Vertebrate Structure and Function
• Skin
• The integument is the outer covering of the body, a
protective wrapping that includes the skin and all structures
that are derived from, or associated with the skin, such as
hair, setae, scales, feathers, and horns.
• In most animals it is tough and pliable, providing
mechanical protection against abrasion and puncture and
forming an effective barrier against the invasion of bacteria.
• It provides moisture—proofing against fluid loss or gain.
• The skin protects the underlying cells against the damaging
action of the ultraviolet rays of the sun.
• But in addition to being a protective cover, the skin serves a
variety of other important functions. for example, in warmblooded (homeothermic) animals, it is vitally concerned
with temperature regulation, since most of the body's heat is
lost through the skin.
• The skin contains receptors of many senses that provide
essential information about the immediate environment.
• It has excretory functions and, in some forms, respiratory
functions as well. Through skin pigmentation the organism
can make itself more or less conspicuous.
• Skin secretions can make the animal attractive or repugnant
or provide olfactory cues that influence behavioral
interactions between individuals.
Types of exocrine glands. Most glands form secretions in three ways: (l)
merocrine, in which secretion is formed by cell; (2) apocrine, in which
part of cell forms secretion; and (3) holocrine, in which entire cell is
discharged in secretion.
• Integument in classes
Elasmobranchii, Osteichthyes,
and Reptilia showing different
types of scales. Placoid scales of
sharks are derived from dermis
and have given rise to teeth in all
higher vertebrates. Teleost fish
have bony scales from dermis,
and reptiles have horny scales
from epidermis. Only dermal
scales are retained throughout life;
epidermal scales are shed.
皮肤系统 Integumentary system
• 基 本 结 构
• (1)皮肤包括表皮与真皮 表皮：上皮组织(外胚
层)。 真皮：结缔组织(中胚层)。
• (2)皮肤衍生物包括外骨骼、腺体及色素。外骨骼：
角质鳞、羽、毛、爪、蹄、洞角。腺体：皮脂腺、
汗腺、乳腺、香腺。
• 基 本 功 能
• (1)保护身体，避免有害的机械性，化学性，冷热，
辐 射，生物等刺激因素的损伤。
• (2)防止体内水分的丧失或过度的吸水 。
• (3)排泄、分泌、呼吸以及感觉等功能。
. SKELETAL SYSTEMS
• Skeletons are supportive systems that provide rigidity to the
body, surfaces for muscle attachment, and protection for
body organs. The familiar bone of the vertebrate skeleton is
only one of several kinds of supportive and connective
tissues, serving various binding and supportive functions,
which we will discuss in this section.
• EXOSKELETON AND ENDOSKELETON
• Although animal supportive and protective structures take
many forms, there are two principal types of skeletons : the
exoskeleton, typical of mollusks and arthropods, and the
endoskeleton, characteristic of vertebrates. Vertebrates have
traces of exoskeleton that serve to remind us of our
invertebrate heritage. These are, for example, scales and
plates of fishes, fin gemails and claws, hair, feathers, and
other comified integumentary structures.
• The vertebrate endoskeleton is formed inside the
body and is composed of bone and cartilage
surrounded by soft tissues. It not only supports and
protects, but it is also the major body reservoir for
calcium and phosphorus. In the higher vertebrates
the red blood cells and certain white blood cells are
formed in the bone marrow.
Plan of the vertebrate skeleton
• The vertebrate skeleton has undergone a great
transformation in the course of evolution. This is
hardly surprising. The move from water to land
forced dramatic changes in respiration and body
form. The most pronounced differences are found in
the bones of the gill apparatus, called the visceral
skeleton, and bones of the skull.
• The early vertebrates tend to have a larger number
of skull bones than more recently evolved forms.
Some fish may have l80 skull bones: Amphibia and
Reptiles, 50 to 95; and mammals, 35 or fewer. Man
has 29.
• The vertebral column varies greatly with different
animals and with different regions of the vertebral
column in the same animal. In fish it is
differentiated only into trunk and caudal vertebrae,
the column in many of the other vertebrates is
differentiated into cervical (neck), thoracic (chest),
lumbar (back), sacral (pelvic), and caudal (tail)
vertebrae. In birds and also in man the caudal
vertebrae are reduced in number and size, and the
sacral vertebrae are fused.
• The number of vertebrae varies among the different
animals. The python seems to lead the list with 435.
• Most vertebrate animals have paired appendages.
None are found in cyclostomes, but both the
cartilaginous and bony fishes have pectoral and
pelvic fins that are supported by the pectoral and
pelvic girdles, respectively. Forms above the fish
(except snakes) have two pairs of appendages, also
supported by girdles. The basic plan of the land
vertebrate limb (tetrapod) is called pentadactyl,
terminating in five digits.
• Among the various vertebrates there are many
modifications in the girdles, limbs, arid digits that
enable animals to meet specific modes of life. For
instance, some amphibians have only three or four
toes on each foot, and the horse has only one.
骨骼系统 Skeletal System
• 基本 结构
• (1)从部位上来分：中轴骨骼：包括头骨、脊柱、肋骨和
胸骨。附肢骨骼：前肢包括肩带和前肢骨，后肢包括腰
带和头 后肢骨
• (2)从发生上来分：软骨原骨：由间充质经过软骨阶段然
后经骨化而成为硬骨
• 膜原骨（听骨）：由间充质直接骨化（鱼类的上、下颌）
• 基本功能：
• (1)构成身体的支架，维持一定的体形
• (2)供肌肉附着，构成运动装置的一部分
• (3)保护体内柔软的器官：保护脑，保护脊髓，胸廊保护
心、肺等
• (4)协助维持体内矿物质(如硬骨 钙，磷)代谢的正常水平。
VERTEBRATE MUSCLE
Vertebrate muscle is broadly classified on the basis
of the appearance of muscle cells (fibers) when
viewed with a light microscope .
• Striated muscle appears transversely striped
(striated), with altemating dark and light bands. We
can recognize two types of striated muscle:
skeletal and cardiac muscle.
• A third kind of vertebrate muscle is smooth
muscle, which lacks the characteristic altemating
bands of the striated type.
肌肉系统Muscular system
• (1)骨骼肌：多附着于骨块上。骨骼、关节和肌肉三者
构成运动装置。能随意活动，又称随意肌。显微镜下观
有横纹，又称横纹肌。
• (2)心肌：构成心脏壁，系特殊的横纹肌。不能随意活动
• (3)平滑肌：构成内脏务器官腔壁的肌肉。细胞质中无横
纹。不能随意活动，又称不随意肌
• (1)受刺激后进行收缩，牵动骨骼完成动作
(2)维持身体的一定姿势
• (3)体内各种物质的运送，食物经过消化管，血液经过血
皆，尿液经过输尿管，生殖细胞经过生殖管道，粪便经
直肠肛门排出
• (4)维持内脏器官在一定的平衡状态，例如：孔道的括约
肌，血管壁的平滑肌
CIRCULATlON SYSTERM
The circulatory system of vertebrates is made up of a
system of tubes, the blood vessels, and a propulsive
organ-- the heart.
• This is a closed circulation because the circu1ating
medium, the blood, is confined to vessels
throughout its journey from the heart to the tissues
and back again. Closed systems are more suitable
for large and active animals because the b1ood can
be moved rapidly to the tissues needing it. In
addition, flow to various organs can be readjusted
to meet changing needs by varying the diameters of
the blood vessel.
PLAN OF THE ClRCULATORY SYSTEM
• All vertebrate vascular systems have certain features in
common. A heart pumps the blood into arteries that branch
and narrow into arterioles and then into a vast system of
capillaries.
• Blood leaving the capillaries enters venules and then veins
that return the blood to the heart. Fig. compares the
circulatory systems of gill-breathing (fish) and lungbreathing (mamma1) vertebrates.
• The principal differences in circu1ation involve the heart in
the transformation from gill to lung breathing. The fish
heart contains two main chambers, the atrium (or auricle)
and the ventricle. Although there are also two subsidiary
chambers, the sinus venosus and conus arteriosus , we still
refer to the fish heart as a "two-chambered" heart.
• Blood makes a single circuit through the fish's
vascular system; it is pumped from the heart to the
gills, where it is oxygenated, and then flows into the
dorsal aorta to be distributed to the body organs.
After passing through the capillaries of the body
organs and musculature, it returns by veins to the
heart. In this circuit the heart must provide sufficient
pressure to push the blood through two sequentia1
capillary systems, one in the gills and the other in
the organ tissues. The principal disadvantage of the
single-circuit system is that the gil1 capillaries offer
so much resistance to blood flow that the pressure
drops considerab1y before entering the dorsal aorta.
This system can never provide high and continuous
blood pressure to the body organs.
• Evolving land forms with lungs and their need for highly efficient
blood delivery had to solve this prob1em by introducing a double
circulation. One systemic circuit with its own pump provides
oxygenated blood to the capillary beds of the body organs: another
pulmonary circuit with its own pump sends deoxygenated blood to the
lungs. Rather than actually developing two separate hearts, the
existing two chambered heart was divided down the center into four
chambers--really two two-chambered hearts lying side-by-side.
Needless to say such a great change in the vertebrate circu1atory plan,
involving not only the heart but the attendant p1umbing as well, took
many millions of years to evolve . The partial division of the atrium
and ventricle began with the ancestors of present-day 1ungfish.
Amphibians accomp1ished the complete separation of the atrium, but
the ventricle is still undivided in this group. In some reptiles the
ventricle is completely divided, and the four-chambered heart appears
for the first time. A1l birds and mammals have the four chambered
heart and two separate circuits—one through the lungs (pulmonary)
and the other through the body (systemic).
• THE HEART. The vertebrate heart is a muscular organ
located in the thorax and covered by a tough, fibrous sac,
the pericardium. As we have seen, the higher vertebrates
have a four-chambered heart. Each half consists of a thinwal1ed atrium and a thick-wal1ed ventricle. Heart (cardiac)
muscle is a unique type of muscle found nowhere else in the
body. It resembles striated muscle, but the cells are
branched, and dense end-to-end attachments between the
cells are cal1ed intercalated disks. There are four sets of
valves. Atrioventricular valves (A-V valves) separate the
cavities of the atrium and ventricle in each half of the heart.
These permit blood to flow from atrium to ventricle but
prevent backflow. Where the great arteries, the pulmonary
from the right ventricle and the aorta from the 1eft ventricle,
leave the heart, semilunar valves prevent backflow. The
contraction of the heart is cal1ed systole, and the relaxation,
diastole. The rate of the heartbeat
• ARTERIES. All vessels leaving the heart are ca1led arteries whether
they carry oxygenated b1ood (aorta) or deoxygenated blood
(pulmonary artery). To withstand high, pounding pressures, arteries
are invested with layers of both elastic and tough, inelastic connective
tissue fibers. The elasticity of the arteries allows them to yield to the
surge of blood leaving the heart during systole and then to squeeze
down on the fluid column during diastole. This smoothes out the
blood pressure. Thus the arterial pressure in man varies only between
a high of 120 mm. Hg (systole) and a low of 80 mm. Hg (diastole),
rather than dropping to zero during diastole as we might expect in a
fluid system with an intermittent pump. As the arteries branch and
narrow into arterioles, the walls become mostly smooth musc1e (Fig.
27-8). Contraction of this muscle narrows the arterioles and reduces
the flow of blood. The arterioles thus control the blood flow to body
organs, diverting it to where it is needed most. The blood must be
given a hydrostatic pressure sufficient to overcome the resistarice of
the narrow passages through which the b1ood must flow.
Consequently large animals tend to have higher blood pressure than
do small animals.
• Capillaries are extremely narrow, averaging less than 10 p
in diameter in mammals, which is hard1y any wider than the
red blood cells that must pass through them. Their walls are
formed of a single layer of thin endothelial cells, held
together by a delicate basement membrane and connective
tissue fibers. Capillaries have a bui1tin leakiness that allows
water and most dissolved substances in the blood plasma to
filter through into the interstitial space. The capillary wall is
selectively permeable, however, which means that it filters
some dissolved materials and retains others. In this case the
plasma proteins, which are the largest dissolved molecu1es
in the plasma, are held back. These proteins, especially the
albumins, contribute an osmotic pressure of about 25 mm.
Hg in mamma1s .
• VEINS. The venules and veins into which the capil1ary blood drains
for its return journey to the heart are thinner walled, less elastic, and
of considerably larger diameter than their corresponding arteries and
arterioles . Blood pressure in the venous system is low, from about 10
mm. Hg where capil1aries drain into venules to about zero in the right
atrium. Because pressure is so low, the venous return gets assists from
valves in the veins, from muscles surrounding the veins, and from the
rhythmic pumping action of the lungs. If it were not for these
mechanisms, the blood might pool in the lower extremities of a
standing animal--a very real problem for people who must stand for
long periods. The veins that lift blood from the extremities to the heart
contain valves that serve to divide the long column of b1ood into
segments. When the muscles around the veins contract, as in even
s1ight activity, the b1ood column is squeezed upward and cannot slip
back because of the va1ves. The well-known risk of fainting while
standing at stiff attention in hot weather can usually be prevented by
deliberately pumpirig the leg muscles. The negative pressure created
in the thorax by the inspiratory movement of the lungs also speeds the
venous return by sucking the blood up the large vena cava into the
heart.
循环系统 Circulatory system
• 基本结构：
• (1)心脏 (2)动脉：从心室输送 (3)小动脉 (4)毛细血管：
连接小动脉、静脉(5)小静脉 (6)静脉：收集全身各部血
液回心房的血管 (7)门静脉：两端都是毛细血管的静脉
(8) 淋巴系境：淋巴管，淋巴结 (9)脾脏 （10）骨髓
• 基本功能：
• (1)运载物质到细胞(如营养物质、水、氧、激素)
• (2)将身体各部代谢产物(如CO2，乳酸，尿素等)运送
至一定器官或排出体外
• （3）维持有机体的内环境的稳定性(如保持血液中水，
氧，盐的含量，酸碱度平衡，体温调节等)
• (4)制造，运输，储存和破坏血细胞。各种血细胞具有
运载氧，防御和免疫等功能
• （5）淋巴循环是血液循环的辅助部分
RESPIRATION
• The energy bound up in food must be released by
oxidative processes. As oxygen is used by the body
cells, carbon dioxide is produced: this process is
called respiration. Most animals are aerobic,
meaning that they require and receive the necessary
oxygen directly from their environment. A few
animals, ca1led anaerobic, are able to live in the
absence of oxygen. However, anaerobic metabolism
often occurs in the muscles of basically aerobic
animals during vigorous muscle contraction.
• GlLLS. Gills are unquestionably the most effective
respiratory device for life in water. Most efficient
are the internal gllls of fishes. Fish gills are thin
filamentous structures, richly supp1ied with blood
vesse1s arranged so that blood How is opposite to
the How of water across the gills. This arrangement,
ca1led countercurrent flow, provides for the greatest
possible extraction of oxygen from water. Water
flows over the gil1s in a steady stream, pushed and
pulled by an efficient branchial pump, and often
assisted by the fish's forward movement through the
water
• LUNGS. The most primitive vertebrate 1ungs are
those of lungfishes (Dipneusti), which use them to
supplement, or even replace, gill respiration during
periods of drought. A1though of simple construction,
the 1ungfish lung is supplied with a capillary
network in its largely unfurrowed walls, a tubelike
connection to the pharynx, and a primitive
ventilating system for moving air in and out of the
lung. Amphibians also have simple baglike lungs,
whereas in higher forms the inner surface area is
vastly increased by numerous lobulations and fo1ds
呼吸系统 Respiratory system
• 基本结构：
• (1)水栖类型：鳃、皮肤
• (2)陆栖类型：肺、呼吸道(鼻腔、咽、喉、气
管等)，鸟类气囊
• 基本功能：
• (1)在动物机体和环境之间进行气体交换(吸进
氧气，排出二氧化碳)
• (2)某些附属功能，如发声，过滤食物等。
EXCRETION AND HOMEOSTASIS
• kidney function
• The kidneys of man and other vertebrates play a critical role in the
body's economy. As vital organs their failure means death, in this
respect they are neither more nor 1ess important than are the heart,
lungs, or liver. The kidney is part of many interlocking mechanisms
that maintain homeostasis --constancy of the internal environment.
• However, the kidney's share in this regulatory council is an especia1ly
large one. It must, and does, individually monitor and regulate most of
the major constituents of the b1ood and several minor constituents as
well. In addition it silently labors to remove a variety of potentially
harmful substances that animals deliberately or unconsciously eat,
drink, or inhale.
• Perhaps even more remarkable than the job the kidney does is the way
in which it does it. These small organs, which in man weigh less than
0.5% of the body's weight, receive nearly 25% of the total blood flow
(cardiac output), amounting to about 2,000 liters of blood per day.
This vast blood flow is channeled to approximately 2 million
nephrons, which comprise the bulk of the two human kidneys.
• Each nephron is a tiny
excretory unit consisting of a
pressure filter (glomerulus)
and a long nephric tubule.
Urine formation begins in the
glomerulus where an
ultrafiltrate of the blood is
squeezed into the nephric
tubule by the hydrostatic
blood pressure. The
u1trafiltrate then flows
steadily down the twisted
tubule. During its trave1 some
substances are added to, and
others are subtracted from, the
ultra filtrate. The final product
of this process is urine.
排泄系统 Excretory system
•
•
•
•
•
•
•
•
基本结构
(1)肾脏
(2)输尿管
(3)膀胱(有或无)
(4)尿道(有或无)
基本功能
(1)排出代谢废物，特别是含氮的代谢废物
(2)调节水盐代谢，酸碱平 衡，保持身体内环境
的相对稳定
DIGESTION AND NUTRITION
All organisms require energy to maintain their highly ordered
and complex structure. This energy. is chemical energy that
is released by transforming complex compounds acquired
from the organism's environment into simpler ones.
Obviously, if living organisms must depend on the
breakdown of complex foodstuffs to build and maintain
their own complexity, these foodstuffs must somehow be
synthesized in the first place. Most of the energy for this
synthesis is provided by the powerful radiations of the sun,
the one great source of energy reaching our planet that is
otherwise a virtually isolated system. Organisms capable of
capturing the sun's energy by the process of photosynthesis
are, or course, the green plants. Green plants are autotrophic
organisms capable of synthesizing all the essential organic
compounds needed for life.
• Autotrophic organisms need only inorganic compounds absorbed from
their surroundings to provide the raw materials for synthesis and
growth. Most autotrophic organisms are the chlorophyll-bearing
phototrophs, although some, the chemosynthetic bacteria, are
chemotrophs, gaining energy from inorganic chemical reactions.
Almost all animals are heterotrophic organisms that depend on already
synthesized organic compounds for their nutritional needs. Animals,
with their limited capacities to perform organic synthesis, must feed
on plants and other animals to obtain the materials they will use for
growth, maintenance, and the reproduction of their kind. The foods of
animals, usually the complex tissues of other organisms, can seldom
be utilized directly. Food is usually too large to be absorbed by the
body cells and may contain material of no nutritional value as well.
Consequently, food must be broken down, or digested, into soluble
molecules sufficiently small to be utilized. One important difference,
then, between autotrophs and heterotrophs is that the latter must have
digestive systems
• ANATOMY OF MAN'S
DlGESTlVE SYSTEM.
• The structural plan of the digestive
system of man is shown in Fig. 28-7.
The mouth is provided with teeth
and a tongue for grasping,
masticating, manipulating, and
swallowing the food. Three pairs of
salivary glands lubricate the food
and, in man at least, perform limited
digestion. ln man and other
mammals two sets of teeth are
formed during life--the temporary,
or "milk," teeth (also called
deciduous teeth) and the permanent
teeth
• The pharynx is the throat cavity that serves for the
passage of food. It is actually a complex reception
chamber, receiving openings from (l) the nasal
cavity, (2) the mouth, (3) the middle ear by way of
two eustachian tubes, (4) the esophagus, and (5) the
trachea via the glottis.
• The esophagus is a muscular tube connecting
pharynx and stomach. It opens into the stomach by
the cardiac opening. The stomach is an enlargement
of the gut between esophagus and intestine. In man
it is divided into the cardiac region (adjacent to
esophagus), fundus (central region), and pyloric
antrum region (adjacent to intestine). The stomach is
principally a storage organ but aids in digestion.
• The small intestine is the principal digestive and absorptive
area of the gut. It is divided grossly into three regions-duodenum, jejunum, and ilium. Two large digestive glands,
the liver and pancreas, empty into the duodenum by the
common bile duct.
• The large intestine (colon) in man is divided into ascending,
transverse, and descending portions, with the posterior end
terminating in the rectum and anus. At the junction of the
large and small intestines is the colic cecum and its vestigial
vermiform appendix. The large intestine lacks villi but
contains glands for lubrication. The stomach, small intestine,
and large intestine are all suspended by mesenteries, thin
sheets of tissue that are modified from the peritoneum, or
lining, of the coelom and the abdominal organs. Organs
such as liver, spleen, and pancreas are also held in place by
mesenteries, which carry blood and lymph vessels as well as
nerves to the various abdominal organs.
消化系统 Digestive system
•
•
•
•
•
•
•
•
基本结构
(1)消化道：咽 口腔食道胃 小肠 大肠 肛门
(2)消化腺，唾液腺 、肝，胰及胃腺，肠腺等
基本功能
(1)摄取营养物质
(2)物理性、化学性分解
(3)吸收其精华
(4)排除其糟粕
NERVOUS SYSTEM
• NERVOUS SYSTEM, SENSE ORGANS, AND
ENDOCRlNE SYSTEM
• The origin of the nervous system is based on one of the
fundamental properties of protoplasm-- irritability. Each cell
responds to stimulation in a mariner characteristic of that
type of cell. But certain cells have become highly
specialized for receiving stimuli and for conducting
impulses to various parts of the body. Through evolutionary
changes, these cells have become the most complex of all
body systemsthe nervous system. The endocrine system is
also important in coordination, but the nervous system has a
wider and more direct control of body functions than does
the endocrine system.
• Vertebrates have, as a rule, a brain much larger than
the spinal cord. In lower vertebrates this difference
is not significant, but higher in the vertebrate
kingdom the brain increases in size, reaching its
maximum in mammals, especially man. Along with
this enlargement has come an increase in complexity,
bringing better patterns of coordination, integration,
and intelligence. The nervous system is commonly
divided into central and peripheral parts: the central
division is chiefly concerned with integrative
activity and the peripheral part with the conduction
of sensory and motor information to all parts of the
body.
• A reflex are at its simplest consists of only two
neurons--a sensory (afferent) neuron and a motor
(efferent) neuron. Usually, however, association
neurons are interposed (Fig. 30-7). Association
neurons may connect afferent and efferent neurons
on the same side of the spinal cord, connect them on
opposite sides of the cord, or connect them on
different levels of the spinal cord, either on the same
or opposite sides. In almost any reflex act a number
of reflex arcs are involved. For instance, a single
afferent neuron may make synaptic junctions with
many efferent neurons. In a similar way an efferent
neuron may receive impulses from many afferent
neurons. In this latter case the efferent neuron is
referred to as the final common path.
• Organization of the nervous system
• The basic plan of the vertebrate nervous system is a dorsal
longitudinal hollow nerve cord that runs from head to tail.
During early embryonic development, the central nervous
system begins as an ectodermal neural groove, which by
folding and enlarging becomes a long, hollow, neural tube.
The cephalic end enlarges into the brain vesicles and the rest
becomes the spinal cord. The spinal nerves (3l pairs in man)
have a dual origin. The spinal ganglia (dorsal root ganglia in
Fig. 30-8), containing the sensory neurons, differentiate
from specialized cells, called neural crest cells, that pinch
off from the edges of the neural groove as it closes to form a
tube.
• The ventral roots contain motor fibers that originate in the
spinal cord. Both dorsal (sensory) and ventral (motor) roots
meet some distance beyond the cord to form a mixed spinal
nerve
• CRANIAL NERVES.
• In the higher vertebrates, including man, there are l2 pairs
of cranial nerves. They are primarily concerned with the
sense organs, glands, and muscles of the head and are more
specialized than spinal nerves. Some are purely sensory
(olfactory, optic, auditory): some are mainly, if not entirely,
motor (oculomotor, trochlear, abducens, spinal accessory,
hypoglossal), and the others are mixed with both sensory
and motor neurons (trigeminal, facial, glossopharyngeal,
vagus). The majority of the cranial nerves arise from or near
the medulla. Some bear autonomic nerve fibers, especially
the facial and vagus. For convenience the various cranial
nerves are also designated by the Roman numerals I to XII,
as well as by specific names. The numbering begins at the
anterior end of the brain and proceeds to the posterior end of
the brain.
• SPINAL NERVES.
• The spinal nerves contain both sensory and motor components in
approximately equal numbers. In higher vertebrates and man there are
3l pairs: cervical, 8 pairs: thoracic, l2 pairs: lumbar, 5 pairs; sacral, s
pairs; and caudal, l pair. Each nerve has two roots by which it is
connected to the spinal cord (Fig. 30-8). All the sensory fibers enter
the cord by the dorsal root, and all the motor fibers leave the cord by
the ventral root. The nerve cell bodies of motor neurons are located in
the ventral horns of the gray zone of the spinal cord: the sensory nerve
cell bodies are in the dorsal spinal ganglia just outside the cord. Near
the junction of the two roots, the spinal nerve divides into a small
dorsal branch (ramus) that supplies structures in the back, a larger
ventral branch that supplies structures in the sides and front of the
trunk and in the appendages, and an autonomic branch that supplies
structures in the viscera. To supply a large area of the body, the ventral
rami of several spinal nerves may join to form a network (plexus).
These are the cervical, brachial, and lumbosacral plexuses.
• Autonomic nervous system
• The autonomic nerves govern
the involuntary functions of
the body that do not
ordinarily affect
consciousness. The cerebrum
has no direct control over
these nerves, thus one cannot
by volition stimulate or
inhibit their action.
Autonomic nerves control the
movements of the alimentary
canal and heart, the
contraction of the smooth
muscle of the blood vessels,
urinary bladder, iris of eye,
etc., and the secretions of
various glands.
神经系统 Nervous System
• 基本结构：
• (1)中枢神经系统：脑和脊髓
• (2)周围神经系统：脑神经（无羊膜类10对，羊
膜类12对。
• (3)植物性神经：包括交感神经和副交感神经
• 基本功能 ：
• (1)调整机体内部各器官系统的动态平衡，并使
机体能动地适应外界环境
• (2)神经系统的基本活动是反射活动
• SENSE ORGANS
• Animals require a constant inflow of information
from the environment to regulate their lives. Sense
organs are specialized receptors designed for
detecting environmental status and change. An
animal's sense organs are its first level of
environmental perception: they are data input
channels for the brain.
• Classification of receptors
• Receptors are classified on the basis of their location.
Those near the external surface are called
exteroceptors and are stimulated by changes in the
external environment. Internal parts of the body are
provided with interocoptors, which pick up stimuli
from the internal organs. Muscles, tendons, and
joints have proprioceptors, which are sensitive to
changes in the tension of muscles and provide the
organism with a sense of position.
• Another way of classifying receptors is on the basis
of the energy form used to stimulate them, such as
chemical, mechanical, photo, or thermal.
感觉器官 Senseorgan
• 分类
• (1)外感受器：皮肤的各种感受末梢
• (2)内感受器：内脏，血管，骨骼肌、肌腱、关
节中的神经末梢感受器
• 基本功能
• (1)感受外界环境的变化
• (2)感受身体内部环境的变化 ，味、嗅、视、
听等感觉器官
ENDOCRINE SYSTEM
• The endocrine system is the second great integrative
system controlling the body's activities. Endocrine glands,
or specialized tissues, secrete hormones (from the Creek
root meaning "to excite") that are transported by the blood
for variable distances to some part of the body where they
produce definite physiologic effects. Hormones are
effective in minute quantities: some are active when
diluted several billion times in the blood. The endocrine
system is a slow-acting integrative system as compared to
the nervous system, and, in general, hormonal effects are
long lasting. Some hormones are excitatory, others
inhibitory. Many physiologic processes are governed by
antagonistic hormones (one that stimulates, the other that
inhibits the process). Such combinations are very effective
in maintairiing homeostatic conditions.
内分泌系统 Endocrine System
• 结构：
• (1)分散在身体各部的没有导管的腺体(又称无管腺)，包
括脑下垂体、甲状腺、甲状旁腺、肾上腺、松果腺等
• (2)分布在其他器官组织内，如胰腺内的胰岛、睾丸内的
间质细胞、卵巢内的卵泡和黄体。
• 基本功能：
• (1)其分泌物(激素)经血液循环运输到全身，对动物
• 体的代谢，生长发育、生殖等生理机能起着支配和
• 调节的作用
REPRODUCTIVE SYSTEM
• The gonads are paired ridgelike structures
on the dorsal side of the coelom. Each
gonad appears to have been formed by the
fusion of a number of units. Since they lack
genital ducts, the adult lampreys shed their
gametes into the coelom, where an opening
into the mesonephric duct allows the
gametes to escape to the outside through the
urinogenital papillae.
生殖系统 REPRODUCTIVE
SYSTEM
•
•
•
•
•
•
•
基本结构
（1）生殖腺：卵巢、精巢，一般成对。
（2）生殖导管，有些类群还有外生殖器。
基本功能：
后代的繁衍
（1）生殖腺产生生殖细胞
（2）生殖导管输送生殖细胞在体内或体外受
精、发育。