Lecture 11: Circulation of Blood

Not much to know...

What are the 2 major factors that determines the flow (F) of blood from point A to point B? 𝛥

Pressure difference between A and B (𝛥P) / Resistance to flow (R)

What is the equation for flow of blood?

F = 𝛥P / R

What is the Darcy’s law?

Flow of a fluid through a porous medium

What is the terminology for the physics of blood flow?

Haemodynamic

What is haemodynamic?

The physics of blood flow

What are all the factors affecting friction and vascular resistance?

Vessel length / blood viscosity / vessel radius

What would dramatically affect tissue blood flow?

Small changes in arteriole diameter

What would cause high viscosity in blood flow?

High RBC or protein content

What is η in the Hagen-Poiseuille formula?

Blood viscosity

The flow of blood is directly proportional to what on the vessel?

r^4

If a blood pressure is read as 120 / 70, what is the 120 showing?

Systolic pressure

If a blood pressure is read as 120 / 70, what is the 70 showing?

Diastolic pressure

What is the numerical range of ideal systolic pressure?

90-120

What is the numerical range of ideal diastolic pressure?

60-80

How do you work out the pulse pressure?

Systolic - diastolic pressures

How do you work out the mean arterial pressure?

Diastolic pressure + 1/3 pulse pressure

What does the cardiac conduction system do?

Rapidly carries electrical impulses across the heart, initiating contraction / relaxation

What does ECG stand for?

Electrocardiogram

What does ECG do?

Detect electrical activity (ionic movement) across the heart

What is the first wave in an ECG?

P wave

What is the green compartment?

P wave

What is the red compartment? (RHS)

T wave

What is the blue compartment?

PR segment

What is the yellow compartment?

ST segment

What is the orange compartment? (LHS)

PR interval

What is the brown compartment? (top)

QRS complex

What is the purple compartment?

QT interval

What is the green circle?

R

What is the red circle?

Q

What is the blue circle?

S

What does the P wave represent?

Atrial depolarization → contraction

What follows the P wave?

QRS complex

What does the QRS complex represent?

Ventricular depolarization → contraction / atrial repolarization → relaxation

What follows the QRS complex?

T wave

What does the T wave represent?

Ventricular repolarization