basic principles of animal form and function bio fall 2012/40...cellular respiration ... inc....

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

PowerPoint Lectures for Biology, Seventh Edition

Neil Campbell and Jane Reece

Lectures by Chris Romero

Chapter 40Chapter 40

Basic Principles of Animal Form and Function


Overview: Diverse Forms, Common Challenges

• Animals inhabit almost every part of the biosphere

• All animals face a similar set of problems, including how to nourish themselves

• The comparative study of animals reveals that form and function are closely correlated


• Anatomy is the study of the structure of an organism

• Physiology is the study of the functions an organism performs


Concept 40.1: Physical laws and the environment constrain animal size and shape

• Physical laws and the need to exchange materials with the environment place limits on the range of animal forms


Physical Laws and Animal Form

• The ability to perform certain actions depends on an animal’s shape and size

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

Video: Shark Eating Seal

Video: Galápagos Sea Lion

LE 40-2

Tuna

Shark

Penguin

Dolphin

Seal


Exchange with the Environment

• An animal’s size and shape directly affect how it exchanges energy and materials with its surroundings

• Exchange occurs as substances dissolved in the aqueous medium diffuse and are transported across the cells’ plasma membranes


• A single-celled protist living in water has a sufficient surface area of plasma membrane to service its entire volume of cytoplasm

Video: Hydra Eating Daphnia

LE 40-3

Diffusion

Mouth

Diffusion

Two cell layersSingle cell

Diffusion

Gastrovascularcavity


• Multicellular organisms with a sac body plan have body walls that are only two cells thick, facilitating diffusion of materials


• More complex organisms have highly folded internal surfaces for exchanging materials

LE 40-4

Digestivesystem

Circulatorysystem

Excretorysystem

Interstitialfluid

Cells

Nutrients

Heart

Animalbody

Respiratorysystem

CO2FoodMouth

External environment

O2

50 µ

m

A microscopic view of the lung reveals that it is much more spongelike than balloonlike. This construction provides an expansive wet surface for gas exchange with the environment (SEM).

10 µm

Inside a kidney is a mass of microscopic tubules that exchange chemicals with blood flowing through a web of tiny vessels called capillaries (SEM).

The lining of the small intestine, a digestive organ, is elaborated with fingerlike projections that expand the surface area for nutrient absorption (cross-section, SEM).

Unabsorbedmatter (feces)

Metabolic wasteproducts (urine)

Anus

0.5 cm


• Most animals are composed of specialized cells organized into tissues that have different functions

• Tissues make up organs, which together make up organ systems

Concept 40.2: Animal form and function are correlated at all levels of organization


• Different tissues have different structures that are suited to their functions

• Tissues are classified into four main categories: epithelial, connective, muscle, and nervous

Tissue Structure and Function

LE 40-5_1EPITHELIAL TISSUE

Stratifiedcolumnarepithelium

Simplecolumnarepithelium

Pseudostratifiedciliated columnarepithelium

Columnar epithelia, which have cells with relativel y large cytoplasmic volumes, are often located where secretion or active absorption of sub stances is an important function.

StratifiedsquamousepitheliaSimple squamous

epithelia

Cuboidalepithelia

Basement membrane

40 µm

LE 40-5_2CONNECTIVE TISSUE

CollagenousfiberElasticfiber

120 µm

100

µm

ChondrocytesChondroitinsulfate

Cartilage

150

µm

Adipose tissueFat droplets

Blood

Red blood cells

White blood cell

55 µm

Plasma

BoneCentralcanal

700 µm

Osteon

30 µm

Fibrousconnective tissue

Nuclei

Looseconnectivetissue

LE 40-5_3MUSCLE TISSUE

Multiplenuclei

100 µm

Skeletal muscle

Cardiac muscle

Smooth muscle

Neuron

Muscle fiber

Sarcomere

Intercalateddisk

Nucleus 50 µm

Nucleus

25 µm

Musclefibers

Process

Nucleus

50 µm

Cell body

NERVOUS TISSUE


Epithelial Tissue

• Epithelial tissue covers the outside of the body and lines the organs and cavities within the body

• It contains cells that are closely joined


Connective Tissue

• Connective tissue mainly binds and supports other tissues

• It contains sparsely packed cells scattered throughout an extracellular matrix


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, cardiac, and smooth


Nervous Tissue

• Nervous tissue senses stimuli and transmits signals throughout the animal


Organs and Organ Systems

• In all but the simplest animals, tissues are organized into organs

• In some organs, the tissues are arranged in layers

LE 40-6

Lumen ofstomach

Mucosa: an epitheliallayer that lines thelumen

Submucosa: a matrix ofconnective tissue thatcontains blood vesselsand nerves

Muscularis: consistsmainly of smooth muscletissue

Serosa: a thin layer ofconnective and epithelialtissue external to the muscularis0.2 mm


• Organ systems carry out the major body functions of most animals


• All organisms require chemical energy for growth, repair, physiological processes, regulation, and reproduction

Concept 40.3: Animals use the chemical energy in food to sustain form and function


• Bioenergetics, the flow of energy through an animal, limits behavior, growth, and reproduction

• It determines how much food an animal needs

• Studying bioenergetics tells us much about an animal’s adaptations

Bioenergetics


Energy Sources and Allocation

• 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

LE 40-7

Externalenvironment

Organic moleculesin food

Animalbody Digestion and

absorption

Nutrient moleculesin body cells

Carbonskeletons

Cellularrespiration

Biosynthesis:growth,

storage, andreproduction

Cellularwork

ATP

Heat

Heat

Heat

Energylost in urine

Heat

Energylost in feces


• Metabolic rate is the amount of energy an animal uses in a unit of time

• One way to measure it is to determine the amount of oxygen consumed or carbon dioxide produced

Quantifying Energy Use

LE 40-8

This photograph shows a ghost crab in a respirometer. Temperature is held constant in the chamber, with air of known O 2 concentration flowing through. The crab’s metabolic rate is calculated from the difference between the amount of O 2entering and the amount of O 2 leaving the respirometer. This crab is on a treadmill, running at a constant speed as measurements are made.

Similarly, the metabolic rate of a man fitted with a breathing apparatus is being monitored while he exercises on a stationary bike.


• An animal’s metabolic rate is closely related to its bioenergetic strategy

• Birds and mammals are mainly endothermic: Their bodies are warmed mostly by heat generated by metabolism

• Endotherms typically have higher metabolic rates

Bioenergetic Strategies


• Amphibians and reptiles other than birds are ectothermic: They gain their heat mostly from external sources

• Ectotherms generally have lower metabolic rates


• Metabolic rates are affected by many factors besides whether an animal is an endotherm or ectotherm

• Two of these factors are size and activity

Influences on Metabolic Rate


Size and Metabolic Rate

• Metabolic rate per gram is inversely related to body size among similar animals

• Researchers continue to search for the causes of this relationship


• The basal metabolic rate (BMR) is the metabolic rate of an endotherm at rest

• The standard metabolic rate (SMR) is the metabolic rate of an ectotherm at rest

• Activity greatly affects metabolic rate

• In general, maximum metabolic rate is inversely related to the duration of the activity

Activity and Metabolic Rate

LE 40-9

A = 60-kg alligator

A = 60-kg human

Key

Existing intracellular ATP

ATP from glycolysis

ATP from aerobic respiration

Time interval

1second

1minute

1hour

1day

1week

500

100

50

10

5

1

0.5

0.1

Max

imum

met

abol

ic ra

te(k

cal/m

in; l

og s

cale

)

A H

A H

A

H

A

H

A

H


• Different species use energy and materials in food in different ways, depending on their environment

• Use of energy is partitioned to BMR (or SMR), activity, homeostasis, growth, and reproduction

Energy Budgets

LE 40-10

800,000

Endotherms

340,000

Basal(standard)metabolism

ReproductionTemperatureregulation

Growth

Activity

60-kg female humanfrom temperate climate

4-kg male Adélie penguinfrom Antarctica (brooding)

4,000

0.025-kg female deer mousefrom temperateNorth America

4-kg female pythonfrom Australia

8,000

Ectotherm

Total annual energy expenditures. The slices of the pie charts indicate energy expenditures for various functions.

Energy expenditures per unit mass (kcal/kg•day). Co mparing the daily energy expenditures per kg of body weight for the four animals reinforc es two important concepts of bioenergetics. First, a small animal, such as a mou se, has a much greater energy demand per kg than does a large animal of the same taxonom ic class, such as a human (both mammals). Second, note again that an ectotherm, suc h as a python, requires much less energy per kg than does an endotherm of equivalent size, such as a penguin.

438

233

36.55.5

Python

Human

Deer mouse Adélie penguin


Concept 40.4: Animals regulate their internal environment within relatively narrow limits

• The internal environment of vertebrates is called the interstitial fluid and is very different from the external environment

• Homeostasis is a balance between external changes and the animal’s internal control mechanisms that oppose the changes


• Regulating and conforming are two extremes in how animals cope with environmental fluctuations

• A regulator uses internal control mechanisms to moderate internal change in the face of external, environmental fluctuation

• A conformer allows its internal condition to vary with certain external changes

Regulating and Conforming


• Mechanisms of homeostasis moderate changes in the internal environment

• A homeostatic control system has three functional components: a receptor, a control center, and an effector

Mechanisms of Homeostasis

Animation: Negative Feedback

Animation: Positive Feedback

LE 40-11Response

No heatproduced

Roomtemperaturedecreases

Roomtemperature

increases

Set point

Toohot

Set point

Heaterturnedoff

Toocold

Set point

Control center:thermostat

Heaterturnedon

Response

Heatproduced


• Most homeostatic control systems function by negative feedback, where buildup of the end product shuts the system off

• In positive feedback, a change in a variable triggers mechanisms that amplify rather than reverse the change


Concept 40.5: Thermoregulation contributes to homeostasis and involves anatomy, physiology, and behavior

• Thermoregulation is the process by which animals maintain an internal temperature within a tolerable range


• Ectotherms include most invertebrates, fishes, amphibians, and non-bird reptiles

• Endotherms include birds and mammals

• In general, ectotherms tolerate greater variation in internal temperature than endotherms

Ectotherms and Endotherms

LE 40-12

River otter (endotherm)

Largemouth bass (ectotherm)

Ambient (environmental) temperature (°C)0 10 20 30 40

40

Bod

y te

mpe

ratu

re (

°C)

30

20

10


• Endothermy is more energetically expensive than ectothermy

• It buffers the animal’s internal temperatures against external fluctuations

• It also enables the animal to maintain a high level of aerobic metabolism


Modes of Heat Exchange

• Organisms exchange heat by four physical processes: conduction, convection, radiation, and evaporation

LE 40-13

Radiation

Evaporation

Conduction

Convection


Balancing Heat Loss and Gain

• In thermoregulation, physiological and behavioral adjustments balance heat loss and gain

• Five general adaptations help animals thermoregulate:

– Insulation

– Circulatory adaptations

– Cooling by evaporative heat loss

– Behavioral responses

– Adjusting metabolic heat production


Insulation

• Insulation is a major thermoregulatory adaptation in mammals and birds

• It reduces heat flow between an animal and its environment

• Examples are skin, feathers, fur, and blubber

• In mammals, the integumentary system acts as insulating material

LE 40-14

Epidermis

Dermis

Hypodermis

Adipose tissue

Blood vessels

Hair

Sweatpore

Sweatgland

Muscle

Nerve

Oil glandHair follicle


• Many endotherms and some ectotherms can alter the amount of blood flowing between the body core and the skin

• In vasodilation, blood flow in the skin increases, facilitating heat loss

• In vasoconstriction, blood flow in the skin decreases, lowering heat loss

Circulatory Adaptations


• Many marine mammals and birds have an arrangement of blood vessels called a countercurrent heat exchanger

• Countercurrent heat exchangers are important for reducing heat loss

LE 40-15

Blood flow

VeinArtery

Pacificbottlenose

dolphin

Canadagoose

VeinArtery

33°

27°

18°

9°

35°C

30°

20°

10°


• Some bony fishes and sharks also have countercurrent heat exchangers

LE 40-16a

Bluefin tuna

Body cavity

31°29°

25°27°23°

21°

LE 40-16b

Vein

Artery

Skin

Capillarynetwork withinmuscle

Bloodvesselsin gills

Heart

Artery andvein underthe skin Dorsal aorta

Great white shark


• Many endothermic insects have countercurrent heat exchangers that help maintain a high temperature in the thorax


Cooling by Evaporative Heat Loss

• Many types of animals lose heat through evaporation of water in sweat

• Panting augments the cooling effect in birds and many mammals

• Bathing moistens the skin, helping to cool an animal down


• Both endotherms and ectotherms use behavioral responses to control body temperature

• Some terrestrial invertebrates have postures that minimize or maximize absorption of solar heat

Behavioral Responses


Adjusting Metabolic Heat Production

• Some animals can regulate body temperature by adjusting their rate of metabolic heat production

• Many species of flying insects use shivering to warm up before taking flight

LE 40-20

PREFLIGHT PREFLIGHTWARMUP

FLIGHT

Abdomen

Thorax

Time from onset of warmup (min)

420

40

35

30

25

Tem

pera

ture

(°C

)


• Mammals regulate body temperature by negative feedback involving several organ systems

• In humans, the hypothalamus (a part of the brain) contains nerve cells that function as a thermostat

Feedback Mechanisms in Thermoregulation

LE 40-21Thermostat inhypothalamusactivates coolingmechanisms.

Increased bodytemperature (suchas when exercising

or in hotsurroundings)

Body temperaturedecreases;thermostat

shuts off coolingmechanisms.

Sweat glands secretesweat that evaporates,cooling the body.

Blood vesselsin skin dilate:capillaries fillwith warm blood;heat radiates fromskin surface.

Body temperatureincreases;thermostat

shuts off warmingmechanisms.

Decreased bodytemperature

(such as whenin cold

surroundings)

Blood vessels in skin constrict, diverting bloodfrom skin to deeper tissuesand reducing heat lossfrom skin surface.

Skeletal muscles rapidlycontract, causing shivering,which generates heat.

Thermostat in hypothalamusactivateswarmingmechanisms.

Homeostasis:Internal body temperatureof approximately 36–38°C


Adjustment to Changing Temperatures

• In acclimatization, many animals adjust to a new range of environmental temperatures over a period of days or weeks

• Acclimatization may involve cellular adjustments or (as in birds and mammals) adjustments of insulation and metabolic heat production


Torpor and Energy Conservation

• Torpor is a physiological state in which activity is low and metabolism decreases

• Torpor enables 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

LE 40-22

Actualmetabolism

Additional metabolism that would benecessary to stay active in winter

Arousals

200

100

0

Bodytemperature

Outsidetemperature Burrow

temperature

35

30

25

20

15

10

5

0

–5

–10

–15June August October December February April


• Estivation, or summer torpor, enables animals to survive long periods of high temperatures and scarce water supplies

• Daily torpor is exhibited by many small mammals and birds and seems adapted to feeding patterns

basic principles of animal form and function bio fall 2012/40...cellular respiration ... inc....

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