Cardio Vascular system

Question 1

Gap Juntions

Answer 1

interconnect myocardial cells and allow action potentials to spread from one cell to another

Question 2

ECG: P, QRS, T

Answer 2

P = atrial depolarisation 
QRS = ventricular depolarisation 
T = ventricular repolarisation

Question 3

Pacemaker action potential

Answer 3

• slow depolarisation (F type channels)
• no resting membrane potential
• calcium ions cause depolarisation (voltage gated)
• repolarization caused by potassium efflux

Question 4

Cardiomyocyte action potential

Answer 4

• Depolarisation: Na influx
• minor repolarization: transient K efflux
• plateau phase: inward Ca flow (L type channels) balanced by K efflux
• repolarisation: Ca channels close, delayed opening of K channels

Question 5

sympathetic regulation of heart rate

Answer 5

• noradrenaline on B1
• increases the slope of the pacemaker potential by increasing F-type channel permeability resulting in sodium influx and faster depolarisation

Question 6

parasympathetic regulation of heart rate

Answer 6

• acetylcholine on M2 receptor –> increased opening of K+ channels
• less rapid depolarisation

Question 7

factors that affect stroke volume

Answer 7

end diastolic volume, contractility, after load

Question 8

sympathetic regulation of contractility

Answer 8

• Noradrenaline acts on B1 receptors to increase contractility
• increased contraction force at any given end diastolic volume

Question 9

Vasodilators

Answer 9

Adrenaline (B2), No, K+, adenosine, histamine, bradykinin, low O2

Question 10

vasoconstrictors

Answer 10

Noradrenaline and adrenaline(A1), angioteninsin II, vasopressin, endothelin oxygen