cardiovascular: introduction

Question 1

vena cava pressure

Answer 1

3-8 mmHg (close to atm)

Question 2

blood velocity

Answer 2

25cm/sec

Question 3

blood composition, osmolality, protein content

Answer 3

composition: 45% cells
osmolality: 290micro-osmols/L
protein content: 70g/L

Question 4

location of SA node and AV node

Answer 4

SA: at junction of superior vena cava and RA
AV: bottom of RA

Question 5

EDV/ESV/CO values

Answer 5

EDV: 120
ESV: 50
CO: 5L

Question 6

proportion of blood contained in venous system

Answer 6

70%

Question 7

calculate mean arterial pressure

why is it weighted towards diastolic pressure

Answer 7

MAP= diastolic + (sys- diastolic)/3

most of cardiac cycle is spent in diastole

Question 8

relationship between (change in pressure), flow and resistance

Answer 8

change in pressure= flow x resistance

Question 9

components of microcirculation, do they contain smooth muscle

Answer 9

terminal arterioles (have smooth muscle)
capillaries
post-capillary venules
lymphatic capillaries

Question 10

how does inspiration affect flow through the venous system

Answer 10

inspiration-> thorax volume increases-> thorax pressure drops-> vena cava pressure drops-> pressure gradient between venules and vc increases

Question 11

which receptors can NA and adr act on

Answer 11

NA: beta 1/ alpha 1
adr: beta 1/ alpha 1/ beta 2