CV system: Cardiac structure and function

Question 1

How does the heart receive its blood supply?

Answer 1

Via coronary arteries

Question 2

What is myocardial infarction (MI)?

Answer 2

• Blockage in coronary blood flow results in cell damage.
• Exercise training protects against heart damage during an MI.

Question 3

The Heart Wall: What are the characteristics and function of the endocardium?

Answer 3

Characteristics: endothelial tissue and a thick subendothelial layer of elastic and collagenous fibres.

Function: Serves as protective inner lining of the chambers and valves.

Question 4

The Heart Wall: What are the characteristics and function of the myocardium?

Answer 4

Characteristics: Cardiac muscle tissue separated by CT and including blood capillaries, lymph capillaries, and nerve fibres.

Function: Provides muscular contractions that eject blood from the heart chambers

Question 5

The Heart Wall: What are the characteristics and function of the epicardium (visceral pericardium)?

Answer 5

Characteristics: Serous membrane including blood capillaries, lymph capillaries, and nerve fibres.

Function: Serves as lubricating outer covering.

Question 6

What is pericarditis?

Answer 6

The pericardial cavity is filled with pericardial fluid which lubricates. Pericarditis is when there is not enough fluid. It is the inflammation of the lining around your heart.

Question 7

Describe how an AP travels through the heart.

Answer 7

• APs originate in the SA node and travel across the atrium wall from SA to AV node.
• APs pass through AV node and along AV bundle (extends from AV node) through fibrous skeleton, into the interventricular septum.
• The AV bundle divides into right and left bundle branches, and APs descend to the apex of each ventricle along the bundle branches
• APs area carried by the Purkinje fibres from the bundle branches to the ventricular walls.

Question 8

What does the P wave show?

Answer 8

Atrial depolarization

Question 9

What does the QRS complex show?

Answer 9

Ventricular depolarization and atrial repolarisation

Question 10

What does the T wave show

Answer 10

Ventricular repolarization

Question 11

What is end diastolic volume?

Answer 11

The maximum amount of blood in the ventricles

Question 12

What is systolic volume?

Answer 12

Amount of blood remaining in heart after ventricular contraction

Question 13

In exercise, O2 extraction can increase but increased O2 delivery relies mainly on what?

Answer 13

An increase in coronary blood flow.

Question 14

What is heart O2 consumption principally required for?

Answer 14

Contraction, with requirements for maintaining basal metabolism comprising only 10-20% of total O2 consumption

Question 15

Coronary blood flow is closely related to cardiac work. What are coronary blood vessels mainly controlled by?

Answer 15

Metabolic - main metabolic vasodilator is ADENOSINE.
-Also β-adrenergic vasodilation (via ANS)

Question 16

When does coronary blood flow take place during rest, and heavy exercise?

Answer 16

Rest - 80% during diastole due to vessel compression during systole.
Exercise - 40-50% during systole (less time in diastole)