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Chapter 20
Unifying Concepts of Animal
Structure and Function
PowerPoint Lectures for
Campbell Biology: Concepts & Connections, Seventh Edition
Reece, Taylor, Simon, and Dickey
© 2012 Pearson Education, Inc.
Lecture by Edward J. Zalisko
Introduction
 How can geckos climb walls and stick to the
ceiling?
– The surfaces of gecko toes are covered by millions of
microscopic hairs.
– Each hair has a slight molecular attraction that helps it
stick to the surface.
– This adhesive relationship is an example of the
correlation between structure and function.
© 2012 Pearson Education, Inc.
Figure 20.0_1
Figure 20.0_2
Chapter 20: Big Ideas
Structure and Function
in Animal Tissues
External Exchange and
Internal Regulation
Organs and Organ
Systems
Figure 20.0_3
STRUCTURE AND FUNCTION
IN ANIMAL TISSUES
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20.1 Structure fits function at all levels of
organization in the animal body
 Anatomy is the study of structure.
 Physiology is the study of function.
 Animals consist of a hierarchy of levels or
organization.
– Tissues are an integrated group of similar cells that
perform a common function.
– Organs perform a specific task and consist of two or
more tissues.
– Organ systems consist of multiple organs that together
perform a vital body function.
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Figure 20.1
Cellular level
Muscle cell
Tissue level
Muscle tissue
Organ level
Heart
Organ system level
Circulatory system
Organism level
Many organ systems
functioning together
20.2 EVOLUTION CONNECTION: An
animal’s form reflects natural selection
 The body plan or design of an organism
– reflects the relationship between form and function,
– results from natural selection, and
– does not imply a process of conscious invention.
 Streamlined and tapered bodies
– increase swimming speeds and
– have similarly evolved in fish, sharks, and aquatic birds
and mammals, representing convergent evolution.
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Video: Galápagos Sea Lion
Use windows controls to play
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Video: Shark Eating a Seal
Use windows controls to play
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Figure 20.2
Shark
Seal
Penguin
20.3 Tissues are groups of cells with a common
structure and function
 Tissues
– are an integrated group of similar cells that perform a
common function and
– combine to form organs.
 Animals have four main categories of tissues:
1. epithelial tissue,
2. connective tissue,
3. muscle tissue, and
4. nervous tissue.
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20.4 Epithelial tissue covers the body and lines
its organs and cavities
 Epithelial tissues, or epithelia, are sheets of
closely packed cells that
– cover body surfaces and
– line internal organs and cavities.
 Epithelial cells come in three shapes:
1. squamous—like a fried egg,
2. cuboidal—as tall as they are wide, and
3. columnar—taller than they are wide.
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20.4 Epithelial tissue covers the body and lines
its organs and cavities
 Epithelial tissues are named according to the
– number of cell layers they have and
– shape of the cells on their apical surface.
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Figure 20.4
Apical surface of
epithelium
Basal
lamina
Underlying
Cell nuclei
tissue
Simple squamous
epithelium
Pseudostratified
ciliated columnar
epithelium
Simple cuboidal
epithelium
Simple columnar
epithelium
Stratified squamous
epithelium
20.5 Connective tissue binds and supports other
tissues
 Connective tissue can be grouped into six major
types.
1. Loose connective tissue
– is the most widespread,
– consists of ropelike collagen and elastic fibers that are strong
and resilient, and
– helps to join skin to underlying tissues.
2. Fibrous connective tissue
– has densely packed collagen fibers and
– forms tendons that attach muscle to bone.
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20.5 Connective tissue binds and supports other
tissues
3. Adipose tissue stores fat in large, closely packed cells
held in a matrix of fibers.
4. Cartilage
– is a strong and flexible skeletal material and
– commonly surrounds the ends of bones.
5. Bone
– has a matrix of collagen fibers
– embedded in a hard mineral substance containing calcium,
magnesium, and phosphate.
6. Blood transports substances throughout the body.
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Figure 20.5
White blood
cells
Red blood
cell
Central
canal
Plasma
Cell
nucleus
Collagen
fiber
Elastic
fibers
Matrix
Blood
Bone
Loose connective tissue
(under the skin)
Cell nucleus
Collagen
fibers
Cartilageforming
cells
Fat
droplets
Fibrous connective
tissue (forming a tendon)
Boneforming
cells
Matrix
Cartilage
(at the end
of a bone)
Adipose
tissue
Figure 20.5_1
Cell
nucleus
Collagen
fiber
Elastic
fibers
Loose connective tissue
(under the skin)
Figure 20.5_2
Cell nucleus
Collagen
fibers
Fibrous connective
tissue (forming a tendon)
Figure 20.5_3
Fat
droplets
Adipose
tissue
Figure 20.5_4
Cartilageforming
cells
Matrix
Cartilage
(at the end
of a bone)
Figure 20.5_5
Central
canal
Matrix
Bone
Boneforming
cells
Figure 20.5_6
White blood
cells
Red blood
cell
Plasma
Blood
20.6 Muscle tissue functions in movement
 Muscle tissue is the most abundant tissue in most
animals.
 There are three types of vertebrate muscle tissue:
1. Skeletal muscle causes voluntary movements.
2. Cardiac muscle pumps blood.
3. Smooth muscle moves walls of internal organs, such
as the intestines.
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Figure 20.6
Muscle
fiber
Unit of
muscle
contraction
Muscle
fiber
(cell)
Nuclei
Junction
between
two cells
Nucleus
Cardiac
muscle
Muscle
fiber
Nucleus
Skeletal
muscle
Smooth
muscle
Figure 20.6_1
Unit of
muscle
contraction
Muscle
fiber
(cell)
Nuclei
Skeletal
muscle
Figure 20.6_2
Muscle
fiber
Junction
between
two cells
Nucleus
Cardiac
muscle
Figure 20.6_3
Muscle
fiber
Nucleus
Smooth
muscle
20.7 Nervous tissue forms a communication
network
 Nervous tissue
– senses stimuli and
– rapidly transmits information.
 Neurons carry signals by conducting electrical
impulses.
 Other cells in nervous tissue
– insulate axons,
– nourish neurons, and
– regulate the fluid around neurons.
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Figure 20.7
Dendrites
Cell body
Axon
ORGANS AND
ORGAN SYSTEMS
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20.8 Organs are made up of tissues
 Each tissue performs specific functions.
 The heart has
– extensive muscle that generates contractions,
– epithelial tissues that line the heart chambers,
– connective tissues that make the heart elastic, and
– neurons that regulate contractions.
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20.8 Organs are made up of tissues
 The small intestine
– is lined by a columnar epithelium,
– includes connective tissues that contain blood vessels,
and
– has two layers of smooth muscle that help propel food.
 The inner surface of the small intestine has many
fingerlike projections that increase the surface area
for absorption.
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Figure 20.8
Small intestine
Lumen
Epithelial tissue
(columnar epithelium)
Connective tissue
Smooth muscle
tissue (two layers)
Connective tissue
Epithelial tissue
20.9 CONNECTION: Bioengineers are learning to
produce tissues and organs for transplants
 Bioengineering is seeking ways to repair or replace
damaged tissues and organs.
 New tissues and organs are being grown using a
patient’s own cells.
 These techniques
– remove the risk of tissue rejection and
– may someday reduce the shortage of organs available
for transplants.
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Figure 20.9
20.10 Organ systems work together to perform
life’s functions
 Each organ system
– typically consists of many organs,
– has one or more functions, and
– works with other organ systems to create a functional
organism.
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Figure 20.10_L
Circulatory
system
Respiratory
system
Nasal
cavity
Integumentary system
Pharynx
Hair
Larynx
Skin
Trachea
Heart
Bronchus
Nails
Lung
Blood
vessels
Skeletal system
Bone
Cartilage
Urinary
system
Muscular system
Digestive
system
Mouth
Esophagus
Skeletal muscles
Liver
Kidney
Ureter
Urinary
bladder
Urethra
Stomach
Small
intestine
Large
intestine
Anus
Figure 20.10_R
Endocrine system
Hypothalamus
Pituitary gland
Thymus
Thyroid gland
Adrenal
gland
Parathyroid
gland
Lymphatic and
immune systems
Thymus
Lymph
nodes
Spleen
Appendix
Bone
marrow
Pancreas
Lymphatic
vessels
Testis
(male)
Ovary
(female)
Reproductive
system
Nervous system
Brain
Seminal
vesicles
Sense organ
(ear)
Spinal cord
Nerves
Female
Male
Oviduct
Prostate
gland
Ovary
Vas
deferens
Uterus
Penis
Vagina
Testis
Urethra
20.10 Organ systems work together to perform
life’s functions
 The skeletal and muscular systems support and
move the body.
 The digestive and respiratory systems obtain
food and oxygen.
 The circulatory system transports these
materials.
 The urinary system disposes of wastes.
 The integumentary system covers the body.
© 2012 Pearson Education, Inc.
Figure 20.10_1
Circulatory
system
Respiratory
system
Nasal
cavity
Heart
Pharynx
Larynx
Trachea
Bronchus
Lung
Blood
vessels
Figure 20.10_2
Integumentary system
Hair
Skin
Nails
Figure 20.10_3
Skeletal system
Bone
Cartilage
Figure 20.10_4
Muscular system
Skeletal muscles
Figure 20.10_5
Urinary
system
Digestive
system
Mouth
Esophagus
Liver
Kidney
Ureter
Urinary
bladder
Urethra
Stomach
Small
intestine
Large
intestine
Anus
20.10 Organ systems work together to perform
life’s functions
 The lymphatic and immune systems protect the
body from infection.
 The nervous and endocrine systems control and
coordinate body functions.
 The reproductive system produces offspring.
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Figure 20.10_6
Endocrine system
Hypothalamus
Pituitary gland
Thymus
Thyroid gland
Adrenal
gland
Parathyroid
gland
Pancreas
Testis
(male)
Ovary
(female)
Figure 20.10_7
Lymphatic and
immune systems
Lymph
nodes
Thymus
Spleen
Appendix
Bone
marrow
Lymphatic
vessels
Figure 20.10_8
Nervous system
Brain
Sense organ
(ear)
Spinal cord
Nerves
Figure 20.10_9
Reproductive
system
Seminal
vesicles
Female
Male
Oviduct
Prostate
gland
Ovary
Vas
deferens
Uterus
Penis
Vagina
Testis
Urethra
20.11 CONNECTION: New imaging technology
reveals the inner body
 New technologies
– are used in medical diagnosis and research and
– allow physicians to examine organ systems without
surgery.
 X-rays help create images of hard structures such as
bones and teeth.
 Magnetic resonance imaging (MRI)
– takes advantage of the behavior of the hydrogen atoms in
water molecules and
– provides three-dimensional images of very small
structures.
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Figure 20.11A
Femur
(thigh bone)
Torn meniscus
Tibia (shin bone)
20.11 CONNECTION: New imaging technology
reveals the inner body
 A newer X-ray technology called computed
tomography (CT)
– produces high-resolution images of cross sections of the
body and
– can detect small differences between normal and
abnormal tissues in many organs.
 Positron-emission tomography (PET) helps identify
metabolic processes at specific body locations.
 CT and PET images can be combined for an even
more informative image.
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Figure 20.11B
20.12 The integumentary system protects the body
 The skin consists of two layers:
1. The epidermis
– is a stratified squamous epithelium and
– forms the surface of the skin.
2. The dermis
– forms a deeper skin layer and
– is composed of dense connective tissue with many resilient
elastic fibers and strong collagen fibers.
– The dermis contains hair follicles, oil and sweat glands, muscle
cells, nerves, sensory receptors, and blood vessels.
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Figure 20.12
Hair
Epidermis
Sweat
pore
Muscle
Dermis
Nerve
Sweat
gland
Hypodermis
(under the skin)
Adipose tissue
Blood vessels
Oil gland
Hair follicle
20.12 The integumentary system protects the body
 Skin has many functions.
– The epidermis
– resists physical damage,
– decreases water loss, and
– prevents penetration by microbes.
– The dermis
– collects sensory information,
– synthesizes vitamin D, and
– helps regulate body temperature.
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20.12 The integumentary system protects the body
 Exposure of the skin to ultraviolet light
– causes skin cells to release melanin, which contributes
to a visible tan, and
– damages DNA of skin cells and can lead to
– premature aging of the skin,
– cataracts, and
– skin cancers.
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20.12 The integumentary system protects the body
 Hair
– is an important component of the integumentary system
of mammals,
– helps to insulate their bodies, and
– consists of a shaft of keratin-filled dead cells.
 Oil glands release oils that
– are associated with hair follicles,
– lubricate hair,
– condition surrounding skin, and
– inhibit the growth of bacteria.
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EXTERNAL EXCHANGE AND
INTERNAL REGULATION
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20.13 Structural adaptations enhance exchange
with the environment
 Every organism is an open system that must
exchange matter and energy with its surroundings.
 Cells in small and flat animals can exchange
materials directly with the environment.
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20.13 Structural adaptations enhance exchange
with the environment
 However, as organisms increase in size, the surface
area
– is too small for the corresponding volume and
– too far away from the deepest cells of the body.
– In these organisms, evolutionary adaptations
– consist of extensively branched or folded surfaces, which
increase the area of these surfaces and
– provide for sufficient environmental exchange.
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20.13 Structural adaptations enhance exchange
with the environment
 The respiratory system exchanges gases between
the external environment and blood.
 The digestive system acquires food and eliminates
wastes.
 The excretory system eliminates metabolic waste.
 The circulatory system
– distributes gases, nutrients, and wastes throughout the
body and
– exchanges materials between blood and body cells
through the interstitial fluid that bathes body cells.
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Figure 20.13A
EXTERNAL ENVIRONMENT
CO2
O2
Food
Mouth
ANIMAL
Respiratory
system
Digestive
system
Interstitial
fluid
Heart
Nutrients
Circulatory
system
Body
cells
Intestine
Urinary
system
Anus
Unabsorbed
matter (feces)
Metabolic waste
products (urine)
Figure 20.13B
Trachea
20.14 Animals regulate their internal environment
 Homeostasis is the active maintenance of a
steady state within the body.
– External environmental conditions may fluctuate wildly.
– Homeostatic mechanisms regulate internal conditions.
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Figure 20.14_UN
Figure 20.14
External
environment
Homeostatic
mechanisms
Large
fluctuations
Internal
environment
Small
fluctuations
20.15 Homeostasis depends on negative feedback
 Control systems
– detect change and
– direct responses.
 Negative-feedback mechanisms
– keep internal variables steady and
– permit only small fluctuations around set points.
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Animation: Negative Feedback
Right click on animation / Click play
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Animation: Positive Feedback
Right click on animation / Click play
© 2012 Pearson Education, Inc.
Figure 20.15_s1
Homeostasis:
Body temperature
approximately 37°C
Figure 20.15_s2
Brain activates
cooling
mechanisms.
Temperature rises
above set point
Homeostasis:
Body temperature
approximately 37°C
Temperature falls
below set point
Brain
activates
warming
mechanisms.
Figure 20.15_s3
Sweat evaporates,
cooling the body.
Brain activates
cooling
mechanisms.
Blood vessels dilate.
Temperature rises
above set point
Homeostasis:
Body temperature
approximately 37°C
Temperature falls
below set point
Blood vessels constrict.
Shivering generates
heat.
Brain
activates
warming
mechanisms.
Figure 20.15_s4
Sweat evaporates,
cooling the body.
Brain activates
cooling
mechanisms.
Blood vessels dilate.
Temperature
decreases
Cooling mechanisms
shut off.
Temperature rises
above set point
Homeostasis:
Body temperature
approximately 37°C
Temperature
increases
Warming mechanisms
shut off.
Temperature falls
below set point
Blood vessels constrict.
Shivering generates
heat.
Brain
activates
warming
mechanisms.
Figure 20.15_5
Sweat glands secrete sweat that
evaporates, cooling the body.
The thermostat
in the brain
activates cooling
mechanisms.
Blood vessels in the skin dilate,
increasing heat loss.
Temperature
decreases
The thermostat shuts off
the cooling mechanisms.
Homeostasis:
Body temperature
approximately 37°C
Temperature rises
above set point
Figure 20.15_6
Homeostasis:
Body temperature
approximately 37°C
Temperature
increases
The thermostat shuts off
the warming mechanisms.
Temperature falls
below set point
Blood vessels in the skin constrict,
minimizing heat loss.
Skeletal muscles contract;
shivering generates heat.
The thermostat
in the brain
activates
warming
mechanisms.
You should now be able to
1. Describe the levels of organization in an animal’s
body.
2. Explain how size and shape can influence the
structure of an animal.
3. Define a tissue, describe the four main types of
animal tissue, and note their structures and their
functions.
4. Explain how the structure of organs is based on
the cooperative interactions of tissues.
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You should now be able to
5. Explain how artificial tissues are created and
used.
6. Describe the general structures and functions of
the 12 major vertebrate organ systems.
7. Describe and compare X-ray, CT, MRI, and PET
imaging technologies.
8. Relate the structure of the skin to its functions.
© 2012 Pearson Education, Inc.
You should now be able to
9. Describe the systems that help an animal
exchange materials with its environment.
10. Describe examples of adaptations to increase
the surface-to-volume ratio.
11. Define the concept of homeostasis and illustrate
it with examples.
12. Explain how negative feedback is used to
regulate internal body temperature.
© 2012 Pearson Education, Inc.
Function
20.5 Connective
tissue binds and
supports other
tissues.
20.6 Muscle
tissue functions
in movement.
20.7 Nervous tissue
forms a
communication
network.
Sheets of closely
packed cells
Sparse cells in extracellular matrix
Long cells (fibers)
with contractile
proteins
Neurons with
branching extensions;
supporting cells
Skeletal muscle
Neuron
Example
20.4 Epithelial tissue
covers the body and
lines its organs and
cavities.
Structure
Figure 20.UN01
Columnar epithelium
Loose connective tissue
Function
20.5 Connective
tissue binds and
supports other
tissues.
Sheets of closely
packed cells
Sparse cells in extracellular matrix
Example
20.4 Epithelial tissue
covers the body and
lines its organs and
cavities.
Structure
Figure 20.UN01_1
Columnar epithelium
Loose connective tissue
20.6 Muscle
tissue functions
in movement.
20.7 Nervous tissue
forms a
communication
network.
Long cells (fibers)
with contractile
proteins
Neurons with
branching extensions;
supporting cells
Skeletal muscle
Neuron
Example
Structure Function
Figure 20.UN01_2
Figure 20.UN02
a.
b.
c.
d.
e.