A&P of Cardiac System

Question 1

What is the position of the heart?

Answer 1

In mediastinum
Left of midline
Above diaphragm
Between medial/lower borders of lungs
Behind sternum
3rd to 6th intercostal cartilage

Question 2

How can the position vary from person to person?

Answer 2

Body build
Chest configuration
Diaphragm level
Dextrocardia
Heart positioned to the right, either rotated or displaced, or as a mirror image
If the heart and stomach are placed to the right and the liver to the left, this habitus is termed situs inversus

Question 3

What is the structure of the pericardium?

Answer 3

Tough, double-walled, fibrous sac encasing and protecting the heart
Several milliliters of fluid are present between the inner and outer layers of the pericardium, providing for low-friction movement

Question 4

What are the three layers of the pericardium and what are they composed of?

Answer 4

Epicardium
Thin outermost muscle layer covering heart, inner layer of pericardium
Myocardium
Thick, muscular middle layer responsible for pumping
Endocardium
Innermost layer, lining chambers and covering valves

Question 5

What is the function of the atria?

Answer 5

Thin-walled chambers that act primarily as reservoirs for blood returning to the heart from the veins throughout the body

Question 6

What is the function of the ventricles?

Answer 6

Thick-walled chambers that pump blood to the lungs and throughout the body

Question 7

What divides the right side from the left?

Answer 7

The septum

Question 8

What are the the valves between the atrias and ventricles and how are they described?

Answer 8

Tricuspid valve, which has three cusps (or leaflets), separates the right atrium from the right ventricle.
Mitral valve, which has two cusps, separates the left atrium from the left ventricle.

Question 9

What are the the valves between the ventricles and vessels and how are they described?

Answer 9

Two semilunar valves, each has three cusps
Pulmonic valve separates the right ventricle from the pulmonary artery.
Aortic valve lies between the left ventricle and the aorta.

Question 10

Describe what happens during systole.

Answer 10

Ventricles contract.
Blood is ejected from the left ventricle into the aorta and from the right ventricle into the pulmonary artery.
Mitral and tricuspid valves close(first heart sound).
Pressure continues to rise.
Aortic and pulmonic valves open.
Blood ejected into arteries.
Pressure falls.
Aortic and pulmonic valves close(second heart sound).

Question 11

Describe what happens during diastole.

Answer 11

Mitral and tricuspid valves open.
Blood moves from atria to ventricles (3rd heart sound).
Ventricles dilate, an energy-requiring effort that draws blood into the ventricles as the atria contract, thereby moving blood from the atria to the ventricles.
Atria contract as ventricles almost filled.
Causes complete emptying of atria (4th heart sound)

Question 12

Describe the flow of electrical activity within the heart.

Answer 12

Coordinates the sequence of muscular contractions taking place during the cardiac cycle:
Sinoatrial node (SA node)
Atrioventricular node (AV node)
Bundle of His
Purkinje fibers