Chapter 40

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


What you need to know…

• The 4 types of tissues and their general functions.

• The importance of homeostasis and examples.

• How feedback systems control homeostasis, and one example of positive feedback and one example of negative feedback.


• Animals inhabit almost every part of the biosphere

• Despite their amazing diversity

– 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

Figure 40.1


40.1 Basic Principles of Animal Form and Function

• Physical laws and the need to exchange materials with the environment

– Place certain limits on the range of animal forms

• The ability to perform certain actions

– Depends on an animal’s shape and size


• Evolutionary convergence

– Reflects different species’ independent adaptation to a similar environmental challenge

Figure 40.2a–e

(a) Tuna

(b) Shark

(c) Penguin

(d) Dolphin

(e) Seal


Exchange with the Environment

• An animal’s size and shape

– Have a direct effect on how the animal exchanges energy and materials with its surroundings

• Exchange with the environment 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

Figure 40.3a

Example of Form and Function

Diffusion

(a) Single cell


Example of Form and Function

• Multicellular organisms with a sac body plan

– Have body walls that are only two cells thick, facilitating diffusion of materials

Figure 40.3b

Mouth

Gastrovascularcavity

Diffusion

Diffusion

(b) Two cell layers


Levels of Organization

• Tissues – groups of cells that have a common structure and function

• Organs – functional units of tissues

• Organ Systems – groups of organs that work together (ex. Digestive, circulatory, or excretory systems)


Lumen ofstomach

Mucosa. The mucosa is anepithelial layer that linesthe lumen.

Submucosa. The submucosa isa matrix of connective tissuethat contains blood vesselsand nerves.

Muscularis. The muscularis consistsmainly of smooth muscle tissue.

0.2 mm

Serosa. External to the muscularis is the serosa,a thin layer of connective and epithelial tissue.

• In some organs

– The tissues are arranged in layers

Figure 40.6


Types of Tissues

•4 Types of tissues

– Epithelial tissue

– Connective tissue

– Muscle tissue

– Nervous tissue


Epithelial Tissue

– Covers the outside of the body and lines organs and cavities within the body

– Contains cells that are closely joined


Connective Tissue

– Functions mainly to bind and support other tissues

– Contains sparsely packed cells scattered throughout an extracellular matrix


Muscle Tissue

– Is composed of long cells called muscle fibers capable of contracting in response to nerve signals

– Is divided in the vertebrate body into three types: skeletal, cardiac, and smooth


Nervous Tissue

– Senses stimuli and transmits signals throughout the animal, including to other neurons (nerve cells), glands, muscles, and the brain.


Organ Systems in Mammals


2 Systems that Specialize Coordination and Control

• For survival, tissues, organs, and organ systems must act in a coordinated way:

• 2 Systems specialize in this:

1. Endocrine system – chem. Signals called hormones = released. Each hormone cause specific effects

2. Nervous system (neurons) – transmit info between specific locations


• The internal environment of vertebrates

– Is called the interstitial fluid, and is very different from the external environment

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

40.2 Feedback control loops maintain homeostasis


Homeostatic Control

• Functions by having a set point (like a body temp to maintain)

– It has sensors to detect any stimulus above or below the set point

– A physiological response helps return the body to its set point

Response

No heatproduced

Roomtemperaturedecreases

Heaterturnedoff

Set point

Toohot

Setpoint

Control center:thermostat

Roomtemperatureincreases

Heaterturnedon

Toocold

Response

Heatproduced

Setpoint


Homeostatic Control Systems

– Negative feedback systems (most) –

• Where buildup of the end product of the system shuts the system off

• Ex. In response to exercise, the body temp rises, which initiates sweating to cool the body


Homeostatic Control Systems

– Positive feedback systems

• involves a change in some variable that triggers mechanisms to amplify the change

• Ex. During birth, pressure of the baby’s head against receptors near the opening of the uterus stimulates greater uterine contractions, which cause greater pressure against the uterine opening, which heightens the contractions and so forth


40.3 Homestatic processes for thermoregulation

• Thermoregulation

– process by which animals maintain an internal temperature within a tolerable range

– 2 Types of regulation

• Endotherms – (such as mammals and birds) – warmed mostly by heat generated by metabolism

• Ectotherms – (such as most invertebrates, fishes, amphibians, and reptiles) – generate relatively little metabolic heat, gaining most of their heat from external sources


• In general, ectotherms

– Tolerate greater variation in internal temperature than endotherms

Ectoderms

Figure 40.12

River otter (endotherm)

Largemouth bass (ectotherm)

Ambient (environmental) temperature (°C)

Bod

y te

mpe

ratu

re (

°C)

40

30

20

10

10 20 30 400


• Endothermy is more energetically expensive than ectothermy

– But buffers animals’ internal temperatures against external fluctuations

– And enables the animals to maintain a high level of aerobic metabolism

Endoderms


Modes of Heat Exchange

• Organisms exchange heat by four physical processes

Radiation is the emission of electromagnetic waves by all objects warmer than absolute zero. Radiation can transfer heat between objects that are not in direct contact, as when a lizard absorbs heat radiating from the sun.

Evaporation is the removal of heat from the surface of aliquid that is losing some of its molecules as gas. Evaporation of water from a lizard’s moist surfaces that are exposed to the environment has a strong cooling effect.

Convection is the transfer of heat by the movement of air or liquid past a surface, as when a breeze contributes to heat loss from a lizard’s dry skin, or blood moves heat from the body core to the extremities.

Conduction is the direct transfer of thermal motion (heat) between molecules of objects in direct contact with each other, as when a lizard sits on a hot rock.

Figure 40.13


Balancing Heat Loss and Gain

• Thermoregulation involves physiological and behavioral adjustments

– That balance heat gain and loss

– Examples include

• Insulation

• Vasodilation

• Vasocontriction

• Countercurrent Exchange


Balancing Heat Loss and Gain

• Insulation

– Reduces the flow of heat between an animal and its environment

– May include feathers, fur, or blubber

• In vasodilation

– Blood flow in the skin increases, facilitating heat loss

• In vasoconstriction

– Blood flow in the skin decreases, lowering heat loss


• Many marine mammals and birds

– Have arrangements of blood vessels called countercurrent heat exchangers that are important for reducing heat loss

– Antiparallel blood vessels going from the middle of the body where the blood is warm to the extremities

Countercurrent Exhange

In the flippers of a dolphin, each artery issurrounded by several veins in acountercurrent arrangement, allowingefficient heat exchange between arterialand venous blood.

Canadagoose

Artery Vein

35°C

Blood flow

VeinArtery

30º

20º

10º

33°

27º

18º

9º

Pacific bottlenose dolphin

2

1

3

2

3

Arteries carrying warm blood down thelegs of a goose or the flippers of a dolphinare in close contact with veins conveyingcool blood in the opposite direction, backtoward the trunk of the body. Thisarrangement facilitates heat transferfrom arteries to veins (blackarrows) along the entire lengthof the blood vessels.

1

Near the end of the leg or flipper, wherearterial blood has been cooled to far below the animal’s core temperature, the artery can still transfer heat to the even colderblood of an adjacent vein. The venous bloodcontinues to absorb heat as it passes warmer and warmer arterial blood traveling in the opposite direction.

2

As the venous blood approaches the center of the body, it is almost as warm as the body core, minimizing the heat lost as a result of supplying blood to body partsimmersed in cold water.

3

Figure 40.15

1 3


Countercurrent Heat Exhange

• Some specialized bony fishes and sharks

– Also possess countercurrent heat exchangers

Figure 40.16a, b

21º25º 23º

27º

29º31º

Body cavity

SkinArtery

Vein

Capillarynetwork withinmuscle

Dorsal aortaArtery andvein underthe skin

Heart

Bloodvesselsin gills

(a) Bluefin tuna. Unlike most fishes, the bluefin tuna maintainstemperatures in its main swimming muscles that are much higherthan the surrounding water (colors indicate swimming muscles cutin transverse section). These temperatures were recorded for a tunain 19°C water.

(b) Great white shark. Like the bluefin tuna, the great white sharkhas a countercurrent heat exchanger in its swimming muscles thatreduces the loss of metabolic heat. All bony fishes and sharks loseheat to the surrounding water when their blood passes through thegills. However, endothermic sharks have a small dorsal aorta, and as a result, relatively little cold blood from the gills goes directly to the core of the body. Instead, most of the blood leaving the gillsis conveyed via large arteries just under the skin, keeping cool bloodaway from the body core. As shown in the enlargement, smallarteries carrying cool blood inward from the large arteries under theskin are paralleled by small veins carrying warm blood outward fromthe inner body. This countercurrent flow retains heat in the muscles.


Countercurrent Heat Exchange

• Many endothermic insects

– Have countercurrent heat exchangers that help maintain a high temperature in the thorax

Figure 40.17


Adjustment to Changing Temperatures

• In a process known as acclimatization

– Many animals can adjust to a new range of environmental temperatures over a period of days or weeks


Torpor and Energy Conservation

• Torpor

– Is an adaptation that enables animals to save energy while avoiding difficult and dangerous conditions

– Is a physiological state in which activity is low and metabolism decreases


• Hibernation is long-term torpor

– That is an adaptation to winter cold and food scarcity during which the animal’s body temperature declines

Additional metabolism that would benecessary to stay active in winter

Actualmetabolism

Bodytemperature

Arousals

Outsidetemperature Burrow

temperature

June August October December February April

Tem

pera

ture

(°C

)M

etab

olic

rat

e(k

cal p

er d

ay)

200

100

0

35

30

25

20

15

10

5

0

-5

-10

-15

Figure 40.22


• 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 to be adapted to their feeding patterns

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