Transcript video slide

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 inhabit almost every part of the biosphere
• All animals face a similar set of problems,
including how to nourish themselves
• The comparative study of animals reveals that
form and function are closely correlated
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Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Anatomy is the study of the structure of an
organism
• Physiology is the study of the functions an
organism performs
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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
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Physical Laws and Animal Form
• The ability to perform certain actions depends on
an animal’s shape and size
• Evolutionary convergence reflects different
species’ adaptations to a similar environmental
challenge
Video: Shark Eating Seal
Video: Galápagos Sea Lion
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LE 40-2
Tuna
Shark
Penguin
Dolphin
Seal
Exchange with the Environment
• 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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• A single-celled protist living in water has a
sufficient surface area of plasma membrane to
service its entire volume of cytoplasm
Video: Hydra Eating Daphnia
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LE 40-3
Mouth
Diffusion
Gastrovascular
cavity
Diffusion
Diffusion
Single cell
Two cell layers
• Multicellular organisms with a sac body plan have
body walls that are only two cells thick, facilitating
diffusion of materials
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• More complex organisms have highly folded
internal surfaces for exchanging materials
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LE 40-4
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
• 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, connective, muscle, and nervous
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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
Epithelial Tissue
• Epithelial tissue covers the outside of the body
and lines the organs and cavities within the body
• It contains cells that are closely joined
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Connective Tissue
• Connective tissue mainly binds and supports other
tissues
• It contains sparsely packed cells scattered
throughout an extracellular matrix
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Muscle Tissue
• Muscle tissue consists of long cells called muscle
fibers, which contract in response to nerve signals
• It is divided in the vertebrate body into three types:
skeletal, cardiac, and smooth
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Nervous Tissue
• Nervous tissue senses stimuli and transmits
signals throughout the animal
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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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LE 40-6
Lumen of
stomach
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
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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Bioenergetics
• Bioenergetics, the flow of energy through an
animal, 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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Energy Sources and Allocation
• Animals harvest chemical energy from food
• Energy-containing molecules from food are
usually used to make ATP, which powers cellular
work
• After the needs of staying alive are met, remaining
food molecules can be used in biosynthesis
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LE 40-7
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
• Metabolic rate is the amount of energy an animal
uses in a unit of time
• One way to measure it is to determine the amount
of oxygen consumed or carbon dioxide produced
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LE 40-8
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.
Bioenergetic Strategies
• An animal’s metabolic rate is closely related to its
bioenergetic strategy
• Birds and mammals are mainly endothermic: Their
bodies are warmed mostly by heat generated by
metabolism
• Endotherms typically have higher metabolic rates
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• Amphibians and reptiles other than birds are
ectothermic: They gain their heat mostly from
external sources
• Ectotherms generally have lower metabolic rates
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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
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Size and Metabolic Rate
• Metabolic rate per gram is inversely related to
body size among similar animals
• Researchers continue to search for the causes of
this relationship
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
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
• Activity greatly affects metabolic rate
• In general, maximum metabolic rate is inversely
related to the duration of the activity
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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
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
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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 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
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Regulating and Conforming
• Regulating and conforming are two extremes in
how animals cope with environmental fluctuations
• A regulator uses internal control mechanisms to
moderate internal change in the face of external,
environmental fluctuation
• A conformer allows its internal condition to vary
with certain external changes
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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
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
LE 40-11
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
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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
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Ectotherms and Endotherms
• Ectotherms include most invertebrates, fishes,
amphibians, and non-bird reptiles
• Endotherms include birds and mammals
• In general, ectotherms tolerate greater variation in
internal temperature than endotherms
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LE 40-12
40
River otter (endotherm)
Body temperature (°C)
30
20
Largemouth bass (ectotherm)
10
0
10
20
40
30
Ambient (environmental) temperature (°C)
• 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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Modes of Heat Exchange
• Organisms exchange heat by four physical
processes: conduction, convection, radiation, and
evaporation
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LE 40-13
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
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
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
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LE 40-14
Hair
Epidermis
Sweat
pore
Muscle
Dermis
Nerve
Sweat
gland
Hypodermis
Adipose tissue
Blood vessels
Oil gland
Hair follicle
Circulatory Adaptations
• Many endotherms and some ectotherms can alter
the amount of blood flowing between the body
core and the skin
• In vasodilation, blood flow in the skin increases,
facilitating heat loss
• In vasoconstriction, blood flow in the skin
decreases, lowering heat loss
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• Many marine mammals and birds have an
arrangement of blood vessels called a
countercurrent heat exchanger
• Countercurrent heat exchangers are important for
reducing heat loss
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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
• Some bony fishes and sharks also have
countercurrent heat exchangers
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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
• Many endothermic insects have countercurrent
heat exchangers that help maintain a high
temperature in the thorax
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Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
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 an
animal down
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Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
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
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Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
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
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LE 40-20
PREFLIGHT
40
Temperature (°C)
FLIGHT
PREFLIGHT
WARMUP
Thorax
35
30
Abdomen
25
0
2
Time from onset of warmup (min)
4
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
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
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.
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
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Torpor and Energy Conservation
• Torpor is a physiological state in which activity is
low and metabolism decreases
• Torpor enables animals to save energy while
avoiding difficult and dangerous conditions
• Hibernation is long-term torpor that is an
adaptation to winter cold and food scarcity
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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
• Estivation, or summer torpor, enables animals to
survive long periods of high temperatures and
scarce water supplies
• Daily torpor is exhibited by many small mammals
and birds and seems adapted to feeding patterns
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