Heart

Question 1

Flow of the heart

Answer 1

Vena cava> RA> AV valve> RV> SL valve> pulmonary artery
>pulmonary vein> LA> AV valve> LV> SL valve> aorta

Question 2

Role of valves

Answer 2

Ensure unidirectional blood flow in the cardiac cycle

Question 3

Pressure in LV> p in LA

Answer 3

AV valve closes

Question 4

Pressure in LV> pressure in aorta

Answer 4

SL valve opens

Question 5

Pressure in aorta> pressure in LV

Answer 5

SL valve closes

Question 6

Pressure in aorta> pressure in LV

Answer 6

AV opens

Question 7

Cardiac cycle

Answer 7

-Diastole: increase pressure in atria due to filling so AV opens slightly
-atrial systole: increase in pressure in atria due to contraction so AV opens
-ventricular systole: increase pressure in ventricle due to filling AV closed (lub sound”
Further increase in pressure as contraction in V So SL opens
-Diastole again: artery pressure increases and ventricles pressure falls so SL valve closes Dub sound

Question 8

Capillaries

Answer 8

For exchange between blood and tissues

Question 9

Capillary structure

Answer 9

-1 cell thick wall for short DD
-narrow lumen to allow more time for diffusion
-pores

Question 10

Artery structure

Answer 10

-thick cell wall with elastic and muscle to withstand high pressure
-elastic wall to allow stretch and recoil maintain smooth blood flow
-narrow lumen
-smooth endothelium

Question 11

Arteriole

Answer 11

-carry blood from arteries to capillaries
-smooth muscle and elastic walls to narrow lumen to reduce blood flow to capillaries

Question 12

Veins

Answer 12

-Thin cell walls
-Wide lumen and smooth endothelium
-Valves to prevent back flow