Transcript Nervous tissue

What 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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Overview: Diverse Forms, Common Challenges
• More complex organisms have highly folded internal surfaces
Animal
body
Respiratory
system
0.5 cm
50 µm
Cells bathed in
interstitial fluid
External environment
CO2
Food
O2
Mouth
Lung tissue
Nutrients
Heart
Cells
Circulatory
system
10 µm
Interstitial
fluid
Digestive
system
Excretory
system
Lining of small intestine
Kidney tubules
Anus
Unabsorbed
matter (feces)
Metabolic waste products
(nitrogenous waste)
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Overview: Diverse Forms, Common Challenges
Rate of exchange related to SA
Amount of exchange related to V
Mouth
Gastrovascular
cavity
Exchange
Exchange
Exchange
0.15 mm
1.5 mm
(a) Single cell
(b) Two layers of cells
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Tissue Structure and Function
• Tissues are classified into four main categories:
epithelial, connective, muscle, and nervous
Humans: 210 different cell types – can you name them?! ;)
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Tissue Structure and Function
Epithelial Tissue
Cuboidal
epithelium
Simple
columnar
epithelium
Pseudostratified
ciliated
columnar
epithelium
Stratified
squamous
epithelium
Simple
squamous
epithelium
Note differences in cell shape and type of layering
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Tissue Structure and Function
Apical surface
Basal surface
Basal lamina
40 µm
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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Tissue Structure and Function
Connective Tissue
Loose
connective
tissue
Chondrocytes
Cartilage
Elastic fiber
Chondroitin
sulfate
Nuclei
Fat droplets
Adipose
tissue
Osteon
150 µm
Fibrous
connective
tissue
30 µm
100 µm
120 µm
Collagenous fiber
White blood cells
Blood
55 µm
700 µm
Bone
Central canal
Plasma
Red blood
cells
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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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Tissue Structure and Function
Muscle Tissue
Multiple
nuclei
Muscle fiber
Sarcomere
Skeletal
muscle
Nucleus
100 µm
Intercalated
disk
50 µm
Cardiac muscle
Nucleus
Smooth
muscle
Muscle
fibers
25 µm
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Tissue Structure and Function
Nervous Tissue
• Nervous tissue senses stimuli, transmits signals
Nervous tissue contains:
40 µm
Dendrites
Neurons
transmit nerve
impulses
Glial cells
nourish, insulate,
and replenish
neurons
Cell body
Glial cells
Axon
Neuron
Axons
Blood vessel
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15 µm
Self-Check
Tissue Category
Tissues/Cells Included; Functions
Epithelial
Connective
Muscle
Nervous
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Feedback control loops maintain the internal
environment in many animals
Response:
Heater
turned
off
Room
temperature
decreases
Examples of negative
and positive feedback?
Stimulus:
Control center
(thermostat)
reads too hot
Set
point:
20ºC
Stimulus:
Control center
(thermostat)
reads too cold
Room
temperature
increases
Response:
Heater
turned
on
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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
Balancing Heat Loss and Gain
• Five general adaptations
help animals
thermoregulate:
– Insulation
– Circulatory adaptations
– Cooling by evaporative
heat loss
– Behavioral responses
– Adjusting metabolic heat
production
Dragonfly “obelisk” posture
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Temperature Regulation
• Thermoregulation: process
by which animals maintain
an internal temperature
• Endothermic animals
generate heat by
metabolism (birds and
mammals)
• Ectothermic animals gain
heat from external sources
(invertebrates, fishes,
amphibians, and nonavian reptiles)
(a) A walrus, an endotherm
(b) A lizard, an ectotherm
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Temperature Regulation
• Homoeotherm: animals
with constant temperature
• Ex: River otter
• Poikilotherm: animals with
varied body temperature
with environment
• Ex: Largemouth bass
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Energy Use
• Metabolic rate is the amount of energy an animal uses in
a unit of time
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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Energy Use
103
BMR (L O2/hr) (log scale)
Elephant
Horse
102
Human
Sheep
10
Cat
Dog
1
10–1
Rat
Ground squirrel
Shrew
Mouse
Harvest mouse
10–2
10–3
10–2
102
1
10–1
10
Body mass (kg) (log scale)
(a) Relationship of BMR to body size
103
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Energy Use
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Shrew
BMR (L O2/hr) (per kg)
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Human average daily metabolic
rate is only 1.5X BMR!
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5
4
Harvest mouse
3
Mouse
2
Rat
1
Ground squirrel
0
10–3
10–2
Sheep
Human Elephant
Cat
Dog
Horse
1
10
102
10–1
Body mass (kg) (log scale)
103
(b) Relationship of BMR per kilogram of body mass to body size
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Energy Budgeting
• Torpor =
physiological
state with low
activity and
metabolism
decreased –
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
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Metabolic rate
(kcal per day)
Energy Use
200
Actual
metabolism
100
0
35
30
Temperature (°C)
Additional metabolism that would be
necessary to stay active in winter
Arousals
Body
temperature
25
20
15
10
5
0
–5
Outside
temperature
Burrow
temperature
–10
–15
June
August
October
December
February
April
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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.