Blood Pressure

Question 1

What is the percentage difference of blood distribution in veins and arteries?

Answer 1

64% veins, 13% arteries

Question 2

How does oxygenated blood get from the heart to the capillaries and what happens there?

Answer 2

From heart through arteries and arterioles to capillaries where gaseous exchange occurs.

Question 3

How does deoxygenated blood return to the heart?

Answer 3

Via venules and veins.

Question 4

What is the difference between arteries and arterioles?

Answer 4

Arteries: large, thick-walled, muscular and elastic
Arterioles: cmall, less connective tissue, contain precapillary sphincters

Question 5

What is the role of arterioles and what do the precapillary sphincters do?

Answer 5

Arterioles regulate & fine-tune flow into tissues (perfusion). Sphincters close to increase resistance.

Question 6

What are the capillaries, what do they do?

Answer 6

Small, thin-walled, endothelial. Diffusion of nutrients, O2, CO2 and wastes.

Question 7

What are the blood vessels innervated by?

Answer 7

All except capillaries innervate by SNS.

Question 8

What is vasoconstriction/vasodilation?

Answer 8

Vasoconstriction: increased contraction-> increased resistance & decreased flow
Vasodilation: decreased contraction-> decreased resistance & increased flow

Question 9

What are the major determinants in regulation of blood pressure?

Answer 9

Peripheral resistance in arterioles, cardiac output (HR, stroke volume), blood volume, viscosity, elasticity of arterial wall.

Question 10

What may cause high BP?

Answer 10

High peripheral resistance in arterioles, high/thick viscosity of blood, low elasticity of arterial wall (high SBP)

Question 11

What may cause low BP?

Answer 11

Low blood volume, low viscosity, low resistance in arterioles etc.

Question 12

What does systolic and diastolic BP mean?

Answer 12

Systolic BP: pressure exerted on arterial walls during ventricular systole (contraction)
Diastolic BP: pressure exerted on arterial walls during ventricular diastole (relaxation

Question 13

How does cardiac output maintain BP levels?

Answer 13

Decrease in BP -> increase in HR to maintain BP levels

Question 14

What is cardiac output and MAP and how are they measured?

Answer 14

Cardiac output: amount fo blood pumped out by each ventricle in 1 minute =stroke volume x heart rate. MAP (mean arterial pressure) product of cardiac output and systemic vascular resistance MAP=COxSVR

Question 15

What are baroreceptors/ the baroreceptor reflex?

Answer 15

(stretch receptors)- signal BP to vasomotor system of brain stem, adapt within 1-2 days i.e. not long term control
HR and BP are inversely related though baroreceptor reflex- a drop in arterial pressure= increase in HR, except under conditions such as exercise

Question 16

What are Korotkoff sounds?

Answer 16

blood flowing though partly collapsed artery- o Systolic BP: heart contracting- pressure exerted by the blood on ther arterial walls when the left ventricle is in systole, Agv: 120mmHG
Absence of korotkoff sounds:
o Diastolic BP: heart resting between contractions avg: 80mmHG

Question 17

How do you calculate pulse pressure?

Answer 17

SBP-DBP: Avg= 30-40

Question 18

What does the RAS system do?

Answer 18

• Long term regulation of BP via renal function-balance fluid intake/output
• Decreased renal blood volume/pressure-> renin->angiotensin II
• Angiotensin II-> vasoconstriction-> increased BP
• Angiotensin II -> Aldosterone -> kidneys retain Na+ (and hence water)-> increase blood volume -> increased BP