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Circulation & Gas Exchange
From Ch. 42
13 July 2009 1Circulation & GasEx.ppt
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13 July 2009 Circulation & GasEx.ppt 2
Animal Life
Four critical processes
Obtain energy and material
Ingest, digest, absorb
Obtain oxygen
Dispose of nitrogenous waste
NH3, urea, uric acid
Dispose of CO2
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Animal Life
Harder for multicellular
organisms
Internal circulation
Coordination,information transfer
Structural maintenance
Movement
Maintenance ofhomeostatic internal
environment
13 July 2009 Circulation & GasEx.ppt 3
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Circulatory System
Why have a circulatory System? Small animals often dont.
Cnidarians, flatworms, nematodes
Cells get sufficient O2, diffusion from environment
Cells dispose of wastes to environment
Cells get nutrients from gut by diffusion
13 July 2009 Circulation & GasEx.ppt 4
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Circulatory System
Why have a circulatory System?
Larger animals MUST have circulatory system
Most cells too far from surface and too far from gut
Diffusion would take too long!!!
Circulatory systems bring O2, food, to all tissues
All cells close enough to a capillary
Circulatory systems carry away metabolic wastes
Circulatory systems carry regulatory signaling
molecules
13 July 2009 Circulation & GasEx.ppt 5
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Circulatory System
Open and closed circulatory systems Open: hemolymph flows through hemocoel
Closed: blood confined to vessels
13 July 2009 Circulation & GasEx.ppt 6
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Circulatory System
Vertebrate circulatory systems
Amphibians & Reptiles
13 July 2009 Circulation & GasEx.ppt 8
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Circulatory System
Vertebrate circulatory
systems
Mammalian systems
4-chambered heart Gas exchange in lungs
13 July 2009 Circulation & GasEx.ppt 9
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13 July 2009 Circulation & GasEx.ppt 10
Organization of the
Cardiovascular System
Heart = muscular double pump
Blood = circulating fluid tissue
Vessels
Arteries carry blood FROM the heart,
Capillaries distribute O2, nutrient molecules,
and pick up wastes,
Veins return blood TOWARD the heart
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13 July 2009 Circulation & GasEx.ppt 11
Organization of the
Cardiovascular System
Two circulations
Pulmonary
To and from lungs
Systemic
To and from all other tissues
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13 July 2009 Circulation & GasEx.ppt 12
The Heart
Ya gotta have heart, miles and miles
and miles of heart.
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The Heart
Mammalian heart
Hollow, muscular
Double pump
Right: Pulmonarycirculation
Left: Systemic
circulation
13 July 2009 Circulation & GasEx.ppt 13
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The Heart
Location
Thoracic region in
pericardial sac, between
lungs
2/3 of mass left of
midsagittal plane
Apex = lower tip of left
ventricle
Base = flat superior
side, tops of atria.
13 July 2009 Circulation & GasEx.ppt 14
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The Heart
Chambers
2 Atria
receive venous return
2 Ventricles receive blood from
atria,
pump blood out
through major arteries
13 July 2009 Circulation & GasEx.ppt 15
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The Heart
Valves direct bloodflow through the heart
2 Atrioventricular
valves Tricuspid Bicuspid or Mitral
2 Semilunar valves
Pulmonary Aortic
Operation of valves
13 July 2009 Circulation & GasEx.ppt 16
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Vessels
Arteries
Carry blood from heart
Thick muscular wall
Veins Carry blood to heart
This nwall
Capillaries Extremely thin
membrane for
exchange
13 July 2009 Circulation & GasEx.ppt 17
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Vessels
Blood pressure Systolic
Diastolic
13 July 2009 Circulation & GasEx.ppt 18
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Vessels
Capillary Exchange
Filtration & bulk flow
Diffusion
Osmosis
Excess fluid picked up
by lymphatic system
13 July 2009 Circulation & GasEx.ppt 19
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Vessels
13 July 2009 Circulation & GasEx.ppt 20
Venous return
Low venous pressures
Venous pumps
Muscular pump
Respiratory pump
Valves