8. Blood pressure and electrical activity

Question 1

what does diastolic pressure mean

Answer 1

minimum pressure

Question 2

what does systolic pressure mean

Answer 2

maximum pressure

Question 3

how do you work out pulse pressure

Answer 3

Systolic pressure- diastolic pressure

Question 4

how do u measure blood pressure

Answer 4

sphygmomanometer

or electrical device

Question 5

how does a blood pressure device work

Answer 5

pressure in the cuff exceeds SP and cuts off blood flow, as u release pressure you can hear blood entering the lower part of the arm, this makes noise called Korotkoff sounds (can be heard via stethoscope). when sounds disappear diastolic pressure can be measured

Question 6

what is a normal blood pressure reading

Answer 6

120/80 mm Hg

Question 7

what is a hypertensive blood pressure reading

Answer 7

~150/ 95 mm Hg

Question 8

what is atherosclerosis

Answer 8

build up of fatty deposits in the artery walls, narrowing lumen

Question 9

what term describes an atherosclerotic plaque which dislodged and moved around the body

Answer 9

embolism

Question 10

heart muscle is myogenic, what does this mean

Answer 10

the heart is able to produce its own electronic signals to stimulate its contraction

Question 11

the heart is made up of two types of cells, what are these

Answer 11

myocardial cells and pacemaker cells

Question 12

where are pacemaker cells most concentrated in the heart

Answer 12

the sinoatrial node and the atrioventricular node

Question 13

describe the process of signal transduction in the heart

Answer 13

1. SA node passes signal to both atria which contract simultaneously
2. signal reaches AV node and there is a delay.
3. AV node passes signal down bundle of His to purkinje fibres at heart apex
4. signal at apex of the heart facilitates complete ventricular contraction

Question 14

what happens when the impulse reaches papillary muscles

Answer 14

trigger chordae tendinae to ensure closure of AV valves preventing prolapse into atrium

Question 15

why is there a delay at the AV node

Answer 15

allows both atria to contract fully and push remaining blood into the ventricles

Question 16

how long is the AV nodal delay

Answer 16

0.1 seconds

Question 17

how does a pacemaker potential graph differ from a normal action potential graph

Answer 17

no steady resting potential

slowly depolarises until threshold is met

Question 18

what channel is responsible for the slow depolarisation in pacemaker potentials

Answer 18

funny channels

Question 19

describe ion influx/ efflux in a pacemaker potential

Answer 19

1. slow depolarisation- k+ channels close, funny channels open
2. before threshold- calcium channels open, slow influx of calcium
3. threshold- rapid calcium influx
4. repolarisation- calcium influx decreases, potassium efflux increases

Question 20

define cardiac output

Answer 20

the volume of blood pumped out of each ventricle in one minute

Question 21

what is the formula for cardiac output

Answer 21

heart rate x stroke volume

Question 22

what is the effect of sympathetic input on the heart

Answer 22

increase in heart rate and cardiac output

AV nodal delay is decreased and ventricles contract more forcibly

Question 23

what is the effect of parasympathetic input of the heart

Answer 23

AV nodal delay increases reducing activity of the heart

Question 24

what is starlings law

Answer 24

when blood flow rate into the heart changes, the heart automatically adjusts its output to match the input