lec 4

Question 1

Cardiac Skeleton is

Answer 1

Dense fibrous CT framework lies

at the junction of the atria with the ventricles.

Question 2

Cardiac Skeleton is in the form of

Answer 2

4 rings:

Question 3

4 rings of Cardiac Skeleton

Answer 3

1. Right fibrous ring (of tricuspid valve)
2. Left fibrous ring (of Mitral valve)
3. Fibrous ring of pulmonary valve
4. Fibrous ring of aortic valve

Question 4

Functions of Cardiac Skeleton

Answer 4

1- Supports the valves.

2- Electrically separating atria from ventricles.

Question 5

Operation of the atrioventricular (AV) valves of the heart

Answer 5

1. B returning to the atria puts pressure against AV valve > AV valve opens
2. As the ventricular fill , the AV cusps
   hang limply into ventricles
3. atria contract , forcing ++++ B into ventricles
4. ventricles contract forcing b against AV valve cusps
5. AV valve close
6. chordae tendineae tighten preventing
   valve cusps from everting into artria

Question 6

Operation of the semilunar

of the heart

Answer 6

1. as a ventricles contract and intraventricular P ↑ > B is pushed up against semilunar valve forcing them to open
2. as a ventricles relaxed and intraventricular P ↓ B flows back from arteries → filling the cusps of semilunar valves close

Question 7

The “lub” is produced by the

Answer 7

the closing of the AV valves at the start of

ventricular systole

Question 8

The “dup” is produced by the

Answer 8

closing of the semilunar valves at the

end of ventricular systole

Question 9

Nerve supply of the heart By

Answer 9

cardiac plexus

Question 10

cardiac plexus branches from

Answer 10

sympathetic & parasympathetic fibers

Question 11

Cardiac plexus lies superficially

Answer 11

inferior to aortic arch

Question 12

Cardiac plexus lies deeply

Answer 12

between aortic arch and trachea

Question 13

The parasympathetic fibers arise from

Answer 13

the vagus nerves.

Question 14

The sympathetic fibers arise from

Answer 14

the cervical & upper thoracic ganglia of

sympathetic trunks.

Question 15

Sympathetic Fibers function

Answer 15

increases heart rate & force of contraction.

Question 16

Parasympathetic Fs

Answer 16

decreases heart rate, decreases force of contraction, & constricts the coronary arteries.

Question 17

The beating of the heart is regulated by

Answer 17

the intrinsic conduction (nodal) system

Question 18

intrinsic conduction (nodal) system function

Answer 18

to ensure that the chambers of the heart

contract in the proper rhythm and sequence

Question 19

The cardiac pacemaker is

Answer 19

sinuatrial (SA) node.

Question 20

SA node is located at

Answer 20

superior end of the crista terminalis at the junction of the SVC and the right atrium.

Question 21

SA node is called

Answer 21

the pacemaker of the heart, because it generates the impulse

Question 22

The atrioventricular (AV) node is located at

Answer 22

the junction of the atria and the ventricles, near the opening of the coronary sinus.

Question 23

atrioventricular (AV) bundle (bundle of His) is located in the

Answer 23

interventricular septum

Question 24

atrioventricular (AV) bundle (bundle of His) Divided into

Answer 24

right and left bundles to the right and left ventricles

Question 25

atrioventricular (AV) bundle (bundle of His) terminates with

Answer 25

purkinje fibers

Question 26

The heart contraction begins with

Answer 26

an electrical impulse in the SA node.

Question 27

The impulse spreads

Answer 27

the two atria and triggers their contraction → it reaches the AV node → AV bundle → Purkinje fibers

Question 28

Purkinje fibers

Answer 28

triggers ventricles contraction