L2 - haemodynamics

Question 1

Describe constituents of whole blood

Answer 1

Plasma (a fluid containing proteins and electrolyes) and cells (RBC’s, WBC’s and platelets

Question 2

What can effect the viscosity of the blood?

Answer 2

Mainly due to changes in acute phase proteins in the plasma (generally from inflammation)

Question 3

What is the effect of increased viscosity on blood flow?

Answer 3

Increased viscosity can turn blood flow from laminar to turbulent which can damage vessels leading to increased BP (turbulent blood flow can be heard)

Question 4

Which vessels provide the bigget contribution to TPR and why?

Answer 4

arterioles - because they have the biggest pressure change across vessel class

Question 5

why is resistance much less in the pulmonary circulation?

Answer 5

Because it contains shorter and wider vessels

Question 6

What is the equation to work out resistance?

Answer 6

change in pressure/flow

Question 7

What does the term velocity mean when related to blood?

Answer 7

The disance blood moves in a given time

Question 8

What effects velocity?

Answer 8

Cross-sectional diameter - thus velocity is slowest at the capillary level to allow time for diffusion of materials

Question 9

What is the equation for pulse pressure?

Answer 9

Systolic BP - Diastolic BP

Question 10

What are the three ways of working out MABP?

Answer 10

Diastolic BP + 1/3PP 
or 
Diastolic BP + 1/3 (systolic - diastolic BO)
or 
MABP = CO X TPR

Question 11

What problem happens if MABP becomes too low?

Answer 11

inadequate organ perfusion

Question 12

Describe factors which will affect arterial and venous blood pressure

Answer 12

Cardiac output/TPR/compliance of vessels/blood volume

Question 13

In terms of the systemic circulation, what is the flow and TPR?

Answer 13

The blood flow is the cardiac output

The TPR is the degree of vasodilation/constriciton of the vessels.

Question 14

How do you calculate cardiac output?

Answer 14

CO = SV X HR

Question 15

What factors affect the resistance to blood flow?

Answer 15

Vessel diameter/length of vessel/viscosity

Question 16

What cause pathological turbulent flow?

Answer 16

atheroma

Question 17

What are korotkoff sounds?

Answer 17

Sounds heard when laminar flow replaces turbulent flow. The first is heard during auscultation (listening to sounds from the heart) when returning blood flow to a patients arm, the pressure at which this is heard is equal to the systolic BP

Question 18

if the cuff size is too small will BP be over or underestimated?

Answer 18

overestimated