2275811
Description
Flashcards by Charlotte Hewson, updated more than 1 year ago
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Created by Charlotte Hewson
over 9 years ago
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| Question | Answer |
| what do arteries do? | carry blood away from the heart into arterioles |
| what are arterioles and what do they do?? | smaller arteries that control blood flow from arteries to cappilaries |
| what are capillaries? | tiny vessels that link arterioles to veins |
| which three vessels share the same basic layered structure? | arteries, arterioles and veins. |
| name the basic structures in blood vessels from the outside inwards. | -tough outer layer -muscle layer -elastic layer -thin inner lining (endothelium) -lumen |
| what is the tough outer layer for in a blood vessel? | resist pressure changes from both within and outside |
| what is the muscle layer for in blood vessels? | can contract to control blood flow. |
| what does the elastic layer in a blood vessel do? | helps maintain blood pressure by stretching and springing back |
| what does the endothelium do in a blood vessel? | smooth to prevent friction and thin to allow diffusion |
| what is the lumen? | the central cavity of the blood vessel through which blood flows |
| what is the muscle layer like in an artery compared to a vein? | thick so smaller arteries can constrict and dilate to control the volume of blood passing through them |
| why is the elastic layer thicker in arteries than veins? | -pressure needs to be kept high so blood can reach bodies extremities -stretched at each beat (systole) -springs back between beats (diastole) |
| what does the recoil action of the elastic layer in an artery help with? | -maintain high blood pressure -smooth pressure surges from the beating of the heart |
| why is the overall thickness of an artery large? | resists the vessel bursting under pressure |
| are there any valves in an artery? | only in the arteries leaving the heart |
| why are there no valves in most arteries? | blood is under constant high pressure so doesn't tend to flow backwards |
| what are two ways arterioles differ from arteries? | muscle layer is thicker and elastic layer is thinner |
| why is the muscle layer thicker in arterioles? | because they contract, causing the lumen to constrict. this restricts blood flow and controls flow into capillaries |
| why is the elastic layer thinner in arterioles than arteries? | the blood is at a lower pressure |
| what are the 4 main structural features of veins? | -thin muscle layer -thin elastic layer -overall thickness is small -valves throughout |
| what are the 5 structural features of capillaries? | -walls made of just the lining layer -numerous and highly branched -narrow diameter that permeate cells -lumen is narrow so red blood cells are squished against the side reducing diffusion distance -spacing between lining cells to let white blood cells esccape |
| capillaries cant serve every cell directly. how does our body counter this? | a liquid solution that bathes the tissues. called tissue fluid. |
| what 5 components does tissue fluid contain? | -glucose -amino acids -fatty acids -salts -oxygen |
| tissue fluid supplies cells with certain substances. what does it get in return? | carbon dioxide and other waste materials from the tissues |
| what is tissue fluid formed from? | blood plasma |
| what is the composition of blood plasma controlled by? | various homeostatic systems |
| blood is pumped through arteries, then narrower arterioles, then narrower capillaries. what kind of pressure does this create? | hydrostatic pressure |
| what does hydrostatic pressure do to blood plasma? | forces tissue fluid out of it |
| what to forces is the outward pressure opposed by? | -hydrostatic pressure of tissue fluid outside the capillaries which prevents outward movement of liquid -lower water potential of blood due to plasma proteins that pulls water back into capillaries |
| the overall pressure is enough to get some molecules out of the capillaries. what is this filtration called? | ultrafiltration |
| how does tissue fluid get back into the capillaries? | -loss of t.f. in capillaries reduces hydrostatic pressure inside them -by the time blood reaches the vein end of the capillary, the pressure in the capillaries is less than the surrounding tissue fluid -tissue fluids forced back in as pressure outside is greater -osmotic forces also pull water back into capillaries |
| what happens to the fluid that doesnt return to the capillaries? | carried by the lymphatic system |
| how does fluid move through the lymphatic system? | -hydrostatic pressure -contraction of body muscles |
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