1What things to animals do to maintain homeostasis?

2

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

5

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

8

Apical surface

Basal surfaceBasal lamina

40 µm

Tissue Structure and Function

Epithelial cells are attached to a basal lamina at their base.

9

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

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?

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

22

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

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.