Blood vessels and their functions

Question 1

what are the four different types of blood vessel?

Answer 1

artery, arterioles, capillaries, vein

Question 2

what order does blood flow through the different blood vessels?

Answer 2

ARTERIES carry blood from the heart into the ARTERIOLES. ARTERIOLES control the blood flow into the CAPILLARIES. The CAPILLARIES link arterioles to VEINS which carry blood back to the heart.

Question 3

what are the 5 basic layers from outside inwards of arteries, veins and arterioles?

Answer 3

tough outer layer
muscle layer
elastic layer
thin inner layer
lumen

Question 4

what is the function of the tough outer layer?

Answer 4

to resist pressure changes from inside and outside

Question 5

what is the function of the muscle layer?

Answer 5

to CONTRACT and control the flow of blood

Question 6

what is the function of the elastic layer?

Answer 6

maintain BLOOD PRESSURE by stretching and springing back

Question 7

what is the function of the thin inner layer?

Answer 7

smooth- prevents friction and thin- allow diffusion

Question 8

what is the lumen?

Answer 8

central cavity of the blood vessel where the blood flows

Question 9

what is the structure of a capillary?

Answer 9

lumen and lining layer

Question 10

what is the function of arteries?

Answer 10

to transport blood RAPIDLY under high pressure FROM the heart to the tissues.

Question 11

how is the structure of arteries adapted to their function?

Answer 11

• the muscle layer is THICK compared to veins. can be constricted + dilated control what’s going through.
• the elastic layer is RELATIVLEY THICK compared to veins. maintain high pressure
• the OVERALL THICKNESS of the wall is large. resist vessel bursting
• there are NO VALVES. blood is under constant pressure- doesn’t tend to flow backwards.

Question 12

what is the function of arterioles?

Answer 12

carry blood, under lower pressure than arteries, from arteries to capillaries.

Question 13

how are arterioles adapted to their function?

Answer 13

• muscle layer relatively THICKER than artery. restrict blood flow, controls movement into capillaries.
• elastic layer THINNER than arteries- blood pressure lower

Question 14

what is the function of veins?

Answer 14

transport blood SLOWLY, under pressure from the tissues to the heart.

Question 15

how are veins adapted for their function?

Answer 15

• muscle layer relatively thin compared to arteries. can’t control flow of blood.
• elastic layer relatively thin compared to arteries. low pressure of blood won’t cause to burst
• overall thickness of wall is SMALL. pressure too low create risk bursting
• valves throughout- blood doesn’t flow backwards

Question 16

what is the function of capillaries?

Answer 16

to exchange metabolic materials eg oxygen, glucose, carbon dioxide between the blood and the cells of the body.

Question 17

why is the flow of blood much slower in the capillaries? What does this allow more time for?

Answer 17

the pressure is very low.

more time to exchange materials

Question 18

how are capillaries adapted to their function?

Answer 18

• walls only lining layer- short diffusion distance
• numerous + highly branched, large SA for diffusion
• narrow diameter- no cell is far from capillary
• lumen is narrow- red blood cells squeezed flat, even closer to cells
• spaces between the lining and cells- allow WHITE BLOOD CELLS escape to deal with infections in tissues

Question 19

what is tissue fluid?

Answer 19

watery liquid that contains GLUCOSE, AMINO ACIDS, FATTY ACIDS, SALTS + OXYGEN.
it supplies these substance to tissues

Question 20

what does tissue fluid receive from tissues?

Answer 20

carbon dioxide and other waste materials

Question 21

what is tissue fluid formed from?

Answer 21

blood plasma

Question 22

how is HYDROSTATIC PRESSURE created and what role does it play in tissue fluid?

Answer 22

• blood is pumped along narrower blood vessels (artery, arterioles and capillaries)- creates hydrostatic pressure at arterial end of capillaries.

hydrostatic pressure forces tissue fluid out of the blood plasma

Question 23

what is the outward hydrostatic pressure opposed by?

Answer 23

• hydrostatic pressure of tissue fluid OUTSIDE capillaries-prevents outward movement of liquid
• lower WATER POTENTIAL of blood due to plasma proteins - pulls water back into blood with capillaries

Question 24

what is the combined effect of hydrostatic pressure at the end of capillaries, hydrostatic pressure outside capillaries and lower water potential in the blood?

Answer 24

create an overall pressure that pushes tissue fluid OUT of the capillaries. force small molecules out BUT leave cells and proteins inside the blood.

Question 25

what is ultrafiltration?

Answer 25

filtration capable of removing small molecules under pressure

Question 26

what happens to tissure fluid after it has exchanged metabolic materials with the cells?

Answer 26

it returns to the circulatory system

Question 27

how does most tissue fluid return to the blood plasma directly via the capillaries?

Answer 27

• the loss of tissue fluid from capillaries REDUCE hydrostatic pressure in them
• when the blood reaches the venous end of the capillary network it’s hydrostatic pressure is less than the tissue fluid outside
• tissue fluid FORCED back into the capillaries
• in addition osmotic forces resulting from PROTEINS in the blood plasma pull water back into the capillaries

Question 28

how is the remainder of the tissue fluid carried back to the blood plasma?

Answer 28

by the LYMPHATIC SYSTEM
a system of vessels that begin in the tissues, gradually merge into larger vessels that form a network throughout the body

Question 29

what is the lymphatic system?

Answer 29

a system of vessels that begin in the tissues, gradually merge into larger vessels that form a network throughout the body

Question 30

how are the contents of the lymphatic system moved?

Answer 30

• HYDROSTATIC PRESSURE of tissue fluid that left the capillaries
• CONTRACTION OF BLOOD VESSELS squeeze the lymph vessels