Basic Principles of Animal Form and Function

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Mammalian integumentary system

Epidermis

Dermis

Hypodermis

Adipose tissue

Blood vessels

Hair

Sweat

pore

Muscle

Nerve

Sweat

gland

Oil gland

Hair follicle

Slide 42

Five general adaptations help animals thermoregulate:

Insulation

Circulatory adaptations

Cooling by evaporative heat loss

Behavioral responses

Adjusting metabolic heat production.

Slide 43

Insulation

Insulation is a major thermoregulatory adaptation in mammals and birds.

Skin, feathers, fur, and blubber reduce heat flow between an animal and its environment.

Slide 44

Circulatory Adaptations

Regulation of blood flow near the body surface significantly affects thermoregulation.

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.

Slide 45

The arrangement of blood vessels in many marine mammals and birds allows for countercurrent exchange.

Countercurrent heat exchangers transfer heat between fluids flowing in opposite directions.

Countercurrent heat exchangers are an important mechanism for reducing heat loss.

Slide 46

Countercurrent heat exchangers

Canada goose

Bottlenose

dolphin

Artery

Artery

Vein

Vein

Blood flow

33º

35ºC

27º

30º

18º

20º

10º

9º

Slide 47

Cooling by Evaporative Heat Loss

Many types of animals lose heat through evaporation of water in sweat = evaporative cooling.

Panting increases the cooling effect in birds and many mammals.

Sweating or bathing moistens the skin, helping to cool an animal down.

Slide 48

Behavioral Responses

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

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

Slide 49

Adjusting Metabolic Heat Production

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