What things to animals do to maintain homeostasis?

1What things to animals do to maintain homeostasis?

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Lecture 9 Outline (Ch. 40)

I. Brief Organ Systems Overview

II. Animal Size/Shape and the Environment

III. TissuesA. Epithelial

B. ConnectiveC. Muscle

D. Nervous

IV. Feedback Control and Heat Balance

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

• Evolutionary convergence: reflects different species’ adaptations to similar environmental challenge

(a) Tuna

(b) Penguin

(c) Seal

Organ Systems

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• Communication and integration– detect external stimuli, coordinate the body’s responses

• Support and movement

5

Organ Systems• Regulation and maintenance

– regulate and maintain the body’s chemistry

• Reproduction and development– In females, also nurtures developing embryo/fetus

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Organ Systems• Defense

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• Levels or organiziation: smallest largest?

Hierarchical Organization of Body Plans• Vertebrates have a “tube within a tube” structure

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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


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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


Cells bathed in interstitial fluid

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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


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Apical surface

Basal surfaceBasal lamina

40 µm


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

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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

There are six main types of connective tissue.

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Connective Tissue

Collagenous fiberLooseconnectivetissue

Elastic fiber120

µm

Cartilage

Chondrocytes

100

µm

Chondroitinsulfate

Adiposetissue

Fat droplets

150

µm

White blood cells

55 µ

m

Plasma Red bloodcells

Blood

Nuclei

Fibrousconnectivetissue

30 µ

m

Osteon

Bone

Central canal

700

µmTissue Structure and Function

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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

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Muscle Tissue

50 µmSkeletalmuscle

Multiplenuclei

Muscle fiber

Sarcomere

100 µm

Smoothmuscle

Cardiac muscle

Nucleus

Musclefibers

25 µm

Nucleus Intercalateddisk


Glial cells

Nervous Tissue

15 µm

DendritesCell body

Axon

Neuron

Axons

Blood vessel

40 µm

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• Nervous tissue senses stimuli and transmits signals throughout the animal

• Nervous tissue contains:Neurons, or

nerve cells, transmit nerve impulses

Glial cells, or glia, help nourish, insulate, and replenish neurons

Which animals tissue below is connective?

1. Cardiac cells2. Glia3. Lining of intestines4. Tendons5. 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?


• Animals manage their internal environment by regulating or conforming to the external environment

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• 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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• 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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• Bioenergetics: overall flow of energy in an animal

• Determines how much food is needed due to animal’s size, activity, and environment

Organic moleculesin foodExternal

environment

Animalbody Digestion and

absorption

Nutrient moleculesin body cells

Carbonskeletons

Cellularrespiration

ATP

HeatEnergy lostin feces

Energy lost innitrogenouswaste

Heat

Biosynthesis

Heat

Heat

Cellularwork

Energy Allocation and Use

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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 squirrelRat

Cat Dog

SheepHuman

Horse

Elephant

Body mass (kg) (log scale)

BM

R (L

O2/h

r) (l

og s

cale

)

(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

O2/

hr) (

per k

g)Shrew

Harvest mouse

MouseRat

Ground squirrelCat

Sheep

DogHuman

HorseElephant

Energy Use

Human average daily metabolic rate is only 1.5X BMR!

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Ann

ual e

nerg

y ex

pend

iture

(kca

l/hr)

60-kg female humanfrom temperate climate

800,000Basal(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 Budgeting

• 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

Which animal would have the highest BMR per unit body weight?

1. human2. dog3. mouse4. whale5. turtle

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Additional metabolism that would benecessary to stay active in winterActual

metabolism

Arousals

Bodytemperature

Outsidetemperature Burrow

temperature

Met

abol

ic ra

te(k

cal p

er d

ay)

Tem

pera

ture

(°C

)

June August October December February April–15

–10–5

05

15

10

25

20

3530

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 human or a snake? Why?

4. Explain the difference between torpor and hibernation.

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What things to animals do to maintain homeostasis?