Blood Pressure Flashcards Preview

BAMS: Cardiovascular System > Blood Pressure > Flashcards

Flashcards in Blood Pressure Deck (49)
Loading flashcards...
1

What is the Mean Arterial Blood Pressure (MABP)?

The driving force for blood flow through the organs/systemic circulation (everything except the lungs)

2

Why is Mean Arterial Blood Pressure important?

Ensures adequate blood flow to organ systems

3

What value is arterial blood pressure maintain at?

120/80 mmHg

4

What is systolic blood pressure (SBP)?

Pressure in arteries (aorta) during myocardial contraction (systole)

5

What is diastolic blood pressure (DBP)?

Pressure in arteries (aorta) during myocardial relaxation (diastole) i.e. when ventricles are refilling

6

How do you calculate pulse pressure?

SBP - DBP

7

How do you calculate Mean Arterial Blood Pressure?

DBP + 1/3 pulse pressure
OR
CO x TPR

8

What does TPR stand for?

Total peripheral resistance
Refers to systemic vascular resistance

9

When is blood pressure the highest?

Waking up

10

When is blood pressure the lowest?

Sleeping

11

What can you use to measure blood pressure?

A sphygmomanometer
Occlude the artery of an extremity (e.g. arm) with an inflatable cuff and by auscultation of for detection of Korotkoff sounds

12

What are the 2 main mechanisms of blood pressure regulation?

1. Rapid regulation e.g. nerves, hormones
2. Long-term regulation e.g. blood volume

13

What are baroreceptors?

Mechanoreceptors that detect changes in blood pressure by detecting the degree of stretch in the blood vessel walls

14

Which 2 locations are baroreceptors most abundant?

1. Aortic arch
2. Carotid sinus

15

Describe the carotid sinus

- Two carotid arteries supply the head and neck (right and left)
- Each carotid artery divides into 2 smaller arteries
- Where the artery wall is thinner and contains a large number of branching nerve endings - this are is the carotid sinus

16

Which nerve innervates the carotid sinus baroreceptors?

Nerve of Hering (a branch of the glossopharyngeal nerve; CN IX)

17

Which nerve innervates he aortic arch baroreceptors?

Aortic nerve (combines with vagus nerve)

18

Which baroreceptors (carotid sinus or aortic arch) are most sensitive to pressure change/changes in stretch?

Aortic arch baroreceptors
Have a higher threshold pressure

19

What is 'normal' BP?

120/80 mmHg

20

Describe the frequency of baroreceptor firing when blood pressure is increased or decreased

- Frequency of baroreceptor firing is constant within normal blood pressure ranges
- Elevation in BP: frequency of AP firing by baroreceptors is quickened
- Decrease in BP: decrease in AP firing by baroreceptors

21

What effect does an increase in baroreceptor AP firing have on sympathetic discharge?

Increased baroreceptor AP firing leads to decreased sympathetic discharge. Trying to reduce cardiac output and reduce blood pressure

22

What effect does a decrease in baroreceptor AP firing have on sympathetic discharge?

Decreased baroreceptor AP firing leads to increased sympathetic discharge. Trying to increase heart rate and blood pressure

23

Where is the medullary cardiovascular centre located?

In the medulla oblongata

24

What is the Vasalva Manoeuvre?

Attempting to expire against a closed glottis
Associated with exhaling when mouth and nose are closed e.g. lifting heavy weights

25

What does the vasalva manoeuvre lead to ?

1) Increased intra-thoracic pressure
2) Raising BP. Increased baroreceptor firing
3) Heart rate falls transiently - impeding venous return of blood to the heart
4) Fall in CO and MAP
5) As MAP decreases, HR increases and stabilises blood pressure

26

What happens after the vasalva manoeuvre i.e. when the glottis is re-opened to allow expiration?

1) Intra-thoracic pressure falls.
2) BP falls initially
3) Venous return is rapidly restored
4) EDV and CO increase, increasing BP
5) Increased BP is sensed by baroreceptors and this results in bradycardia - slowing of the heart

27

Why are baroreceptors ineffective monitors of absolute pressure of blood in carotid arteries to the brain?

Because baroreceptor activity adapts over time and heart rate will increase at the same level
Baroreceptors are short term regulators of blood pressure only

28

What effect does baroreceptor resetting have during exercise?

Maintains cardiac output as heart rate does not fall in response to increased blood pressure accompanying exercise

29

What is the major influence for long-term regulation of blood pressure?

Blood volume

30

Describe the negative feedback loop of increasing blood volume on blood pressure

- Increased blood volume increases arterial pressure
- However, an increased arterial pressure reduces blood plasma volume via increasing renal excretion of salt and water