Carrier & mediium, pump & contributory flow mechanisms, Distribution system & a surface for exchange - facilitate diffusion from carrier to tissues
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Function of arterioles
Control vessels by changing diameter & therefore also flow and pressure in the system
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How Homeostasis is helped maintained by circulatory system
transport of O2, nutrient, waste, products, metabolic heat and hormones
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Arteries deliver...
Oxygenated blood and nutrients
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Veins remove
De-oxygenated blood and waste products
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Major arteries
Aorta, carotid, brachial, radial iliac, femoral, gastric, hepatic and renal
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Major veins
vena cava, jugular, brachial, basilic & cephalic, common iliac and femoral
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Arteries divide into...
arterioles then capillaries
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Where does blood and tissue exchange occur?
Capillaries
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What do capillaries reform to join?
Venules then veins then they return the blood to the heart
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structure of arteries
Layers of elastin and lots of muscle
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Structure of arterioles
Lack elastin
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Structure of capillaries
no elastin of muscle - only thin endothelium and basement membrane
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'structure of veins
Less muscle and elastin that arteries
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Types of capillary
Continuous, fenestrated and discontinuous
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Continuous
Continuous capillaries have a sealed endothelium and only allow small molecules, like water and ions to diffuse.
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Fenestrated
have pores in the endothelial cells (60-80 nm in diameter) that are spanned by a diaphragm of radially oriented fibrils and allow small molecules [2][3] and limited amounts of protein to diffuse.
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Discontinuous
pecial fenestrated capillaries that have larger openings (30-40 μm in diameter) in the endothelium to allow red and white blood cells (7.5μm - 25μm diameter) and various serum proteins to pass, a process that is aided by a discontinuous basal lamina
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effect of pre-capillary sphincters
(band of smooth muscle) effectively shuts down capillaries at rest - sympathetic tone
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Effect of noradrenaline on circulatory system
causes vasoconstriction
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Efffect of adrenaline on circulatory system
dilates blood vessels in heart& skeletal muscle
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Function of valve system
Blood in veins pumped against gravity. Valves prevent backflow of blood. contracted muscle pushes blood through valves. venous valve prevents backflow.
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Blood pressure
The pressure exerted by the blood on the inside wall of an artery - measures diastolic, systolic nd mean pressure
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BP equation
cardiac output x total peripheral resistance - measured mmHg
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Peripheral resistance
resistance caused by blood viscosity + friction between blood and vessel wall
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hypertension
High BP
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Short term BP maintence
Kept within limit by baroreceptor reflex - a homeostatic negative feedback system - vagus NF slow heart rate & velocity with Ach at SA & VA nodes
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Funciton of mechanoreceptors
Protect brain from excess presser - in aortic arch and carotid sinus - fire if BP increases
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Systolic BP
When the heart is beating - increases during exercise
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Diastolic BP
When the heart is relaxed
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Other cards in this set
Card 2
Front
Function of arterioles
Back
Control vessels by changing diameter & therefore also flow and pressure in the system
Card 3
Front
How Homeostasis is helped maintained by circulatory system
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