Most other vertebrates, the basic feature is the secretion of milk by the mother's breast-feeding newborn son. In addition to the minimum so as oviparous monotremes, other mammals are viviparous.
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Definition
Mammals (mammal) is a constant temperature of mammals, vertebrates, body hair, most of them are viviparous, and by breast-feeding children. Mammal is an animal most advanced stage of history, is the closest relationship with a human group.
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The main characteristics of mammals
Mammals have a number of unique features, which during evolution was a great success. The most important features are: intellectual and sensory capacities of further development; to maintain constant temperature; breeding efficiency; access to food and food handling capacity enhancement; surface hairy, viviparous, hairy surface of the body feeding, usually separately, neck, trunk, limbs and tail of five parts; have lungs; body temperature constant, is the temperature of animals; brain larger and developed. Breast-feeding and the placental mammals the most significant features. In the development of embryos in the womb, the mother animal direct output fetus. Mother animal has mammary glands that secrete milk feeding animals, Aberdeen. All this involves changes in the structure of the various parts of the body, including brain size increases and the emergence of new brain skin, visual, and highly developed sense of smell and hearing than other vertebrates have a greater specialization; teeth and the digestive system in favor of specialization effective use of food; limbs specialized activity increased. Facilitate access to food and avoid predators; respiratory and circulatory systems were perfect and unique coverage of the hair helps maintain a constant surface temperature, to ensure they survive under broad environmental conditions; viviparous, nursing and other unique features to ensure that their offspring have a higher survival rate and some types of complex social behavior development.
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1. Skin
Mammalian skin tight, structured, has an important protective role, with good resistance to water, control of body temperature and a keen sense of functionality. To adapt to changing external conditions, the skin's texture, color, odor, temperature and other conditions in harmony with the environment. The main features of mammalian skin: (1) improve the skin's structure Mammalian epidermis and dermis of skin from the composition of the surface of the epidermis is the stratum corneum, the epidermis composed of living cells deep to the germinal layer. Epidermis has many derivatives, such as glands and hair, horns, claws, nails, hooves. Leather developed by the collagen fibers and elastic connective tissue fibers, two fiber staggered, during distribution of a variety of connective tissue cells, receptors, motor nerve endings and blood vessels, lymphatic and so on. Have developed in the cellular subcutaneous tissue, most mammals are rich in this fat storage, it is also known as subcutaneous fat cell layer. (2) derivatives of various skin Derivatives of mammalian skin, including skin glands, hair, horns, claws, nails, hoofs. 1) skin glands: highly developed, derived from the germinal layer of the epidermis, according to the different structure and function can be divided into breast, sweat glands, skin glands, scent glands (musk glands) and so on. Another skin glands to sweat glands, is a tubular gland, its main function is to eliminate part of the steaming heat and metabolic waste. Evaporation of surface water cooling is sweating, is a mammal an important way of regulating body temperature, some types of sweat glands developed, mainly by the mouth, tongue and nose surface evaporation cooling. Sebaceous glands for the bubbly, open at the base of hair follicles, glands for the whole pulp, the secretion of oil, hair and skin lubrication, it is also an important source of foreign hormones. Smell the sweat glands or sebaceous gland derivatives, the main function is to mark the field, transmission of information, and some also have self-protection. Dozens of odor glands, such as the musk gland. Anal glands, abdominal gland, lateral gland, dorsal gland, preputial glands and so on. Scent gland of the emergence and level of development, usually with the mammalian sense of smell as the primary way associated predators, and the visual as the main group Locator their sense of smell and odor glands were significantly degraded. 2) Mao: The structure is unique to mammals, is a product of epidermal keratinocytes. Hair from the hair shaft and hair root composition. Hair shaft cortex and medulla by the Ministry of composition; hair root follicles was born inside and outside the hair sheath, said terminal globular enlargement of the hair bulb, the base of the leather composed of dermal papilla, is rich in blood vessels, can transport Mao nutrients necessary for growth. There are sebaceous glands in the hair follicle openings, can secrete oil, lubricating hair and skin; vertical hair follicles there are muscles attached to the base, erect hair contraction can help regulate body temperature. By gross morphology, can be divided into long hair and have some tough hair to the hairs (bristle), no hair to the hair soft and made from the hairs touch specialized hair. In vitro formation of mammalian hair coat are often the main function is insulation, insulation. Basically hairless aquatic mammal species such as whales, have developed subcutaneous fat in order to maintain constant body temperature. Often subject to wear and fade hair, usually a year, the second periodic molting, usually the summer is short and thin hair, never heat is poor, dense and long hair in winter, good insulation properties. Terrestrial mammals, coat color of their living environment, often consistent, usually forest or dense vegetation in the lower mammals hair was dark, gray open areas, mostly desert sand yellow. 3) The angle: It is true mammalian epidermis and Peter head of the product. Epidermal keratinocytes produce angle, such as cattle, sheep and rhino horn sheath epidermal angle, angle of dermal bone formation, such as antlers. Mammals can be divided into the corner hole angle, solid angle, pronghorn horn, giraffe angle, angle of five types of skin. Hole angle, from the heart and the horny sheath of bone composition, horny sheath that is called the angle of study, pairs was born in the frontal bone, the lifetime does not change, there is a growing trend. Hole angle of bovine animals are endemic. Solid angle, the angle of bifurcation of the bone, no horn sheath. A new angle in the bone Nenpi heart, known as antlers, such as velvet. Into a corner after a long, dried skin aging, loss, retaining only the last branch of the bone angle, such as antlers. Periodic shedding antlers each year and re-growth, it is the characteristics of deer. Apart from a few angles, such as gender with reindeer, or a corner, such as musk deer, deer, the males generally only a corner. Pronghorn angle between the holes is a kind of angle and the angle between the antlers. Heart does not bifurcation angle bone sheath with a small fork, bifurcation integration on the corner of the hair sheath, the sheath hairy angle off each year for the reproductive period, the heart does not fall off bone. This angle is specific to the male pronghorn, and only a short female pronghorn horn horns heart without sheath. Giraffe angle, posed by the skin and bone, skin, bone and other body heart of sub-skin almost no difference. Epidermal angle, entirely by stratum corneum composed of fibers of hairy skin, no bone composition, specific subjects for the rhino. Angle of the students in a unique position in the nasal middle of the types of corners were two horns in tandem, was born in front nose, the growth in the maxillary posterior horn of the Ministry. 4) claws, armor and shoes: are derivatives of the skin, is the (toe) end of the Deformation of the stratum corneum, but the shape of different functions. Claw, for most mammals possess, the type of activities engaged in mining in particular developed claws. Shiquan sharp claws like meat, such as cats sharp claws and can stretch is an effective predator weapons. A, essentially flat claws, is unique to primates. Hoof, as thickening of the claw, ungulates developed, and may continue to hyperplasia, to compensate for the wear parts.
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2. Skeleton
Mammalian skeletal system development, support, protection and functional movement. Mainly by the axial skeleton and appendicular skeleton of two parts. Its structure and function of the major features are: a greater specialization of the skull, the occipital bone with the two ankles, lower jaw bone by a single tooth structure, tooth shaped; spine partition obvious structure of a solid and flexible, cervical 7; limbs down to the ventral surface, appears and knee, will prop up the body to adapt to rapid movement on land. (1) axial skeleton Including the skull, spine, sternum and ribs. (2) appendicular skeleton Including straps, belts, front limb bones and after limb bones. 1) Shoulder: the shoulder blade, black beak bone, collarbone composition. Terrestrial mammals, the scapula is well developed shoulder strap, black pecked on the bone degenerates into a protruding shoulder blade. Clavicle and more tends to degradation, some non collarbone, such as class and cloven-hoofed Perissodactyla. In for climbing, digging soil and fly life groups in the clavicle is well developed. Shows the degree of forelimb clavicle modalities developed close ties, where the forelimbs for the type of activities before and after the degradation of the clavicle, the left and right forelimb for the type of the clavicle developed. 2) Belt: from the ilium, ischium and pubic bone composition. Iliac bone and the relevant section of the sacrum, left and right ischium and pubic bone healing in the belly of the line into a piece of bone marrow to form closing the pelvis. Mammals belt healing, strengthen the firmness of hindlimb support.
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3. Muscle
Muscle system of mammals and reptiles are similar, but the structure and function were further refined. Main properly features: the limbs and trunk muscles with a high degree of plasticity. In order to meet the different sports in different muscle patterns emerged, such as adapting the fast running and carnivorous ungulate limb muscles strong. Skin-muscle is well developed. Mammalian skin-muscle can be divided into two groups: one group of muscles for the lipid membranes, can vibrate the whole body or local skin, in order to expel the foreign body attached to mosquitoes and shaken. Muscle lipid membranes can also be the body curled into a ball, or the erection of defensive spines predators, such as Ling Li, porcupines, hedgehog. Mammal species in the lipid membranes of higher muscle degeneration, only in the chest, shoulder and groin occasional reservations. Another group of skin-muscle sphincter for the neck, the ventral surface of the platysma face along the chin and face and neck extension, the formation of facial muscles and facial expression muscles. Mammalian species in low expressionless muscle, muscle predators of emotion, the expression of primate good muscle development, and human expression of the most developed muscles, about 30 blocks. Around the mouth lip around the complex, in the sucking played a very important role. In addition, the distribution in the cranial and zygomatic arch, beyond the mandible (dentary) of the temporal muscle and mas_set_er muscle power, which is prey, defense, and is closely related to chewing mouth. Specific for the mammalian diaphragm muscle, a transverse position of the voluntary muscles, the organs into the chest cavity and abdominal cavity separation, the activities of the diaphragm helps breathing.
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4. Digestion
Mammals, including the digestive tract and digestive gland digestive system. In the structure and function to show the main features is the high degree of differentiation digestive tract, there has been oral digestion, a marked improvement in digestion. Is associated with well-developed digestive gland. (1) digestive tract Including the oral cavity, pharynx, esophagus, stomach, small intestine, large intestine and so on. 1) Oral: Oral mammalian chewing and digestion method caused large changes in the oral structures. Appeared fleshy lips, the breast pump, feeding, supporting the vital organs of mastication, and articulation organs of pronunciation part. Lips grazing mammals developed, and some have cleft upper lip, such as the rabbit. To meet the chewing activity, mammals gape narrow, and there on both sides of the outside of the cheek teeth, some types of cheek pouch has also developed the structure of the cheek pouch was used to store food, such as the monkey. Top wall of oral hard palate and soft palate by the bone structure, thereby opening the nasal cavity (the nose) and oral separated from the access road that is along the hard palate nose. Underwent soft palate, until now the site of the throat, nose, after opening in the pharynx. Often horny palate epithelium edge to prevent slippage of food. Herbivorous and carnivorous species have developed skin edge. There are well-developed oral tongue muscles, help feeding, mixing and swallowing, as well as auxiliary organs of the human voice. Distribution of the tongue surface, taste buds, the taste organs. Upper and lower jaws are shaped teeth on the students, tooth from the alveolar to grow, in the medullary cavity, filled with connective tissue, blood vessels and nerves. Because of the shape and function of different teeth, one by one cutting food can be divided into incisors, canines tear food � �, � � molar biting, cutting, pressing, grinding and other food function. Different feeding habits of mammals, the shape of their teeth, have a large number of changes. But the same types of gear type and number of teeth is stable. Therefore, the number of teeth for the mammalian tooth shape and an important basis for classification, usually expressed in gear. Half of the maxillary teeth to write online, writing online mandibular teeth under half (equivalent formula is written), such as wolves and foxes, upper and lower incisors on either side of three (3 / 3), one canine (1 / 1 ), 4 premolars (4 / 4) and two upper molars and lower molars 3 (2 / 3). Can be abbreviated as i.3 / 3, c.1.1, p.4 / 4, m · 2 / 3 = 42; or 3/3.1/1, 4 / 4, 2 / 3 = 42; or derived from a few 42 gear twice, because the number of teeth gear list only half of the total. The basic number of teeth with placental most, 44 (3 / 3, 1 / 1, 4 / 4, 3 / 3), but tends to reduce the number of animals, some species entirely without teeth (such as anteaters, pangolins); CD There are some specialized whale teeth over 44; marsupials some families have more teeth. Mammals within the parotid gland mouth, submandibular and sublingual gland and other 3 pairs of salivary glands, a conduit opening in the mouth, salivary amylase secretion, oral digestion of foods. In addition, some mammals, evaporative water loss in oral salivary gland, as a form of body temperature regulation. 2) pharynx: pharyngeal structure mammalian improve the interface chamber before and after laryngeal and esophagus. Since the formation of the secondary palate, the nose is also opening up the throat, so the throat is the intersection of digestive tract and respiratory tract. There are syringes on both sides of the throat (eustachian tube) opening, adjustable air pressure in the middle ear cavity to protect the tympanic membrane. Lymph node around the throat (tonsils) distribution. One will be outside the operculum laryngeal cartilage, which open and close to solve the pharynx, larynx and cross parts of the contradiction between breathing and swallowing. 3) the esophagus: immediately after the pharynx, is a slender tube, under the termination stomach. Access to food through the esophagus, without digestion. 4) stomach: an important part of the digestive tract in mammals, its morphology often varies due to diet, most mammals, a single stomach; herbivorous mammals are complex stomach, also known as the ruminant stomach, usually consists of 4 chambers, namely, rumen, reticulum (reticulum), omasum and proventriculus (abomasum). Only the stomach glandular body, with glandular epithelium can secrete gastric juice, the other three rooms are of the esophagus stomach and deformation. With a complex stomach herbivorous animals, the digestive process in food to be regurgitated many times, until the full break down of food so far. 5) the small intestine: the mammalian small intestine is the longest part of the digestive tract, including duodenum, jejunum and ileum. High degree of intestinal differentiation, and its rich mucosal villi, blood vessels, lymph and thoracic duct, increased absorption of nutrients. 6) large intestine: shorter than the small intestine, the mucosa is no fluff, the mucus glands that secrete alkaline mucus to protect and lubricate the intestinal wall, to facilitate the feces. Started in the large intestine of a blind branch of the Ministry of the cecum, the terminal one appendix. Cecum herbivores in a single chamber of the stomach developed, except walruses, armadillos, ant bear, hyraxes, which are one pair of the cecum, other mammals have only one appendix. Mammals can be divided into colon and rectal colon, rectum, anus open directly in vitro (cloaca disappeared), is the mammals and amphibians, reptiles, birds, a significant difference. (2) digestive gland Digestive gland in mammals than 3 on the salivary glands, the back of the diaphragm, liver and pancreas nearby small intestine, bile and pancreatic juice, respectively, into the duodenum. In addition to the secretion of hepatic bile, there is glycogen storage, regulation of blood sugar, so that the excess oxygen to form amino acids and other compounds in urine, certain toxic substances into non-toxic substances, plasma protein synthesis and other functions.
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5. Respiratory
Mammalian respiratory system is well developed, especially in the respiratory efficiency has improved significantly. Outside air through the nose, nasal cavity, larynx, trachea and lungs. (1) nasal Mammalian olfactory nasal cavity can be divided into upper part and lower part of the respiratory ventilation. Have developed the upper nasal turbinate, olfactory cells within the mucosa. In addition, the skull bone extends into the paranasal sinus cavity to enhance the nasal cavity of the air warm, moist and filtering effect. It is also the voice of the resonator. (2) throat Construction of mammalian throat perfect. Swollen throat as part of the front of the trachea, both respiratory channel, but also vocal organs. Hose from the cartilage, ligaments, muscles and mucous membrane composition. Said entrance throat throat, larynx abdominal wall will be the leading edge of operculum cartilage covering the throat when swallowing, food and water by the Council operculum above into the esophagus, preventing food and water strayed into the trachea. Usually open throat, trachea and out of the air portal. By the thyroid cartilage and cricoid cartilage of the throat, in the middle of the wall on the formation of vocal fold mucosa as the vocal organs, began to appear in tailless amphibians, but the most advanced mammals (only one hole has bags of class and class absent). (3) tracheal Located in the ventral esophagus into the chest after the bifurcation into a pass into the lungs of bronchial. Trachea and bronchi in the structure of the main features are: the back wall by a number of convergence of the cartilage ring is not supported, thus ensuring the smooth flow of air. Ciliated tracheal mucosa epithelium and mucus glands, can filter the air, mucus gland secretion of mucus can stick in the air inhaled dust particles, dust particles in the cilia to move under the impetus of throat, nasal or oral discharge. (4) lung and pleural The most complex structure of mammalian lung, is a complex "bronchial tree," the composition of the blind-side is the bronchial alveolar branch. Alveolar volume is very large, thus greatly increasing the respiratory surface area, such as the sheep up to the total area of alveolar 50 ~ 90m2, the alveoli of horses 500m2, human alveolar to 70m2, the equivalent of 40 times the surface area to significantly increase the gas exchange effect. Between the distribution of alveolar elastic fibers in the lungs can breathe with the passive retraction the next. Pleural cavity is the capacity of the lung, the mammals are unique, when the respiratory activity, the lung elastic mouth bit, so that the chest was negative pressure, so that the parietal and visceral pleura close together. In addition, unique to mammals, the chest and abdomen separated from the diaphragm, chest in the movement to change the dirty volume, coupled with the movements of the ribs to expand or reduce the volume of the chest, so that the mammalian lung expansion and retraction passive, to complete the exhale and inhale.
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6. Cycle
Mammalian circulatory system including blood, heart, blood vessels and lymphatic system. The salient feature of rapid cycling in the maintenance of a very prominent, to ensure adequate oxygen and nutrients to maintain constant body temperature. Left aortic arch with the body. Seedless red blood cells. (1) blood The blood of mammals and other vertebrates is different: a nuclear-free red blood cells, showing the two hollow resembling a flat, only the camel and the giraffe Section Division oval-shaped red blood cells; red blood cell volume smaller than the other classes of vertebrates, such as the frog red blood cells length of the diameter of 22.8μmxl5.8μm, dove for the 14.7μmx6.5μm, cattle 5.1μmx5.1μm, musk deer as 2.5μmx2.5μm; the number of red blood cells as breast-feeding more than other vertebrates such as mammals up to 600 13 million. These features greatly increase its surface area, and increased ability to bind with oxygen. (2) heart The heart of mammals left in the middle of the chest at the pericardial cavity, cavity with a small amount of liquid, can reduce the friction when the heart beats. The internal structure of the heart essentially the same with birds, but also for the four-chamber, full of double-loop, mixed arterial and venous blood is not within the heart. Right atrium and right ventricle and pulmonary artery and vein form the pulmonary circulation. Right atrial and ventricular walls are thin, the stored blood, the tricuspid valve between AV. Left atrium and left ventricle with arteriovenous constitute the systemic circulation. Left atrial and ventricular wall thick, internal storage arterial, atrioventricular with mitral valve. All of these valves function is to ensure that blood flows in one direction, to prevent blood reflux. Heart muscle's blood supply is accomplished by the coronary circulation. (3) vascular Including arteries, veins and capillaries. Prominent feature of mammalian arterial system are: the body with only the left aortic arch. Dorsal arterial arch bend the left side to reach the end of dorsal aorta, the body along the way to reach all branches of issue. Mammals tend to simplify the venous system, the first large single vein (superior vena cava), and after a large vein (IVC) instead of the lower tetrapod paired emperor before the main vein and vein. Renal portal vein disappeared, tail and hind legs after the blood directly into the large vein Huixin. This reduces the steps a through tiny blood vessels, help to speed up blood flow and increase blood pressure. In addition, mammals disappeared in the adult abdominal vein. (4) lymph Lymphatic system is well developed in mammals, which may be arterial and venous vascular pressure, tissue fluid is difficult to directly related to intravenous Huixin. Originated in the interstitial lymphatic vessels, the tip for the blind side of the lymphatic capillaries, some way into the tissue fluid through the infiltration of lymphatic capillaries. Lymphatic capillaries into the tissue fluid, its composition and plasma approximation, but less protein content, no red blood cells and platelets. Lymphatic capillaries together into larger lymphatic vessels, the latter mainly through the thoracic duct into the large vein Huixin before. Therefore, only for lymph tissues to the veins to the heart from the one-way flow. There are valves to prevent lymphatic lymph reflux. Secondary lymphatic tissue fluid back, play an important role in maintaining blood volume. In addition, lymphatic transport of fat is the main way, the small intestine lymphatic (lacteal) carry fat through the thoracic duct before the large vein Huixin input. Lymphocytes in lymph nodes is the main organ formation, and has block foreign body, protect the body's functions. Mammalian lymph nodes is very developed, over the body of the lymphatic system access, especially in the neck, armpit, the Ministry of Squirrel Creek, mesenteric and other parts more concentrated. In addition, the tonsils, spleen and thymus is a lymphoid organ.
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7. Excretion
Improve the drainage system constructed in mammals, including kidney, ureter, bladder and urethra. In addition, the skin is also unique excretory organ of mammals. The main function of excretory system is that the waste will be removed from the body cell metabolism and cell survival depends on maintaining the environment is relatively stable. Kidney is the main excretory organ, the mammalian kidney is usually composed by a pair, located in the back of the abdominal cavity, on both sides of the spine. Was bean-shaped kidney, the renal inner edge, said recessed door, arteries, veins, nerves and out of office deduction ureters. Renal cortex and medulla by the two parts. In the renal hilum, ureter Qiduan expanded into the renal pelvis. The outer cortex of the kidney by numerous renal corpuscles, tubules and blood vessels. Each renal corpuscle and renal tubules to form a unit, each kidney or even hundreds of thousands of millions of nephrons, renal corpuscle and made by the glomerular capillary coiled and double-wrapped in its external wall renal capsule composition. From the kidney capsule through a coiled tubular slender, extending from the cortex to the medulla. Tubules within the pool to the medulla collecting duct, and many form the renal papillary collecting duct opening in the pelvis, the urine through the ureter into the bladder that result, and then excreted through the urethra. The formation of urine, including the role of glomerular filtration, tubular reabsorption to the role of collecting duct and secretion. Glomerular blood flow, due to the ball diameter smaller than the afferent arteries of small arteries, it is within the capillary blood pressure increase, the addition of plasma proteins in the water and most other substances through capillary walls small wall and into the kidney and renal capsule. Therefore, the production of urine, caused by the blood pressure level of filtration. Mammalian form of urine is urea, uric acid compared with other amniotes form. By the renal tubular secretion of urea produced, the urine can thicken.
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8. Nerve
Mammalian nervous system is highly developed, mainly in the brain and cerebellum volumes increased, the development of new brain skin, forming a complex folds of the brain surface (ditch and back), a new brain greatly increased skin surface area. (1) New brain skin By lateral growth from the outer wall of the nerve substance, and surrounded by primary cerebral cortex (the original brain skin), the original remnants of the brain called the hippocampus of the skin, in the lateral ventricle, the smell is still central. Cerebral cortex from developed a new form, which accepts a variety of feelings from the body of the device came the impulse, through comprehensive analysis and in accordance with the established neural connections and a corresponding reflected. Left and right cerebral hemispheres to contact each other through a number of nerve fibers. Pathway composed of nerve fibers called the corpus callosum, is a mammal (with Yi-disc type)-specific structures. (2) between the brain Covered by the cerebral hemispheres, which have a pineal gland, the endocrine body, the pineal gland of mammals tend to shrink. Issued in the ventral surface of the optic nerve between the brain and form the optic nerve cross, said cross, and subsequently edged associated with the pituitary gland. Between the brain cavity, also known as the third ventricle, is developed. Wall between the brain's neural structures are also known as the back side of the thalamus and ventral thalamus hypothalamus. Hypothalamus is the central and cerebral cortex low-level intermediate station between the parser, the sensory impulses from the body are focused on here, the gray matter between the brain of a neuronal re-entry for the cerebral cortex. Ventral hypothalamus is the central autonomic activity, is closely related with the coordination of visceral activities, and body temperature regulation center. (3) in the brain Developed in the mammalian brain, the volume is very small, the stenosis was a brain, the brain known as the aqueduct, and the third and fourth ventricle traffic. The back side of the brain with four stacked body, in front of a pair of the visual reflex center, behind a pair for the auditory reflex center. In the bottom of the downward movement of the brain nerve fibers constitute a more significant brain enough. (4) cerebellum Mammalian brain in the back is a very well-developed cerebellum, and its main function is to coordinate muscle movements and body posture to maintain the normal balance of the central body. Mammals in the structure of the cerebellum has a unique feature is a cerebellar cortex, the gray matter covering the surface, the formation of cerebellar cortex, deep white matter, gray matter was dendritic. In addition, between the two cerebellar hemispheres, the nerve fibers to run wild mammals pose unique pons, pons, cerebellum and the brain is the middle path between the contact points. (5), medulla Connected with the spinal cord, similarities between the two structures. In addition to the spinal cord and medulla constitute the senior center to contact the pathway, in the white matter within the uplink and downlink in the transmission path. Dispersion for a number of gray matter nucleus, nucleus of the nerve fibers and the corresponding associated sensory and motor organs. Medulla is also an important center of visceral activities, you can adjust the respiratory, digestive, circulatory, sweat gland secretion and a variety of defensive reflex. Extension of the back of the fourth ventricle of the brain.
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9. Sense
Mammals rely on highly developed senses to find food, avoid predators, and to find a suitable habitat, but also the communication links between species and a series of behavioral responses can not be separated organs. Of course, not all of the groups have reached a highly developed senses the level of some species in the degraded state in many ways, but in one respect are highly specialized. Mammals in the deterioration of eyesight, such as certain types of rapid movement, also developed a special high and low frequency acoustic pulse system, by hearing and acoustic echo to locate the bat echolocation that high frequency sound waves, high frequency and low frequency dolphin echolocation sound of water in two. This study has important significance in bionics. Highly developed senses of mammals, mainly in their vision, hearing and smell the Perfection. (1) sense of smell Most mammals have developed to expand the nasal cavity and nasal bones, sense of smell. Such as meat, artiodactyls and rodents that is well-developed sense of smell. But the whales, primates developed part of the brain's sense of smell, so the smell insensitive, dolphins and porpoises are the lack of olfactory organs. (2) visual Most of the visual organs of mammals and amniotes similar. Most mammalian eye development is good. However, some living under the insectivorous camps, rodents and whales eye is extremely degraded, and even some species maintain only the ability to distinguish light and dark. Overall, the feeling of mammals on the light sensitivity, but poor sensibility of color vision, which most mammals are nocturnal activities. Primates of the color discrimination ability and the object size and distance judgments than accurate.
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10. Endocrine
Mammalian endocrine system is very developed. Scattered throughout the body by the endocrine glands, including the pituitary gland, thyroid, parathyroid, adrenal, pancreatic gland, thymus and gonads and so on. They secrete different hormones have different effects, there is a certain mutual association to form a common endocrine system.
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11. Reproductive
The main features of mammalian reproductive system are: females have two functional ovaries, fertilized eggs in the oviduct, the embryo in the womb of the amniotic fluid-filled sac in the development, embryonic development of the necessary nutrients from the maternal placental blood. (1) male gonads Testis by the seminiferous tubules of many composition, the organ is to produce sperm. Between the seminiferous tubules with Leydig cells that secrete male hormones. Seminiferous tubules with a small pipe is connected the output epididymis, the tube wall cells secrete acidic mucus in order to ensure appropriate conditions for sperm survival. Associated with the vas deferens, epididymis bottom, the bottom of the vas deferens in the urethra. Semen through the urethra, penis quintana outside. In addition, the seminal vesicles, prostate, bulbourethral gland is important subsidiary glands and their secretions constitute the main body of semen, and can promote the activity of sperm. Prostaglandin prostate secretion which can promote uterine contractions to help fertilization. Penis for mating organs, mainly constituted by the corpus cavernosum, urethra consistent line of them. (2) female gonads A pair of ovaries, the surface of the germinal epithelium, there are produced by the germinal epithelium at different developmental stages of follicles, each follicle contains an egg cell, its external follicular fluid, containing the female hormones, the eggs mature follicles broken eggs and follicular fluid is discharged. Other remnants of follicles that shrink by a yellow filled cells, a corpus luteum, which secretes hormones to promote the uterus and mammary gland development, to prepare for the pregnancy. Mature egg into the fallopian tube after the front of the discharge opening, fertilized in the fallopian tube after completion of the previous paragraph, along the fallopian tube down of the uterus, the fertilized egg is planted in the uterine wall for development. Uterus by the vaginal opening in the body. There are many types of mammalian uterus, and some to the original double uterus, such as Lagomorpha, rodents and hyraxes head; some double points for the uterus, such as cetaceans; some of the double horn of uterus, such as Insectivora , scales present, Carnivora, Sirenia, Proboscidea, Perissodactyla head, Artiodactyla, Chiroptera and Primates in some species; there is a complete healing for both the uterus is a single uterus, such as Chiroptera and some primate species. These different types of uterine development, is the original double uterus to a single uterine development. The number of single uterine litter size is usually less than the double uterus.
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Categories
A wide range of mammals, are widely distributed, mainly by shape, skull, teeth, limb, and reproductive methods to divide, it is customary three subclasses: subclass of the original animal (including the following 1 to 3), after the animal sub- Programme (including the following 4 to 10), real animals subclass (including the following 11 to 27), the existing target of about 4,000 kinds of 27. Summary of mammalian classification 1 2 shrew monotremes negative negative Shumu Lu Zhi Shu Mu 3 4 5 possums Head bags Head Ferret 6 marsupial bandicoots Head 7 Head 8 Head 9 mole Kangaroo Head bags of 10 orders, 11 Insectivora poor teeth 12 mesh tree shrew 13 Leather Wing Chiroptera orders 14 16 15 Primates Carnivora Cetacea 18 17 19 Proboscidea Sirenia 21 hyraxes 20 Perissodactyla Head Gear Head 23 Head 22 24 Artiodactyla scales of 26 orders, 25 Rodentia Lagomorpha 27 projects like shrews
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Mammal - on behalf of animals
Human beings are higher mammals! Tapir mice tigers sloth deer mink zebra monkey bear dog fox musk ox lion as leopard panda koala reindeer rhinoceros warthog antelope giraffe panda pangolin anteater lynx otter civet gorilla dolphin manatee platypus hedgehog walrus arctic fox armadillo Kangaroo Koala bears armadillo Hippo seals whales Ferret The platypus is a mammal in particular, it is not viviparous but oviparous, but still classified as mammals
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Nerve
Mammalian nervous system is highly developed, mainly in the brain and cerebellum volumes increased, the development of new brain skin, forming a complex folds of the brain surface (ditch and back), a new brain greatly increased skin surface area. (1) New brain skin By lateral growth from the outer wall of the nerve substance, and surrounded by primary cerebral cortex (the original brain skin), the original remnants of the brain called the hippocampus of the skin, in the lateral ventricle, the smell is still central. Cerebral cortex from developed a new form, which accepts a variety of feelings from the body of the device came the impulse, through comprehensive analysis and in accordance with the established neural connections and a corresponding reflected. Left and right cerebral hemispheres to contact each other through a number of nerve fibers. Pathway composed of nerve fibers called the corpus callosum, is a mammal (with Yi-disc type)-specific structures. (2) between the brain Covered by the cerebral hemispheres, which have a pineal gland, the endocrine body, the pineal gland of mammals tend to shrink. Issued in the ventral surface of the optic nerve between the brain and form the optic nerve cross, said cross, and subsequently edged associated with the pituitary gland. Between the brain cavity, also known as the third ventricle, is developed. Wall between the brain's neural structures are also known as the back side of the thalamus and ventral thalamus hypothalamus. Hypothalamus is the central and cerebral cortex low-level intermediate station between the parser, the sensory impulses from the body are focused on here, the gray matter between the brain of a neuronal re-entry for the cerebral cortex. Ventral hypothalamus is the central autonomic activity, is closely related with the coordination of visceral activities, and body temperature regulation center. (3) in the brain Developed in the mammalian brain, the volume is very small, the stenosis was a brain, the brain known as the aqueduct, and the third and fourth ventricle traffic. The back side of the brain with four stacked body, in front of a pair of the visual reflex center, behind a pair for the auditory reflex center. In the bottom of the downward movement of the brain nerve fibers constitute a more significant brain enough. (4) cerebellum Mammalian brain in the back is a very well-developed cerebellum, and its main function is to coordinate muscle movements and body posture to maintain the normal balance of the central body. Mammals in the structure of the cerebellum has a unique feature is a cerebellar cortex, the gray matter covering the surface, the formation of cerebellar cortex, deep white matter, gray matter was dendritic. In addition, between the two cerebellar hemispheres, the nerve fibers to run wild mammals pose unique pons, pons, cerebellum and the brain is the middle path between the contact points. (5), medulla Connected with the spinal cord, similarities between the two structures. In addition to the spinal cord and medulla constitute the senior center to contact the pathway, in the white matter within the uplink and downlink in the transmission path. Dispersion for a number of gray matter nucleus, nucleus of the nerve fibers and the corresponding associated sensory and motor organs. Medulla is also an important center of visceral activities, you can adjust the respiratory, digestive, circulatory, sweat gland secretion and a variety of defensive reflex. Extension of the back of the fourth ventricle of the brain. (6) IQ Mammalian nervous system is highly developed, particularly in the brain become more complex, the emergence of new brain reptile skins are highly developed mammals, the formation of higher nervous activity center. Neurons increase in number, between the two hemispheres of the horizontal nerve fibers connected to each other, that the corpus callosum. And cerebellar development, the first time in cerebellum. Mammalian cerebral cortex ever developed, which for the operation, logic provides the necessary foundation. This is all the animals before in mammals is not available. Therefore, IQ higher than that of other non-mammalian mammals.
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Categories
Mammals belonging to the animal kingdom, chordates door, vertebrate subphylum, MAMMALIA. A wide range of mammals, are widely distributed, mainly by shape, skull, teeth, limb, and reproductive methods to divide, it is customary three subclasses: subclass of the original animal (including the following 1 to 3), after the animal sub- Programme (including the following 4 to 10), real animals subclass (including the following 11 to 28), about 28 existing 4,000 kinds of projects. Summary of mammalian classification: 1. Monotremes 2. Shrew negative Shumu 3. Chi Lu negative Shumu 4. Bags Ferret Head 5. Possums present 6. Bandicoot Head 7. A Bag Head 8. Bags mole head 9. Kangaroo Head 10. Poor gear mesh 11. Insectivora 12. Tree shrew Head 13. Paper Wings Head 14. Chiroptera 15. Primates 16. Carnivores 17. Cetaceans 18. Sirenia 19. Proboscidea 20. Perissodactyla Head 21. Hoof Rabbit Head 22. Tube gear head 23. Artiodactyla 24. Scutes present 25. Rodent 26. Lagomorpha 27. Like a shrew Head 28. Fins present
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Representatives of mammals, animals
Human (and other mammals the highest) tigers monkey mouse deer sable dog zebra fox tapir sloth bear the lion as leopard panda warthog antelope musk oxen reindeer rhinoceros lynx koala panda pangolin anteater giraffe orangutan otter civet manatee dolphin walrus platypus hedgehog kangaroo, koala bears arctic fox armadillo Hippo seals whales Ferret Including platypus, echidna (or short-beaked Echidna), the original mole (or Long-beaked Echidna) is particularly mammals, they are not viviparous but oviparous, but still classified as mammals. They are living in Australia.
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Most mammals
The largest mammals: the blue whale Largest land mammal: African elephants Most mammals: giraffe Fastest mammal: cheetah Most smelly mammal: American Skunk
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Encyclopedia
Mammal Vertebrates, such as a key link in the top (Mammalia, Mammalia). These groups of animals, both in body structure or physiological function and even aspects of behavior are the most complex and most complete. Main feature is, ① viviparous (except a few are oviparous outside) and breastfeeding. In vivo fertilization, embryo development in the uterus, during the development of amniotic and allantoic in fetal and maternal placenta and umbilical cord by means of contact. Postnatal pups to maternal milk feeding, which is a unique phenomenon in the animal kingdom, is the key link animal its name. ② highly developed nervous system, brain very well developed, there is a complex groove back. Developed sensor head (eyes, ears, nose), teeth had been divided. Thus these group of animals to changes in the external environment to make quick and accurate and sensitive response, greatly improving the adaptability of life. ③ temperature. More than a surface coat (except whales, but it developed subcutaneous fat), a protective role in the body and maintain body temperature. ④ high level of body metabolism. A highly differentiated digestive system; digestive gland well developed; dental morphological differentiation into incisors, canines, premolars and molars, and in some division of functions; small intestinal mucosa rich in villi (cloth has a large number of capillaries and lymphatic), so strengthening the function of feeding and digestion and absorption. Increased metabolism to promote the further improvement of the respiratory system. Lung by the enlarged end of a large number of bronchioles and alveolar composition. Alveolar capillaries with clouds, it makes gas exchange surface area increases. There is a muscular body cavity of the diaphragm, the chest and abdominal cavity into two. Diaphragm with increased respiratory function. Heart and circulatory system, like birds, completely divided into four rooms, ie atrium, two ventricles. To achieve a good double-loop, to ensure that the body tissues of nutrients and oxygen demand. Classification system is also in such a case group.
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English Expression
n.: animal, Mammals, mammalia, mammalian, any of the class of animals that give birth to live offspring and feed their young on milk from the breast