CVS factoids and Definitions

Question 0

Define Flow

Answer 0

The volume of fluid passing a given point per unit oui me

Question 1

What factors affect diffusion?

Answer 1

• Area
• Diffusion resistance
  - nature of the molecule, barrier, path length
• Concentration gradient
  - rate of use, perfusion rate

Question 2

Define velocity

Answer 2

The rate of movement of fluid particles along a tube

Distance particles travel per unit time

Question 3

Relationship between flow, velocity and area?

Answer 3

V= Q/A

When flow is fixed, velocity is inversely proportional to cross sectional area.

Question 4

Factors which cause turbulent flow

Answer 4

Increased viscosity, resistance and velocity

Question 5

Define viscosity

Answer 5

The extent to which fluid layers resist sliding over one another. Increased viscosity decreases the velocity gradient in a tube

Question 6

When pressure is fixed, what is the relationship between velocity and area?

Answer 6

Velocity is proportional to cross sectional area of tube

Question 7

What is the relationship between pressure, flow and resistance?

Answer 7

Q=P/R

Question 8

Resistance ____ as viscosity ____?

Resistance ____ with the ____ power of the radius?

Answer 8

Resistance increases as viscosity increases

Resistance decreases with the fourth power of the radius- small increases in radius have large effect on resistance

Question 9

Resistance decreases with vessels in parallel or series?

Answer 9

Parallel. Capillaries are in parallel so overall resistance is low

Question 10

Define pre-load

Answer 10

The end diastolic stretch of higher myocardium determined by venous pressure

Question 11

Define after-load

Answer 11

Force necessary to expel blood to arteries

Question 12

How does Starlings Law lead to higher stroke volume?

Answer 12

The more the heart fills (higher preload), the more it stretches and the harder it contracts- so bigger stroke volume

Question 13

Define Contractility

Answer 13

Gradient of the slope between venous pressure and stroke volume. Determines the extent of increase in SV for a given venous pressure (stretch). Makes the heart more sensitive to venous pressure. Contractility is independent of preload or afterload, affected by changes in intracellular calcium.

Question 14

Force of Contraction is determined by…

Answer 14

EDV (venous pressure/stretch/preload)

Contractility

Question 15

How to neurones secure oxygen supply?

Answer 15

Structurally-anastomoses 
Functionally- 
    myogenic autoregulation, 
    metabolic regulation (pco2 and local metabolites), 
    Cushing's reflex

Question 16

Pulmonary circulation works at ___ pressure and ____ resistance

Answer 16

Low pressure (12-15mmHg mean arterial, 9-12mmHg mean capillary, 5mmHg mean venous) 
And low resistance- arterioles have relatively less smooth muscle in pulmonary, capillaries in parallel circuits, short, wide vessels

Question 17

What are the gas exchange adaptations?

Answer 17

High capillary density and short diffusion distance

Add NO production by coronary endothelium for adaptation for coronary

Question 18

How is ventilation:perfusion matched?

Answer 18

Hypoxia pulmonary vasoconstriction- chronically can cause RV failure

Question 19

Tissue fluid formation in systemic vs pulmonary

Answer 19

Systemic- venous pressure determines hydrostatic pressure. Net formation of lymph as hydrostatic pressure is high
Pulmonary- venous and arterial pressure determined hydrostatic pressure. (Also have interstitial oncotic pressure working with hydrostatic). decreased capillary pressure prevents formation of lymph (therefore prevents pulmonary oedema).