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Flashcards in Blood Pressure Deck (18):

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

64% veins, 13% arteries


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

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


How does deoxygenated blood return to the heart?

Via venules and veins.


What is the difference between arteries and arterioles?

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


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

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


What are the capillaries, what do they do?

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


What are the blood vessels innervated by?

All except capillaries innervate by SNS.


What is vasoconstriction/vasodilation?

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


What are the major determinants in regulation of blood pressure?

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


What may cause high BP?

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


What may cause low BP?

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


What does systolic and diastolic BP mean?

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


How does cardiac output maintain BP levels?

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


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

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


What are baroreceptors/ the baroreceptor reflex?

(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


What are Korotkoff sounds?

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


How do you calculate pulse pressure?

SBP-DBP: Avg= 30-40


What does the RAS system do?

•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