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Flashcards in Physiology Deck (74)
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1

What is the equation for MABP?

((2 x diastolic pressure) + systolic pressure)/3

2

What is a different equation for MABP?

diastolic pressure + 1/3 (systolic - diastolic)

3

What is the normal range of MABP?

70-105 mmHg

4

What is the minimum MABP required for perfusion of coronary arteries, brain and kidneys?

60 mmHg

5

What effect does sympathetic stimulation have on the arterioles and veins?

Vasoconstriction

6

Which system controls the short term regulation of mean arterial blood pressure?

The baroreceptor reflex

7

Where are the baroreceptors?

Aortic arch
Carotid sinus

8

Which nerves do the baroreceptor signals travel in to reach the brain and where in the brain do they go?

CN IX and CN X
Medulla

9

How do the baroreceptors respond to a decrease in blood pressure?

Decrease firing from baroreceptors
Decrease vagal activity, so sympathetic activity increases
Heart rate and stroke volume increase ergo cardiac output increases
Vasocontriction occurs, so TPR increases
Venoconstriction occurs, so venous return increases and SV increases

10

How do the baroreceptors respond to an increase in blood pressure?

Increase firing from baroreceptors
Increase vagal activity
HR decreases, SV decreases, CO decreases
Vasodilatation occurs, so TPR decreases
Venodilatation occurs, so venous return decreases and SV decreases

11

Which receptor regulates the contraction of vascular smooth muscle?

L-type Ca2+ channels

12

What molecule does the calcium-calmodulin compound activate?

Myosin light chain kinase

13

What does myosin light chain kinase do that allows contraction?

Phosphorylates, and thus activates, myosin light chain

14

What effect does phosphorylation of MLCK have on it?

Inactivates it

15

Which enzyme dephosphorylates phosphorylated MLC?

Myosin-LC-phosphatase

16

What molecule activates myosin-LC-phosphatase and this stimulates relaxation?

cGMP

17

Where are the electrical signals of the heart generated?

Within the heart itself - pacemaker cells of the sinal atrial node

18

Where is the SA node located?

In the upper right atrium close to where the SVC enters the right atrium

19

What is the term given to the state where the heart is controlled by the sinal atrial node?

Sinus rhythm

20

What is the pacemaker potential?

The potential that must be taken to threshold potential to generate an action potential in the SA node

21

What generates the pacemaker potential?

It is slow depolarisation caused by a decrease in potassium efflux and a slow sodium influx

22

What is the "funny current"?

The slow sodium influx of the pacemaker potential

23

What causes the rising phase of the action potential?

Activation of voltage gated Ca2+ channels
Rapid influx of Ca2+

24

What is the falling phase of the action potential caused by?

Potassium efflux

25

Which junctions spread electrical excitation from cell to cell?

Gap junctions

26

Where is the AV node located?

At the base of the right atrium, just above the junction between atria and ventricles

27

What is the only point of electrical contact between atria and ventricles?

AV node

28

What structures allow the spread of the action potential to the ventricles?

The bundle of His
Perkinje fibres

29

What is the resting potential of the ventricular muscle cell?

-90mV

30

What is the rising phase of the ventricular muscle action potential caused by?

Fast sodium influx
This is phase 0