the heart

Question 1

semilunar valves

Answer 1

link the ventricles to the pulmonary artery and the aorta

Question 2

AV valves

Answer 2

link the atrium to the ventricles

Question 3

importance of valves

Answer 3

they only open one way, this prevents a backflow of blood

Question 4

blood flow through the heart (3)

Answer 4

ventricles relax and atria contracts pushing the blood through the AV valves into the ventricles

atria relaxes and ventricles contract increasing the pressure and shutting the AV valves to prevent back flow, this opens the semi lunar valves so blood is forced out the pulmonary artery and aorta

ventricles and atria (fills with blood) relaxes, increase in pressure by the PA and Aorta closes the semi lunar valves, ventricle pressure falls lower than atrial pressure opening the AV valves

Question 5

cardiac diastole

Answer 5

heart is relaxed

Question 6

systole

Answer 6

contracting

Question 7

how the heart beats (6)

Answer 7

SA node sends waves of EA to the atrial walls causing them to contract

non conducting tissue prevents the impulse from sending to the ventricle walls

waves go from SAnode to AV node

from AV node to bundle of his (delay so ventricle walls contract after atrium has emptied)

from bundle of his to purkyne tissue

to right and left ventricle causing them to contract simultaneously

Question 8

transport of oxygen (5)

Answer 8

co2 leaves respiring tissue and diffuses into RBCs where it reacts with water to form carbonic acid (carbonic anhydrase)

carbonic acid dissociates into h+ions and hydrogen carbonate ions

haemoglobin unloads its oxygen and binds with h+ions to from heamoglobinic acid

hydrogen carbonate ions diffuse out of the RBCs into blood plasma and chloride ions diffuse in

once blood reaches lungs, hydrogen carbonate ions and h+ions recombine to form co2 (diffuses into alveoli and is breathed out)