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BIOLOGY
CONCEPTS & CONNECTIONS
Fourth Edition
Neil A. Campbell • Jane B. Reece • Lawrence G. Mitchell • Martha R. Taylor
CHAPTER 20
Unifying Concepts of Animal
Structure and Function
Modules 20.1 – 20.7
From PowerPoint® Lectures for Biology: Concepts & Connections
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Climbing the Walls
• The function of any part of
an animal results from its
unique structure
• Consider the gecko, a small
lizard commonly
found in the tropics
– A gecko can walk up a wall
and across ceilings
– How does it do that?
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• The explanation relates to
hairs, called setae, on the
gecko’s toes
– They are arranged
in rows
– Each seta ends in
many split ends
called spatulae,
which have
rounded tips
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– The ability to “stick” to surfaces results from
attractions between molecules on the spatulae
and molecules on the surface
– The structure of the gecko’s feet leads to a
unique function
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THE HIERARCHY OF STRUCTURAL
ORGANIZATION IN AN ANIMAL
20.1 Structure fits function in the animal body
• The correlation between structure and function
is one of biology’s most fundamental concepts
Forearm
Wrist
Finger 1
Palm
Finger 2
Shaft
Vane
WING
Bone structure
Finger 3
Shaft
Feather
structure
Barb
Barbule
Hook
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Figure 20.1
20.2 Animal structure has a hierarchy
• Structure and
function are
correlated at
each level in
the structural
hierarchy of an
animal’s body
A. CELLULAR LEVEL:
Muscle cell
B. TISSUE LEVEL:
Muscle tissue
C. ORGAN LEVEL:
Heart
D. ORGAN SYSTEM LEVEL:
Circulatory system
E. ORGANISM LEVEL:
Many organ systems
functioning together
Figure 20.2
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20.3 Tissues are groups of cells with a common
structure and function
• A tissue is a cooperative of many similar cells
that perform a specific function
• Animals have four major categories of tissue
– Epithelial tissue
– Connective tissue
– Muscle tissue
– Nervous tissue
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20.4 Epithelial tissue covers and lines the body and
its parts
• Epithelial tissue occurs as sheets of closely
packed cells
– It covers surfaces and lines internal organs and
cavities
– Examples: epidermis, stomach lining
• The structure of each type of epithelium fits its
function
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Free surface of
epithelium
Underlying
tissue
Basement
Membrane
(extracellular
matrix)
Cell
nuclei
A. SIMPLE SQUAMOUS EPITHELIUM
(lining the air sacs of the lung)
D. STRATIFIED SQUAMOUS EPITHELIUM
(lining the esophagus)
B. SIMPLE CUBOIDAL EPITHELIUM
(forming a tube in the kidney)
C. SIMPLE COLUMNAR EPITHELIUM
(lining the intestine)
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Figure 20.4
20.5 Connective tissue binds and supports other
tissues
• Connective tissue is characterized by sparse
cells
– The cells manufacture and secrete an
extracellular matrix
– The matrix is composed of fibers embedded in a
liquid, solid, or gel
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• There are six major types of connective tissue
Cell
nucleus
Cell
Collagen
fiber
Collagen
fibers
Other
fibers
A. LOOSE CONNECTIVE TISSUE
(under the skin)
D. FIBROUS CONNECTIVE TISSUE
(forming a ligament)
Fat
droplets
Cells
Cell
nucleus
Matrix
B. ADIPOSE TISSUE
E. CARTILAGE
(at the end of a bone)
White blood
cells
Central
canal
Matrix
Red blood
cells
Cells
Plasma
C. BLOOD
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F. BONE
Figure 20.5
20.6 Muscle tissue functions in movement
• Skeletal muscle is responsible for voluntary
body movements
• Cardiac muscle pumps blood
• Smooth muscle moves the walls of internal
organs such as the stomach
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Unit of
muscle
contraction
Muscle
fiber
Muscle
fiber
Nucleus
Junction between
two cells
Nucleus
Muscle fiber
Nucleus
B. CARDIAC MUSCLE
A. SKELETAL MUSCLE
C. SMOOTH MUSCLE
Figure 20.6
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20.7 Nervous tissue forms a communication
network
• The branching neurons of nervous tissue
transmit nerve signals that help control body
activities
Cell body
Nucleus
Cell
extensions
Figure 20.7
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20.8 Several tissues are organized to form an organ
• Each organ is made of several tissues that
cooperate to perform specific functions
Lumen
Columnar
epithelium
Epithelial
tissue
Lumen
Connective
tissue
Blood
vessel
Smooth
muscle
tissue
(2 layers)
Connective
tissue
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Figure 20.8
20.9 The body is a cooperative of organ systems
• The level of organization higher than an organ
is an organ system
• Each organ system has one or more functions
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• The digestive system
gathers food
Mouth
• The respiratory system
gathers oxygen
Larynx
Trachea
Esophagus
Liver
Stomach
Bronchus
Lung
Small
intestine
Large
intestine
Anus
A. DIGESTIVE
SYSTEM
B. RESPIRATORY
SYSTEM
Figure 20.9A, B
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• The circulatory system,
aided by the lymphatic
system, transports the
food and oxygen
• The immune system
protects the body from
infection and cancer
Bone
marrow
Thymus
Heart
Spleen
Lymph
nodes
Blood
vessels
C. CIRCULATORY
SYSTEM
Lymph
vessels
D. LYMPHATIC AND
IMMUNE SYSTEMS
Figure 20.9C, D
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• The excretory system disposes of certain wastes
Kidney
Ureter
Urinary
bladder
Urethra
E. EXCRETORY
SYSTEM
Figure 20.9E
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• The endocrine and nervous systems control
and coordinate body functions
Pineal gland
Brain
Pituitary gland
Thyroid gland
Sense
organ
Thymus gland
Adrenal gland
Pancreas
Spinal
cord
Nerves
Testis (male)
Ovary
(female)
F. ENDOCRINE
SYSTEM
H. NERVOUS
SYSTEM
Figure 20.9F, H
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• The integumentary
system covers and
protects the body
Hair
Cartilage
Skin
• The skeletal system
supports and protects
the body
Nails
Bones
J. SKELETAL AND
INTEGUMENTARY
SYSTEMS
Figure 20.9J
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• The muscular system enables movement
Skeletal
muscles
I. Muscular
system
Figure 20.9I
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• The reproductive system perpetuates the
species
MALE
Penis
FEMALE
Seminal
vesicles
Ovary
Oviduct
Prostate gland
Uterus
Vas
deferens
Vagina
Urethra
G. REPRODUCTIVE SYSTEMS
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Testis
Figure 20.9G
20.10 Connection: New imaging technology reveals
the inner body
• New technologies enable us to see body organs
without surgery
– Computed tomography (CT)
Figure 20.10A, B
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– Magnetic resonance
imaging (MRI)
– Positron-emission
tomography (PET)
Figure 20.10C, D
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EXCHANGES WITH THE EXTERNAL
ENVIRONMENT
20.11 Structural adaptations enhance exchange
between animals and their environment
• Animals are not closed systems
– An animal must exchange materials and heat
with its environment
– This exchange must extend to the cellular level
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• Small animals with simple body construction
have enough surface to meet their cells’ needs
– Hydras can exchange materials with the
environment though direct diffusion
Mouth
Diffusion
Diffusion
Gastrovascular
cavity
Two
cell
layers
Figure 20.11A
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• Larger, complex
animals have
specialized
internal
structures that
increase surface
area
Mouth
External environment
CO2
Food
O
2
Animal
RESPIRATORY
SYSTEM
DIGESTIVE
SYSTEM
Cells
Nutrients
Interstitial
fluid
CIRCULATORY
SYSTEM
EXCRETORY
SYSTEM
Anus
Unabsorbed
matter (feces)
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Metabolic waste
products (urine)
Figure 20.11B
• The respiratory system
has an enormous
internal surface area
associated with a vast
number of capillaries
• In complex animals, the
exchange of materials
between blood and body
cells takes place through
the interstitial fluid
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Figure 20.11C
20.12 Animals regulate their internal environment
• In response to changes in external conditions,
animals regulate their internal environment
– They must do this to achieve homeostasis, an
internal steady state
External environment
Internal environment
Large
external
fluctuations
Small
internal
fluctuations
Control
systems
ANIMAL
Cells of
body
Figure 20.12A, B
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20.13 Homeostasis depends on negative feedback
• Control systems sense change
Signal
via wire
ON
Set point
Sensor
OFF
CONTROL CENTER
Temperature
of room
Heater
STIMULUS
EFFECTOR
Heat produced
RESPONSE
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Figure 20.13A
• Negative feedback
mechanisms keep
fluctuations in
internal conditions
within the narrow
range compatible
with life
Heat given off by
1. Blood vessels dilating
2. Sweating
Blood
pressure
decreases
Skin
“Too
hot”
Brain
Signals
via blood
Signals to
skin via nerves
CONTROL
CENTER
Blood
temperature
increases
Skin
Heat conserved by
1. Blood vessels constricting
2. No sweating
Figure 20.13B
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“Too
cold”