- Created by: Hannah
- Created on: 17-05-13 09:52
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
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
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
What are venules?
carry blood from capillary back to veins
What are arterioles?
have thin wall of elastics fibres and smooth muscle they can increase or decrease flow of blood by narrowing/widening lumen
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
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.
What is the passage of deoxgenated blood?
deoxy blood-vena cava-right atrium-right ventricle-plumonary artery-lungs
Whats passage of oxygenated blood?
oxygenated blood lungs- plumonary vein-left atrium-left ventricle-aorta-body
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
Advantage of closed circulatory system?
more complete separation of function between organs
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
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
What is blood pressure measured in
KPA units or mmhg
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
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
Why will people feel faint and unconcious with low
not enough blood circulating to supply our cells with glucose and o2 needed for respiration
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