Circulation - The Heart

Question 1

what are the 5 steps of impulse conduction through the heart.

Answer 1

1 action potential initiated in SA node.
2 action potential recieved by cells of AV node
3 action potential travel through bundle of HIS
4 action potential travel through right and left bundle branches.
5 action potential travel into network of purkinje fibres.

Question 2

what are the main 3 types of ions involved in electric signal?

Answer 2

potassium ions= K+
sodium ions= Na+
calcium ions= Ca2+

Question 3

what is depolarisation?

Answer 3

a change in membrane potential.

Question 4

what is repolarisation?

Answer 4

returns the membrane potential to its resting state.

Question 5

what are the 3 major wave complexes on a ecg?

Answer 5

P wave= atrial depolarisation
QRS complex= ventiricular depolarisation
T wave= ventricular repolarisation

Question 6

what is arrythmia?

Answer 6

unusual heart rhythm

Question 7

bradycardia?

Answer 7

slow heart rate= 60 beats or less a min

Question 8

tachycardia?

Answer 8

fast heart rate 100 beats or more a min

Question 9

atrial fibrillation?

Answer 9

atria depolarize repeatedly in irregular uncontrolled manner.

Question 10

ventricular fibrillation?

Answer 10

ventrilicles contract rapidly and unsynchronised, pumping little or no blood.

Question 11

defibrillation?

Answer 11

electrically shocking the heart to depolarise the myocardium, interrupt chaotic twitching and establish sinus rhythm

Question 12

stroke volume?

Answer 12

amount of blood pumped out of ventricle during contraction.

Question 13

cardiac output

Answer 13

the amount of blood pumped out of ventricle in one minute

usually stroke volume×HR

Question 14

mmhg?

Answer 14

milimetres of mercury

Question 15

arterial BP?

Answer 15

reflects elasticity of arteries and amount of blood forced into them at any given time.

Question 16

Diastolic pressure?

Answer 16

lowest level of arterial pressure during a ventricular cycle.

Question 17

mean arterial pressure?

Answer 17

average pressure of blood on artery walls

pulse pressurs+ diastolic pressure= MAP

Question 18

pulse pressure

Answer 18

difference between systollic and diastolic

Question 19

how do you calculate MAP or mean arterial pressure?

Answer 19

you divide pulse pressure by 3 and add to diastolic pressure.

Question 20

the pacemaker of the heart is?

Answer 20

the sa node

Question 21

the volume of blood pumped each cycle is?

Answer 21

the stroke volume

Question 22

the chamber of the heart that endures the most pressure is?

Answer 22

the left ventricle

Question 23

blood returning from systemic circuit first enters?

Answer 23

right atrium

Question 24

coronary disease that diminishes blood flow to myocardial?

Answer 24

myocardial Infarction

Question 25

blood vessels enter and exit through?

Answer 25

base of the heart

Question 26

blood from pulmonary veins returns to?

Answer 26

the left atrium

Question 27

what prevents tetanic contraction of the heart?

Answer 27

long refractory period.

Question 28

what does the P wave indicate?

Answer 28

atrial depolarisation.

Question 29

what does QRS wave represent?

Answer 29

ventricular depolarisation.

Question 30

what does the T wave represent?

Answer 30

ventricular repolarisation

Question 31

when is the tricuspid valve closed?

Answer 31

during ejection