and that of vertebrates by a spine consisting of cartilaginous or bony vertebrae.
Independent individual work with a textbook to identify the structural features of a vertebra (Fig. 147 of the textbook on p. 195), followed by a conclusion about the progressive significance of the appearance of vertebrae in the axial skeleton.
(consists of the body, upper and lower arches, the ends of the upper arches of the vertebrae, fused together, form a canal in which the spinal cord is located, ribs are attached to the ends of the lower arches directed to the sides)
The appearance of vertebrae is an important progressive feature, as they give strength and flexibility to the skeleton and protect the spinal cord.
6. STRUCTURE OF INSIDE-OUTSIDE SECURITY( all the guys in group A form an outer circle, and the guys in group B find partners by face and stand in front of him).
Question 1. What types of bone connections have you learned? (students from the outer circle answer their partners, then change roles, the inner circle answers).
Turn left and count 3 people, greet your new partner.
Question 2. How many parts does the skeleton consist of, name them? (the inner circle answers, then switch roles).
Turn to the right and count 2 people, greet your partner.
Question 3. What are the functions of the internal skeleton? (those partners who are higher answer, then change roles).
Thank you for the warm-up, thank your given partner and take your seats.
Let's trace changes in the skeletons of vertebrates of different systematic groups
4. different systematic groups of vertebrates - fish, amphibians, reptiles, birds, mammals
Group work with textbook and flashcard
(3 groups identify the features of skeletons, amphibians, birds, mammals, perform the corresponding tasks on cards) followed by a discussion of conclusions about the main directions of the evolution of the skeleton of vertebrates.
Experts will carefully listen to the presentations of representatives of all three groups and help us draw appropriate conclusions about the main directions of the evolution of the vertebrate skeleton.
Group 1. Task: to identify the structural features of the amphibian skeleton.
Textbook – text on pages 195, 197-198, fig. 149 on page 196.
Complication of the spine - cervical (1), trunk (7 with ribs ending freely), sacral (1 with pelvic bones attached to it) sections + caudal section in caudates
There is a skull, skeleton of limbs and their belts
Group 2. Task: to identify the structural features of the bird skeleton.
Textbook – text on pages 197, 198, fig. 151 on page 197.
5 sections of the spine - cervical (9-25 vertebrae, movably connected), thoracic (fused thoracic vertebrae - 3-10 - and the ribs connected to the sternum form the rib cage; many have a keel), lumbar, sacral, caudal - 6- 9 (the last thoracic, lumbar, sacral and first caudal vertebrae are fused, forming a powerful sacrum for greater strength, for support of the hind limbs
Light bones (many have cavities inside)
There is a skull, a skeleton of the limbs and their girdles (the skeleton of the upper limb
(hand) modified in connection with the development of the wing - an adaptation for flight)
Group 3.Assignment: identify the structural features of the mammalian skeleton.
Textbook - text on pp. 197-198, fig. 152 on page 198.
5 clearly defined sections of the spine - cervical (7 vertebrae with rare exceptions), thoracic (12-15 vertebrae), lumbar (2-9 vertebrae), sacral (usually 4 fused vertebrae), caudal
There is a skull (cerebral and facial sections), a skeleton of the limbs and their girdles (shoulder and pelvic)
CONCLUSION ABOUT THE DIRECTIONS OF EVOLUTION OF THE SKELETON OF VERTEBRATE ANIMALS (EXPERTS):
Differentiation of the axial skeleton - spine
Movable connection of the cervical vertebrae
The appearance and development of the chest
Differentiation of the skull and brain and facial parts, development of the brain
The appearance and development of paired fore and hind limbs and their girdles - shoulder and pelvic
The appearance and development of particular adaptations in connection with the secondary loss of limbs in snakes, in connection with flight in birds, etc.
7. Information about homework
(before consolidating the educational material of the topic and checking its mastery, let's write down the homework in our diaries, pay attention to the differentiated part of it)
§ 37, observe the methods of movement of your pets (aquarium fish, birds, hamsters, cats, dogs) and prepare a short oral story about the methods of their movement, about whether they are able to change the method of movement when conditions change, for example, when touched.
8. Application of knowledge (consolidation of learned material)
1. Collective discussion of biological problems (CREATIVE ADVANCED TASK using INTERNET resources)
Problem 1. It is known that fish cannot turn their heads. Can frogs and newts do this? Explain your answer.
They can; frogs can only raise and lower their heads - they have one vertebra in the cervical region; newts can also turn their heads, since their cervical vertebrae are movably connected
Problem 2. The skeleton of snakes lacks a rib cage. Why was it lost in these animals? (pp. 125-126 of the textbook - if students do not answer the question))
Due to the absence of limbs and the development of a special method of movement through lateral bending of the spine and ribs, which with their lower ends are capable of moving forward and backward
Problem 3. Any extra cargo would be a hindrance during the flight. What changes have occurred in the birds' support structure due to this?
Bones are thin and filled with air
Jaws without teeth
Task 4. The neck of mammals has different lengths: a dog’s is short, a giraffe’s is long. What determines such differences?
This does not depend on the number of cervical vertebrae (there are 7), but on the length of their bodies
2.Biological task:
What is evidenced by the different positions of the limbs relative to the body?
in different classes of vertebrates?
On the evolution of limbs from amphibians and reptiles to birds and mammals; that a body raised above the ground gives animals much more opportunities in terms of active movement in search of food, protection from enemies (in amphibians, the limbs rest on the ground on the sides of the body; in reptiles, too, but the body is more elevated; only in birds and mammals limbs support the body from below)
3.Answers to questions about consolidating educational material
Question 1. What underlies the evolutionary changes in the musculoskeletal system?
The basis of evolutionary changes in the musculoskeletal system lies, first of all, in the transition of animals from an aquatic habitat to a land-air habitat. The new environment required greater strength from the musculoskeletal system and the ability to carry out more complex and varied movements. An example is the appearance of compound paired limbs with movable (articular) joints of parts and complex muscles in representatives of the class of amphibians - the first land vertebrates.
Question 2. What does the similar structure of the skeletons of different vertebrates indicate?
The general plan of the structure of the skeletons of different vertebrates indicates a common origin and evolutionary relationship. And the presence of similar private formations means that animals lead a similar lifestyle in similar environmental conditions. For example, both flying birds and bats have a bony ridge (keel) on the sternum.
Question 3. What conclusion can be drawn after becoming familiar with the general functions of the musculoskeletal system in animal organisms?
Despite significant differences in the structure of musculoskeletal structures in different animals, their skeletons perform similar functions: supporting the body, protecting internal organs, moving the body in space.
4.Checking the level of mastery of the lesson material
Completing a written test task (exit ticket)
Commentary on the grades for the lesson (each student will receive a grade for the completed test, plus those guys who completed advanced creative tasks for the lesson, actively worked in the lesson - answered, supplemented - will receive an additional grade, I think, the highest possible (the experts will help me not to forget anyone )
Exit ticket
Answer the questions (multiple answers possible).
1.A strong exoskeleton is characteristic of:
A) worms;
B) insects;
B) arachnids;
D) crustaceans.
2.The advantages of the internal skeleton are:
A) ability to grow;
B) formed by connective tissue;
B) supplements body weight;
D) has a structure that does not interfere with movement.
3. The axial skeleton of the lancelet is:
A) spine;
B) chitinous cover;
D) exoskeleton impregnated with lime.
4.The keel has many sternums:
A) mammals;
B) reptiles;
B) amphibians;
5.The skeleton of various representatives of chordates performs similar functions:
A) body support;
B) protection of internal organs;
C) better air supply to the lungs;
D) movement in space.
6. The internal skeleton is characteristic of:
B) crustaceans;
B) mammals;
D) amphibians.
7. Significant disadvantages of the exoskeleton are:
A) location on the surface of the body;
B) inability to grow;
B) supporting function for muscles;
D) protection of internal organs.
8. In fish, the following are attached to the spine:
A) caudal fin; B) ribs; C) pectoral fins; D) skull.
9. Reptiles can move their heads thanks to the movable connection of the vertebrae of the section:
A) sacral; B) thoracic; C) cervical; D) lumbar.
9. Summing up the lesson. Reflection
Remember the course of the lesson; analyze your activities or the activities of your comrades; formulate your impressions...
-Was our lesson on this topic important?
-Are you satisfied with your work in class? The work of your classmates?
All organs of movement that ensure the movement of the body in space are combined into a single system. This includes bones, joints, muscles and ligaments. The human musculoskeletal system performs certain functions due to the peculiarities of the formation and structure of the organs of movement.
Importance of the musculoskeletal system
The human skeleton performs several vital functions:
- supporting;
- protective;
- provides movement;
- takes part in hematopoiesis.
Disorders of the musculoskeletal system cause pathological processes in the functioning of many body systems. Muscles attached to bones move them relative to each other, which ensures the movement of the body in space. The muscular apparatus has its own functional feature:
- surrounds the cavities of the human body, protecting them from mechanical damage;
- perform a supporting function, supporting the body in a certain position.
During the development of the human musculoskeletal system, the development of the central nervous system is stimulated. The development of muscles and nerve cells are mutually dependent processes. Knowing what functions of the musculoskeletal system are necessary for the normal functioning of the body, we can conclude that the skeleton is a vital structure of the body.
During the period of embryogenesis, when the body is practically not affected by any irritants, fetal movements cause irritation of muscle receptors. From them, impulses go to the central nervous system, stimulating the development of neurons. At the same time, the developing nervous system stimulates the growth and development of the muscular system.
Skeletal anatomy
Skeleton is a set of bones that perform supporting, motor and protective functions. The human musculoskeletal system has about 200 bones (depending on age), of which only 33-34 bones are unpaired. There are axial (chest, skull, spine) and accessory (free limbs) skeletons.
Bones are formed from a type of connective tissue. It consists of cells and a dense intercellular substance, which contains many mineral components and collagen, which provides elasticity.
The skeleton is a container for vital human organs: the brain is located in the skull, the spinal cord is located in the spinal canal, the chest provides protection to the esophagus, lungs, heart, main arterial and venous trunks, and the pelvis protects the organs of the genitourinary system from damage. Disorders of the musculoskeletal system can cause damage to internal organs, sometimes incompatible with life.
Bone structure
The bones contain a spongy and compact substance. Their ratio varies depending on the location and functions of a certain part of the musculoskeletal system.
The compact substance is localized in the diaphysis, which provides support and locomotor functions. Spongy substance is located in flat and short bones. The entire surface of the bone (with the exception of the articular surface) is covered with periosteum (periosteum).
Bone Formation
In ontogenesis, the formation of the musculoskeletal system goes through several stages - membranous, cartilaginous and bone. From the second week after conception, cartilaginous rudiments form in the mesenchyme of the membranous skeleton. By the 8th week, cartilage tissue is gradually replaced by bone tissue.
Replacement of cartilage tissue with bone tissue can take place in several ways:
- perichondrial ossification - the formation of bone tissue along the perimeter of the cartilage;
- periosteal ossification - production of young osteocytes by the formed periosteum;
- enchondral ossification - the formation of bone tissue within cartilage.
The process of bone tissue formation involves the growth of blood vessels and connective tissue from the periosteum into the cartilage (cartilage destruction occurs in these places). From some of the osteogenic cells, spongy bone subsequently develops.
During the period of intrauterine development of the fetus, ossification of the diaphyses of the tubular bones occurs (ossification points are called primary), then after birth, ossification of the epiphyses of the tubular bones occurs (secondary ossification points). Until the age of 16-24 years, a cartilaginous epiphyseal plate remains between the epiphyses and diaphyses.
Thanks to its presence, the organs of the musculoskeletal system are lengthened. After the bone is replaced and the diaphyses and epiphyses of the tubular bones fuse, human growth stops.
The structure of the spinal column
The spinal column is a series of overlapping vertebrae that are connected by the intervertebral discs, joints and ligaments that form the basis of the musculoskeletal system. The functions of the spine are not only support, but also protection, preventing mechanical damage to internal organs and the spinal cord passing in the spinal canal.
There are five sections of the spine - coccygeal, sacral, lumbar, thoracic and cervical. Each section has a certain degree of mobility; only the sacral spine is completely immobile.
The movement of the spine or its parts is ensured with the help of skeletal muscles. The correct development of the musculoskeletal system in the neonatal period provides the necessary support for internal organs and systems and their protection.
Structure of the chest
The rib cage is an osteochondral formation consisting of the sternum, ribs and 12 thoracic vertebrae. The shape of the chest resembles an irregular truncated cone. The chest has 4 walls:
- anterior - formed by the sternum and cartilage of the ribs;
- posterior - formed by the vertebrae of the thoracic spine and the posterior ends of the ribs;
- 2 lateral - formed directly by the ribs.
In addition, there are two openings of the chest - the upper and lower apertures. The organs of the respiratory and digestive system (esophagus, trachea, nerves and blood vessels) pass through the upper opening. The lower aperture is closed by a diaphragm, in which there are openings for the passage of large arterial and venous trunks (aorta, inferior vena cava) and the esophagus.
Structure of the skull
The skull is one of the main structures that forms the musculoskeletal system. The functions of the skull are to protect the brain, sensory organs and support the initial parts of the respiratory and digestive systems. It consists of paired and unpaired bones and is divided into the brain and facial sections.
The facial section of the skull consists of:
- from the maxillary and mandibular bones;
- two nasal bones;
The brain section of the skull includes:
- paired temporal bone;
- paired sphenoid bone;
- steam room;
- occipital bone.
The brain section performs a protective function for the brain and is its container. The facial region provides support for the initial portion of the respiratory and digestive systems and sensory organs.
Musculoskeletal system: functions and structure of the limbs
In the process of evolution, the skeleton of the limbs acquired extensive mobility due to the articulation of the bones (especially the radial and carpal joints). The thoracic and pelvic girdles are distinguished.
The upper girdle (pectoral) includes the scapula and two clavicle bones, and the lower (pelvic) is formed by the paired pelvic bone. The following sections are distinguished in the free part of the upper limb:
- proximal - represented by the humerus;
- middle - represented by the ulna and radius bones;
- distal - includes the carpal bones, metacarpal bones and finger bones.
The free part of the lower limb consists of the following sections:
- proximal - represented by the femur;
- middle - includes the tibia and fibula;
- distal - tarsal bones, metatarsal bones and finger bones.
The skeleton of the limbs provides the possibility of a wide range of actions and is necessary for normal work activity, which is provided by the musculoskeletal system. The functions of the skeleton of free limbs are difficult to overestimate, since with their help a person performs almost all actions.
The structure of the muscular system
Skeletal muscles are attached to bones and, when contracted, provide movement of the body or its individual parts in space. Skeletal muscles are based on striated muscle fibers. In addition to supporting and motor functions, muscles provide the function of breathing, swallowing, chewing, and take part in facial expressions, heat production and speech articulation.
The main properties of skeletal muscles are:
- excitability - the activity of muscle fibers is carried out under the influence of nerve impulses;
- conductivity - from the nerve endings to the central nervous system there is a rapid conduction of the impulse;
- contractility - as a result of the movement of a nerve impulse, contractility of the skeletal muscle occurs.
A muscle consists of tendinous ends (tendons that attach the muscle to the bone) and a belly (consisting of striated muscle fibers). The coordinated work of the musculoskeletal system is carried out by the correct functioning of the muscles and the necessary nervous regulation of muscle fibers.
Phylogenesis of motor function underlies the progressive evolution of animals. Therefore, the level of their organization primarily depends on the nature of motor activity, which is determined by the peculiarities of the organization of the musculoskeletal system, which in the Chordata type has undergone major evolutionary transformations due to changes in habitats and changes in forms of locomotion. Indeed, the aquatic environment in animals that do not have an exoskeleton involves monotonous movements due to the bending of the entire body, while life on land is more conducive to their movement with the help of their limbs.
Skeleton. Chordates have an internal skeleton. According to its structure and functions, it is divided into the axial skeleton, the skeleton of the limbs and the head.
Axial skeleton. In the skullless subtype there is only an axial skeleton in the form of a chord. It is built of highly vacuolated cells, tightly adjacent to each other and covered on the outside with common elastic and fibrous membranes. The elasticity of the chord is given by the turgor pressure of its cells and the strength of the membranes.
Throughout life in vertebrates, the notochord is retained only in cyclostomes and some lower fish. In all other animals it is reduced. In humans, in the postembryonic period, rudiments of the notochord are preserved in the form of nuclei of intervertebral discs. Preservation of an excess amount of notochordal material when its reduction is impaired is fraught with the possibility of developing tumors in humans - chordomas, arising on its basis. In all vertebrates, the notochord is gradually replaced by vertebrae developing from the sclerotomes of the somites and is functionally replaced by the vertebral column. The formation of vertebrae in phylogeny begins with the development of their arches, covering the neural tube and becoming sites of muscle attachment. Beginning with cartilaginous fish, cartilagination of the shell of the notochord and the growth of the bases of the vertebral arches are detected, as a result of which the vertebral bodies are formed. The fusion of the upper vertebral arches above the neural tube forms the spinous processes and the spinal canal, which encloses the neural tube. Replacing the notochord with the spinal column - a more powerful support organ with a segmental structure - allows you to increase the overall size of the body and activates motor function. Further progressive changes in the spinal column are associated with the replacement of cartilaginous tissue with bone, which is found in bony fish, as well as with its differentiation into sections. Fish have only two parts of the spine: the trunk and the caudal. This is due to their movement in water due to the bending of the body. Amphibians also acquire cervical and sacral sections, each represented by one vertebra. The first provides greater mobility of the head, and the second provides support for the hind limbs. In reptiles, the cervical spine lengthens, the first two vertebrae of which are movably connected to the skull and provide greater mobility of the head. The lumbar region appears, still weakly delimited from the thoracic region, and the sacrum already consists of two vertebrae. Mammals are characterized by a stable number of vertebrae in the cervical region, equal to 7. The lumbar and thoracic regions are clearly demarcated from each other. In fish, all the trunk vertebrae bear ribs that are not fused with each other or with the sternum. In reptiles, part of the thoracic ribs fuses with the sternum, forming the chest, and in mammals the chest includes 12-13 pairs of ribs.
The ontogeny of the human axial skeleton recapitulates the main phylogenetic stages of its formation: during the period of neurulation, the notochord is formed, which is subsequently replaced by a cartilaginous and then a bone spine. A pair of ribs develops on the cervical, thoracic and lumbar vertebrae, after which the cervical and lumbar ribs are reduced, and the thoracic ribs fuse in front with each other and with the sternum, forming the rib cage. Disruption of the ontogenesis of the axial skeleton in humans can be expressed in such atavistic developmental defects as nonfusion of the spinous processes of the vertebrae, resulting in the formation of a spinal canal defect. In this case, the meninges often protrude through the defect and a spina bifida is formed. Violation of the reduction of the cervical and lumbar ribs underlies their preservation in postnatal ontogenesis.
Skeleton of the head. A continuation of the axial skeleton in front is the axial, or cerebral, skull, which serves to protect the brain and sensory organs. Next to it, the visceral or facial skull develops, forming the support of the anterior part of the digestive tube. Both parts of the skull develop differently and from different rudiments. At the early stages of evolution and ontogenesis they are not connected with each other, but later this connection arises. Phylogenetically, the brain skull went through three stages of development: membranous, cartilaginous and bony. In cyclostomes it is almost all membranous and does not have an anterior, unsegmented part. The skull of cartilaginous fish is almost completely cartilaginous, and includes both the posterior, primarily segmented part, and the anterior one. In bony fishes and other vertebrates, the axial skull becomes bone due to the processes of ossification of cartilage in the area of its base and due to the appearance of integumentary bones in its upper part. Widely known in humans are such anomalies of the brain skull as the presence of interparietal bones, as well as two frontal bones with a metopic suture between them. They are not accompanied by any pathological phenomena and are therefore usually discovered by chance after death.
The visceral skull also appears for the first time in lower vertebrates. It is formed from mesenchyme of ectodermal origin, which is grouped in the form of arch-shaped condensations in the spaces between the gill slits of the pharynx. The first two arches receive particularly strong development and give rise to the maxillary and hyoid arches of adult animals. In cartilaginous fish, in front of the jaw arch there are usually 1-2 more pairs of premaxillary arches, which are rudimentary in nature. Amphibians, in connection with the transition to terrestrial existence, have undergone significant changes in the visceral skull. The branchial arches are partially reduced, and partially, changing their functions, they become part of the cartilaginous apparatus of the larynx. The lower jaw of mammals articulates with the temporal bone with a complex joint that allows not only the capture of food, but also complex chewing movements.
Limb skeleton. Chordates have unpaired and paired limbs. Unpaired amphibians are the main organs of locomotion in amphibians, fish and, to a lesser extent, in caudate amphibians. Fish also develop paired limbs - pectoral and pelvic fins, on the basis of which paired limbs of terrestrial four-legged animals subsequently develop.
In modern amphibians, the number of fingers in the limbs is five or they are oligomerized to four. Further progressive transformation of the limbs is expressed in an increase in the degree of mobility of bone joints, in a decrease in the number of bones in the wrist, first to three rows in amphibians and then to two in reptiles and mammals. At the same time, the number of phalanges of the fingers also decreases. Lengthening of the proximal parts of the limb and shortening of the distal parts are also characteristic. Numerous disorders are possible in human ontogenesis, leading to the formation of atavistic congenital malformations of the limbs. Thus, polydactyly, or an increase in the number of fingers, inherited as an autosomal dominant trait, is the result of the development of the anlages of additional fingers, which are normally characteristic of distant ancestral forms. The phenomenon of polyphalanx is known, characterized by an increase in the number of phalanges, usually the thumb. A serious malformation is a violation of heterotopia of the upper limb girdle from the cervical region to the level of the 1st-2nd thoracic vertebrae. This anomaly is called Sprengel's disease or congenital high scapula. It is expressed in the fact that the shoulder girdle on one or both sides is several centimeters higher than the normal position.
Muscular system . In representatives of the phylum Chordata, the muscles are divided according to the nature of development and innervation into somatic and visceral. Somatic muscles develop from myotomes and are innervated by nerves, the fibers of which exit the spinal cord as part of the ventral roots of the spinal nerves. Visceral muscles develop from other parts of the mesoderm and are innervated by the nerves of the autonomic nervous system. All somatic muscles are striated, and visceral muscles can be either striated or smooth
