Lecture 10

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Question 1 of 22

What is the min and max of cardiac output?
Min = 5 l.m-1 Max = 20 l.m-1.

Question 1 of 22

Question 2 of 22

What is the cardiac reserve?
Max – min = cardiac reserve (15 l.m-1).

Question 2 of 22

Question 3 of 22

When does heart rate go up before exercise?
Just thinking about it – brain stimulates sympathetic nervous system.

Question 3 of 22

Question 4 of 22

How does exercise increase demand?
Consumption of O2, amino acids, glucose. Production of waste (CO2).

Question 4 of 22

Question 5 of 22

How does this affect heart?
Increase demand for oxygen and nutrients demands more blood from heart. The heart responds by increasing CO.

Question 5 of 22

Question 6 of 22

What is the equation for cardiac output?
CO = HR x SV.

Question 6 of 22

Question 7 of 22

How does the heart increase supply? (2)
↑HR or ↓SV.

Question 7 of 22

Question 8 of 22

What is preload?
The amount of stretch cardiac fibres undergo due to volume of blood entering ventricle during diastole.

Question 8 of 22

Question 9 of 22

How do you increase preload? (2)
Increase duration of ventricular filling / increase venous return.

Question 9 of 22

Question 10 of 22

What is the second way the heart increases SV?
Increase contractility.

Question 10 of 22

Question 11 of 22

And the third way?
Decrease afterload.

Question 11 of 22

Question 12 of 22

What is afterload?
The amount of aterial pressure the ventricle must overcome to open SL valves and eject blood into artery.

Question 12 of 22

Question 13 of 22

What can increase inotrophy? (3)
Ca 2+ ↑, innervation by SNS, norepinephrine / epinephrine.

Question 13 of 22

Question 14 of 22

What is the ejection fraction? What is typical?
The percentage of blood ejected from the lumen of the ventricle during systole 60-70%.

Question 14 of 22

Question 15 of 22

How does high afterload (hypertension) over an extended period of time decrease ejection fraction?
(no answer)

Question 15 of 22

Question 16 of 22

Draw pressure volume loop.
(Drawing)

Question 16 of 22

Question 17 of 22

What is the End Diastolic Volume?
The amount of blood in the ventricle at the end of diastole.

Question 17 of 22

Question 18 of 22

What factors determine EDV?
Duration of diastole, venous return.

Question 18 of 22

Question 19 of 22

Why do people with low heart rates have large SV?
Diastolic duration is longer.

Question 19 of 22

Question 20 of 22

How does the SV of the left ventricle affect the SV of the right?
Increase in venous return = ↑preload.

Question 20 of 22

Question 21 of 22

Draw supply/demand map of cardiac output.
(Drawing)

Question 21 of 22

Question 22 of 22

What factors affect after load?
Hypertension, atherosclerosis.

Question 22 of 22


 

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Question 1 of 37

What is the function of the SA node?
Repeatedly generate action potentials.

Question 1 of 37

Question 2 of 37

Where is it located?
In the wall of the /RA inf and lat to opening of VC.

Question 2 of 37

Question 3 of 37

What is the intrinsic rate of the SA node?
100 B p/m.

Question 3 of 37

Question 4 of 37

What slows it down?
ANS.

Question 4 of 37

Question 5 of 37

How does scar tissue affect the conduction system?
Impedes conduction.

Question 5 of 37

Question 6 of 37

Draw the action potential in cardiac fibre.
(Graph)

Question 6 of 37

Question 7 of 37

What is the resting voltage?
-90 mV.

Question 7 of 37

Question 8 of 37

What is the voltage after influx of sodium?
20 mV.

Question 8 of 37

Question 9 of 37

What is the voltage during plateau period?
10 mV.

Question 9 of 37

Question 10 of 37

What happens during the first phase of depolarisation? (ion)
Na+ influx.

Question 10 of 37

Question 11 of 37

What happens during the plateau? (ion)
Ca2+ influx.

Question 11 of 37

Question 12 of 37

What happens during the repolarisation? (ion)
K+ outflow.

Question 12 of 37

Question 13 of 37

What stage represents the refractory period?
Platar.

Question 13 of 37

Question 14 of 37

How does this affect the H/R or beating of the heart?
Heart is physically unable to beat faster than 250 b p/m.

Question 14 of 37

Question 15 of 37

What does an ECG measure?
Summation of electrical activity of the heart from various locations?

Question 15 of 37

Question 16 of 37

What does the P wave represent?
Atrial depolarisation.

Question 16 of 37

Question 17 of 37

What does that flat period after the P wave represent?
Atrial contraction.

Question 17 of 37

Question 18 of 37

What does the QRS wave represent?
Ventricular depolarisation.

Question 18 of 37

Question 19 of 37

What does the flat period after QRS represent?
Ventricular contraction.

Question 19 of 37

Question 20 of 37

What does the T wave represent?
Ventricular repolarisation.

Question 20 of 37

Question 21 of 37

What does the flat period after the T wave represent?
Ventricular diastole.

Question 21 of 37

Question 22 of 37

What might an elevated P wave indicate?
Enlarged atria.

Question 22 of 37

Question 23 of 37

What might an elevated R wave indicate?
Enlarged ventricle.

Question 23 of 37

Question 24 of 37

Describe start and end points for P-Q interval?
Start of P start of Q. (Medium)

Question 24 of 37

Question 25 of 37

Describe start and end points for S – T interval?
End of S start of T. (Shortest)

Question 25 of 37

Question 26 of 37

Describe start and end points for Q – T interval?
Start of Q end of T. (Longest)

Question 26 of 37

Question 27 of 37

What inputs may affect HR? (5) (cause a change)
Blood pressure, blood volume, blood chemistry, stress brain, exercise (demand).

Question 27 of 37

Question 28 of 37

How does the parasympathetic nervous system affect the heart? (1)
Slows it down.

Question 28 of 37

Question 29 of 37

Which nerve does the PNS utilise?
Vagus nerve.

Question 29 of 37

Question 30 of 37

What does increase in vagus nerve activity do to HR?
Decrease HR.

Question 30 of 37

Question 31 of 37

What does increase in vagus nerve activity do to HR?
Decrease HR.

Question 31 of 37

Question 32 of 37

How does sympathetic nerve activity affect CO (cardiac artery)? (2)
Increase HR increase SV.

Question 32 of 37

Question 33 of 37

How does sympathetic nerves increase SV?
Contractility, preload

Question 33 of 37

Question 34 of 37

Which nerves are utilised by sympathetic nervous system?
Cardiac accelerator nerves.

Question 34 of 37

Question 35 of 37

What might an increased P-Q interval indicate?
Scar tissue impedes conduction.

Question 35 of 37

Question 36 of 37

What might enlarged Q wave indicate?
Cardiac infarction.

Question 36 of 37

Question 37 of 37

What might enlarged T wave indicate?
Insufficient oxygen.

Question 37 of 37