chapter 40 introduction to animal structure and function
TRANSCRIPT
Chapter 40Chapter 40
Introduction to Animal Structure and Function
Overview: Diverse Forms, Common Challenges
• Anatomy is the study of the biological form of an organism
• Physiology is the study of the biological functions an organism performs
(a) Tuna
(b) Penguin
(c) Seal
Exchange with the Environment
• An animal’s size and shape directly affect how it exchanges energy and materials with its surroundings
• Multicellular organisms with a sac body plan have body walls that are only two cells thick, facilitating diffusion of materials
• More complex organisms have highly folded internal surfaces for exchanging materials
• In vertebrates, the space between cells is filled with interstitial fluid, which allows for the movement of material into and out of cells
Exchange
0.15 mm
(a) Single cell
1.5 mm
(b) Two layers of cells
Exchange
Exchange
Mouth
Gastrovascularcavity
0.5 cmNutrients
Digestivesystem
Lining of small intestine
MouthFood
External environment
Animalbody
CO2 O2
Circulatorysystem
Heart
Respiratorysystem
Cells
Interstitialfluid
Excretorysystem
Anus
Unabsorbedmatter (feces)
Metabolic waste products(nitrogenous waste)
Kidney tubules
10 µm
50 µ
m
Lung tissue
• Most animals are composed of specialized cells organized into tissues that have different functions
• Tissues make up organs, which together make up organ systems
Hierarchical Organization of Body Plans
Tissue Structure and Function- Epithelial Tissue
• Epithelial tissue covers the outside of the body and lines the organs and cavities within the body
• Shape: cuboidal (like dice), columnar (like bricks on end), or squamous (like floor tiles)
• Arrangement: simple (single cell layer), stratified (multiple tiers of cells), or pseudostratified (a single layer of cells of varying length)
Epithelial Tissue
Cuboidalepithelium
Simplecolumnarepithelium
Pseudostratifiedciliatedcolumnarepithelium
Stratifiedsquamousepithelium
Simplesquamousepithelium
Tissue Structure and Function- Connective Tissue
• Connective tissue mainly binds and supports other tissues
– Collagenous fibers provide strength and flexibility
– Elastic fibers stretch and snap back to their original length
– Reticular fibers join connective tissue to adjacent tissues
• Connective tissue contains cells, including
– Fibroblasts that secrete the protein of extracellular fibers
– Macrophages that are involved in the immune system
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
• Loose connective tissue binds epithelia to underlying tissues and holds organs in place
• Cartilage is a strong and flexible support material
• Fibrous connective tissue is found in tendons (attach muscles to bones) and ligaments (connect bones at joints)
• Adipose tissue stores fat for insulation and fuel
• Blood is composed of blood cells and cell fragments in blood plasma
• Bone is mineralized and forms the skeleton
Connective Tissue
Collagenous fiber
Looseconnectivetissue
Elastic fiber12
0 µ
m
Cartilage
Chondrocytes
10
0 µ
m
Chondroitinsulfate
Adiposetissue
Fat droplets
15
0 µ
m
White blood cells
55
µm
Plasma Red bloodcells
Blood
Nuclei
Fibrousconnectivetissue
30
µm
Osteon
Bone
Central canal
70
0 µ
m
Loose connective tissue
Fibrous connective tissue
Bone
Cartilage
Adipose tissue
Blood
Tissue Structure and Function- Muscle Tissue
– Skeletal muscle, or striated muscle, is responsible for voluntary movement
– Smooth muscle is responsible for involuntary body activities
– Cardiac muscle is responsible for contraction of the heart
Muscle Tissue
50 µmSkeletalmuscle
Multiplenuclei
Muscle fiber
Sarcomere
100 µm
Smoothmuscle
Cardiac muscle
Nucleus
Musclefibers
25 µm
Nucleus Intercalateddisk
Skeletal muscle
Multiplenuclei
Muscle fiber
Sarcomere
100 µm
Smooth muscle
Nucleus
Musclefibers
25 µm
Nucleus Intercalateddisk
Cardiac muscle
50 µm
Tissue Structure and Function- Nervous Tissue
• Nervous tissue senses stimuli and transmits signals throughout the animal
• Nervous tissue contains:
– Neurons, or nerve cells, that transmit nerve impulses
– Glial cells, or glia, that help nourish, insulate, and replenish neurons
Glial cells
Nervous Tissue
15 µm
Dendrites
Cell body
Axon
Neuron
Axons
Blood vessel
40 µm
Dendrites
Cell body
Axon
40 µm
Neuron
Glial cells
Axons
Blood vessel
Glial cells and axons15 µm
Stimulus
Hormone
Endocrinecell
Signal travelseverywherevia the bloodstream.
Bloodvessel
Response
(a) Signaling by hormones
Stimulus
Neuron
AxonSignal
Signal travelsalong axon toa specificlocation.
Signal
Axons
Response
(b) Signaling by neurons
Coordination and Control
Homeostasis
• Organisms use homeostasis to maintain a “steady state” or internal balance regardless of external environment
• In humans, body temperature, blood pH, and glucose concentration are each maintained at a constant level
Response:Heater turnedoff
Stimulus:Control center(thermostat)reads too hot
Roomtemperaturedecreases
Setpoint:20ºC
Roomtemperature
increases
Stimulus:Control center(thermostat)
reads too cold
Response:Heater turnedon
Feedback Loops in Homeostasis
• Negative feedback -returns a variable to either a normal range or a set point, buildup of the end product shuts the system off
• Positive feedback- the end product accelerates the systems further
• Endothermic animals generate heat by metabolism; more active; energy expensive
• Ectothermic animals gain heat from external sources; less active; less energy needed
Endothermy and Ectothermy
(a) A walrus, an endotherm
(b) A lizard, an ectotherm
Quantifying Energy Use
• Metabolic rate is the amount of energy an animal uses in a unit of time
• Basal metabolic rate (BMR) is the metabolic rate of an endotherm at rest at a “comfortable” temperature
• Standard metabolic rate (SMR) is the metabolic rate of an ectotherm at rest at a specific temperature
• Ectotherms have much lower metabolic rates than endotherms of a comparable size
Size and Metabolic Rate
• Metabolic rate per gram is inversely related to body size among similar animals
• The higher metabolic rate of smaller animals leads to a higher oxygen delivery rate, breathing rate, heart rate, and greater (relative) blood volume, compared with a larger animal
Shrew
Harvest mouseMouse
Ground squirrel
Rat
Cat Dog
Sheep
Human
Horse
Elephant
Body mass (kg) (log scale)
BM
R (
L O
2/h
r) (
log
sc
ale
)
(a) Relationship of BMR to body size
10–3 10–210–2
10–1
10–1
1
1
10 102 103
10
102
103
10310210110–110–210–30
1
2
3
4
5
6
7
8
Body mass (kg) (log scale)
(b) Relationship of BMR per kilogram of body mass to body size
BM
R (
L O
2/h
r) (
pe
r kg
)Shrew
Harvest mouse
Mouse
Rat
Ground squirrel
Cat
Sheep
DogHuman
Horse
Elephant
• 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, thermoregulation, growth, and reproduction
Energy Budgets
An
nu
al e
ner
gy
exp
end
itu
re (
kcal
/hr)
60-kg female humanfrom temperate climate
800,000Basal(standard)metabolism
ReproductionThermoregulation
Growth
Activity
340,000
4-kg male Adélie penguinfrom Antarctica (brooding)
4,000
0.025-kg female deer mousefrom temperateNorth America
8,000
4-kg female easternindigo snake
Endotherms Ectotherm
An
nu
al e
ne
rgy
ex
pe
nd
itu
re (
kc
al/h
r)
60-kg female humanfrom temperate climate
800,000Basal(standard)metabolism
ReproductionThermoregulation
Growth
Activity
Reproduction
Thermoregulation
Activity
Basal(standard)metabolism
4-kg male Adélie penguinfrom Antarctica (brooding)
An
nu
al e
ner
gy
exp
end
itu
re (
kcal
/yr)
340,000
Reproduction
Thermoregulation
Basal(standard)metabolism
Activity
4,000
0.025-kg female deer mousefrom temperateNorth America
An
nu
al e
ner
gy
exp
end
itu
re (
kcal
/yr)
Reproduction
Growth
Activity
Basal(standard)metabolism
4-kg female easternindigo snake
8,000
An
nu
al e
ner
gy
exp
end
itu
re (
kcal
/yr)