exam Q's

Question 1

what are advantages of keeping blood inside vessels

Answer 1

-maintains high pressure of blood
-can increase rate of blood flow, how fast blood flows
-it can direct the flow of blood

Question 2

how are walls of arteries adapted to
-withstand pressure
-to maintain pressure

Answer 2

to withstand pressure =
-thick muscle wall made of collagen which provides strength
-endothelium is folded so can stretch

to maintain the pressure=
-smooth muscle and constrict and narrow the lumen
–elastic tissue can recoil

Question 3

describe and explain four features of capillaries that enable efficient exchange

Answer 3

-permeable capillary wall
-capillary was is a single cell thick= reduce diffusion distance
-wall made up of flattened endothelial cell= reduces diffusion distance
-have small diameter
-narrow lumen to reduce flow rate giving more time for diffusion
-red blood cells are in contact with capillary wall to give short diffusion distance

Question 4

explain how water from tissue fluid is returned to the circulatory system

Answer 4

-plasma protein remain in the capillaries
-this creates a water potential gradient between the venule end of the capillary and the tissue fluid
-water moves into the capillary at the venule end by osmosis
-water returns to the blood by the lymphatic system

Question 5

a high concentration of salt in the blood plasma can cause salt to enter the capillaries , explain how this can lead to a build-up of tissue fluid

Answer 5

-higher salt concentration causes a lower water potential of tissue fluid
-so less water returns to the capillary by osmosis