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Chapter 40
Basic Principles of Animal
Form and Function
PowerPoint Lectures for
Biology, Seventh Edition
Neil Campbell and Jane Reece
Lectures by Chris Romero
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Overview:
Diverse Forms, Common Challenges
• Animals very different
• All animals common problems
– Obtain O2
– Obtain nourishment
– Excrete waste prodts
– Move
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The comparative study of animals reveals that
form and function are closely correlated
Sphinx moth long,
thin tonguelike
proboscis
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Anatomy is the study of the structure of an
organism
Physiology is the study of the functions an
organism performs
Natural selection fits structure to function
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Bioenergetics: how organisms obtain, process
& use energy
Homeostasis: animal’s regulation of its internal
environment; energy required
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Concept 40.1: Physical laws and the
environment constrain animal size and shape
• Physical laws and the need to exchange
materials with the environment limits range of
animal forms
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A. Physical Laws Constrain Animal Form
• The ability to perform certain actions depends
on an animal’s shape and size
• Different species’ adaptations to similar
environmental challenge
Video: Shark Eating Seal
Video: Galápagos Sea Lion
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Tuna
Fast
swimmers
adapted to fit
laws of
hydrodynamics
Shark
Penguin
Dolphin
Seal
B. Exchange with Environment
Constrain Animal Form
• An animal’s size and shape directly affect how
it exchanges energy and materials with its
surroundings
• Exchange occurs as substances dissolved in
the aqueous medium diffuse and are
transported across the cells’ plasma
membranes
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Video: Hydra Eating Daphnia
Diffusion
Mouth
Gastrovascular
cavity
Diffusion
Diffusion
A single-celled protist living in water
has a sufficient surface area of plasma
membrane to service its entire volume
of cytoplasm
Single cell
Multicellular organisms with a sac
body plan have body walls that are
two cells thick, facilitating diffusion
of materials
Two cell layers
• More complex organisms have highly folded
internal surfaces for exchanging materials.
• Cells must be bathed in aqueous medium to
maintain integrity of its plasma membranes.
• Exchange with environment occurs as
dissolved substances transported acx memb
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Mammals have surfaces specialized for exchanging specific molecules
Respiratory
system
0.5 cm
Heart
Nutrients
Digestive
system
50 µm
External environment
CO2 O
Food
2
Mouth
Animal
body
A microscopic view of the lung
reveals that it is much more
spongelike than balloonlike. This
construction provides an expansive
wet surface for gas exchange with
the environment (SEM).
Cells
Circulatory
system
10 µm
Interstitial
fluid
Excretory
system
The lining of the small intestine, a digestive
organ, is elaborated with fingerlike
projections that expand the surface area for
nutrient absorption (cross-section, SEM).
Anus
Unabsorbed
matter (feces)
Metabolic waste
products (urine)
Inside a kidney is a mass of microscopic
tubules that exchange chemicals with
blood flowing through a web of tiny
vessels called capillaries (SEM).
Concept 40.2: Animal form and function are
correlated at all levels of organization
• Animals are composed of specialized cells
organized into tissues that have different
functions
• Tissues make up organs, which together make
up organ systems
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
A. Tissue Structure and Function
• Different tissues have different structures that
are suited to their functions
• Four main categories tissues
– epithelial
– connective
– muscle
– nervous
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1.
EPITHELIAL TISSUE
Columnar epithelia, which have cells with relatively large cytoplasmic volumes, are often
located where secretion or active absorption of substances is an important function.
Simple
columnar
epithelium
Stratified
columnar
epithelium
Pseudostratified
ciliated columnar
epithelium
Cuboidal
epithelia
Simple squamous
epithelia
Basement membrane
40 µm
Stratified
squamous
epithelia
CONNECTIVE TISSUE
2.
120 µm
Chondrocytes
Chondroitin
sulfate
Collagenous
fiber
Elastic
fiber
100 µm
Loose
connective
tissue
Cartilage
Fibrous
connective tissue
Adipose tissue
Fat droplets
150 µm
Nuclei
30 µm
Blood
Central
canal
Bone
Red blood cells
White blood cell
Plasma
Osteon
700 µm
55 µm
MUSCLE TISSUE
3.
100 µm
a.
Multiple
nuclei
Skeletal muscle
Muscle fiber
Sarcomere
b.
Cardiac muscle
Nucleus Intercalated 50 µm
disk
c.
Nucleus
Smooth muscle
Muscle
fibers
25 µm
4.
NERVOUS TISSUE
Neuron
Process
Cell body
Nucleus
50 µm
1. Epithelial
Cells are closely joined
Covers body surface and lines hollow organs, body
cavities, and ducts
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2. Connective Tissue
• Connective tissue mainly binds and supports
other tissues
• It contains sparsely packed cells scattered
throughout an extracellular matrix
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Protect and support body and organs, bind
organs together, store E as fat, help provide
immunity (ANYTHING NOT epith, musc, neural)
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elastic cartilage
(lungs)
bone
blood
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Phys Spg 03
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23
3. Muscle
fibers contract in response to nerve signals
skeletal
generates
physical
force for
cardiac
movement
smooth
Phys Spg 03
24
4. Nervous
detects changes and responds with nerve
impulses to help maintain homeostasis
Phys Spg 03
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25
B. Organs and Organ Systems
• In all but the simplest animals, tissues are
organized into organs
• In some organs, the tissues are arranged in layers
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Lumen of
stomach
4 tissue layers
Mucosa: an epithelial
layer that lines the
lumen
Submucosa: a matrix of
connective tissue that
contains blood vessels
and nerves
Muscularis: consists
mainly of smooth muscle
tissue
0.2 mm
Serosa: a thin layer of
connective and epithelial
tissue external to the muscularis
Organ systems carry out the major body
functions of most animals
e.g.,
Integumentary System
Nervous System
Skeletal System
Respiratory System
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Concept 40.3: Animals use the chemical
energy in food to sustain form and function
• All organisms require chemical energy for
growth, repair, physiological processes,
regulation, and reproduction
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A. Bioenergetics (flow of energy through an animal)
energy measured in cal or kcal
• Bioenergetics limits behavior, growth, and
reproduction
• It determines how much food an animal needs
• Studying bioenergetics tells us much about an
animal’s adaptations
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External
environment
Organic molecules
in food
Animal
body
Animals
harvest chem
energy from
food &
make ATP,
which powers
cellular work
After the
needs of
staying alive
are met,
remaining
food
molecules can
be used in
biosynthesis
Digestion and
absorption
Heat
Energy
lost in
feces
Nutrient molecules
in body cells
Carbon
skeletons
Cellular
respiration
Energy
lost in
urine
Heat
ATP
Biosynthesis:
growth,
storage, and
reproduction
Cellular
work
Heat
Heat
B. Quantifying Energy Use
• Metabolic rate = amount of energy an animal
uses per unit time
• Measure = detm O2 consumed or CO2 produced
Ghost crab in respirometer. T is held
constant in chamber, with air of known O2
conc flowing through. The crab’s
metabolic rate is calculated from diff
between O2 entering & O2 leaving the
respirometer. Crab is on a treadmill,
running at constant speed.
Metabolic rate of man fitted with
breathing apparatus is being
monitored while he exercises on
a stationary bike
Could alternatively measure rate of heat loss
to get metabolic rate since nearly all chemical
energy eventually appears as heat
C. Bioenergetic Strategies
Animal’s metabolic rate closely related to its
bioenergetic strategy
– Endothermic
– Ectothermic
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• Birds and mammals are mainly endothermic:
their bodies are warmed mostly by heat
generated by metabolism
• Endotherms typically have higher metabolic
rates
• Amphibians and reptiles other than birds are
ectothermic: They gain their heat mostly from
external sources
• Ectotherms generally have lower metabolic
rates
D. Influences on Metabolic Rate
• Metabolic rates are affected by many factors
besides whether an animal is an endotherm or
ectotherm
• Two of these factors are size and activity
1. Body Size and Metabolic Rate
• Energy required to maintain body = metabolic
rate per gram is inversely related to body size
among similar animals
• Researchers continue to search for the causes
of this relationship
Each gm mouse requires
20x as many calories as gm
of elephant to maintain
tissue.
Mouse has higher rate
respiration, higher blood
vol/size, higher heart rate &
requires eat more food/gm
body wt
2. Activity and Metabolic Rate
• The basal metabolic rate (BMR) is the
metabolic rate of an endotherm at rest =
minimum rate to power basic functions to
support life, e.g. breathing, heartbeat, etc.
• The standard metabolic rate (SMR) is the
metabolic rate of an ectotherm at rest
• Activity greatly affects metabolic rate
• In general, maximum metabolic rate is
inversely related to the duration of the activity
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500
Max MR over diff time spans
A = 60-kg alligator
A H
Maximum metabolic rate
(kcal/min; log scale)
100
A
H
A = 60-kg human
50
H
10
H
H
5
A
1
A
A
0.5
0.1
1
second
1
minute
1
hour
1
day
1
week
MR for
sedentary life
style < MR for
more active life
style
Time interval
Key
Existing intracellular ATP
ATP from glycolysis
ATP from aerobic respiration
Human MR > Alligato MR and
human ability to sustain long time
> alligator’s ability to sustain
E. Energy Budgets
• Different species use energy and materials in
food in different ways, depending on their
environment
• Use of energy is partitioned to BMR (or SMR),
activity, homeostasis, growth, and
reproduction
Endotherms
800,000
Reproduction
Basal
(standard)
metabolism
Temperature
regulation
Ectotherm
TOTAL ENERGY REQUIREMENT
Growth
Activity
340,000
8,000
4,000
60-kg female human
from temperate climate
4-kg male Adélie penguin
from Antarctica (brooding)
Total annual energy expenditures. The slices of the pie charts indicate energy
expenditures for various functions.
0.025-kg female deer mouse
from temperate
North America
4-kg female python
from Australia
438
ENERGY REQUIREMENT/UNIT WEIGHT
Human
233
Python
Deer mouse
Adélie penguin
36.5
Energy expenditures per unit mass (kcal/kg•day). Comparing the daily energy expenditures
per kg of body weight for the four animals reinforces two important concepts of
bioenergetics. First, a small animal, such as a mouse, has a much greater energy demand
per kg than does a large animal of the same taxonomic class, such as a human (both
mammals). Second, note again that an ectotherm, such as a python, requires much less
energy per kg than does an endotherm of equivalent size, such as a penguin.
5.5
Concept 40.4: Animals regulate their internal
environment within relatively narrow limits
• The internal environment of vertebrates is
called the interstitial fluid and is very different
from the external environment
• Homeostasis is a balance between external
changes and the animal’s internal control
mechanisms that oppose the changes =
maintenance of body environment within
steady state narrow limits
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
A. Regulating and Conforming
(two extremes how animals cope with change in environmental)
• Regulator uses internal control mechanisms to
moderate internal change in the face of
external, environmental fluctuation
• Conformer allows its internal condition to vary
with certain external changes
B. Mechanisms of Homeostasis
• Mechanisms of homeostasis moderate
changes in the internal environment
• A homeostatic control system has three
functional components: a receptor, a control
center, and an effector
Animation: Negative Feedback
Animation: Positive Feedback
Homeostasis = systems work together to
maintain equilibrium in body
• HOMEOSTASIS ESSENTIAL FOR LIFE
• SLIGHT AND TEMPORARY DEVIATIONS CAN BE
TOLERATED = BODY RESPOSE & RETURN TO
HOMEOSTASIS
• LARGE VARIATION NEEDS MEDICAL INTERVENTION
FOR RETURN TO HOMEOSTASIS
FEEDBACK
SYSTEMS
MAINTAIN
HOMEOSTASIS
Components:
1. Receptors
2. Control
Center
3. Effectors
NEGATIVE
FEEDBACK
►decreases
an action
►stops when
return to
normal
►most
homeostatic
control
mechanisms
are negative
feedback
POSITIVE
FEEDBACK
(reinforces)
►increases
an action
►must be turned
off by outside
event
►decreases
an action
►could run away
= death
* blood loss
- ↓ B.P.
- ↓ heart beat
- ↓ B.P.
* blood clotting
Response
No heat
produced
Heater
turned
off
Room
temperature
decreases
Set
point
Too
hot
Set point
Control center:
thermostat
Room
temperature
increases
Too
cold
Heater
turned
on
Response
Heat
produced
Set
point
• Most homeostatic control systems function by
negative feedback, where buildup of the end
product shuts the system off
• In positive feedback, a change in a variable
triggers mechanisms that amplify rather than
reverse the change
Concept 40.5:
Thermoregulation
example of homeostasis
• Thermoregulation is the process by which
animals maintain an internal temperature
within a tolerable range
• Internal temperature affects enzyme activities
and cell membrane properties
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
A. Ectotherms and Endotherms
(based upon source of heat used to maintain body
temperature)
Ectotherms: invertebrates, fishes, amphibians,
Endotherms: birds & mammals
In general, ectotherms tolerate greater variation
in internal temperature than endotherms
Relationship between body temperature &
Environmental temperature
40
River otter (endotherm)
Body temperature (°C)
30
20
Largemouth bass (ectotherm)
10
10
20
30
0
Ambient (environmental) temperature (°C)
40
• Endothermy is more energetically expensive
than ectothermy
• It buffers the animal’s internal temperatures
against external fluctuations
• It also enables the animal to maintain a high
level of aerobic metabolism
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B. Modes of Heat Exchange
• Organisms exchange heat by four physical processes:
conduction, convection, radiation, and evaporation
Radiation: radiate heat
between objects not in contact.
Evaporation: removal heat
from surface of liquid lost
as gas
Convection: transfer
heat by mvt air
Conduction: direct transfer
heat between molecules
in contact
B. Balancing Heat Loss and Gain
• In thermoregulation, physiological and
behavioral adjustments balance heat loss and
heat gain
• 5 general adaptations in animals’
thermoregulation:
– Insulation
– Circulatory adaptations
– Cooling by evaporative heat loss
– Behavioral responses
– Adjusting metabolic heat production
1. Insulation
• Insulation is a major thermoregulatory adaptation in
mammals and birds
• It reduces heat flow between an animal and its
environment
• Examples are skin, feathers, fur, and blubber
• In mammals, the integumentary system acts as
insulating material
2. Circulatory Adaptations
• Many endotherms & some ectotherms alter
amount of blood flowing between the body core
& skin
• Vasodilatation = ↑ blood flow in skin = ↑ heat
loss
• Vasoconstriction = ↓ blood flow in skin =
↓ heat loss
• Many marine mammals & birds have
arrangement blood vessels called counter
current heat exchanger which are
important for reducing heat loss
3. Cooling by Evaporative Heat Loss
• Many types of animals lose heat through evaporation
of water in sweat
• Panting augments the cooling effect in birds and many
mammals
• Bathing moistens the skin, helping to cool animal
4. Behavioral Responses
• Both endotherms and ectotherms use behavioral
responses to control body temp
• Some terrestrial invertebrates have postures that
minimize or maximize absorp solar heat
More extreme
behavioral
adaptations =
hibernation or
migration to
more suitable
climate
5. Adjusting Metabolic Heat Production
• Some animals can regulate body temperature by
adjusting their rate of metabolic heat production
• Many species of flying insects use shivering to warm
up before taking flight
Preflight warmup in
hawkmoth = shiver-like to
help muscles produce
enough power to take off
C. Feedback Mechanisms in Thermoregulation
• Mammals regulate body temperature by
negative feedback involving several organ
systems
• In humans, the hypothalamus (a part of the
brain) contains nerve cells that function as a
thermostat
D. Adjustment to Changing Temperatures
• In acclimatization, many animals adjust to a
new range of environmental temperatures over
a period of days or weeks
• Acclimatization may involve cellular
adjustments or (as in birds and mammals)
adjustments of insulation and metabolic heat
production
• Thicker fur coat for winter, shed in summer