b. ch 42 circulation

8/2/2019 B. CH 42 Circulation

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AP Biology

CH 42Circulatory Systems


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Exchange of materials

Animal cells exchange material acrosstheir cell membrane

fuels for energy

nutrients oxygen

waste (urea, CO2)

If you are a 1-cell organism thats easy! diffusion

If you are many-celled thats harder


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AP Biology

Overcoming limitations of diffusion

O2CHO

CHO

aa

aaCH

CO2NH3aa

O2

CH

aa

CO2 CO2

CO2CO2

CO2

CO2 CO2

CO2

CO2CO2

NH3

NH3 NH3NH3

NH3NH3

NH3NH3O2aaCH

aa

CHO

O2 Diffusion is not adequate for moving

material across more than 1-cell barrier


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AP Biology

In circulation

What needs to be transported nutrients & fuels

from digestive system

respiratory gases

O2 & CO2 from & to gas exchange systems: lungs, gills intracellular waste

waste products from cells

water, salts, nitrogenous wastes (urea)

protective agents

immune defenses white blood cells & antibodies

blood clotting agents

regulatory molecules hormones


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Circulatory systems

All animals have: circulatory fluid = blood

tubes = blood vessels

muscular pump = heartopen closed

hemolymph

blood


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AP Biology

Open circulatory system

Taxonomy invertebrates

insects,arthropods,mollusks

Structure

no separation

between blood &interstitial fluid

hemolymph


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Closed circulatory system

Taxonomy invertebrates

earthworms, squid,octopuses

vertebrates

Structure blood confined to

vessels & separatefrom interstitial fluid

1 or more hearts

large vessels to smallervessels

material diffusesbetween blood vessels& interstitial fluid

closed system = higher pressures


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AP Biology

Vertebrate circulatory system

Adaptations in closed system number of heart chambers differs

4 chamber heart is double pump = separates oxygen-rich &oxygen-poor blood; maintains high pressure

Whats the adaptive value of a 4 chamber heart?

2 3 4

lowpressureto body

low O2tobody

high

pressure& high O2to body


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Evolution of vertebrate circulatory system

fish amphibian reptiles birds & mammals

A A

V

V V VV

A AAA

A

V

2 chamber 3 chamber 3 chamber 4 chamber

Birds ANDmammals!

Wassssup?!


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AP Biology

Evolution of 4-chambered heart

convergentevolution

Selective forces increase body size

protection from predation

bigger body = bigger stomach forherbivores

endothermy can colonize more habitats

flight decrease predation & increase prey

capture Effect of higher metabolic rate

greater need for energy, fuels, O2,waste removal endothermic animals need 10x energy

need to deliver 10x fuel & O2 to cells


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AP Biology

Vertebrate cardiovascular system

Chambered heart atrium = receive blood

ventricle = pump blood out

Blood vessels arteries = carry blood away from heart

arterioles

veins = return blood to heart venules

capillaries = thin wall, exchange / diffusion

capillary beds = networks of capillaries


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Blood vessels

arteriesarterioles

capillariesvenules

veins

artery

arteriolesvenules

veins


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Arteries: Built for high pressure pump

Arteries thicker walls

provide strength for highpressure pumping of blood

narrower diameter

elasticity

elastic recoil helps

maintain bloodpressure evenwhen heart relaxes


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Veins: Built for low pressure flow

Veins thinner-walled

wider diameter blood travels back to heart

at low velocity & pressure

lower pressure distant from heart

blood must flow by skeletal muscle

contractions when we move squeeze blood through veins

valves in larger veins one-way valves

allow blood to flow only toward heart

Openvalve

Blood flows

toward heart

Closed valve


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Capillaries: Built for exchange

Capillaries very thin walls

lack 2 outer wall layers

only endothelium enhances exchange

across capillary

diffusion

exchange betweenblood & cells


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AP Biology

Controlling blood flow to tissues

Blood flow in capillaries controlled bypre-capillary sphincters

supply varies as blood is needed

after a meal, blood supply to digestive tract increases

during strenuous exercise, blood is diverted fromdigestive tract to skeletal muscles

capillaries in brain, heart, kidneys & liver usuallyfilled to capacity

sphincters open sphincters closed

Why?


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AP Biology

Exchange across capillary walls

Arteriole

Bloodflow

Venule

Lymphatic

capillary

Interstitialfluid

Fluid & solutes flowsout of capillaries totissues due to bloodpressure

bulk flow

Interstitial fluid flowsback into capillariesdue to osmosis plasma proteins osmotic

pressure in capillary

BP > OP BP < OP

15% fluid returnsvia lymph

85% fluid returnsto capillaries

What about

edema?

Capillary


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Lymphatic system

Parallel circulatory system transports white blood cells

defending against infection

collects interstitial fluid &returns to blood

maintains volume & proteinconcentration of blood

drains into circulatory systemnear junction of vena cava &right atrium


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Lymph systemProduction & transport of WBCs

Traps foreign invaders

lymph node

lymph vessels(intertwined amongst blood vessels)


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Mammalian

circulation

What do bluevs. red areas represent?

pulmonary

systemic

systemic


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Mammalian heart

Coronary arteries

to neck & head

& arms


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Coronary arteries

bypass surgery


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AV

SL

AV

Heart valves

4 valves in the heart flaps of connective tissue

prevent backflow

Atrioventricular (AV) valve

between atrium & ventricle keeps blood from flowing back

into atria when ventricles contract lub

Semilunar valves between ventricle & arteries

prevent backflow from arteries intoventricles while they are relaxing dub


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AV

SL

AV

Lub-dub, lub-dub

Heart sounds closing of valves

Lub

recoil of blood against

closed AV valves

Dub

recoil of blood againstsemilunar valves

Heart murmur defect in valves causes hissing sound when

stream of blood squirts backward through valve


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Cardiac cycle

systolic________

diastolic

pump(peak pressure)_________________

fill(minimum pressure)

1 complete sequence of pumping heart contracts & pumps

heart relaxes & chambers fill

contraction phase systole

ventricles pumps blood out

relaxation phase

diastole atria refill with blood

110____

70


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AP Biology

Measurement of blood pressure

High Blood Pressure (hypertension)

if top number (systolic pumping) > 150

if bottom number (diastolic filling) > 90

b. ch 42 circulation

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