Circulation and gas exchange Salmon gill. Life exists in a friendly, watery medium What are the...
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Transcript of Circulation and gas exchange Salmon gill. Life exists in a friendly, watery medium What are the...
Life exists in a friendly, watery medium
• What are the needs of the cell?• What is the fluid that supplies the
needs of the cell? What are its characteristics?
• What keeps that fluid “friendly?”
Overview of circulatory systems• Three (or four) components:
– Fluid bathing cells = interstitial fluid– Circulatory fluid = “hemolymph” or “blood”– Tubes = blood vessels– Muscular pump = heart (usually)
• Pressure produced by the heart moves blood through vessels down a pressure gradient, and the blood eventually returns to the heart
• Two types of circulatory systems– Open– Closed
Open circulatory system• Arthropods and
mollusks• Blood and interstitial
fluid are not separated; they form hemolymph
• Hemolymph pumped through sinuses (spaces around organs) and returned via pores, or ostia
Fig. 42.3a
Closed circulatory system• Blood and
interstitial fluid are separated
• Earthworms, squid, octopus, and vertebrates
• All exchange between blood and tissues happens by diffusion in capillary beds.
Fig. 42.3b
A few more terms
• Cardiovascular system of vertebrates• Hearts are composed of atria (chambers
that receive blood) and ventricles (chambers that pump blood out)
• Arteries contain blood moving away from the heart and towards capillaries
• Veins contain blood moving towards the heart and away from capillaries
• Sinuses are spaces where blood collects• But the thin-walled capillaries are still
where all the real action is.
Circulation in vertebrates• Exchanging oxygen and carbon dioxide
PICK UP OXYGEN
LET OXYGEN GO2 chambers
Single circulation
• Single Circulation Allows only Low Pressure Circulation to the tissues
PICK UP OXYGEN
LET OXYGEN GO2 chambers
PICK UP OXYGEN
LET OXYGEN GO2 chambers 3 chambers
Single circulation;Loses pressure
Double circulation;Maintains pressure
• Three chambered hearts and dual circulation maintain pressure but allow mixing
PICK UP OXYGEN
LET OXYGEN GO2 chambers 3 chambers
Single circulation;Loses pressure
Double circulation;Maintains pressure
O2 mixing?
Dual circulation with a 4-chambered heart: high pressure, no mixing: most efficient
PICK UP OXYGEN
LET OXYGEN GO2 chambers 3 chambers 4 chambers
Single circulation;Loses pressure
Double circulation;Maintains pressure
O2 mixing?
Mammalian heart• Wall
thickness• Valves: AV
& semilunar• Lub-dup =
valves closing
• A heart murmur is a defect in a valve
Fig. 42.7
• Needs of the cell - friendly, watery medium• Structure of circulatory systems
– Interstitial fluid– Circulating fluid– Pumping organ– Blood vessels and spaces
• Functions– Transport (of nutrients, oxygen, wastes). The role of
respiratory pigments.– Defense
• Types of circulatory systems– None– Open– Closed
• Circulation in vertebrates– Types of circuit
• Single• Double/three chambered heart• Double/four chambererd heart
• Blood pressure
Blood vessels• 1 to 3 layers• Endothelium: layer of smooth, flattened cells
Fig. 42.8
ElasticThicker
Thinner
Elastic
Cardiovascular disease• Heart attacks—death of cardiac muscle due to prolonged blockage
of coronary arteries (which bring oxygenated blood to heart)• Strokes—death of nervous tissue in the brain due to blockage or
rupture of arteries in head• Atherosclerosis—chronic condition often leading to the above
conditions; plaques (fibrous connective tissue + lipids) narrow arteries
Normal Plaque
InternalGills
• Water vs. air– 4 – 8 vs. 210 ml O2 per liter– Diffusion speed– Continuously pumping water