Hepatic adaptations to maintain metabolic homeostasis in response ...
What things to animals do to maintain homeostasis?
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Transcript of What things to animals do to maintain homeostasis?
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1What things to animals do to maintain homeostasis?
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Lecture 9 Outline (Ch. 40)
I. Animal Size/Shape and the Environment
II. Tissues
A. Epithelial
B. Connective
C. Muscle
D. Nervous
IV. Feedback Control and temperature regulation
V. Metabolic Rate and Energy Use
VI. Preparation for next lecture
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Overview: Diverse Forms, Common Challenges
• Anatomy: study of biological form of an organism
• Physiology: study of biological functions of an organism
• Communication and integration
• Support and movement
• Regulation and maintenance
• Defense• Reproduction and
development
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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
Overview: Diverse Forms, Common Challenges
Cells bathed in interstitial fluid
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Exchange
0.15 mm
(a) Single cell
1.5 mm
(b) Two layers of cells
Exchange
Exchange
Mouth
Gastrovascularcavity
Rate of exchange related to SAAmount of exchange related to V
Overview: Diverse Forms, Common Challenges
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• Tissues are classified into four main categories: epithelial, connective, muscle, and nervous
Tissue Structure and Function
Humans: 210 different cell types – can you name them?! ;)
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Epithelial Tissue
Cuboidalepithelium
Simplecolumnarepithelium
Pseudostratifiedciliatedcolumnarepithelium
Stratifiedsquamousepithelium
Simplesquamousepithelium
Note differences in cell shape and type of layering
Tissue Structure and Function
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Apical surface
Basal surfaceBasal lamina
40 µm
Tissue Structure and Function
Epithelial cells are attached to a basal lamina at their base.
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Connective Tissue
Connective tissue
binds / supports other tissues•sparsely packed cells scattered in extracellular matrix•matrix - fibers in a liquid, jellylike, or solid foundation
There are six main types of connective tissue.
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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
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Muscle Tissue
• Muscle tissue: long cells (muscle fibers) that contract in response to nerve signals
Skeletal muscle - striated, voluntary movement
Smooth muscle – not striated, involuntary body activities
Cardiac muscle – striated, contraction of the heart
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Muscle Tissue
50 µmSkeletalmuscle
Multiplenuclei
Muscle fiber
Sarcomere
100 µm
Smoothmuscle
Cardiac muscle
Nucleus
Musclefibers
25 µm
Nucleus Intercalateddisk
Tissue Structure and Function
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Glial cells
Nervous Tissue
15 µm
Dendrites
Cell body
Axon
Neuron
Axons
Blood vessel
40 µm
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Tissue Structure and Function
• Nervous tissue senses stimuli, transmits signals
Nervous tissue contains:
Neurons transmit nerve
impulsesGlial cells nourish, insulate,
and replenish neurons
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Self-Check
Tissue Category Tissues/Cells Included; Functions
Epithelial
Connective
Muscle
Nervous
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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
Examples of negative and positive feedback?
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Feedback control loops maintain the internal environment in many animals
• Animals manage their internal environment by regulating or conforming to the external environment
control center
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• 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
Dragonfly “obelisk” posture
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Temperature Regulation
• 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)
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• Homoeotherm: animals with constant temperature• Ex: River otter
• Poikilotherm: animals with varied body temperature with environment• Ex: Largemouth bass
Temperature Regulation
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• Metabolic rate is the amount of energy an animal uses in a unit of time
Energy Use
Measured by amount of oxygen consumed or carbon dioxide produced
• Basal metabolic rate (BMR) is the metabolic rate of an endotherm at rest at a “comfortable” temperature
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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
Energy Use
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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
Human average daily metabolic rate is only 1.5X BMR!
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Energy Budgeting
• Hibernation is long-term torpor that is an adaptation to winter cold and food scarcity
• Torpor = physiological state with low activity and metabolism decreased – allows animals to save energy while avoiding difficult and dangerous conditions
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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
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Things To Do After Lecture 9…Reading and Preparation:
1. Re-read today’s lecture, highlight all vocabulary you do not understand, and look up terms.
2. Ch. 40 Self-Quiz: #1, 2, 3, 4, 5, 6 (correct answers in back of book)
3. Read chapter 40, focus on material covered in lecture (terms, concepts, and figures!)
4. Skim next lecture.
“HOMEWORK” (NOT COLLECTED – but things to think about for studying):
1. Describe the relationship between surface area and volume for a small cell compared to a large cell. Which is more efficient at exchange with the environment?
2. List the four types of tissues in animals – for each one, give several examples.
3. Define basal metabolic rate. Which would use more energy for homeostatic regulation, a small human or a large snake? Why?
4. Explain the difference between torpor and hibernation.