Heart Cycle

Question 1

LUB DUB sound

Answer 1

LUB (first heart sound louder): AV valves (tricuspid and bicuspid valves) snap shut avoiding back flow
DUB (second heart sound weaker): semilunar valves (aortic valve and pulmonary valve) snap shut avoiding 
back flow

Question 2

three parts

Answer 2

a,b,c

Question 3

a

Answer 3

atria: systole, ventricles: diastole, atria contract. high pressure in atria so blood flows to ventricles. high pressure in ventricles closes valves can be accelerated by adrenaline

Question 4

b

Answer 4

atria: diastole, ventricles: systole, ventricles contract, semilunar valves are open can be accelerated by adrenaline

Question 5

c

Answer 5

atria: diastole, ventricles: diastole. this is shortened if intense physical activity occurs

Question 6

ECG

Answer 6

electrocardiograph. a tracing of the electrical signals in your heart.

Question 7

What happens in heart during contraction

Answer 7

The electrical depolarization stimulates muscle contraction
 The contraction and relaxation of muscles causes changes in pressure 
in different chambers
 The changes in pressure cause opening and closing of valves

Question 8

What happens in heart during contraction (nerve signals)

Answer 8

SA node pacemaker cells initiate signal (atria contract), AV node (ventricles contract) sends signal down septum and causes heart to contract from bottom up

Question 9

PR interval

Answer 9

• SA node signaling
• atria cells - depolarization
• interval before the next wave (AV node delays 

its signal)

Question 10

QRS wave

Answer 10

• AV node signaling (Q)

- ventricular cells: depolarization (R-S)

Question 11

T wave

Answer 11

repolarization of ventricles (refilling with blood)

and about repolarization of atria???