BIOL 102 Chp 40 PowerPoint
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Transcript of BIOL 102 Chp 40 PowerPoint
Chapter 40:
Basic Principles of Animal Form & Function
Rob Swatski
Associate Professor of Biology
HACC – York Campus
1
Exchange with the Environment
• An animal’s size & shape directly affect how it exchanges energy & materials with its environment
• Exchange occurs as dissolved substances diffuse & are transported across the cells’ plasma membranes
• A unicellular protist living in
water has enough surface area of plasma membrane to service its entire volume of cytoplasm
2
Multicellular organisms with a
sac body plan have body walls that are only 2 cells thick, which facilitates
diffusion
3
More complex organisms have highly folded internal surfaces for exchanging materials
0.5 cm Nutrients
Digestive system
Lining of small intestine
Mouth Food
External environment
Animal body
CO2 O2
Circulatory system
Heart
Respiratory system
Cells
Interstitial fluid
Excretory system
Anus
Unabsorbed matter (feces)
Metabolic waste products (nitrogenous waste)
Kidney tubules
10 µm
50
µm
Lung tissue
4
Epithelial Tissue
Cuboidal
epithelium Simple columnar epithelium
Pseudostratified
ciliated
columnar epithelium
Stratified squamous epithelium
Simple squamous
epithelium
5
Connective Tissue Collagenous fiber
Loose connective tissue
Elastic fiber 12
0 µ
m Cartilage
Chondrocytes
10
0 µ
m
Chondroitin sulfate
Adipose tissue
Fat droplets
15
0 µ
m
White blood cells
55
µm
Plasma Red blood cells
Blood
Nuclei
Fibrous connective tissue
30
µm
Osteon
Bone
Central canal
70
0 µ
m
6
Muscle Tissue
50 µm Skeletal muscle
Multiple nuclei
Muscle fiber
Sarcomere
100 µm
Smooth muscle
Cardiac muscle
Nucleus
Muscle fibers
25 µm
Nucleus Intercalated disk
7
Glial cells
Nervous Tissue
15 µm
Dendrites
Cell body
Axon
Neuron
Axons
Blood vessel
40 µm
8
Coordination and Control
• Depends on both the endocrine & nervous systems
• The endocrine system: transmits chemical signals (hormones) to receptive cells throughout the body via blood
- a hormone may affect 1 or more regions throughout the body
• Hormones are relatively slow acting, but can have long-lasting effects
9
Stimulus
Endocrine cell
Hormone
Signal travels everywhere via the bloodstream.
Blood vessel
Response
(a) Signaling by hormones 10
• The nervous system: transmits information between specific locations
• The information conveyed depends on a nerve signal’s (impulse) pathway, not the type of signal
- impulse transmission is very fast
- impulses can be received by neurons, muscle cells, & endocrine cells
11
Stimulus
Neuron
Axon Signal
Signal travels along axon to a specific location.
Signal
Axons
Response
(b) Signaling by neurons 12
Feedback Control Loops
• Animals manage their internal environment by regulating or conforming to the external environment
• Regulators: use internal control mechanisms to moderate internal change in the face of external, environmental fluctuation
• Conformers: allow internal conditions to vary with certain external changes
13
River otter (temperature regulator)
Largemouth bass (temperature conformer)
Bo
dy
tem
pe
ratu
re (
°C)
0 10
10
20
20
30
30
40
40
Ambient (environmental) temperature (ºC) 14
Homeostasis
• Organisms use homeostasis to maintain a “steady state” (internal balance) regardless of external environment
• In humans, body temperature, blood pH, & glucose concentration are each maintained at a constant level
15
Mechanisms of Homeostasis
• Moderate changes in the internal environment
• For a given variable, fluctuations above or below a set point act as a stimulus
- stimuli are detected by a sensor & trigger a response
- the response returns the variable back to the set point
16
Response: Heater turned off
Stimulus: Control center (thermostat) reads too hot
Room temperature
decreases
Set point: 20ºC
Room temperature
increases
Stimulus: Control center (thermostat)
reads too cold
Response: Heater turned on 17
Homeostasis
Stimulus: Perturbation/stress
Response/effector
Control center
Sensor/receptor 18
Feedback Loops in Homeostasis
• The dynamic equilibrium of most homeostasis is maintained by negative feedback loops
- helps to return a variable to either a normal range or a set point
- buildup of the end product shuts the system off
• Positive feedback loops: do not usually contribute much to homeostasis
19
Alterations in Homeostasis
• Set points & normal ranges can change with age or show cyclic variation
• Homeostasis can adjust to changes in external environment, a process called acclimatization
20
Thermoregulation: process where animals maintain an internal temperature within a tolerable range
• Ectothermic animals: gain heat from external sources
- include most invertebrates, fishes, amphibians, & reptiles
• Endothermic animals: generate heat by metabolism
- birds & mammals
21
• Ectotherms generally tolerate more internal temperature variations
• Endotherms are active at a greater range of external temperatures
- more energetically expensive than ectothermy
22
Variation in Body Temperature
• Poikilotherm: body temperature varies with its environment
• Homeotherm: body temperature is relatively constant
23
Balancing Heat Loss and Gain
Organisms exchange heat by 4 physical processes:
Conduction
Convection
Radiation
Evaporation
24
Radiation Evaporation
Convection Conduction 25
Heat regulation in mammals often involves the integumentary system: skin, hair, & nails
Epidermis
Dermis
Hypodermis
Adipose tissue
Blood vessels
Hair
Sweat pore
Muscle
Nerve
Sweat gland
Oil gland
Hair follicle 26
5 general adaptations help animals thermoregulate:
– Insulation
– Circulatory adaptations
– Cooling by evaporative heat loss
– Behavioral responses
– Adjusting metabolic heat production 27
Insulation
Major thermoregulatory adaptation in mammals & birds
Skin, feathers, fur, & blubber reduce heat flow between an animal & its environment
28
Circulatory Adaptations
• Regulation of blood flow near the body surface significantly affects thermoregulation
• Many endotherms (& some ectotherms) can alter the amount of blood flowing between the body core & the skin
- Vasodilation: blood flow in the skin increases, facilitating heat loss
- Vasoconstriction: blood flow in the skin decreases, reducing heat loss
29
• The arrangement of blood vessels in many marine mammals & birds allows for countercurrent exchange
- transfer heat between fluids flowing in opposite directions
- important mechanism for minimizing heat loss
30
Canada goose Bottlenose dolphin
Artery
Artery
Vein Vein
Blood flow
33º 35ºC
27º 30º
18º 20º
10º 9º
31
Some bony fishes & sharks also use countercurrent heat exchange
Many endothermic insects also use this to help maintain a high temperature in the thorax
32
Cooling by Evaporative Heat Loss
• Many types of animals lose heat through evaporation of water in sweat
• Panting increases the cooling effect in birds & many mammals
• Sweating or bathing moistens the skin, helping to cool an animal down
33
Behavioral Responses
• Both endotherms & ectotherms use behavioral responses to control body temperature
- some terrestrial invertebrates have postures that minimize or maximize absorption of solar heat
34
Adjusting Metabolic Heat Production
• Some animals can regulate body temperature by adjusting their rate of metabolic heat production
• Heat production is increased by muscle activity (moving or shivering)
35
RESULTS
Contractions per minute
O2 c
on
sum
pti
on
(m
L O
2/h
r) p
er
kg
0 0
20
20 15 10 5 25 30 35
40
60
80
100
120
36
PREFLIGHT PREFLIGHT WARM-UP
FLIGHT
Thorax
Abdomen
Time from onset of warm-up (min)
Tem
pe
ratu
re (
ºC)
0 2 4
25
30
35
40
37
Acclimatization in Thermoregulation
• Birds & mammals can vary their insulation to acclimatize to seasonal temperature changes
• When temperatures are subzero, some
ectotherms produce “antifreeze” compounds to prevent ice formation in their cells
- “plugs” gaps in existing crystals
38
39
Physiological Thermostats and Fever
• Thermoregulation is controlled by a region of the brain called the hypothalamus
- triggers heat loss or heat-generating mechanisms
• Fever is the result of a change to the set point for a biological thermostat
40
Sweat glands secrete sweat, which evaporates, cooling the body.
Thermostat in hypothalamus activates cooling mechanisms.
Blood vessels in skin dilate: capillaries fill; heat radiates from skin.
Increased body temperature
Decreased body temperature
Thermostat in hypothalamus activates warming mechanisms.
Blood vessels in skin constrict, reducing heat loss.
Skeletal muscles contract; shivering generates heat.
Body temperature increases; thermostat
shuts off warming mechanisms.
Homeostasis:
Internal temperature of 36–38°C
Body temperature decreases; thermostat
shuts off cooling mechanisms.
41
Energy requirements are related to animal size, activity, and environment
• Bioenergetics: the overall flow & transformation of energy in an animal
• It determines how much food an animal needs & relates to an animal’s size, activity, & environment
42
Energy Allocation and Use
• 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
• Biosynthesis includes body growth & repair, synthesis of storage material (fat), & production of gametes
43
Organic molecules in food External
environment
Animal body Digestion and
absorption
Nutrient molecules in body cells
Carbon skeletons
Cellular respiration
ATP
Heat
Energy lost in feces
Energy lost in nitrogenous waste
Heat
Biosynthesis
Heat
Heat
Cellular work
44
Quantifying Energy Use
• Metabolic rate: the amount of energy an animal uses in a unit of time
• Measured by determining the amount of O2 consumed or CO2 produced
45
Minimum Metabolic Rate and Thermoregulation
• Basal metabolic rate (BMR): the metabolic rate of an endotherm at rest at a “comfortable” temperature
• Standard metabolic rate (SMR): the metabolic rate of an ectotherm at rest at a specific temperature
• Both rates assume a nongrowing, fasting, & nonstressed animal
• Ectotherms have much lower metabolic rates than endotherms of a comparable size
46
Shrew
Harvest mouse
Mouse
Ground squirrel
Rat
Cat Dog
Sheep
Human
Horse
Elephant
Body mass (kg) (log scale)
BM
R (
L O
2/h
r) (
log
scal
e)
(a) Relationship of BMR to body size
10–3 10–2 10–2
10–1
10–1
1
1
10 102 103
10
102
103
47
Size and Metabolic Rate
• Metabolic rate per gram is inversely related to body size among similar animals
- 1 g of mouse body mass requires 20-times more calories than 1 g of elephant body mass!
• Smaller animals have a higher metabolic rate per gram
- leads to a higher O2 delivery rate, breathing rate, heart rate, & greater (relative) blood volume, compared with a larger animal
- must also eat much more food per unit of body mass
48
103 102 10 1 10–1 10–2 10–3 0
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
Dog Human
Horse
Elephant
49
Activity and Metabolic Rate
• Activity greatly affects metabolic rate for endotherms & ectotherms
• In general, the maximum metabolic rate an animal can sustain is inversely related to the duration of the activity
50
Energy Budgets
• Different species use energy & materials in food in different ways, depending on their environment
• Use of energy is partitioned to BMR (or SMR), activity, thermoregulation, growth, & reproduction
51
An
nu
al e
ne
rgy
exp
en
dit
ure
(kc
al/h
r)
60-kg female human from temperate climate
800,000
Basal (standard) metabolism
Reproduction Thermoregulation
Growth
Activity
340,000
4-kg male Adélie penguin from Antarctica (brooding)
4,000
0.025-kg female deer mouse from temperate North America
8,000
4-kg female eastern indigo snake
Endotherms Ectotherm
52
Torpor and Energy Conservation
• Torpor: physiological state in which activity is low & metabolism decreases
- enables animals to save energy while avoiding difficult & dangerous conditions
• Hibernation: long-term torpor that is an adaptation to winter cold & food scarcity
53
Additional metabolism that would be necessary to stay active in winter Actual
metabolism
Arousals
Body temperature
Outside temperature
Burrow temperature
Met
abo
lic r
ate
(k
cal p
er
day
) Te
mp
era
ture
(°C
)
June August October December February April –15
–10
–5
0
5
15
10
25
20
35
30
0
100
200
54
Estivation (summer torpor): enables animals to
survive long periods of high temperatures and scarce water supplies
Daily torpor: exhibited by many small birds &
mammals
- adapted to feeding patterns
55