physiology of the heart 🪢

Question 1

autorhythmicity

Answer 1

heart will continue to beat rhythmically following removal from the body

Question 2

Cells of SA node

Answer 2

The cells of the SA node have an unstable resting potential

Question 3

Repolarisation of the myocardial cells occurs when

Answer 3

the voltage dependent calcium channels inactivate.

Question 4

Seps of heart contraction ventricles

Answer 4

1 depolarisation due to Na+ influx from voltage gated Na+ channels opening 
2 plateau(maintained depolarisation) dut to Ca2+ inflow voltage gated Ca2+ open K+ flows out when K+ channels open 
3 repolarisaton due to closing of Ca2+ 
and outflow K+ channels  + voltage gated K+ channels open

Question 5

P wave

Answer 5

Atrial depolarisation

Question 6

QRS complex

Answer 6

Onset of ventricler depolarisation

Question 7

T wave

Answer 7

Ventricular repolarisation

Question 8

P-Q =

Answer 8

Atrial contraction

Question 9

Q- T

Answer 9

Ventricular contraction

Question 10

P wave =

Answer 10

SA node firing

Question 11

Input to the cardio Center (in Brain)

Answer 11

• From higher brain centres, cerebral cortex lambic system hypothalamus
• from proprioceptors, joint movements
• from baroreceptors,monitor blood pressure
• from chemoreceptors moitor blood acidity H+, CO2 ,O2

Question 12

Medulla oblongata

Out put effectors increased frequency of nerve impulses (parasympathetic) vagus nerves

Answer 12

Heart rate decreases

Question 13

Medulla oblongata

Out put effectors increased frequency of nerve impulses, cardiac accelerator nerve (sympathetic)

Answer 13

Increased heart rate and contrarily

Question 14

Medulla oblongata

Out put effectors increased frequency of nerve impulses,vasomotor nerves (sympathetic)

Answer 14

Vasoconstriction

Question 15

Out put to hear (not effectors) cardiac accelerator (sympathetic) 2 answers 1,2,

Answer 15

1, increased rate of spontaneous depolarisation in SA node. And AV node =increased heart rate
2, increased contractility of atria and ventricles increases SV

Question 16

Out put to hear (not effectors)vagus nerve (parasympathetic)

Answer 16

Decreased rate of spontaneous depolarisation in SA and AV node decreased heart rate.

Question 17

Increased end diastolic volume (stretch on the heart ) =

Answer 17

Increased pre load

Question 18

Increased preload

Answer 18

Cardiac muscles contract more forcefully = increases SV

Question 19

Positive inotropic agents = 5

Answer 19

1 increased sympathetic stimulation 
2 catecholamines 
3 glucagon 
4 thyroid hormones in blood 
5 Ca 2+ in extracellular fluid

Question 20

Positive inotropic agents

1 increased sympathetic stimulation 
2 catecholamines 
3 glucagon 
4 thyroid hormones in blood 
5 Ca 2+ in extracellular fluid =

Answer 20

Increased force of contraction = increased SV

Question 21

Decreased arterial blood pressure during sidedly

=

Answer 21

Decreased after load

Question 22

Decreased after lode =

Answer 22

Semilunar valves open sooner when Bp in the aorta and pulmonary artery are lower

Question 23

Semilunar valves open sooner when Bp in the aorta and pulmonary artery are lower

Answer 23

Increased SV

Question 24

Increased HR and SV

Answer 24

Increases CO

Question 25

What is fabulation

Answer 25

Lace of contraction

Question 26

P-Q delay

Answer 26

To top up vent

Question 27

Max HR

Answer 27

Refractory period