CHAPTER 43
LECTURE
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The Animal Body and
Principles of Regulation
Chapter 43
Organization of Vertebrate Body
• There are four levels of organization
1.
2.
3.
4.
Cells
Tissues
Organs
Organ systems
• Bodies of vertebrates are composed of
different cell types
– Humans have 210
3
Organization of Vertebrate Body
• Tissues
– Groups of cells that are similar in structure
and function
– 3 fundamental embryonic tissues are called
germ layers
• Endoderm, mesoderm, and ectoderm
– In adult vertebrates, there are four primary
tissues
• Epithelial, connective, muscle, and nerve
4
Organization of Vertebrate Body
• Organs
– Combinations of different tissues that form a
structural and functional unit
• Organ systems
– Groups of organs that cooperate to perform
the major activities of the body
– Vertebrate body contains 11 principal organ
systems
5
Organization of Vertebrate Body
6
Organization of Vertebrate Body
• General body plan of all vertebrates is
essentially a tube within a tube
– Inner tube – digestive tract
– Outer tube – main vertebrate body
• Supported by a skeleton
– Outermost layer – skin and its accessories
7
Organization of Vertebrate Body
• 2 main body cavities
– Dorsal body cavity
• Forms within skull and vertebrae
– Ventral body cavity
• Bounded by the rib cage and vertebral column
• Divided by the diaphragm into
– Thoracic cavity – heart and lungs
» Pericardial cavity: Around the heart
» Pleural cavity: Around the lungs
– Abdominopelvic cavity – most organs
» Peritoneal cavity – coelomic space
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9
10
Epithelial Tissue
• An epithelial membrane, or epithelium,
covers every surface of the vertebrate
body
• Can come from any of the 3 germ layers
• Some epithelia change into glands
• Cells of epithelia are tightly bound together
– Provide a protective barrier
11
Epithelial Tissue
• Epithelia possess remarkable regenerative
powers replacing cells throughout life
• Epithelial tissues attach to underlying
connective tissues by a fibrous membrane
– Basal surface – secured side
– Apical surface – free side
– Inherent polarity important for their function
12
Epithelial Tissue
• Two general classes
– Simple – one layer thick
– Stratified – several layers thick
• Each class subdivided into
– Squamous cells – flat
– Cuboidal cells – about as wide as tall
– Columnar cells – taller than they are wide
13
Simple Epithelium
• Simple squamous epithelium
– Lines lungs and blood capillaries
– Delicate nature permits diffusion
• Simple cuboidal epithelium
– Lines kidney tubules and several glands
• Simple columnar epithelium
– Lines airways of respiratory tract and most of
the gastrointestinal tract
– Contains goblet cells – secrete mucus
14
15
Simple Epithelium
• Glands of vertebrates form from
invaginated epithelia
• Exocrine glands
– Connected to epithelium by a duct
– Sweat, sebaceous, and salivary glands
• Endocrine glands
– Ductless – lost duct during development
– Secretions (hormones) enter blood
16
Stratified Epithelium
• 2 to several layers thick
• Named according to the features of their
apical cell layers
• Epidermis is a stratified squamous
epithelium
– Terrestrial vertebrates have a keratinized
epithelium
• Contains water-resistant keratin
– Lips are covered with nonkeratinized,
stratified squamous epithelium
17
18
Connective Tissues
• Derive from embryonic mesoderm
• Divided into two major classes
– Connective tissue proper
• Loose or dense
– Special connective tissue
• Cartilage, bone, and blood
• All have abundant extracellular material
called the matrix
– Protein fibers plus ground substance
19
Connective Tissue Proper
• Fibroblasts produce and secrete
extracellular matrix
• Loose connective tissue
– Cells scattered within a matrix that contains a
large amount of ground substance
– Strengthened by protein fibers
• Collagen – supports tissue
• Elastin – makes tissue elastic
• Reticulin – helps support the network of collagen
20
Connective Tissue Proper
• Adipose cells (fat cells) also occur in loose
connective tissue
– Develop in large groups in certain areas,
forming adipose tissue
21
Connective Tissue Proper
• Dense connective tissue
– Contains less ground substance than loose
connective tissue
– Dense regular connective tissue
• Collagen fibers line up in parallel
• Makes up tendons and ligaments
– Dense irregular connective tissue
• Collagen fibers have different orientations
• Covers kidney, muscles, nerves, and bone
22
23
Special Connective Tissue
• Cartilage
– Ground substance made from characteristic
glycoprotein (chondroitin) and collagen fibers
in long, parallel arrays
– Firm and flexible tissue that does not stretch
– Great tensile strength
– Found in joint surfaces and other locations
– Chondrocytes (cartilage cells) live within
lacunae (spaces) in the ground substance
24
Special Connective Tissue
• Bone
– Osteocytes (bone cells) remain alive in a
matrix hardened with calcium phosphate
– Communicate through canaliculi
• Blood
– Extracellular material is the fluid plasma
– Erythrocytes – red blood cells
– Leukocytes – white blood cells
– Thrombocytes – platelets
25
26
Muscle Tissue
• Muscles are the motors of vertebrate
bodies
• Three kinds: smooth, skeletal, and cardiac
– Skeletal and cardiac muscles are also known
as striated muscles
– Skeletal muscle is under voluntary control,
whereas contraction of the other two is
involuntary
27
Muscle Tissue
• Smooth muscle
– Found in walls of blood vessels and visceral
organs
– Contain a single nucleus
• Skeletal muscle
– Usually attached to bone by tendons, so
muscle contraction causes bones to move
– Muscle fibers (cells) are multinucleated
– Contract by means of myofibrils, which
contain ordered actin and myosin filaments
28
Muscle Tissue
• Cardiac muscle
– Composed of smaller, interconnected cells
– Each with a single nucleus
– Interconnections appear as dark lines called
intercalated disks
• Gap junctions link adjacent cells
– Enable cardiac muscle cells to form a single
functioning unit
29
30
Nerve Tissue
• Cells include neurons and their supporting
cells (neuroglia)
• Most neurons consist of three parts
– Cell body – contains the nucleus
– Dendrites – highly branched extensions
• Conduct electrical impulses toward the cell body
– Axon – single cytoplasmic extension
• Conducts impulses away from cell body
31
Nerve Tissue
• Neuroglia
– Do not conduct electrical impulses
– Support and insulate neurons and eliminate
foreign materials in and around neurons
– Associate with axon to form an insulating
cover called the myelin sheath
• Gaps (nodes of Ranvier) are involved in
acceleration of impulses
32
Nerve Tissue
• Nervous system is divided into
– Central nervous system (CNS)
• Brain and spinal cord
• Integration and interpretation of input
– Peripheral nervous system (PNS)
• Nerves and ganglia (collections of cell bodies)
• Communication of signal to and from the CNS to
the rest of the body
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34
Overview of Organ Systems
• Communication and integration
– Three organ systems detect external stimuli
and coordinate the body’s responses
– Nervous, sensory, and endocrine systems
• Support and movement
– Musculoskeletal system consists of two
interrelated organ systems
35
Overview of Organ Systems
• Regulation and maintenance
– Four organ systems regulate and maintain the
body’s chemistry
– Digestive, circulatory, respiratory, and urinary
systems
• Defense
– The body defends itself
– Integumentary and immune systems
36
Overview of Organ Systems
• Reproduction and development
– The biological continuity of vertebrates
– In females, the system also nurtures the
developing embryo and fetus
37
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Nervous System
Endocrine System
Brain
Hypothalamus
Pituitary
Skeletal System
Skull
Thyroid
Thymus
Spinal
cord
Adrenal
gland
Pancreas
Sternum
Pelvis
Testis
(male)
Nerves
Femur
Ovary (female)
38
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Muscular System
Digestive System
Circulatory System
Salivary
glands
Pectoralis
major
Esophagus
Biceps
Liver
Rectus
abdominus
Stomach
Small
intestine
Large
intestine
Heart
Veins
Arteries
Sartorius
Quadriceps
Gastrocnemius
39
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Lymphatic/Immune System
Reproductive System (male)
Reproductive System (female)
Lymph nodes
Thymus
Spleen
Bone marrow
Vas deferens
Penis
Testis
Fallopian
tube
Ovary
Uterus
Vagina
Lymphatic
vessels
40
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Lymphatic/Immune System
Reproductive System (male)
Reproductive System (female)
Lymph nodes
Thymus
Spleen
Bone marrow
Vas deferens
Penis
Testis
Fallopian
tube
Ovary
Uterus
Vagina
Lymphatic
vessels
41
Homeostasis
• As animals have evolved, specialization of
body structures has increased
• For cells to function efficiently and interact
properly, internal body conditions must be
relatively constant
• The dynamic constancy of the internal
environment is called homeostasis
• It is essential for life
42
43
Homeostasis
• Negative feedback mechanisms
– Changing conditions are detected by sensors
(cells or membrane receptors)
– Information is fed to an integrating center,
also called comparator (brain, spinal cord, or
endocrine gland)
– Compares conditions to a set point
– If conditions deviate too far from a set point,
biochemical reactions are initiated to change
conditions back toward the set point
44
Homeostasis
• Humans have set points for body
temperature, blood glucose
concentrations, electrolyte (ion)
concentration, tendon tension, etc.
• Integrating center is often a particular
region of the brain or spinal cord
• Effectors (muscles or glands) change the
value of the condition in question back
toward the set point value
45
Homeostasis
46
Homeostasis
• Mammals and birds are endothermic
– Maintain a relatively constant body
temperature independent of the
environmental temperature
– Humans 37oC or 98.6oF
– Changes in body temperature are detected by
the hypothalamus in the brain
47
Homeostasis
• Negative feedback mechanisms often
oppose each other to produce finer degree
of control
• Many internal factors are controlled by
antagonistic effectors
• Have “push–pull” action
• Increasing activity of one effector is
accompanied by decrease in the other
48
Homeostasis
• Antagonistic effectors are involved in the
control of body temperature
• If hypothalamus detects high temperature
– Promotes heat dissipation via sweating and
dilation of blood vessels in skin
• If hypothalamus detects low temperature
– Promotes heat conservation via shivering and
constriction of blood vessels in skin
49
Homeostasis
50
Homeostasis
• Positive feedback mechanisms
– Enhance a change – not common
– These do not in themselves maintain
homeostasis
– Important components of some physiological
mechanisms
• Blood clotting
• Contraction of uterus during childbirth
51
Homeostasis
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