Systemic Circulation

Question 1

Flow (Q) eqn

Answer 1

Q = v * A
= ∆P/R

v=linear velocity
A=cross sectional area
R=resistance

Question 2

Resistance (R) eqn

Answer 2

R = 8ηl/πr^4

η = viscosity
l = length
r = radius

Question 3

Cardiac Output eqn

Answer 3

CO = SV * HR
= (MAP - RAP)/TPR

SV = stroke vol
HR = heart rate
MAP = mean aortic pressure
RAP = right atrial pressure
TPR = total peripheral resistance

Question 4

Stroke Vol eqn

Answer 4

SV = EDV-ESV

Question 5

Artery Fxn:

Wall structure:

Answer 5

Fxn:
Passage from heart -> organs,
pressure reservoir,
recoil properties ∆ pulse flow to continuous flow

Wall Structure:
thick,
highly elastic,
large radii

Question 6

Arteriole Fxn:

Wall structure:

Answer 6

Fxn:
distribution of cardiac output, 
provide primary (highest) resistance,
regulates blood flow to capillary beds, 
tonically active
largest pressure drop happens here

Wall Structure:
highly muscular (smooth mm),
well-innervated,
small radii

Question 7

Capillary Fxn:

Wall structure:

Answer 7

Fxn:
Exchange site,
determine ECF distribution b/w plasma/ISF
velocity lowest here

Wall Structure:
very thin,
large total cross-sectional area

Question 8

Vein Fxn:

Wall structure:

Answer 8

Fxn:
Passage from organs -> heart,
blood reservoir

Wall Structure:
thinner than arteries,
highly distensible,
large radii

Question 9

Compliance of BV is?

Answer 9

vol of blood a vessel can hold at certain pressure,
more compliant = holds more volume
C = V/P

Question 10

Stressed Volume found in which vessels?

Answer 10

arteries

Question 11

Unstressed Volume found in which vessels?

Answer 11

veins

Question 12

Total blood vol =?

Answer 12

stressed vol + unstressed vol

Question 13

Result of ↓ Vein Compliance

Answer 13

↓ Vein Vol:
blood moves from veins to arteries
Ѧ unstressed vol ↓ , stressed vol ↑

Question 14

Result of ↑ Vein Compliance

Answer 14

↑ Vein Vol:
blood moves from arteries to veins
Ѧ unstressed vol ↑ , stressed vol ↓

Question 15

Largest pressure drop in vessels occurs where?

Answer 15

arterioles to capillaries

Question 16

Arteriosclerosis affects heart how?

Answer 16

narrows opening ->
↓ flow from LV to aorta ->
↓ SV (↓ blood into aorta) ->
↓ SP, PP, MAP

Question 17

Plaque affects heart flow how?

Answer 17

walls become stiff ->
↓ compliance ->
larger P ∆

↓ cross sectional area ->
↑ velocity ->
↑ turbulence ->
can dislodge tissue fragments

Question 18

Pressure drop between venules and veins is?

Answer 18

small

Question 19

Hydrostatic pressure opposes what?

Answer 19

Return of blood to heart

Question 20

Fxn of Venous Valves?

Answer 20

allows flow toward heart,

prevents backflow

Question 21

Factors influencing venous return? (4)

Answer 21

1) mm activity/action of valves
2) sympathetic venous constriction
3) negative R atrial pressure
4) negative intra-thoracic pressure

Question 22

Compliance is greater when?

Answer 22

pressure and volume are low

Question 23

Compliance is lower when?

Answer 23

pressure and volume are high

Question 24

Lower compliance affects ∆ in volume in response to a ∆ in pressure how?

Answer 24

∆ in volume is much greater at low compliance than at high compliance

Question 25

Average pressure at beginning of systemic circulation?

Answer 25

93 mmHg (mean arterial pressure)

Question 26

Pressure at end of system circulation?

Answer 26

0 mmHg