circulatory systemnov 10, 2013 · receives oxygenated blood from the lungs and pumps it into the...
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Circulatory System 10.1
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ARTERIES
• Arteries-blood vessels that carry blood away
from the heart
▫ Thick walls
▫ Inner & Outer layers: connective tissue
▫ Middle layers are muscle and elastic
connective tissue
▫ Stretch to accommodate the in-rush of blood
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ARTERIOLES
• Blood from the arteries passes into smaller
blood vessels carrying blood away from the
heart named ARTERIOLES.
• The middle layer of the arteriole blood
vessels are made up of elastic fibres and
smooth muscle.
3
Source:
http://www.tiscali.co.uk/reference/encyclopaedia/hutchinson/images/0008n031.jpg
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• Smooth muscle relaxes,
causing the walls of the
artery to dilate,
increasing blood flow
(vasodilation)
▫ Blushing, releases heat
• Nerve impulse causes the
smooth muscle in the
artery to contract,
reducing diameter of the
vessel and decreasing
blood flow.
(vasoconstriction)
▫ Turn pale when frightened
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Atherosclerosis
• Excess lipids in the blood is deposited on the
walls of the arteries
• Minerals like calcium deposit on top of the
lipid forming plaque
• Narrows arteries and causes high blood
pressure
• Plaque penetrates artery walls, causing
blood clots to form
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Artherosclerosis
Source: http://www.nlm.nih.gov/medlineplus/ency/imagepages/18020.htm
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Aneurysm
• Bulge that forms in a weakened blood vessel
• Due to artherosclerosis
• Weakened bit of artery protrudes as blood is pumped through
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Capillaries
• Single layer of cells
• Fluid and gas exchange
• Capillary beds are easily damaged
• High blood pressure or impact will rupture
the capillary
• Oxygen is diffused from the blood to the
tissue through the walls of the capillaries
• Oxygenated blood=red
• Deoxygenated blood= deep purple/red
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Veins and Venules
• Capillaries merge and become larger
vessles called venules
• Walls of venules contain smooth muscles
• Venules merge to form veins
• Blood passes through narrow vessels with
weaker walls, pressure is reduced
• When blood reaaches venules, the pressure
is too low to drive blood back to the heart
12
Valves
• One way valves, directing blood back to the
heart
• Skeletal muscles bulge when in use,
reducing the diameter of the vein
• Pressure in the vein increases, the valves
open allowing blood to flow towards the
heart
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Veins
• 65% of your blood is stored in the veins
• Varicose veins
▫ Veins distend and blood pools in the veins and
damages the valves
▫ Blood seeps through the one way valves and
stays collects
▫ Prolonged standing or compressing the veins
(sitting crossed legged) can contribute to the
problem
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Vericose Veins
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Questions
• Pg. 316
▫ 1-3
• Pg. 318
▫ 1, 3, 5, 7
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The Heart 10.2
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Heart
• Pericardium-fluid filled sac that surrounds
the heart, prevents friction
• 4 chambers
• 2 thin walled atria
▫ (chamber that receives blood from the veins)
• 2 thick walled ventricles
▫ (chamber that delivers blood to the arteries)
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Pumps
• 2 parallel pumps are separated by the
septum (wall of muscle). The septum keeps
the oxygenated blood separate from the
deoxygenated blood.
• Pump on the right
▫ Receives deoxygenated blood from the body
and pumps it into the lungs
• Pump on the left
▫ Receives oxygenated blood from the lungs
and pumps it into the body
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Pulmonary Circulatory System
• Blood vessels that carry blood to and from the lungs
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Systemic Circulatory System
• Vessels that
carry blood to
and from the
body
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• Superior vena cava carries deoxygenated
blood from the head and upper body to the
right atrium
• Inferior vena cava carries deoxygenated
blood from all veins below the diaphragm to
the same atrium
• Pulmonary veins carry oxygenated blood
from the lungs to the left atrium
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• Atrioventricular
valves (AV) separate
the atria from the
ventricles
• AV prevent blood
from backflowing
from a ventricle into
an atrium
• Semilunar valves
(SV) separate he
ventricles from the
arteries
• SV prevent blood
from backflowing
from an artery into a
ventricle
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• Aorta carries oxygenated blood away from
the heart
• Coronary arteries supply the muscle cells in
the heart with oxygen and nutrients
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Coronary Bypass Surgery
• Cardiopulmonary bypass
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Artificial Heart
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Cardiac Catheterization
• Catheter is inserted in artery in the groin
• Pushed through aorta into the heart
• Radioactive dye is injected into catheter
• Dye travels through blood vessels, where
restrictions can be seen
• Angioplasty, using an inflatable balloon to
open the blockage
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Angioplasty
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Heartbeat
• Contracts without being stimulated by external nerves (myogenic muscle)
• Beat rate is set by the sinoatrial (SA) node • Upper right atrium sets a rhythm at about 70
bpm • Contractions travel to second node,
atrioventricular (AV) node, which acts as a conductor
• (AV) node passes impulses via 2 Purkinje fibres to the bottom of the heart
• L and R atria contract before the L and R ventricles
Simulation of Heart Pumping
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Heart Sounds
• Closing of the valves causes the lubb dubb
• Diastole is the period of rest when the atria
and ventricles are relaxed
• Atria fill with blood while they are relaxed
• Atria contract, increasing pressure, forcing
the AV valves open
• Blood flows from atria into ventricles
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• Filled ventricles contract, pressure forces
AV valves shut, producing lubb sound and
pushing blood into the arteries
• Period of contraction is called systole
• Ventricles relax, volume increases
• Increased volume, pressure in ventricles
decreases, closing of semilunar valves
creates dubb sound
38
Check your understanding
• Pg. 327
• Questions 1, 2, 5 & 6
• Label heart diagram
39
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