Physiology 4 - Control of Arterial Blood Pressure (1)

Question 1

What is blood pressure?

Answer 1

The outward (hydrostatic) pressure exerted by blood on blood vessel walls

Question 2

What is the systemic systolic arterial blood pressure?

Answer 2

the pressure exerted by the blood on the walls of the aorta and systemic arteries when the heart contracts

Question 3

What should the systemic systolic blood pressure not exceed under resting conditions?

Answer 3

140mmHg

Question 4

What is the systemic diastolic blood pressure?

Answer 4

The pressure exerted by the blood on the walls of the aorta and systemic arteries when the heart relaxes

Question 5

What should the systemic diastolic blood pressure not exceed?

Answer 5

90mmHg

Question 6

What is the word used to describe the way in which blood should normally flow through blood vessels, meaning it is not heard through a blood vessel?

Answer 6

Laminar

Question 7

When is blood flow heard through a stethoscope in terms of taking blood pressure?

Answer 7

Not heard when no pressure is applied (laminar flow) or when pressure greater than the systolic blood pressure is applied (flow is blocked)If the external pressure is between systolic and diastolic pressure, the flow will be turbulent (artery collapses and reopens with each heart beat = snapping sound)These kortkoff sounds can be heard through a stethoscope

Question 8

What is the RA pressure?

Answer 8

Close to 0

Question 9

What drives the blood around the systemic circulation?

Answer 9

A pressure gradient between the aorta and right atrium

Question 10

What is the central venous pressure?

Answer 10

pressure in the right atrium

Question 11

What does the pressure gradient that drives the blood around the systemic circulation =?

Answer 11

Pressure gradient = MAP - CVP

Question 12

What is the mean arterial pressure?

Answer 12

The average arterial blood pressure during a single cardiac cycle, which involves contraction and relaxation of the heart

Question 13

MAP =?

Answer 13

[(2 X diastolic pressure) + systolic pressure] / 3 or DBP + 1/3rd difference between SBP and DBPMAP = CO X TPRMAP = (HR X SV) X TPR

Question 14

How can MAP be estimated?

Answer 14

By adding DBP + 1/3rd of pulse pressure

Question 15

What is pulse pressure?

Answer 15

The difference between systolic and diastolic blood pressure readings

Question 16

What is the norma range of mean arterial blood pressure?

Answer 16

70 - 105 mmHg

Question 17

MAP of at least what is required to perfuse the coronary arteries, brain and kidneys?

Answer 17

60mmHg

Question 18

What is total peripheral resistance?

Answer 18

The sum of resistance of all peripheral vasculature in the systemic circulation

Question 19

What is cardiac output?

Answer 19

The volume of blood pumped by each ventricle of the heart per heart beat

Question 20

Effect of parasympathetic stimulation on MAP?

Answer 20

Decreases heart rate which therefore decreases cardiac output

Question 21

Effect of sympathetic stimulation on the MAP?

Answer 21

Causes it to increase - heart rate and stroke volume due to increase in contractile strength of the heart) increases causing cardiac output to increase - vasoconstriction occurs in both arterioles and veins

Question 22

Where are the 2 groups of baroreceptors located?

Answer 22

Aortic archCarotid sinus

Question 23

What do baroreceptors sense?

Answer 23

Blood pressure

Question 24

Where is the blood pressure control centre?

Answer 24

Medulla

Question 25

What are the blood pressure effectors?

Answer 25

Heart (HR, SV)Blood vessels (TPR)*negative feedback acts to minimise any disturbance to controlled variables)

Question 26

What nerve do the carotid baroreceptors send signals to the medulla via?

Answer 26

CN IX

Question 27

What nerve do the aortic baroreceptors send signals to the medulla via?

Answer 27

CN X

Question 28

What is a short term regulator of blood pressure?

Answer 28

Baroreceptor reflex (only respond to short term changes meaning if there is a sustained change in BP, the baroreceptors will reset)

Question 29

What happens to the various afferent and efferent nerve firing when blood pressure drops e.g. standing?

Answer 29

Blood pressure decreasesThis causes a decreased firing of carotid sinus afferent nerve fibresThis leads to decreased firing of vagal efferent nerves and an increased firing of sympathetic efferent nerves (both cardiac) - also get increased sympathetic vasoconstrictor acitivty= vagal tone of the heart decreases, increase HR and stroke volume and increased TPRIncreased constrictor tone to the veins increases the venous return to the heart and stroke volume

Question 30

What happens to venous return when a person stands up?

Answer 30

It decreases due to gravity

Question 31

What affect does increased venoconstriction have on venous return?

Answer 31

increases it