Chapter 16- Cardiovascular system 1 Part 1 (2)

Question 1

What do the atrioventricular valves do?

Answer 1

Prevents backflow from ventricle to atrium when the ventricle contracts.

Question 2

How many flaps does the right AV and left AV have?

Answer 2

The right AV has three flaps (tricuspid valves)

The left AV has two flaps (bicuspid valves)

Question 3

When the heart is relaxed, what do the flaps do?

Answer 3

The flaps hang down into the ventricle below.

Question 4

When the ventricle contracts in the AV, what happens to the intra ventricular pressure?

Answer 4

It rises, forcing the blood against the valve flaps which closes the valve and prevents blood flow.

Question 5

What does the chordae tendineae do?

Answer 5

Prevents flaps getting blown upwards into the atria by the force of the ventricular contraction.

Question 6

What do the semi lunar valves do?

Answer 6

This prevents backflow from the two large arteries back into the ventricles.

Question 7

When the ventricles contract in the semi lunar valves, what happens?

Answer 7

Intraventricular pressure rises above the pressure in the aorta.

As a result, the valves are forced open and blood flows out.

Question 8

When the ventricles are relaxed in the semi lunar valves, what happens?

Answer 8

Blood flows backwards towards the heart.

The cusps fill forcing them to close. As a result, no blood re-enters the heart.

Question 9

No valves guard what?

Answer 9

The venae cavae or the pulmonary veins.

Question 10

Vein defects include:

Answer 10

1- Stenosis- narrowing of the valve

2- Regurgitation- when the valves fail to close tightly

Question 11

Defective valves are replaced with what?

Answer 11

Artificial valves

Question 12

The cardiac cycle is composed of what phases?

Answer 12

Phases of diastole (relaxation) and systole (contraction)

Question 13

CARDIAC CYCLE PROCESS ON DOC

Answer 13

CARDIAC CYCLE PROCESS ON DOC

Question 14

How is cardiac muscle similar to skeletal muscle?

Answer 14

Cardiac muscle is similar to skeletal muscle in that it is striated and is capable of generating great force.

Question 15

Cardiac muscle does differ from skeletal muscle in that:

Answer 15

1- Cardiac fibres branch

2- Cardiac muscle has more mitochondria and myoglobin

3- Cardiac muscle contains special calcium (Ca2+) channels

Question 16

How are cardiac fibres joined?

Answer 16

By intercalated discs

Question 17

Adjacent myocytes are joined by what?

Answer 17

Intercalated discs

Question 18

What are intercalated discs?

Answer 18

These are bands of proteins and gap junctions that ensure there is a tight coupling between adjacent cells and sharing of the cytoplasm

Question 19

What is syncytium?

Answer 19

A collection of cells that operate as one

Question 20

Why is syncytium functionally important?

Answer 20

Because a partial contraction would be insufficient to pump blood all the way around the body.

Question 21

Cardiac muscle forms two, largely independent syncytia:

Answer 21

1- One around both atria

2- Another around both ventricles

Question 22

Why is there a high number of mitochondria and myoglobin in cardiac muscle?

Answer 22

Because cardiac muscle relies almost exclusively on aerobic respiration

Question 23

Name fuel molecules for cardiac muscle

Answer 23

1- Glucose

2- Lactic acid