Chapter 40
Basic Principles of Animal
Form and Function
These chapters go into the study of ANATOMY AND PHYSIOLOGY
PowerPoint Lectures for
Biology, Seventh Edition
Neil Campbell and Jane Reece
Lectures by Chris Romero
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Essential Knowledges Covered
• Reproduction and rearing of offspring require free energy
beyond that used for maintenance and growth. Different
organisms use various reproductive strategies in response
to energy availability.
• There is a relationship between metabolic rate per unit
body mass and the size of multicellular organisms —
generally, the smaller the organism, the higher the
metabolic rate.
• Excess acquired free energy versus required free energy
expenditure results in energy storage or growth.
• Within multicellular organisms, specialization of organs
contributes to the overall functioning of the organism.
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Essential Knowledges Covered Con’t.
• Organisms use feedback mechanisms to maintain their
internal environments and respond to external
environmental changes.
• Continuity of homeostatic mechanisms reflects common
ancestry, while changes may occur in response to different
environmental conditions.
• Homeostatic control systems in species of microbes, plants
and animals support common ancestry.
• Disruptions at the molecular and cellular levels affect the
health of the organism.
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The comparative study of animals reveals that form
and function are closely correlated
This moth’s proboscis
shows how closely
related form and function
are
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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 place limits on the range of
animal forms
Physical Laws and Animal Form
• The ability to perform certain actions depends on
an animal’s shape and size
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How have these animals adapted their form to fit their
environment?
Video: Galápagos Sea Lion
Tuna
Video: Shark Eating Seal
Shark
Penguin
Dolphin
Seal
Evolutionary
convergence reflects
different species’
adaptations to a
similar environmental
challenge
Prehistoric bug size was governed by the physical
environment
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Exchange with the Environment
• Animal’ s size and shape affect how it exchanges
energy and materials with its surroundings
• Exchange occurs as dissolved substances
diffuse and are transported across the cells’
plasma membranes
– In fact, one of the traits that all animals share
is that they have cells surrounded by an
aqueous environment, to facilitate this diffusion
• In a single-celled protist living in water, the entire
surface area contacts the environment
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LE 40-3
Mouth
Diffusion
Gastrovascular
cavity
Diffusion
Diffusion
Single cell
Two cell layers
More complex organisms have highly folded internal surfaces
for exchanging materials
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
10 µm
Circulatory
system
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
• Most animals are composed of specialized cells
organized into tissues that have different
functions
• Tissues make up organs, which together make up
organ systems
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Tissue Structure and Function
• Different tissues have different structures that are
suited to their functions
• Tissues are classified into four main categories:
– Epithelial – covers body and lines organs and cavities
– Connective – bind and support other tissues; sparsely
packed
– Muscle – contractile and stimulated by nerves. Made
of actin and myosin
– Nervous – sense stimuli
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
LE 40-5_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
LE 40-5_2
CONNECTIVE TISSUE
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
LE 40-5_3
MUSCLE TISSUE
100 µm
Multiple
nuclei
Skeletal muscle
Muscle fiber
Sarcomere
Cardiac muscle
Nucleus Intercalated 50 µm
disk
Nucleus
Smooth muscle
Muscle
fibers
25 µm
NERVOUS TISSUE
Neuron
Process
Cell body
Nucleus
50 µm
Organ systems carry out the major body functions
of most animals
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Concept 40.3: Animals use the chemical energy in
food to sustain form and function
Bioenergetics
• Bioenergetics = the flow of energy through an
animal
• limits behavior, growth, and reproduction
• It determines how much food an animal needs and
what adaptations it may have
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Energy Sources and Allocation
• Animals harvest chemical energy from food to
make ATP
• After the needs of staying alive are met, remaining
food molecules can be used in biosynthesis
– this is the formation of the biological pieces of an
living being
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Overview flow
chart of energy
allocation
External
environment
Organic molecules
in food
Animal
body
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
Quantifying Energy Use
This photograph shows a ghost crab in a
respirometer. Temperature is held constant in the
chamber, with air of known O2 concentration flowing
through. The crab’s metabolic rate is calculated
from the difference between the amount of O2
entering and the amount of O2 leaving the
respirometer. This crab is on a treadmill, running at
a constant speed as measurements are made.
Similarly, the metabolic rate of a man
fitted with a breathing apparatus is
being monitored while he exercises
on a stationary bike.
Metabolic rate is the amount of energy an animal
uses in a unit of time
Bioenergetic Strategies
• An animal’s metabolic rate is closely related to its
bioenergetic strategy
• Endothermic : Their bodies are warmed mostly
by heat generated by metabolism and have
higher metabolic rates
– Aka and examples?
• Ectothermic: They gain their heat mostly from
external sources
– Aka and examples? Mom?
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Ectotherms vs. Endotherms
In general, ectotherms
experience greater
variation in internal
temperature than
endotherms
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Ectotherms vs. Endotherms
• 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
• Advantages to endothermy = permits intense, long
duration activity over a wide range of temps
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LE 40-9
500
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
Time interval
Key
Existing intracellular ATP
ATP from glycolysis
ATP from aerobic respiration
1
day
1
week
Activity and Metabolic Rate
• The basal metabolic rate (BMR) is the metabolic
rate of an endotherm at rest
• The standard metabolic rate (SMR) is the
metabolic rate of an ectotherm at rest
• In general, maximum metabolic rate is inversely
related to the duration of the activity
– The longer the activity takes place the lower
the max. metabolic rate
– The shorter the activity takes place the higher
the max. metabolic rate
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Size and Metabolic Rate
• Metabolic rate per gram is inversely related to
body size among similar animals
• Size goes up then the metabolic rate is lower.
• Size goes down then the metabolic rate is higher
– Still unknown why this is
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
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
– reproduction
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
LE 40-10
Endotherms
800,000
Reproduction
Basal
(standard)
metabolism
Ectotherm
Temperature
regulation
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
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
• Homeostasis is a balance between external
changes and the animal’s internal control
mechanisms that oppose the changes
• Homeostatis works to keep the interstitial fluid
“right”
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Regulating and conforming are two extremes in
how animals cope with environmental fluctuations
• A regulator uses internal control mechanisms to
moderate internal change
• A conformer allows its internal condition to vary
with certain external changes
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Mechanisms of Homeostasis
• negative feedback = where buildup of the end
product shuts the system off
– Most times
• positive feedback = a change in a variable
triggers mechanisms that amplify the change
– Uterine contractions in childbirth
Animation: Negative Feedback
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Animation: Positive Feedback
Response
Mechanisms of
Homeostasis
No heat
produced
Heater
turned
off
Room
temperature
decreases
A homeostatic
control system has
three functional
components: a
receptor, a control
center, and an
effector
Set
point
Too
hot
Set point
Control center:
thermostat
Room
temperature
increases
Too
cold
Heater
turned
on
Response
Heat
produced
Set
point
1. a receptor
2. a control
center
3. an effector
LE 40-21
Sweat glands secrete
sweat that evaporates,
cooling the body.
Thermostat in
hypothalamus
activates cooling
mechanisms.
Increased body
temperature (such
as when exercising
or in hot
surroundings)
Blood vessels
in skin dilate:
capillaries fill
with warm blood;
heat radiates from
skin surface.
Body temperature
decreases;
thermostat
shuts off cooling
mechanisms.
Homeostasis:
Internal body temperature
of approximately 36–38°C
Body temperature
increases;
thermostat
shuts off warming
mechanisms.
Decreased body
temperature
(such as when
in cold
surroundings)
Blood vessels in skin
constrict, diverting blood
from skin to deeper tissues
and reducing heat loss
from skin surface.
Skeletal muscles rapidly
contract, causing shivering,
which generates heat.
Thermostat in
hypothalamus
activates
warming
mechanisms.
Concept 40.5: Thermoregulation contributes to homeostasis
and involves anatomy, physiology, and behavior
• Thermoregulation is the process by which
animals maintain an internal temperature within a
tolerable range
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Modes of Heat Exchange
Radiation
Evaporation
Convection
Conduction
Balancing Heat Loss and Gain
• In thermoregulation, physiological and behavioral
adjustments balance heat loss and gain
• Five general adaptations help animals
thermoregulate:
– Insulation
– Circulatory adaptations
– Cooling by evaporative heat loss
– Behavioral responses
– Adjusting metabolic heat production
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Insulation
• Mostly in
mammals and
birds
• Acts as a barrier
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Circulatory Adaptations
• vasodilation
Increase blood
flow, warms skin
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vasoconstriction
decrease blood
flow and heat
transfer
Bear likes to be warm
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Countercurrent heat exchanger
• Many marine mammals, birds, some bony fishes
• Important for reducing heat loss
• Supplies considerably warmer blood to the core of
the body
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LE 40-15
Canada
goose
Pacific
bottlenose
dolphin
Blood flow
Artery Vein
35°C
33°
30°
27°
20°
18°
10°
9°
Vein
Artery
LE 40-16a
21°
25° 23°
27°
29°
31°
Body cavity
Bluefin tuna
LE 40-16b
Skin
Artery
Vein
Blood
vessels
in gills
Capillary
network within
muscle
Heart
Artery and
vein under
the skin Dorsal aorta
Great white shark
Insects do this as well
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Cooling by Evaporative Heat Loss
panting
bathing
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sweating.
Behavioral Responses
•
Both endotherms and ectotherms use behavioral responses to control
body temperature
•
Some terrestrial invertebrates have postures that minimize or
maximize absorption of solar heat
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Torpor and Energy Conservation
• Torpor is a state in which activity is low and
metabolism decreases
– Save energy and avoid dangerous conditions
• Estivation = summer torpor
– Avoidance of high temps and low water
• Hibernation is long-term torpor that is an
adaptation to winter cold and food scarcity
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
LE 40-22
200
Actual
metabolism
Additional metabolism that would be
necessary to stay active in winter
100
0
35
30
Arousals
Body
temperature
25
20
15
10
5
0
–5
Outside
temperature
Burrow
temperature
–10
–15
June
August
October
December
February
April