Circulation
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Circulation. The Presence of a Circulatory System:. Reduces the distance a substance must travel to enter or leave a cell. Uses “Blood” to carry these molecules to the cells.

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Circulation

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Circulation

Circulation


The presence of a circulatory system

The Presence of a Circulatory System:

  • Reduces the distance a substance must travel to enter or leave a cell.

  • Uses “Blood” to carry these molecules to the cells.

O2 diffuses from the air in the lungs (or similar structures) across epithelium to the “blood” which carries it to all parts of the body.

Once in the capillaries, O2 diffuses across epithelium again to the tissues.

CO2, of course, moves in the opposite direction.


Circulatory systems

Circulatory systems

  • All animals have:

    • circulatory fluid = “blood”

    • tubes = blood vessels

    • muscular pump = heart

open

closed

hemolymph

blood


Open circulatory system

Open circulatory system

  • Invertebrates

    • insects, arthropods, mollusks

  • No separation between blood & interstitial fluid (Hemolymph)


Closed circulatory system

Closed circulatory system

closed system = higher pressures

  • Invertebrates

    • earthworms, squid, octopuses

  • Vertebrates

  • Blood confined to vessels & separate from interstitial fluid

    • 1 or more hearts

    • large vessels to smaller vessels

    • material diffuses between blood vessels & interstitial fluid


Vertebrate circulatory system

Vertebrate circulatory system

  • Adaptations in closed system

    • number of heart chambers differs

2

3

4

low O2to body

low pressureto body

high pressure & high O2to body

What’s the adaptive value of a 4 chamber heart?

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


Evolution of vertebrate circulatory system

Evolution of vertebrate circulatory system

fish

amphibian

reptiles

birds & mammals

2chamber

3 chamber

3 chamber

4 chamber

V

A

A

A

A

A

A

A

V

V

V

V

V


Evolution of 4 chambered heart

Evolution of 4-chambered heart

  • Selective forces

    • increase body size

      • protection from predation

      • bigger body = bigger stomach for herbivores

    • 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

convergentevolution


Vertebrate cardiovascular system

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


Exchange across capillary walls

Exchange across capillary walls

Pressure is greatest in the arteries, lowest in veins

Lymphatic

capillary

Interstitial fluid flows back into capillaries due to osmosis

  • plasma proteins  osmotic pressure in capillary

Fluid & solutes flows out of capillaries to tissues due to blood pressure

  • “bulk flow”

BP > OP

BP < OP

Interstitial

fluid

Blood

flow

85% fluid returns to capillaries

Capillary

15% fluid returns via lymph

Arteriole

Venule


Mammalian circulation

Mammaliancirculation

systemic

pulmonary

systemic

What do bluevs.redareas represent?


Mammalian heart

Mammalian heart

to neck & head& arms


Heart valves

SL

AV

AV

Heart valves

  • 4 valves in the heart

    • flaps of connective tissue

    • prevent backflow

  • Atrioventricular (AV) valves

    • between atrium & ventricle

    • keeps blood from flowing back into atria when ventricles contract

      • “lub”

  • Semilunar valves

    • between ventricle & arteries

    • prevent backflow from arteries into ventricles while they are relaxing

      • “dub”


Lub dub lub dub

Lub-dub, lub-dub

  • Tempo is controlled by Sinoatrial node (SA node)

    • located at right atrium by superior vena cava

    • Contraction at SA node causes both atria to contract (lub)

  • Wave contraction passes down to Atrioventricular node (AV node)

    • Impulse is delayed by 0.1 sec (atria need to empty)

    • Causes ventricle to contract (dub)

  • Heart murmur

    • defect in valves causes hissing sound when stream of blood squirts backward through valve

SL

AV

AV


Cardiac cycle

Cardiac cycle

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

systolic

________

diastolic

pump(peak pressure)

_________________

fill(minimum pressure)


Measurement of blood pressure

Measurement of blood pressure

  • High Blood Pressure (hypertension)

    • if top number (systolic pumping) > 150

    • if bottom number (diastolicfilling) > 90


Blood

Blood:

It’s more than just red stuff.

Plasma:

55%

The fluid portion of blood.

Water accounts for over 90%

Contains:

Electrolytes- to maintain osmotic balance, buffer

  • Nutrients

  • Respiratory gases

  • Hormones

CELLS!

So, if blood is 55% plasma, the rest must be ….._________


Blood1

Blood:

Erythrocytes-also called Red Blood Cells (RBCs)

So, what about those cells?

  • Transport oxygen (which binds to Hemoglobin)

  • Lack nuclei or mitochondria

  • Leukocytes-

also called white blood cells (WBCs)

  • Function in defense and immunity

  • DO have nuclei & mitochondria

Include:

Basophils

Actually spend most of their

time in interstitial fluid and

the lymphatic system.

Lymphocytes

Eosinophils

Neutrophils


Clotting a real fixer upper

Clotting: a real fixer-upper…

Platelets:

  • Clump & stick to the jagged edges of the cut.

Provides immediate but temporary “plug”

2. Release clotting factors which catalyze the reaction:

Fibrinogen  Fibrin

Fibrin aggregates to form the clot


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