Bi102 Ch 40

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Concept40.1

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Animal form & function arecorrelated at all levels of organization

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What limits animal size & shape

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Physicallaws & the environment

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convergentevolution

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reflectsdifferent species independentadaptation to a similarenvironmental challenges

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What directly affects exchange of nutrients, wastes & gases with environment

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size& shape

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all living cells must be bathed inaqueous medium

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contains nutrients / compounds /gases (O2)that diffuse & are transported across plasma membranes

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•tissues

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–groups of cells with a commonstructure & function

–Structure related to its functions

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4 main categories of tissues

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•epithelial,connective, muscle, & nervous

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•organs

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–combinations of various tissues

–Different organs working togethermake up organsystems

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Complexbody plans allows animals living in variableenvironments.......

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tomaintain stableinternalenvironment

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Epithelial tissue

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•covers the outside of the body& lines organs within the body

–cells that are closely joined

–Protection against injury &pathogens

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•Simple squamous epithelium

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–Thin & leaky

–Functions in the exchange ofmaterials by diffusion (O2 & CO2 & nutrients)

–Lines blood vessels, air sacs oflungs

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•Stratified squamous epithelium

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–Regenerates rapidly to replacecells that get sloughed off

–Found on surfaces subject toabrasion

- Skin, linings of esophagus

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Connectivetissue:Blood

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•transport of nutrients & gases& wastes,

•blood cells

–erythrocytes (RBC): carry O2 CO2

–leukocytes (WBC): defense

–platelets: clotting

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Regulator

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•uses internal control mechanisms tomoderate internal change with external, environmental fluctuation

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conformer

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•allows internal condition to varywith external changes

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homeostasis

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•Organisms use homeostasistomaintain a “steady state” or internal balance regardless of externalenvironment

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Mechanismsof Homeostasis

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•For a given variable, fluctuationsabove or below a setpoint serveas a stimulusdetectedby a sensor&trigger a response

•The response returns the variableto the set point

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negativefeedback

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- returns a variable to its normalrange or aset point

-reduces or dampens the stimulus

-maintains dynamic equilibrium

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Positivefeedback

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•amplifies a stimulus and does notusually contribute to homeostasis in animals

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Thermoregulation

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•the process by which animalsmaintain an internal temperature within a tolerable range

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Endothermic

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animalsgenerate heat by metabolism birds & mammals are endotherms

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Ectothermic

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•animals gain heat from externalsources most animals are ectotherms

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•Endotherms use ______ while ectotherms use ______ to thermoregulate

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metabolism, behavioral means

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Endothermic vs Ectothermic

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•Ectotherms tolerate greater variation ininternal temperature, while endotherms are active at a greater range ofexternal temperatures

•Endothermy is more energetically expensivethan ectothermy

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•Thermoregulation involves_____ & ____ adjustments

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physiological, behavioral

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•Balancing heat loss / gain (5 points)

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1. insulation

2. circulatoryadaptations

3. coolingby evaporative heat loss

4. behavioralresponses

5. adjustingmetabolic heat production

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Insulation– decreases heat loss

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•a major thermoregulatory adaptationin mammals & birds

•reduces the flow of heat between ananimal & its environment

•includes hair, feathers, fur,layers of fat

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Circulatoryadaptations

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a)alteration of blood flow betweenbody core & skin

b)countercurrentheat exchangers

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Circulatory adaptations: countercurrentheat exchangers

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•specializedarrangement of blood vessels: decreases heat loss

•transfer of heat between fluidsflowing in opposite directions

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Circulatory adaptations: alteration of blood flow betweenbody core & skin

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Vasodilation –gets bigger – more blood flow – lose heat

Vasoconstriction– gets smaller – less blood flow – don’t lose heat

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Cooling by evaporative heat loss

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•lossof heat throughevaporation of water from skin

–sweating

–panting to cool their bodies

–bathing

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BehavioralResponses

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•movement to cooler / warmer areas

–either locally or more extreme(e.g. migration)

•changing posture

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Adjusting metabolic heat production

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

•Heat production is increased bymuscle activity such as movingor shivering

•Some ectotherms can also shiver to increase bodytemperature

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Thermoregulationis controlled by a region of the brain called the

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hypothalamus