Blood Circulation

arteries

blood flows away from heart

• carries blood under high pressure

blood pressure

force that blood exerts on walls of arteries when it flows through them

factors determining blood pressure

• cardiac output

• peripheral resistance

cardiac output

volume of blood heart pumps per min

peripheral resistance

• vasodilation

• vasoconstriction

vasodilation

blood vessels expand = lower bp

vasoconstriction

blood vessels tighten = higher bp

Fast Regulation of Bp (seconds, minutes)

Receptors:

baroreceptors - sense stretch

chemoreceptors - sense change in O² and CO²

CNS-ischemia receptors - emergency neurons in CNS

Medium Regulation of BP (minutes, hours)

Renin-angiotensin process

Renin-Angiotensin process

1.) decrease in BP

2.) Liver produces angiotensin

3.) Kidney releases renin

4.) renin converts angiotensin to angiotensin 1

5.) angiotensin 1 converted to angiotensin 2 by ACE from lungs

angiotensin 2

• vasoconstrictor = raises bp

• stimulates aldosterone

aldosterone

absorbs Na+ and water

Long term regulation of BP

Renal System

• just water elimination

capillary flux

movement of fluid across capillary walls

capillary flux failure

edema

veins

bring blood from tissues back to heart

venous return

volume of blood that circulates to right atrium

3 forces responsible for venous return

• muscle pump

• respiratory pump

• heart pump