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Animal Structure and
Function: An Introduction
Chapter 38
KEY CONCEPTS
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Structure and function are closely linked at
every level of organization
Learning Objective 1
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Compare the structure and function of the
four main kinds of animal tissues:
epithelial, connective, muscle, and
nervous
Tissue
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A group of similarly specialized cells
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Associated to perform one or more
functions
Epithelial Tissue (Epithelium)
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A continuous layer (sheet) of cells
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covering a body surface
lining a body cavity
Functions in protection, absorption,
secretion, or sensation
Connective Tissue 1
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Relatively few cells separated by
intercellular substance
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fibers scattered throughout a matrix
Intercellular substance fibers
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collagen fibers
elastic fibers
reticular fibers
Connective Tissue 2
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Contains specialized cells
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such as fibroblasts and macrophages
Functions:
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joins other body tissues
supports body and organs
protects underlying organs
Muscle Tissue
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Consists of cells specialized to contract
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Each cell is an elongated muscle fiber
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many contractile units (myofibrils)
Nervous Tissue
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Neurons
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elongated cells
specialized for transmitting impulses
Glial cells
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support and nourish neurons
Learning Objective 2
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Compare the structure and function of the
main types of epithelial tissue
Epithelial Tissue
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Epithelial cell shapes
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squamous, cuboidal, columnar
Epithelial tissue structure
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simple, stratified, pseudostratified
(See Table 38-1)
Simple Squamous Epithelium
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Lines blood vessels and air sacs in lungs
Permits exchange of materials by diffusion
Simple Cuboidal and
Columnar Epithelia
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Line passageways
Specialized for secretion and absorption
Stratified Squamous Epithelium
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Forms outer layer of skin
Lines passageways into the body
Provides protection
Pseudostratified Epithelium
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Lines passageways
Protects underlying tissues
Glands 1
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Specialized epithelial tissue
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Goblet cells
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unicellular exocrine glands that secrete
mucus
Glands 2
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Exocrine glands
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secrete product through a duct onto exposed
epithelial surface
Endocrine glands
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release hormones into interstitial fluid or blood
Glands
Cilia
Unicellular glands
(goblet cells)
Basement
membrane
(a) Goblet cells.
Skin
(b) Sweat gland.
(c) Parotid salivary gland.
Fig. 38-1, p. 809
Membranes
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Epithelial membrane
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Mucous membrane
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sheet of epithelial tissue
layer of underlying connective tissue
lines cavity that opens to outside of body
Serous membrane
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lines cavity that does not open to the outside
Learning Objective 3
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Compare the main types of connective
tissue
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Summarize their functions
Connective Tissues
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Cells embedded in intercellular substance
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microscopic collagen fibers, elastic fibers,
reticular fibers (thin branched fibers)
scattered through a matrix (thin gel of
polysaccharides)
Loose Connective Tissue
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Consists of fibers running in various
directions through a semifluid matrix
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Flexible tissue forms a covering for
nerves, blood vessels, and muscles
Dense Connective Tissue
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Stronger, less flexible than loose
connective tissue
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Collagen fibers arranged in definite pattern
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Forms
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tendons (connect muscles to bones)
ligaments (connect bones to bones)
Dense Connective Tissue
Elastic Connective Tissue
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Consists of bundles of parallel elastic fibers
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Found in lung tissue, walls of large arteries
Reticular Connective Tissue
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Consists of interlacing reticular fibers
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Forms support framework for many organs
Adipose Tissue
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Consists of fat cells
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Found with loose connective tissue in
subcutaneous tissue
Cartilage and Bone
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Form skeletons of vertebrates
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Cartilage consists of chondrocytes
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in lacunae (small cavities in hard matrix)
nonvascular
Osteocytes
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secrete and maintain bone matrix
vascular
Cartilage and Bone
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Cartilage
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Bone
Bone
(a) The human skeleton
consists mainly of bone.
(b) A bone is cut open,
exposing its internal structure.
Fig. 38-2ab, p. 814
Blood and Lymph
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Circulating tissues
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fluid intercellular substances
Help parts of an animal communicate with
one another
Learning Objective 4
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Contrast the three types of muscle tissue
and their functions
Skeletal Muscle
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Striated and under voluntary control
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Elongated, cylindrical fibers with several
nuclei
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Skeletal muscles contract, move parts of
the body
Cardiac Muscle
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Striated, contractions are involuntary
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Elongated, cylindrical fibers branch and
fuse; one or two central nuclei
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Muscle contracts, heart pumps blood
Smooth Muscle
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No striations, contractions involuntary
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Elongated, spindle-shaped fibers with a
single central nucleus
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Smooth muscle moves body organs
(example: pushes food through digestive tract)
Muscle Tissues
Learning Objective 5
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How does the structure of the neuron
relate to its function?
Neuron
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Elongated cell
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Receives and transmits information
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Synapse
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a junction between neurons
Neuron
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Dendrites
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receive signals
transmit signals to cell body
Axon
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transmits signals away from cell body
to other neurons, muscles, glands
Neuron
Neurons
Dendrite
Nuclei
of
glial
cells
Axon
100 µm
Fig. 38-3, p. 817
KEY CONCEPTS
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The main types of tissues in a complex
animal are epithelial, connective, muscle,
and nervous
Learning Objective 6
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Describe the organ systems of a mammal
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Summarize the homeostatic actions of
each organ system
Organ Systems
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Tissues and organs working together
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In mammals, 11 organ systems work
together in the organism
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Each organ system functions to maintain
homeostasis
11 Organ Systems
Integumentary
Skeletal
Muscular
Digestive
Cardiovascular
Immune (lymphatic)
Respiratory
Urinary
Nervous
Endocrine
Reproductive
11 Organ
Systems
11 Organ
Systems
Insert “Human organ
systems”
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Watch body systems work
together by clicking on the figure
in ThomsonNOW.
KEY CONCEPTS
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Tissues and organs form the 11 main
organ systems of a complex animal
Learning Objective 7
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Define homeostasis
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Contrast negative and positive feedback
systems
Homeostasis
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Balanced internal environment (steady
state)
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Homeostatic mechanisms
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control processes that maintain conditions
Negative Feedback Systems 1
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Maintain dynamic equilibrium (homeostasis)
1. Stressor
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causes change in some steady state
2. Triggers a response
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that opposes the change
Negative Feedback Systems 2
3. Sensor detects change
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a deviation from desired condition (set point)
4. Sensor signals an integrator (control center)
5. Integrator activates effectors
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organs or processes that restore steady state
Negative Feedback
HOMEOSTASIS
Stressor
5 Normal condition
(set point) restored.
1 Stressor causes
deviation from
set point.
4 Integrator activates
effectors (homeostatic
mechanisms).
2 Sensor detects
change from
set point.
3 Sensor signals
integrator
(control center).
Fig. 38-5, p. 821
Positive Feedback System
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Deviation from steady state causes
changes that intensify (rather than
reverse) the changes
Positive Feedback
Stressor:
hemorrhage
Homeostasis
1 Loss of blood causes
blood pressure to
decrease.
4 Cardiac output
decreases (heart
pumps less blood).
2 Less blood
circulates
to heart.
3 Heart function
declines.
Fig. 38-7, p. 822
KEY CONCEPTS
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Homeostatic mechanisms are responsible
for the body’s automatic tendency to
maintain a relatively stable internal
environment
Learning Objective 8
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Compare the costs and benefits of
ectothermy
Thermoregulation
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Process of maintaining body temperature
within certain limits
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despite changes in surrounding temperature
Animals have different structural,
behavioral, and physiological strategies
Ectotherms
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In ectotherms, body temperature depends
on temperature of environment
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Use behavioral strategies to adjust body
temperatures
Costs and Benefits
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Benefits of ectothermy
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very little energy used to maintain the
metabolic rate
ectotherms can survive on less food
Disadvantage of ectothermy
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activity limited by daily and seasonal
temperature conditions
Learning Objective 9
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Compare the costs and benefits of
endothermy
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Describe strategies animals use to adjust
to challenging temperature changes
Endotherms
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Have homeostatic
mechanisms
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regulate body
temperature within a
narrow range
Costs and Benefits
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Benefits of endothermy
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high metabolic rate
constant body temperature allows higher rate
of enzyme activity
active even in low winter temperatures
Disadvantage of endothermy
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high energy cost
Temperature
Regulation in
Humans
Decreased muscle
activity
Nerves
Increased
sweating/
panting
Evaporation
Smooth muscle in
blood vessels
relaxes
Blood vessels
dilate
Sensors signal
temperature- regulating
center in hypothalamus
(integrator)
Specialized nerve cells
(sensors) detect change
from set point
Body temperature
decreases (normal
condition restored)
Body temperature
increases
Stressors
HOMEOSTASIS
Stressors
Fig. 38-9, p. 823
Body temperature
increases (normal
condition restored)
Body temperature
decreases
Specialized nerve cells
(sensors) detect change
from set point
Sensors signal temperatureregulating center in
hypothalamus (integrator)
Blood
vessels
constrict
Increase in
metabolic rate
Increase in voluntary
movement; shivering
Nerves
Smooth muscle in
blood vessels
contracts
Thyroid gland
Anterior pituitary
gland
Fig. 38-9, p. 823
Insert “Control of human
body temperature”
hot_guy_m.swf
Acclimatization
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Process of adjustment to seasonal changes
Torpor
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Torpor
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Hibernation
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adaptive hypothermia (in small endotherms
when surrounding temperature drops)
long-term torpor in response to winter cold
Estivation
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torpor due to lack of food or water during
summer heat
KEY CONCEPTS
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Thermoregulation contributes to
homeostasis
Insert “Human
thermoregulation”
temp_regulation.swf
Explore negative feedback and
temperature regulation in
humans and other animals by
clicking on the figures in
ThomsonNOW.