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1
Define ‘homeostasis’
What things to animals do to maintain homeostasis?
2
Lecture 12 Outline (Ch. 40)
I. Animal Size/Shape and the Environment
II. Tissues
III. Feedback control and Heat Balance
IV. Bioenergetics and Energy Use
V. Lecture Concepts
3
Overview: Diverse Forms, Common Challenges
• Anatomy: study of biological form of an organism
• Physiology: study of biological functions of an organism
4
(a) Tuna
(b) Penguin
(c) Seal
Physical Constraints on Animal Size and Shape
• Evolutionary convergence reflects different species’ adaptations to similar environmental challenge
5
Exchange
0.15 mm
(a) Single cell
1.5 mm
(b) Two layers of cells
Exchange
Exchange
Mouth
Gastrovascularcavity
Animals sizes and shapes directly affect how they exchange energy and materials with surroundings
Exchange with the Environment
6
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
• More complex organisms have highly folded internal surfaces
Exchange with the Environment
7
• 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
Table 40.1
8
• Tissues are classified into four main categories: epithelial, connective, muscle, and nervous
Tissue Structure and Function
9
Epithelial Tissue
Cuboidalepithelium
Simplecolumnarepithelium
Pseudostratifiedciliatedcolumnarepithelium
Stratifiedsquamousepithelium
Simplesquamousepithelium
Note differences in cell shape and type of layering
Tissue Structure and Function
10
Apical surface
Basal surfaceBasal lamina
40 µm
Tissue Structure and Function
11
Connective Tissue
• Connective tissue mainly binds and supports other tissues
• It contains sparsely packed cells scattered throughout an extracellular matrix
• The matrix consists of fibers in a liquid, jellylike, or solid foundation
12
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
mTissue Structure and Function
13
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 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
14
Muscle Tissue
50 µmSkeletalmuscle
Multiplenuclei
Muscle fiber
Sarcomere
100 µm
Smoothmuscle
Cardiac muscle
Nucleus
Musclefibers
25 µm
Nucleus Intercalateddisk
Tissue Structure and Function
15
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
16
Glial cells
Nervous Tissue
15 µm
Dendrites
Cell body
Axon
Neuron
Axons
Blood vessel
40 µm
Tissue Structure and Function
17
Self-Check
Tissue Category Tissues/Cells Included; Functions
Epithelial
Connective
Muscle
Nervous
18
Feedback control loops maintain the internal environment in many animals
• Animals manage their internal environment by regulating or conforming to the external environment
Homeostasis
Stimulus:Perturbation/stress
Response/effector
Control center
Sensor/receptor
19
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 control loops maintain the internal environment in many animals
20
Feedback control loops maintain the internal environment in many animals
• Thermoregulation: process by which animals maintain an internal temperature
(a) A walrus, an endotherm
(b) A lizard, an ectotherm
• Endothermic animals generate heat by metabolism (birds and mammals)
• Ectothermic animals gain heat from external sources (invertebrates, fishes, amphibians, and non-avian reptiles)
21
Balancing Heat Loss and Gain
• Organisms exchange heat by four physical processes: conduction, convection, radiation, and evaporation
Radiation Evaporation
Convection Conduction
22
Epidermis
Dermis
Hypodermis
Adipose tissue
Blood vessels
Hair
Sweatpore
Muscle
Nerve
Sweatgland
Oil glandHair follicle
Balancing Heat Loss and Gain
• Balancing temperature usually involves the integumentary system
23
• Five general adaptations help animals thermoregulate:
– Insulation– Circulatory adaptations– Cooling by evaporative heat
loss– Behavioral responses– Adjusting metabolic heat
production
Balancing Heat Loss and Gain
24
• Bioenergetics is the overall flow and transformation of energy in an animal
• It determines how much food an animal needs and relates to an animal’s size, activity, and environment
Organic moleculesin foodExternal
environment
Animalbody Digestion and
absorption
Nutrient moleculesin body cells
Carbonskeletons
Cellularrespiration
ATP
Heat
Energy lostin feces
Energy lost innitrogenouswaste
Heat
Biosynthesis
Heat
Heat
Cellularwork
Energy Allocation and Use
25
• Metabolic rate is the amount of energy an animal uses in a unit of time
Energy Use
Measured by determining the amount of oxygen consumed or carbon dioxide produced
26
• 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
Energy Use
27
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
103Energy Use
28
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) (
per
kg
)Shrew
Harvest mouse
Mouse
Rat
Ground squirrel
Cat
Sheep
DogHuman
Horse
Elephant
Energy Use
29
An
nu
al e
ner
gy
exp
end
itu
re (
kcal
/hr)
60-kg female humanfrom temperate climate
800,000
Basal(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
Energy Use
Different animals budget their energy differently.
30
• Torpor is a physiological state in which activity is low and metabolism decreases – allows 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
Energy Use
31
Additional metabolism that would benecessary to stay active in winterActual
metabolism
Arousals
Bodytemperature
Outsidetemperature Burrow
temperature
Met
abo
lic
rate
(kca
l p
er d
ay)
Tem
per
atu
re (
°C)
June August October December February April–15
–10
–5
0
5
15
10
25
20
35
30
0
100
200
Energy Use
32
Lecture 12 concepts
- Distinguish among the following sets of terms: ectotherms and endotherms, positive and negative feedback; basal and standard metabolic rates; torpor and hibernation.
- Identify and describe the function of the following animal tissues: epithelial, connective tissue (six types), muscle tissue (three types), and nervous tissue (two types).
- Define metabolic rate and explain how it can be determined for animals
- Describe how an animals size affects its interaction with the environment, and metabolic rate.
- Discuss bioenergetics.
- Make a list of new vocabulary with definitions.