参考课件19哺乳类IntheCarbo

1、In the Carboniferous of the Paleozoic 古生代的石炭纪古生代的石炭纪 (3亿年前亿年前) A group of primitive reptiles gave rise to three lineages1. Lacking temporal openings 无颞窝类无颞窝类 Subclass Anapsida 古杯龙类古杯龙类 Turtles2. Two temporal openings 双颞窝类双颞窝类 Most ancient reptiles, archosaurs 初龙初龙and dinosaurs Lizards, snakes, worm

2、lizards, and birds3. A single opening 合颞窝类合颞窝类No reptilian descendants of this group survive todayTherapsids 兽齿类兽齿类, gave rise to the mammals(1) Lacking temporal openings 无颞窝类无颞窝类 characteristic of subclass Anapsida 无孔亚纲无孔亚纲/无无颞窝亚纲颞窝亚纲 古杯龙类古杯龙类Turtles: represent this evolutionary lineage today(2) Tw

3、o temporal openings 双颞窝类双颞窝类 characteristic of subclass Diapsida 双颞窝亚纲双颞窝亚纲, most ancient reptiles archosaurs 初龙初龙 and dinosaursLizards, snakes, worm lizards, and birds: represent this evolutionary lineage today(3) A single opening 合颞窝类合颞窝类 characteristic of subclass Synapsida 合颞窝亚合颞窝亚纲纲No reptilian

4、 descendants of this group survive todayA group of synapsids, therapsids 兽孔类兽孔类, gave rise to the mammalsFrom the late Permian to the early Trias 从晚二叠纪到从晚二叠纪到早三叠纪早三叠纪The earth was dominated by the therapsids 兽孔类兽孔类（哺乳动物祖先）（哺乳动物祖先） During the Trias 三叠纪三叠纪Dinosaurs rose and dominated the earth causing

5、 the therapsids 兽孔类兽孔类 to declineHowever, they have still survived for 100-millon years despite of dinosaur dominanceDespite being small in size, 10 cm to 1.5 mIn the late Cretaceous 晚白垩纪晚白垩纪After extinction of dinosaurs the ancient mammals developedViviparous胎生胎生, lactating哺乳哺乳, endothermic 恒恒温温 am

6、niotes Mammals Structure and function of mammalian bodySkin systemepidermis + dermisCompared with other vertebrates Thicker both in epidermis and dermis Increasing keratinization角质化角质化 in epidermis, with well-developed derivatives 皮肤衍生物皮肤衍生物 Increasing toughness in dermisDerivatives of the skin Hair

7、:derived from the epidermis, unique to mammalsHair follicle毛囊毛囊: an invagination内陷内陷 of the epidermisGuard hairs 针毛针毛: long, lessUnder hairs 绒毛绒毛: short, denseFunctions of mammalian hairs(1) Heat conservation Air spaces in the hair shaft 毛干毛干 Air trapped between the hair and the skin both provide an

8、 effective insulating layerArrector pili muscle 立毛肌立毛肌a band of smooth muscle running between the hair follicle 毛囊毛囊 and the lower epidermisThe muscle contracts hair stands upright the amount of air trapped in the pelage毛发毛发 increases improve insulating properties绝缘特性绝缘特性 of the pelage(2) Pelage col

9、oration to provide protection for animalsDepends on The amount of pigment deposited in the hair The quantity of air in the hair Molting(3) SenseVibrissae 触毛触毛around the mouth, nose, eyes and legs modified from guard hairs 针毛针毛 Claws: present in all amniotic classes derived from accumulations of kera

10、tin角角质蛋白质蛋白 at the tip of the digits HornsSkin glands develop from the epidermis Sebaceous glands 皮脂腺皮脂腺: associated with hair follicles毛囊毛囊 lubricate润滑润滑 and waterproof 防水防水 the skin and hair Sudoriferous glands 汗腺汗腺 Scent glands 气味腺气味腺: around the face, feet, or anus secrete pheromonesused in defe

11、nse, individual recognition, the territorial behaviordogs, foxes, weasels黄鼬黄鼬 Mammary glands 乳腺乳腺 functional in females nonfunctional in malesSkeletonSkullVertebral column Cervical vertebrae颈椎颈椎: 7 Thoracic vertebrae: 10-13 form the thoracic cage along with sternum and ribs protect heart and lungs a

12、id in breathing Lumbar vertebrae腰椎腰椎: 4-7 Sacral vertebrae 荐椎：荐椎：3-6, mostly fusion Coccygeal vertebrae 尾椎尾椎骨骼系统骨骼系统附肢骨：附肢骨：五指趾型四肢，四肢移到腹面，支撑、抬高躯体五指趾型四肢，四肢移到腹面，支撑、抬高躯体带骨：带骨：肩带肩带肩胛骨、锁骨，肩胛骨、锁骨，腰带腰带髋骨、坐骨、耻骨髋骨、坐骨、耻骨Muscles Appendicular muscles: highly developed Skin muscles: developedVarious in expressio

13、n in face Masticatory muscle 咀嚼肌咀嚼肌: developedImportant for feeding, tearingImportant for chewing, physical digestion Diaphragm膈肌膈肌: unique to mammals participate in respiratory movementDigestive systemAdaptations of the teeth and digestive tract: to exploit a wide variety of food resourcesSecondary

14、 palate次生腭次生腭hard palate (extension of the bones of the skull) + soft palate (extension of skin) almost completely separates the nasal passages from the mouth cavity Other vertebrates: swallow food whole or in small pieces Mammals: chewingThe structure and arrangement of teeth important indicators o

15、f mammalian lifestyles Reptiles: homodont 同型齿同型齿 uniformly conical圆锥形的圆锥形的Mammals: heterodont 异型齿异型齿 specialized for different functions Incisors门齿门齿: gnawing or nipping, single roots Canines犬齿犬齿: catching, killing, and tearing prey, single roots Premolars前臼齿前臼齿: chewing, one or two roots Molars臼齿臼齿

16、: chewing, two or three rootsDental formula characteristic of speciesHuman2/2, 1/1, 2/2, 3/3 = 32Dog and wolf3/3, 1/1, 4/4, 2/3 = 42Sheep0/3, 0/0, 3/3, 3/3 = 30门齿，犬齿，前臼齿，臼齿门齿，犬齿，前臼齿，臼齿Two sets of teeth during their lives Milk teeth Permanent teethFeeding habits Herbivores Insectivores CarnivoresDige

17、stive tract Mouth: mastication 咀嚼咀嚼by the teeth and the tonguesaliva secreted by the salivary glands Esophagus: food pathwaylined with stratified squamous epithelium 复层扁平上复层扁平上皮皮 Stomach food storage, digestion Small intestineduodenum 十二指肠十二指肠jejunum空肠空肠 ileum 回肠回肠, digestion, absorption Large intes

18、tine absorption of water, sodium and other minerals AnusCecum盲肠盲肠at the junction of the small and large intestines A fermentation pouch 发酵袋发酵袋 where microorganisms aid cellulose 纤维素纤维素 digestion developed in horses, rabbits, and many rodentsRuminants 反刍动物反刍动物 sheep, cattle, and deerThe stomachs are

19、modified into four chambers Rumen 瘤胃瘤胃 Reticulum 网胃网胃 Omasum 瓣胃瓣胃 sacculations of esophagus Abomasums 皱胃皱胃 true stomachFood mouth esophagus rumen reticulum omasum abomasum small intestineDigestive glands Salivary glands唾液腺唾液腺 LiverMost of its cells: hepatocytes 肝细胞肝细胞which secrete bile胆汁胆汁 gall-blad

20、der胆囊胆囊 small intestine PancreasIts cells produce large quantities of digestive enzymes small intestineExpiratory systemExpiratory tract Natal cavity Pharynx咽咽 Larynx喉喉 Trachea Bronchi细支气管细支气管 Bronchiole微支气管微支气管 Alveoli肺泡肺泡: small air-sacs clustered around the ends of the bronchioles the place where

21、 gas exchange occurs Lungs: within the thoracic cavityPleura 胸膜胸膜 two-layer thin membranes surrounding the lungsPower of respiratory movement negative-pressure mechanismDiaphragm膈肌膈肌: muscles that separates the thoracic and abdominal cavitiesInspirationcontraction of the diaphragm expansion of the r

22、ib cage decrease the intrathoracic胸腔内胸腔内 pressure air enters the lungsExpirationRecoil反弹反弹 of the lungs and relaxation of inspiratory muscles decreases the volume of the thoracic cavity air goes out the lungsCirculatory system Four-chambered heart Avian heart evolved from the archosaur reptilian lin

23、eage 初初龙龙 Mammalian heart evolved the synapsid reptilian lineage 单孔亚纲单孔亚纲Convergent evolution: the evolution of similar structures in different lineagesNitrogenous excretionProtein break down amino acids are delaminated叠成叠成 to form a keto-acid 酮酸酮酸 and ammonia 氨氨Ammonia is dissolvable in water poiso

24、nous to body Fishes and amphibians larvae NH+4 Nitrogenous wastesWhy? Because of abundant available water flushing away 1g of nitrogen: 500ml of water Terrestrial animals: need to conserve waterLiver detoxifies解毒解毒 ammonia into urea 尿素尿素 the main nitrogenous excretory product of mammalsAs a result,

25、90% of water are saved for voidance of 1g of nitrogen Land snails, insects, reptiles and birdsUric acid their principle nitrogenous waste productLess than 10ml of water are required to eliminate 1g of nitrogen For aquatic animals the body fluids need to be in osmotic balance with external fluidsor m

26、aintain a given osmotic pressure by some means of controlMarine mammals drink sea water, but they can produce urine hypertonic 高渗的高渗的 to sea waterA net gain of water Desert mammals: drink little water rely on metabolic water long kidney loops facilitate reabsorbing water from urine, conserving water

27、 Evolution of the vertebrate kidney Fishes and amphibians a single duct to transport urine and spermBut boney fishes have separate sperm ducts Amniotes a ureter尿管尿管 and a sperm duct精管精管Nervous system and sensory organs Increased volumes of the brain, especially cerebrum大脑大脑 and cerebellum小脑小脑 Increa

28、sed complexity of surface of the brain, especially cerebrum and cerebellumFore-brain Cerebrum (cerebral hemispheres大脑半球大脑半球, connected by the callosum 胼胝体胼胝体) correlation, integration, learning, memory and intelligence Corpus striatum 纹状体纹状体 autonomic control 协调控制协调控制 Hippocampus 海马海马 receipt of sen

29、sory impulses, important in emotions and motivation Pineal 松果体松果体 light reception, and in reproductive cycles Hypothalamus 下丘脑下丘脑 center for visceral内脏内脏 activity and homestatic control, important in emotions and motivation Thalamus 丘脑丘脑 processor for sensory input and motor运动运动 outputMid-brainInclu

30、des optic lobes 视叶视叶 optic and auditory reflexesHind-brain Cerebellum小脑小脑 posture姿势姿势, balance and motor-co-ordination运动协调运动协调 Pons 脑桥脑桥 a relay center 一个转换中枢一个转换中枢 Medulla oblongata 延髓延髓 the lower center of ventilation 呼吸呼吸, cardiac rhythms 心率心率, etc.Spinal cord 脊髓脊髓 continues from the hind-brain I

31、t contains sensory and motor neurons, together with interneuronal regions 中间神经中间神经元元Sensory organs External ear Tympanum 鼓膜鼓膜 Auditory ossicle: malleus锤骨锤骨, incus 砧骨砧骨and stapes磴骨磴骨 a lever system Cochlea 耳蜗耳蜗has three fluid-filled canals The upper and lower canals connect at the far end of the coch

32、lea The central canal has sensory hair cellsFluid movement causes vibrations in hair cellsReproduction and developmentReproductive model viviparity and lactationEnhance offspring survival ratesViviparityMembranes surrounding the embryo come into close contact with the uterus 子宫子宫 provides a stable e

33、nvironment for embryo development Placenta through which exchange of nutrients, gases, hormones, antibodies, waste products between the embryo and the mother take placeLactationMammary glands乳腺乳腺 enlarge and develop during pregnancy under the influence of hormones Milks rich in nutrient Human milk:

34、88% water, 6.5-8.0% carbohydrate, 1-2% protein, 3-5% fat and 0.2% saltsTaxonomyClass Mammalia Subclass Prototheria 原兽亚纲原兽亚纲Monotremes 单孔类单孔类 Subclass Metatheria 后兽亚纲后兽亚纲Marsupials 有袋类有袋类 Subclass Theria 真兽亚纲真兽亚纲 Placentals 有胎盘类有胎盘类Subclass Prototheria 原兽亚纲原兽亚纲 Monotremes 单孔类单孔类 Egg-laying Incubation by female With mammary glands, but lacking mammillae 乳头乳头 Lactation Cloaca 泄殖腔泄殖腔 Male copulation organ absent单孔类的特征单孔类的特征Subclass Metrtheria 后兽亚