Animal breathing – set of processes that providehit into the body from environment oxygen , hiscell use for oxidation organic matter Andexcretion carbon dioxide from the body.This kind of breathing is calledaerobic , and organisms -aerobes .
OK. No. 28. Biology.
Green algae chlorella
Ciliate slipper
The breathing process in animals is conventionally divided into three stages :
External respiration = gas exchange. Thanks to this process, the animal receives oxygen and gets rid of carbon dioxide, which is the end product of metabolism.
Transport of gases in the body– this process is provided either by special tracheal tubes or internal body fluids (blood containing hemoglobin- a pigment that can attach oxygen and transport it into cells, as well as carry carbon dioxide out of cells).
Internal breathing- occurs in cells. Simple nutrients (amino acids, fatty acids, simple carbohydrates) with the help of enzymes, cells are oxidized and broken down, during which the ENERGY necessary for the life of the body is released.
The main importance of respiration is the release of energy from nutrients with the help of oxygen, which takes part in oxidation reactions.
Some protozoa - anaerobic organisms, i.e. organisms, not requiring oxygen.
Anaerobes There are facultative and obligate. Facultatively anaerobic organisms are organisms that can live both in the absence of oxygen and in its presence. Obligate anaerobic organisms are organisms for which oxygen is toxic. They can only live in the absence of oxygen. Anaerobic organisms do not need oxygen to oxidize nutrients. 
Brachionella is an anaerobic ciliate
Intestinal Giardia
Human roundworm
By way of breathing and the structure of the respiratory apparatus in animals there are 4 types of respiration:
Skin breathing
- This is the exchange of oxygen and carbon dioxide through the integument of the body. This process is based on the most important physical process - diffusion
. Gases enter only in a dissolved state through the covers shallowly and at low speed. Such respiration occurs in organisms that are small in size, have moist integuments, and lead an aquatic lifestyle. This - sponges, coelenterates, worms, amphibians.
Tracheal breathing
– 
carried out using
connected systems
tubes – trachea , which
permeate the entire body, without
participation of liquids. WITH
their environment
connect special
holes – spiracles.
Organisms with a tracheal
breathing is also small in size (no more than 2 cm, otherwise the body will not have enough oxygen). This - insects, centipedes, arachnids.
Gill breathing – with the help of specialized formations with a dense network of blood vessels. These outgrowths are called gills . In aquatic animals - polychaetes, crustaceans, mollusks, fish, certain species of amphibians. In invertebrate animals, gills are usually external, while in chordates they are internal. Gill-breathing animals have additional forms of respiration through the skin, intestines, surface of the mouth, and swim bladder.
Polychaete with gills
Crustacean gills
Nudibranch
Pulmonary respiration – this is breathing with the help of internal specialized organs – lungs.
Lungs– These are hollow thin-walled bags, braided with a dense network of tiny blood vessels - capillaries. Diffusion of oxygen from the air into the capillaries occurs on the inner surface of the lungs. Accordingly, the larger the internal surface, the more active the diffusion.
Almost all terrestrial vertebrates breathe through their lungs. reptiles, birds, some terrestrial invertebrates - spiders, scorpions, pulmonary mollusks, and some aquatic animals - lungfish. Air enters the lungs through Airways.
Lungs of a mammal
Reptile lung
Respiratory system of birds
Breathing in animals is determined by their way of life and is carried out using the integument, trachea, gills and lungs.
Respiratory system – a set of organs for conducting air or water that contain oxygen and exchanging gases between the body and the environment.
The respiratory organs develop as outgrowths of the outer integument or walls of the intestinal tract. The respiratory system includes the airways and gas exchange organs. In vertebrates Airways – nasal cavity, larynx, trachea, bronchi ; A respiratory system -lungs .
Comparative characteristics of the respiratory organs.
|
Group |
Characteristic features of the respiratory system |
|
Coelenterates |
Gas exchange across the entire surface of the body. There are no special respiratory organs. |
|
Annelids |
External gills (polychaete worms) and entire body surface (oligochaete worms, leeches) |
|
Shellfish |
Gills (bivalves, cephalopods) and lungs (gastropods) |
|
Arthropods |
Gills (crustaceans), trachea and lungs (arachnids), trachea (insects) |
|
Fish |
Gills. Additional organs for breathing: lungs (lungfishes), parts of the oral cavity, pharynx, intestines, swim bladder |
|
Amphibians |
Lungs cellular, gills (in larvae), skin (with big amount vessels). Respiratory tract: nostrils, mouth, tracheal-laryngeal chamber |
|
Reptiles |
Light cellular. Respiratory tract: nostrils, larynx, trachea, bronchi |
|
Birds |
Lungs are spongy. Respiratory tract: nostrils, nasal cavity, upper larynx, trachea, lower larynx with voice box, bronchi. There are air bags. |
|
Mammals |
Alveolar lungs. Respiratory tract: nostrils, nasal cavity, larynx with vocal apparatus, trachea, bronchi. |
Functions of the respiratory system:
Delivery of oxygen to body cells and removal of carbon dioxide from body cells and gas exchange(main function).
Body temperature regulation(because water can evaporate through the surface of the lungs and respiratory tract)
Purification and disinfection of incoming air(nasal mucus)
Questions for self-control.
|
Grade |
Questions for self-control |
|
1.What is breathing? 2. The main stages of breathing? 3. Name the main types of animal respiration. 4. Give examples of animals that breathe using their skin, gills, trachea and lungs. 5. What is the respiratory system? 6. Name the main functions of the respiratory system. |
|
|
7. How important is respiration for the release of energy in animal cells? 8. What determines the type of breathing of animals? 9. What functions does the respiratory system perform? |
|
|
10. Describe the breathing methods of vertebrates. |
Comparative characteristics of the respiratory organs of animals.
|
Respiratory system |
Structural features |
Functions |
Examples |
|
Gills
|
External(comb, filamentous and pinnate) or internal(always associated with the pharynx) thin-walled outgrowths of the body that contain many blood vessels |
Gas exchange in aquatic environment |
In fish, almost all larvae of tailless amphibians, in most mollusks, some worms and arthropods |
|
Trachea
|
Branched tubes that permeate the entire body and open outward with openings (stigmas) |
Gas exchange in the air |
In most arthropods |
|
Lungs
|
Thin-walled bags that have an extensive network of vessels |
Gas exchange in the air |
In some mollusks and fish, terrestrial vertebrates |
The set of processes that ensure the consumption of O 2 and the release of CO 2 in the body is called breathing. There are processes of external and internal respiration. External respiration ensures the exchange of gases between the body and external environment, internal respiration - consumption of O2 and release of CO 2 by the cells of the body.
The factor ensuring the diffusion of gases through the respiratory surfaces is the difference in their concentrations. The movement of dissolved gases occurs in the direction from an area of high concentration to an area of low concentration.
In small organisms, gas exchange, as a rule, occurs diffusely over the entire surface of the body (or cell). In larger animals, gases are transported to the tissues either directly (the tracheal system of insects) or through special vehicles (blood, hemolymph).
The amount of oxygen entering the animal’s tissues depends on the area of the respiratory surface and the difference in oxygen concentration on them. Therefore, growth of the respiratory epithelium is observed in all respiratory organs. To maintain a high gradient of oxygen diffusion on the exchange membrane, movement of the medium (ventilation) is necessary. It is provided by the respiratory rhythmic movements of the entire body of the animal (the oligochaete worm, leeches) or certain parts of it (crustaceans), as well as the work of the ciliated epithelium (molluscs, lancelet).
A number of fairly large animals do not have specialized respiratory organs. In them, gas exchange is carried out through moist skin, equipped with an abundant network of blood vessels (earthworm). Cutaneous respiration as an additional method is characteristic of animals with specialized respiratory organs. For example, in eels that have gills, 60% of their oxygen requirement is met through skin respiration; in frogs that have lungs, this value is more than 50%.
The respiratory organs in the aquatic environment are gills, in the land-air environment - the lungs and trachea.
Gills are organs located outside the body cavity in the form of epithelial surfaces penetrated by a dense network of blood capillaries. Gill respiration is characteristic of polychaete annelids, most mollusks, crustaceans, fish, and amphibian larvae. Gill respiration is most effective in fish. It is based on counterflow phenomenon: Blood in the capillaries of the gill filaments flows in the direction opposite to the flow of water washing the gills.
Lungs, as a rule, are internal organs and are protected from drying out. There are two types: diffusion And ventilation. In the first type of lung, gas exchange occurs only by diffusion. Relatively small animals have such lungs: pulmonary mollusks, scorpions, spiders. Only terrestrial vertebrates have ventilation lungs.
The complication of the structure of the lungs in the series from amphibians to mammals is associated with an increase in the area of the respiratory epithelium. Thus, in amphibians, 1 cm 3 of lung tissue has a total gas exchange surface of 20 cm 2. A similar indicator for human lung epithelium is 300 cm 2.
Simultaneously with the increase in the respiratory surface, the mechanism of lung ventilation is improved, which, starting with reptiles, is carried out due to changes in the volume of the chest, and in mammals - with the participation of the diaphragm muscles. These adaptations allowed warm-blooded animals (birds and mammals) to dramatically increase their metabolic rate.
The third type of respiratory organs is trachea. They are air-filled, thin-walled, branching, non-collapsing invaginations into the body. The trachea communicates with the external environment through openings in the cuticle - spiracles. In insects there are most often 12 pairs of them: 3 pairs on the chest and 9 pairs on the abdomen. The spiracles can close or open depending on the amount of oxygen. At high degree development of the tracheal system (in insects), its numerous branches intertwine everything internal organs And directly provide gas exchange in tissues. The fundamental difference between tracheal breathing and pulmonary and gill breathing is that it does not require the participation of blood as a transport intermediary in gas exchange.
The tracheal system is capable of supporting sufficient high level tissue respiration, thereby ensuring high physiological activity of the insect.
Ventilation of the trachea in insects in the absence of flight is most often carried out by rhythmic contractions of the abdomen, and during flight it is enhanced by movements of the chest.
The aquatic larvae of some insects breathe using tracheal gills. In this case, the tracheal system is devoid of spiracles, i.e. it is closed and filled with air. The branches of the closed tracheal system extend into the “gills” - appendages with a large surface and a thin cuticle that allows gas exchange between water and air of the tracheal system. Such tracheal gills are found, for example, in mayfly larvae. In the larvae of some dragonflies, the tracheal gills are located in the rectal cavity, and the insect ventilates them by drawing water into the intestine and pushing it back out.
Class Amphibians = Amphibians.
The first terrestrial vertebrates that still retained contact with the aquatic environment. The class has 3,900 species and includes 3 orders: tailed (salamanders, newts), legless (tropical caecilians) and tailless (toads, tree frogs, frogs, etc.).
Secondary aquatic animals. Since the egg does not have an amniotic cavity (together with cyclostomes and fish, amphibians are anamnians), they reproduce in water, where they undergo the initial stages of their development. At different stages of their life cycle, amphibians lead a terrestrial or semi-aquatic lifestyle and are distributed almost everywhere, mainly in areas with high humidity along the banks of fresh water bodies and on damp soils. Among amphibians there are no forms that could live in salty sea water. Various modes of movement are characteristic: species are known that make fairly long jumps, move at a walk or “crawl”, lacking limbs (caecilians).
Basic characteristics of amphibians.
Amphibians retained many of the features of their purely aquatic ancestors, but at the same time they acquired a number of features characteristic of true terrestrial vertebrates.
Tailed and tailless animals are characterized by larval development with gill breathing in fresh water (frog tadpoles) and their metamorphosis into an adult breathing with lungs. In legless animals, upon hatching the larva takes the form of an adult animal.
The circulatory system is characterized by two circles of blood circulation. The heart is three-chambered. It has one ventricle and two atria.
The cervical and sacral sections of the spine are separated, each having one vertebra.
Adult amphibians are characterized by paired limbs with articulated joints. The limbs are five-fingered.
The skull articulates movably with the cervical vertebra by two occipital condyles.
The pelvic girdle is tightly attached to the transverse processes of the sacral vertebra.
The eyes have movable eyelids and nictitating membranes to protect the eyes from clogging and drying out. Accommodation improves due to the convex cornea and flattened lens.
The forebrain enlarges and divides into two hemispheres. Midbrain and the cerebellum are slightly developed. 10 pairs of cranial nerves depart from the brain.
The skin is bare, i.e. devoid of any horny or bone formations, permeable to water and gases. Therefore, it is always moist - oxygen first dissolves in the liquid covering the skin, after which it diffuses into the blood. The same thing happens with carbon dioxide, but in the opposite direction.
The kidneys, like those of fish, are primary = mesonephric.
To capture sound waves from the air, the eardrum appears, followed by the middle ear (tympanic cavity), in which the auditory ossicle is located - the stapes, which conducts vibrations to the inner ear. The Eustachian tube communicates with the middle ear cavity and the oral cavity. Choanae appear - internal nostrils, and the nasal passages become through.
Body temperature is not constant (poikilothermia) depends on the ambient temperature and only slightly exceeds the latter.
Aromorphoses:
Lungs and pulmonary breathing appeared.
The circulatory system has become more complex, the pulmonary circulation has developed, i.e. Amphibians have two circles of blood circulation - large and small. The heart is three-chambered.
Paired five-fingered limbs were formed, representing a system of levers with articulated joints and intended for movement on land.
A cervical region has formed in the spine, which provides movement of the head, and a sacral region - the place of attachment of the pelvic girdle.
The middle ear, eyelids, and choanae appeared.
Muscle differentiation.
Progressive development of the nervous system.
Phylogeny.
Amphibians evolved from ancient lobe-finned fish in the Devonian period of the Paleozoic era approximately 350 million years ago. The first amphibians, Ichthyostegas, resembled modern tailed amphibians in appearance. Their structure had features characteristic of fish, including rudiments of the gill cover and lateral line organs.
Cover. Double layer. The epidermis is multilayered, the corium is thin, but abundantly supplied with capillaries. Amphibians have retained the ability to produce mucus, but not with individual cells, as in most fish, but with formed alveolar-type mucous glands. In addition, amphibians often have granular glands with a poisonous secretion varying degrees toxicity. The skin color of amphibians depends on special cells - chromatophores. These include melanophores, lipophores and iridocytes.
Under the skin of frogs there are extensive lymphatic lacunae - reservoirs filled with tissue fluid and allowing, under unfavorable conditions, to accumulate a supply of water.
Skeleton divided into axial and accessory, as in all vertebrates. The vertebral column is more differentiated into sections than in fish and consists of four sections: cervical, trunk, sacral and caudal. The cervical and sacral sections each have one vertebra. Anurans usually have seven trunk vertebrae, and all caudal vertebrae (about 12) merge into a single bone - the urostyle. Caudates have 13 - 62 trunk and 22 - 36 caudal vertebrae; in legless animals the total number of vertebrae reaches 200–300. The presence of a cervical vertebra is important because Unlike fish, amphibians cannot turn their body so quickly, and the cervical vertebra makes the head mobile, but with a small amplitude. Amphibians cannot turn their heads, but they can tilt their heads.
The type of vertebrae in different amphibians may vary. In legless and lower caudate vertebrae are amphicoelous, with a preserved notochord, like in fish. In higher caudates, the vertebrae are opisthocoelous, i.e. The bodies are curved in front and concave in the back. In tailless animals, on the contrary, the anterior surface of the vertebral bodies is concave and the posterior surface is curved. Such vertebrae are called procoelous. The presence of articular surfaces and articular processes not only ensures a strong connection of the vertebrae, but also makes the axial skeleton mobile, which is important for the movement of tailed amphibians in water without the participation of limbs, due to the lateral bending of the body. In addition, vertical movements are possible.
The amphibian skull is a modified skull of a bony fish, adapted to terrestrial existence. The brain skull remains predominantly cartilaginous for life. The occipital region of the skull contains only two lateral occipital bones, which are carried along the articular condyle, with the help of which the skull is attached to the vertebrae. The visceral skull of amphibians undergoes the greatest transformations: secondary upper jaws appear; formed by the premaxillary and maxillary bones. The reduction of gill breathing led to a radical change in the hyoid arch. The hyoid arch is transformed into an element of the hearing aid and a sublingual plate. Unlike fish, the visceral skull of amphibians is directly attached by the palatoquadrate cartilage to the bottom of the brain skull. This type of direct connection of the components of the skull without the participation of elements of the hyoid arch is called autostyly. Amphibians lack elements of the operculum.
The accessory skeleton includes the bones of the girdles and free limbs. Like fish, the bones of the shoulder girdle of amphibians are located in the thickness of the muscles that connect them to the axial skeleton, but the girdle itself is not directly connected to the axial skeleton. The belt provides support for the free limb.
All land animals constantly have to overcome gravity, which fish do not have to do. The free limb serves as a support, allows you to lift the body above the surface and provides movement. The free limbs consist of three sections: proximal (one bone), intermediate (two bones) and distal (relatively large number of bones). Representatives of different classes of terrestrial vertebrates have structural features of one or another free limb, but all of them are of a secondary nature.
In all amphibians, the proximal part of the free forelimb is represented by the humerus, the intermediate part by the ulna and radius in caudates, and a single bone of the forearm (it is formed as a result of the fusion of the ulna and radius) in anurans. The distal section is formed by the wrist, metacarpus and phalanges of the fingers.
The girdle of the hind limbs articulates directly with the axial skeleton, with its sacral section. A reliable and rigid connection of the pelvic girdle with the spinal column ensures the functioning of the hind limbs, which are more important for moving amphibians.
Muscular system differs from muscular system fish The trunk muscles retain their metameric structure only in the legless. In caudates, the metamerism of segments is disrupted, and in tailless amphibians, sections of muscle segments begin to separate, differentiating into ribbon-shaped muscles. The muscle mass of the limbs increases sharply. In fish, the movements of the fins are ensured mainly by muscles located on the body, while the five-fingered limb moves due to muscles located in itself. A complex system of muscles - antagonists - flexor and extensor muscles appears. Segmented muscles are present only in the region of the spinal column. The muscles of the oral cavity become more complex and specialized (masticatory, tongue, floor of the mouth), not only involved in the capture and swallowing of food, but also providing ventilation of the oral cavity and lungs.
Body cavity– in general. In amphibians, due to the disappearance of gills, the relative position of the pericardial cavity has changed. She was pushed to the bottom of the chest into the area covered by the sternum (or coracoid). Above it, in a pair of coelomic canals, lie the lungs. Cavities containing the heart and lungs. Separates the pleurocardial membrane. The cavity in which the lungs are located communicates with the main coelom.
Nervous system. The brain is of the ichthyopsid type, i.e. the main integrating center is the midbrain, but the amphibian brain has a number of progressive changes. The amphibian brain has five sections and differs from the fish brain mainly in the greater development of the forebrain and the complete separation of its hemispheres. In addition, the nerve substance already lines, in addition to the bottom of the lateral ventricles, also the sides and roof, forming the medullary vault - the archipallium. The development of the archipallium, accompanied by strengthening connections with the diencephalon and especially the midbrain, leads to the fact that associative activity regulating behavior in amphibians is carried out not only by the medulla oblongata and midbrain, but also by the forebrain hemispheres. The elongated hemispheres in front have a common olfactory lobe, from which two olfactory nerves originate. Behind the forebrain is the diencephalon. The epiphysis is located on its roof. On the underside of the brain there is an optic chiasm (chiasma). The infundibulum and the pituitary gland (lower medullary gland) extend from the bottom of the diencephalon.
The midbrain is represented as two round optic lobes. Behind the optic lobes lies the underdeveloped cerebellum. Immediately behind it is the medulla oblongata with the rhomboid fossa (fourth ventricle). The medulla oblongata gradually passes into the spinal cord.
In amphibians, 10 pairs of head nerves arise from the brain. The eleventh pair is not developed, and the twelfth pair extends outside the skull.
The frog has 10 pairs of true spinal nerves. The three anterior ones take part in the formation of the brachial plexus, which innervates the forelimbs, and the four posterior pairs take part in the formation of the lumbosacral plexus, which innervates the hind limbs.
Sense organs provide orientation for amphibians in water and on land.
All larvae and adults with an aquatic lifestyle have lateral line organs. They are represented by a cluster of sensitive cells with nerves corresponding to them, which are scattered throughout the body. Sensitive cells perceive temperature, pain, tactile sensations, as well as changes in humidity and chemical composition of the environment.
Olfactory organs. Amphibians have a small external nostril on each side of the head, which leads into an elongated sac that ends in the internal nostril (choana). The choanae open at the front of the roof of the oral cavity. In front of the choanae on the left and right there is a sac that opens into the nasal cavity. This is the so-called vomeronasal organ. In him a large number of sensory cells. Its function is to receive olfactory information about food.
The organs of vision have a structure characteristic of a terrestrial vertebrate. This is expressed in the convex shape of the cornea, the lens in the form of a biconvex lens, and movable eyelids that protect the eyes from drying out. But accommodation, as in fish, is achieved by moving the lens by contracting the ciliary muscle. The muscle is located in the annular ridge surrounding the lens, and when it contracts, the frog's lens moves forward somewhat.
The hearing organ is arranged according to the terrestrial type. A second section appears - the middle ear, in which the auditory bone, the stapes, which first appears in vertebrates, is located. The tympanic cavity is connected to the pharyngeal region by the Eustachian tube.
The behavior of amphibians is very primitive; conditioned reflexes are developed slowly and fade away quickly. The motor specialization of reflexes is very small, so the frog cannot form a protective reflex of withdrawing one leg, and when one limb is irritated, it jerks both legs.
Digestive system begins with the oral fissure leading into the oropharyngeal cavity. It houses a muscular tongue. The ducts of the salivary glands open into it. The tongue and salivary glands first appear in amphibians. The glands serve only to wet the bolus of food and do not participate in the chemical processing of food. On the premaxillary, maxillary bones, and vomer there are simple conical teeth, which are attached to the bone with their base. The digestive tube is differentiated into the oropharyngeal cavity, a short esophagus that carries food into the stomach, and a voluminous stomach. Its pyloric part passes into the duodenum - the beginning of the small intestine. The pancreas lies in the loop between the stomach and duodenum. The small intestine smoothly passes into the large intestine, which ends in a pronounced rectum that opens into the cloaca.
The digestive glands are the liver with the gallbladder and the pancreas. The liver ducts, together with the gallbladder duct, open into the duodenum. The pancreatic ducts empty into the gallbladder duct, i.e. This gland does not have independent communication with the intestines.
That. The digestive system of amphibians differs from the similar system of fish in the greater length of the digestive tract; the final section of the large intestine opens into the cloaca.
Circulatory system closed. Two circles of blood circulation. The heart is three-chambered. In addition, the heart has a venous sinus that communicates with the right atrium, and the conus arteriosus extends from the right side of the ventricle. Three pairs of vessels depart from it, homologous to the gill arteries of fish. Each vessel begins with an independent opening. All three vessels of the left and right sides first go by a common arterial trunk, surrounded by common shell, and then branch out.
The vessels of the first pair (counting from the head), homologous to the vessels of the first pair of gill arteries of fish, are called carotid arteries, which carry blood to the head. Through the vessels of the second pair (homologous to the second pair of gill arteries of fish) - the aortic arches - blood is directed to the back of the body. The subclavian arteries depart from the aortic arches, carrying blood to the forelimbs.
Through the vessels of the third pair, homologous to the fourth pair of gill arteries of fish - the pulmonary arteries - blood is sent to the lungs. Each pulmonary artery gives rise to a large cutaneous artery, which carries blood into the skin for oxidation.
Venous blood from the anterior end of the body is collected through two pairs of jugular veins. The latter, merging with the cutaneous veins, which have already absorbed the subclavian veins, forms two anterior vena cava. They carry mixed blood into the venous sinus, since arterial blood moves through the skin veins.
Amphibian larvae have one circulation; their circulatory system is similar to the circulatory system of fish.
Amphibians develop a new circulatory organ - the red bone marrow of the long bones. Red blood cells are large, nuclear, white blood cells are not the same in appearance. There are lymphocytes.
Lymphatic system. In addition to the lymphatic sacs located under the skin, there are lymphatic vessels and hearts. One pair of lymphatic hearts is placed near the third vertebra, the other - near the cloacal opening. The spleen, which looks like a small round red body, is located on the peritoneum near the beginning of the rectum.
Respiratory system. Fundamentally different from the respiratory system of fish. In adults, the respiratory organs are the lungs and skin. The airways are short due to the absence of the cervical spine. Represented by the nasal and oropharyngeal cavities, as well as the larynx. The larynx opens directly into the lungs with two openings. Due to the reduction of the ribs, the lungs are filled by swallowing air - according to the principle of a pressure pump.
Anatomically, the respiratory system of amphibians includes the oropharyngeal cavity (upper airways) and the laryngeal-tracheal cavity (lower airways), which directly passes into the sac-like lungs. During embryonic development, the lung is formed as a blind outgrowth of the anterior (pharyngeal) section of the digestive tube, and therefore remains connected to the pharynx in adulthood.
That. The respiratory system in terrestrial vertebrates is anatomically and functionally divided into two sections - the airway system and the respiratory section. The airways carry out two-way transport of air, but do not participate in gas exchange itself; the respiratory department carries out gas exchange between the internal environment of the body (blood) and atmospheric air. Gas exchange occurs through the surface liquid and occurs passively in accordance with the concentration gradient.
The system of gill covers becomes unnecessary, therefore the gill apparatus in all terrestrial animals is partially modified, its skeletal structures are partially included in the skeleton (cartilage) of the larynx. Ventilation of the lungs is carried out due to forced movements of special somatic muscles during the respiratory act.
excretory system, as in fish, it is represented by primary, or trunk buds. These are compact bodies of a reddish-brown color, lying on the sides of the spine, and not ribbon-shaped, like those of fish. From each kidney a thin Wolffian canal stretches to the cloaca. In female frogs it serves only as a ureter, and in males it serves as both a ureter and a vas deferens. In the cloaca, the Wolffian canals open with independent openings. It also opens separately into the cloaca and bladder. The final product of nitrogen metabolism in amphibians is urea. In aquatic amphibian larvae, the main product of nitrogen metabolism is ammonia, which is excreted in solution through the gills and skin.
Amphibians are hyperosmotic animals in relation to fresh water. As a result, water constantly enters the body through the skin, which does not have mechanisms to prevent this, like other terrestrial vertebrates. Sea water is hyperosmotic in relation to the osmotic pressure in the tissues of amphibians; when they are placed in such an environment, water will leave the body through the skin. This is why amphibians cannot live in sea water and die in it from dehydration.
Reproductive system. In males, the reproductive organs are represented by a pair of round, whitish testes adjacent to the ventral surface of the kidneys. Thin seminiferous tubules stretch from the testes to the kidneys. Sexual products from the testis are sent through these tubules to the bodies of the kidneys, then to the Wolffian canals and through them to the cloaca. Before flowing into the cloaca, the Wolffian canals form a small expansion - seminal vesicles, which serve for the temporary storage of sperm.
The reproductive organs of females are represented by paired ovaries of a granular structure. Above them are the fat bodies. They accumulate nutrients that ensure the formation of reproductive products during hibernation. In the lateral parts of the body cavity there are highly convoluted light oviducts, or Müllerian canals. Each oviduct into the body cavity in the region of the heart opens with a funnel; the lower uterine part of the oviducts is sharply expanded and opens into the cloaca. Ripe eggs fall out into the body cavity through a rupture in the ovarian walls, then are captured by the funnels of the oviducts and move along them to the cloaca.
Wolffian canals in females perform only the functions of the ureters.
In tailless amphibians, fertilization is external. The eggs are immediately irrigated with seminal fluid.
External sexual characteristics of males:
Males have a genital wart on the inner finger of the forelimbs, which reaches a special development at the time of reproduction and helps males hold females during fertilization of eggs.
Males are usually smaller than females.
Development amphibians are accompanied by metamorphosis. The eggs contain relatively little yolk (mesolecithal eggs), so radial crushing occurs. A larva emerges from the egg - a tadpole, which in its organization is much closer to fish than to adult amphibians. It has a characteristic fish-like shape - a long tail surrounded by a well-developed swimming membrane, on the sides of the head it has two to three pairs of external feathery gills, there are no paired limbs; There are lateral line organs; the functioning kidney is the pronephros (pre-kidney). Soon the external gills disappear, and in their place three pairs of gill slits with their gill filaments develop. At this time, the similarity of the tadpole with a fish is also a two-chambered heart, one circle of blood circulation. Then, by protrusion from the abdominal wall of the esophagus, paired lungs develop. At this stage of development, the arterial system of the tadpole is extremely similar to the arterial system of lobe-finned and lungfishes, and the only difference is that due to the absence of the fourth gill, the fourth afferent gill artery passes into the pulmonary artery without interruption. Even later, the gills are reduced. In front of the gill slits, a fold of skin is formed on each side, which, gradually growing back, tightens these slits. The tadpole switches entirely to pulmonary breathing and swallows air through its mouth. Subsequently, the tadpole develops paired limbs - first the front ones, then the hind ones. However, the anterior ones remain hidden under the skin longer. The tail and intestines begin to shorten, mesonephros appears, the larva gradually moves from plant food to animal food and turns into a young frog.
During the development of the larva, its internal systems are reconstructed: respiratory, circulatory, excretory, digestive. Metamorphosis ends with the formation of a miniature copy of the adult individual.
Ambystomas are characterized by neoteny, i.e. They reproduce with larvae, which for a long time were mistaken for an independent species, which is why they have their own name - axolotl. This larva is larger than the adult. Another interesting group are proteas that constantly live in water, which retain external gills throughout their lives, i.e. signs of a larva.
The metamorphosis of a tadpole into a frog is of great theoretical interest, because not only proves that amphibians descended from fish-like creatures, but makes it possible to reconstruct in detail the evolution of individual organ systems, in particular the circulatory and respiratory systems, during the transition of aquatic animals to terrestrial ones.
Meaning amphibians is that they eat many harmful invertebrates and themselves serve as food for other organisms in the food chain.
Evolution of the respiratory system
Stages of the breathing process
Breath– a set of processes that ensure the supply of oxygen to the body from the environment, necessary for the oxidation of organic substances in the mitochondria of the cell, and the release of carbon dioxide
Types of breathing:
Breathing type:
Cellular.
Organisms: single-celled animals (amoeba, green euglena, slipper ciliates); coelenterates (jellyfish, coral polyps) ; some worms.
Single-celled organisms absorb oxygen dissolved in water over the entire surface of the body by diffusion.
Oxygen is involved in the breakdown of complex organic substances, resulting in the release of energy that is necessary for the life of the animal.
The carbon dioxide produced as a result of respiration is also released through the entire surface of the body.
Tracheal breathing is breathing using a system of united tracheal tubes that permeate the entire body.
Organisms: class Insects (beetles, butterflies, grasshoppers, flies)
The insect's abdomen is divided into 5–11 parts (segments). Each of them has a pair of small holes - spiracle. Branching tubes extend inward from each spiracle - trachea, which permeate the entire body of the insect. Watching the cockchafer, you can notice how its abdomen either decreases in volume or increases in size. These are breathing movements. When you inhale, air containing oxygen enters the body through the spiracles, and when you exhale, air saturated with carbon dioxide comes out.
In spiders (class Arachnids), the respiratory organs are represented not only by tracheas, but also by pulmonary sacs, which communicate with the external environment through the respiratory openings.
Gill respiration is breathing using specialized structures with a dense network of blood vessels.
Organisms: many aquatic inhabitants (fish, crayfish, mollusks)
Fish breathe oxygen dissolved in water with the help of special branched skin outgrowths called gills.
Fish constantly swallow water. From the oral cavity, water passes through the gill slits, washes the gills and comes out from under the gill covers. Gills consist of gill arches And gill filaments, which are penetrated by many blood vessels. From the water that washes the gills, oxygen enters the blood, and carbon dioxide is removed from the blood into the water. The gills located inside the body are called internal gills.
Some animals, such as amphibians, have dense tufts of gills on the surface of their bodies. Such gills are called - external. This is the structure of Proteus, a blind cave animal from the western regions of Yugoslavia, and axolotls (which are similar in general appearance to newts) - their homeland is Mexico.
The evolution of breathing.
1) Diffuse breathing- This is the process of equalizing the concentration of oxygen inside the body and in its environment. Oxygen penetrates the cell membrane in single-celled organisms.
2) Skin breathing- this is the exchange of gases through the skin in lower worms and in vertebrates (fish, amphibians), which have special respiratory organs.
Gill breathing
PINUS GILLS(skin outgrowths on both sides of the body) appear in marine annelids, aquatic arthropods, and in mollusks in the mantle cavity.
GILLS- respiratory organs of vertebrate animals, formed as invaginations of the digestive tube.
In the lancelet, the gill slits penetrate the pharynx and open into the circumbranchial cavity with frequent changes of water.
Fish have gills from gill arches with gill filaments pierced by capillaries. The water swallowed by the fish enters the oral cavity, passes through the gill filaments outward, washes them and supplies the blood with oxygen.
4) Tracheal and pulmonary breathing- more effective, since oxygen is absorbed directly from the air, and not from water. Characteristic of terrestrial mollusks (sac-like lungs), arachnids, insects, amphibians, reptiles, birds, and mammals.
Arachnids have lung sacs (scorpions), tracheas (mites), and spiders have both.
INSECTS have tracheas - the respiratory organs of terrestrial arthropods - a system of air tubes that open with respiratory openings (stigmas) on the lateral surfaces of the chest and abdomen.
AMPHIBIANS They have 2/3 cutaneous respiration and 1/3 pulmonary respiration. The airways appear for the first time: larynx, trachea, bronchial rudiments; lungs are smooth-walled bags.
REPTILES have developed airways; the lungs are cellular, there is no skin respiration.
BIRDS have developed airways, spongy lungs. Some of the bronchi branch outside the lungs and form air sacs.
Air bags- air cavities connected to the respiratory system, 10 times larger than the volume of the lungs, serving to enhance air exchange in flight, do not perform the function of gas exchange. Breathing at rest is carried out by changing the volume of the chest.
Breathing in flight:
1. When the wings rise, air is sucked through the nostrils into the lungs and rear air sacs (I gas exchange in the lungs);
Front air bags← light - rear air bags
2. When the wings lower, the air sacs are compressed, and air from the rear air sacs enters the lungs (II gas exchange in the lungs).
Front air bags - light ← rear air bags
Double Breathing- This is the exchange of gases in the lungs during inhalation and exhalation.
MAMMALS- gas exchange is almost entirely in the lungs (through the skin and alimentary canal -2%)
Airways: nasal cavity → nasopharynx → pharynx → larynx → trachea → bronchi (bronchi branch into bronchioles, alveolar ducts and end with alveoli - pulmonary vesicles). The lungs have a spongy structure and consist of alveoli intertwined with capillaries. The respiratory surface is increased 50-100 times compared to the surface of the body. The type of breathing is alveolar. The diaphragm, which separates the chest cavity from the abdominal cavity, as well as the intercostal muscles, provide ventilation to the lungs. Complete separation of the oral and nasal cavities. Mammals can breathe and chew at the same time.
