Cardiovascular System

Question 1

What is the role of the pericardium

Answer 1

The pericardium is a fibrous sac that protects the heart by providing lubrication during its constant movement
It helps anchor the heart against the spine

Question 2

What is pulmonary circulation

Answer 2

Connected to the heart in ‘series’ which means that the entire blood volume has to pass through it every time it circulates the body

Question 3

What is systematic circulation

Answer 3

Connected to the heart in ‘parallel’ which means there is a choice of which part of the body receives more or less of the available blood volume

Question 4

What is the typical total blood volume for the average person

Answer 4

5 litres (7% body weight)

Question 5

What is the typical cardiac output for the average person

Answer 5

5liters/min

Question 6

What is driving pressure

Answer 6

Flow is created by the pressure difference between two points

Question 7

What is Darcy’s law

Answer 7

Flow = pressure difference / resistance

Question 8

Increased driving pressure =

Answer 8

Increased flow

Question 9

Increased resistance =

Answer 9

Decreased flow

Question 10

What is Poiseuille’s law

Answer 10

Resistance = 1 / r ⁴

Question 11

Darcy’s and Poiseulle’s laws combined

Answer 11

Flow = pressure difference x r ⁴

Question 12

Increased driving pressure + increased radius of vessel =

Answer 12

Increased flow

Question 13

What does flow velocity of blood depend on

Answer 13

The cumulative radius of all vessels at a similar distance from the heart

Question 14

What is large XSA and very low blood flow velocity important for in tissues

Answer 14

Diffusion of gases and exchange of nutrients / waste

Question 15

How is cardiac muscle similar to smooth muscle

Answer 15

It’s involuntary

Question 16

What do gap junctions allow

Answer 16

An electrical signal to originate from a specialised part of the heart and propagate from fibre to fibre in a structured and organised pattern

Question 17

What does contraction of cardiac muscle cells depend on

Answer 17

Extracellular Ca2+

Question 18

What is meant by cardiac muscle being highly oxidative

Answer 18

It is dependent on o2 supply

Question 19

What is the SA node

Answer 19

The SA node has an intrinsic rate of approximately 100bpm and can initiate cardiac contraction in the absence of any external control (hormonal or nervous)

Question 20

How can SA node cells initiate an action potential

Answer 20

Due to an unstable membrane potential that is continuously drifting towards the threshold

Question 21

What does the rate of firing from the cells of the SA node depend on

Answer 21

1) initial value of the membrane potential
2) the slope of the drift towards threshold

Question 22

Where is the tricuspid valve

Answer 22

Separates the right atrium and ventricle

Question 23

When does the tricuspid valve open and close

Answer 23

Opens; when R atrial pressure > R ventricular pressure
Closes; when R atrial pressure < R ventricular pressure

Question 24

Where is the mitral (bicuspid) valve

Answer 24

Separates left atrium and ventricle

Question 25

When does the mitral valve open and close

Answer 25

Opens; when L atrial pressure > L ventricular pressure
Closes; when L atrial pressure < L ventricular pressure

Question 26

Where is the pulmonary valve

Answer 26

Separates the right ventricle and pulmonary artery (PA)

Question 27

When does the pulmonary valve open and close

Answer 27

Opens; when R ventricular pressure > PA pressure
Closes; when R ventricular pressure < PA pressure

Question 28

Where is the aortic valve

Answer 28

Separates left ventricle and aorta

Question 29

When does the aortic valve open and close

Answer 29

Opens; when L ventricular pressure > aortic pressure
Closes; when L ventricular pressure < aortic pressure