Cardio 4

Question 1

The right ventricle is part of the …

Answer 1

pulmonary low-pressure circulation system

Question 2

The left ventricle is part of the…

Answer 2

systemic high-pressure circulation system (thick walls)

Question 3

What can a blockage of the coronary arteries result in?

Answer 3

A Myocardial infarction (MI) also called a heart attack

Question 4

some deoxygenated blood doesn’t empty out into the SVC. Where is that blood coming from?

Answer 4

The coronary circulation of the heart empties out via the coronary sinus, directly into the right atrium

Question 4

What are the names of the two valves in the right (pulmonary) circulation?

Answer 4

1. the tricuspid valve (AV valve)
2. the pulmonary semilunar valve

Question 5

What are the cardiac AV valves there for? (2)

Answer 5

1. They stop the blood from coming back into the atrium during systole
2. They create a fibrous ring separating the atriums from the ventricles to avoid current propagation (since the atrium and ventricles don’T contract at the same time)

Question 6

What are the names of the two valves in the left (systemic) circulation?

Answer 6

1. the bicuspid or mitral valve (AV valve)
2. the aortic semilunar valve

Question 6

What are the papillary muscles for?

Answer 6

They contract as the valve close to avoid the valves from prolapsing into the atria during systole

Question 7

What are the three functions of the pericardium?

Answer 7

1. Prevent overflowing since it doesn’t expand
2. Protects the heart physically
3. Lubricates the heart for smooth movement (generated from the serous membrane)

Question 7

What are chordae Tendinae?

Answer 7

non-contractile tissue that links the AV valves to the papillary muscles

Question 8

When the left and right bundle branches are activated, how is the septum going to contract?

Answer 8

Since the right branch is well insulated and the left branch is not isolated, propagation in the septum goes from left to right, top to bottom

Question 8

What is the activation sequence of the heart’s electrical system (happens at every heartbeat)?

Answer 8

1. Sinus Node
2. Atria
3. AV node
4. Bundle of His
5. Left and right bundle branches –> activates the septum to contract
6. Purkinje fibres
7. Left and right ventricle myocardium –> walls of the heart contract from inside to outside

Question 8

What are the layers of the heart wall?

Answer 8

epicardium
myocardium
endocardium

Question 9

What does the sinus node do?

Answer 9

initiate the impulse

Question 10

What does the AV node do?

Answer 10

transfers the signal from the atria to the ventricles via the branches. This imposes a delay between atrial and ventricular contraction

Question 11

What do the Purkinje fibres do?

Answer 11

They activate all cells in both ventricles at roughly the same time, from inside to outside. The coordination of the contraction maximises pressure

Question 12

How does the signal travel between myocytes?

Answer 12

Each myocyte can carry electrical waves and cause its neighbouring cell to fire.

Question 13

What are the two ways myocytes are connected?

Answer 13

1. intercalated disk
2. gap junctions

Question 14

What do intercalated disks do?

Answer 14

They allow cells to adhere strongly to eachother

Question 15

What do gap junctions do?

Answer 15

They allow communication between myocytes as well as the flow of ions

Question 16

Where are the gap junctions on myocytes?

Answer 16

Gap junctions are concentrated at the ends of cells. some are on the sides of cells but there are less of them

Question 17

If a cardiac cell is depolarized, what will happen around it?

Answer 17

Local circuit currents
the ions will start moving due to the electrical gradient between the cells. K+(and a little Na+) will move through the gap junctions in the cytoplasm to reach the next cell. Na+ (and a bit of K+) will move towards the first cell in the interstitial fluid –> this interstitial current can be sensed at the body surface

Question 18

What happens when the first cell repolarises?

Answer 18

The local circuit will flow int he opposite direction than during depolarization