physiology of BP

Question 1

what is pulse pressure

Answer 1

the difference between systolic and diastolic pressure

Question 2

what is mean arterial blood pressure

Answer 2

the average arterial pressure exerted over the course of a cardiac cycle

Question 3

hypotension values

Answer 3

<90/60mmHg

Question 4

normotension values

Answer 4

90/60 - 129/85 mmHg

Question 5

high normotension values

Answer 5

130/85 - 139/89 mmHg

Question 6

stage 1 hypertension values

Answer 6

140/90 - 159/99 mmHg

Question 7

stage 2 hypertension values

Answer 7

160/100 - 179/119 mmHg

Question 8

stage 3 hypertension values

Answer 8

> 180/120mmHg

Question 9

mean arterial blood pressure equation

Answer 9

MAPB = DP + 1/3(SP-DP)
DP - diastolic pressure
SP - systolic pressure

Question 10

why is MABP closer to the diastolic value than systolic

Answer 10

diastole lasts about twice as long as systole

Question 11

what happens to aortic pressure over the cardiac cycle

Answer 11

it stays at a more constant higher pressure during the cycle (than the LV)

Question 12

how does elastic recoil allow for maintained pressure in the aorta (4) and why is this necessary

Answer 12

1. blood enters aorta/arteries during sytole causing them to expand and pressure to be built up in the elastic walls;
2. semi lunar valve shuts during diastole to prevent back flow;
3. elastic recoil of arteries sends blood forwards into the rest of the circulatory system;
4. this recoil allows for the pressure to be maintained through the peripheral circulation

this is necessary as it allows for less turbulent flow and more constant pressure throughout the circulatory system

Question 13

MABP, CO and TPR relationship

Answer 13

MABP = CO x TPR

(so if CO increases or any components that affect CO (SV, HR) increase then MABP rises)

Question 14

cardiac output relationship with SV and HR

Answer 14

CO = SV X HR

Question 15

short term vs long term control of MABP (non stressed conditions)

Answer 15

short term - neuronal;
long term - hormonal

Question 16

3 things that increase total peripheral resisitance

Answer 16

increased blood viscosity; increased total blood vessel length; decreased blood vessel radius

Question 17

4 things that determine MABP

Answer 17

1. blood volume - change in fluid retention/intake can increase or decrease blood volume;
2. effectiveness of the heart as a pump (CO) - primarily increased by sympathetic stimulation and decreased by parasympathetic;
3. resistance of the system to blood flow - vasoconstriction/dilation affect MABP
4. distribution of blood between arterial and venous blood vessels - venous vasodilation can increase the amount of venous blood and thus decrease MABP

Question 18

what is the baroreceptor refelx

Answer 18

1. baroreceptors sre situated in th ewall of the arch of aorta and carotid sinus;
2. they monitor the BP by firing more often when they are stretched (i.e. as pressure increases)
3. impulses are sent from these receptors to the medullary cardiovascular control centre;
4. increased activity causes activation of the parasymp system and inactivation of the sympathetic (and vice verse for decreased);
5. overall effect is to change MABP by regulating HR and SV

Question 19

what nerve do the baroreceptors arise from

Answer 19

terminal ends of the glossopharngeal (CN 9) - carotid sinus and the vagus (CN 10)

Question 20

carotid sinus vs carotid bodies

Answer 20

carotid sinus - contains baroreceptors that monitor BP;
carotid body - monitor CO2/O2 levels

Question 21

HR/SV regulation pathway in brain

Answer 21

inhibitory: afferent nerves -> nucleus tractus solitarus (brainstem medulla) -> cardio inhibitory area (nucleus ambiguous, dorsal motor nucleus) -> preganglionic vagal parasympathetic neurons;

excitatory: afferent nerves -> nucleus tractus solitarus (brainstem medulla) -> ventrolateral medulla -> bulbospinal fibres -> intermediolateral column of spinal chord -> preganglionic sympathetic neurons

Question 22

sympathetic control of arterial diameter

Answer 22

release of NA -> interacts with a-1 receptors on smooth muscle cells -> vasoconstriction

Question 23

what system is used to regulate BP changes when body position changes (stand to sitting etc.)

Answer 23

baroreceptor reflex as it is fast

Question 24

what is the Bainbridge effect

Answer 24

an increase in stretch leading to an increase in HR (not contrctoin force)

Question 25

apart from arch of aorta and carotid sinus, where are baroreceptors found in the cardiovascular system

Answer 25

in the arterial walls - main at their junctions w vena cava pulmonary veins

Question 26

myocardial stretch leads to the release of what hormones

Answer 26

atrial natriuretic peptide (atrial stretch due to increased blood volume) and brain natiuretic peptide (ventricular stretch, marker of HF)

Question 27

natriuetic peptide MOA

Answer 27

act on natriuetic peptide receptors -> net increase in salt and water excretion -> reduce blood volume -> reduce pressure

Question 28

model for hypertension genesis (3)

Answer 28

1. early systolic hypertension in the young - usually caused by increased CO
2. established diastolic/combined hypertension of middle age - TPR will start to increase permanently;
3. isolated systolic hypertension in older adults - further increase in TPR, CO begins to fall leading to circulatory system failure

Question 29

what are the aims of lowering BP (8)

Answer 29

reduce the risk of:
1. stroke;
2. CHD;
3. HF;
4. renal dysfunction;
5. aortic dilation and dissection;
6. ocular complications;
7. vascular demential
8. other vascular complications

Question 30

what is vascular dementia

Answer 30

a condition caused by poor blood flow in the brain, resulting in symptoms like memory loss, confusion, and thinking difficulties