Human biology 1.2.2

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Describe structure of arteries?

Thick wall- under high blood pressure to carry blood away from the heart 

Thick and lots of elastic fibres - allow artery wall to strech when ventricles contract and recoil when relaxed

Small lumen- keep blood under high pressure

lots of smooth muscle- which contracts and relaxes to regulate blood pressure by changing diameter of lumen

endothelium- helps blood flow by preventing friction

collagen- for protection

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Describe structure of veins?

Thinner layer of smooth muscle and elastic fibres as under much lower pressure as carrys blood towards the heart 

large lumen as under less pressure so blood flows more smoothly

valves help to make sure blood flows in one direction as muscles contract valves squeeze the veins which raises the pressure in veins and closes valves behind but open valves ahead this all prevents backflow

endothelium- reduce friction

collagen- for protection

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Describe structure of capillary?

Single layer of thin flattened endothelium

very thin wall to allow exchange between blood and tissues

fenestrations which allow substances to be exchanged between capillaries and tissues and allow phagocytes to migrate to these tissues

diffussion distances are small 

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What are venules?

carry blood from capillary back to veins

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What are arterioles?

have thin wall of elastics fibres and smooth muscle they can increase or decrease flow of blood by narrowing/widening lumen

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Define mass transport?

everything is moving in a stream in one direction the cells,plasma and dissolved substances are all moving together in the blood

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Explain importance of closed and double circulator

Closed- blood stays in blood vessels at all time expect from when body is injured

Double- 2 circuits pulomonary circulation heart-lungs-heart

and systemic circulation heart-body organs-heart goes through heart twice.

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What is the passage of deoxgenated blood?

deoxy blood-vena cava-right atrium-right ventricle-plumonary artery-lungs

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Whats passage of oxygenated blood?

oxygenated blood lungs- plumonary vein-left atrium-left ventricle-aorta-body

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advantage of double circulatory system?

oxy+ deoxy blood do not mix

bp can be maintained at high level

o2 to respiring cells can be optimised

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Advantage of closed circulatory system?

more complete separation of function between organs

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How is a spyhgmomanometer used to measure bp?

remove any tight clothing on upper arm

sit down relaxed for atleast 5 mins before

inflatable cuff placed around upper arm

place stethoscope over brachial artery  so you can hear pulse

pump air slowly into the cuff so it inflates which tightens upper arm and restricts blood

when you no longer hear a pulse release cuff as soon as you hear the pulse again record reading this is systolic pressure

allow cuff to deflate slowly until no sound again record pressure this is diastolic pressure

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How is a digital sphgmomanometer is used?

sit down for atleast 5 mins before 

remove tight clothing from upper arm

place inflatable cuff around upper arm indicator mark should be where brachial artery is

cuff will automatically inflate/deflate. bp reading will be shown on digital display

repeat twice

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What is blood pressure measured in

KPA units or mmhg

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What is systolic and diastolic pressure?

s-always shown first in bp reading is pressure in artery when left ventricle contracts

d- pressure generated by elastic recoil between beats

130/85 below normal bp

180/110-severe hypertension

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What happens if you have low blood pressure?

exchange of nutrients and o2 within tissues will not happen effiecently which can lead to key organs not function such as the kidney

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Why will people feel faint and unconcious with low

not enough blood circulating to supply our cells with glucose and o2 needed for respiration

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Why is swelling cause by high bp?

more tissue fluid is formed in capillaries but cant all return to the blood vessels so accumalates in feet and legs because of effects of gravity

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