CV system: Cardiac structure and function Flashcards

1
Q

How does the heart receive its blood supply?

A

Via coronary arteries

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2
Q

What is myocardial infarction (MI)?

A
  • Blockage in coronary blood flow results in cell damage.
  • Exercise training protects against heart damage during an MI.
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3
Q

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

A

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

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

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4
Q

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

A

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

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5
Q

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

A

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

Function: Serves as lubricating outer covering.

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6
Q

What is pericarditis?

A

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.

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7
Q

Describe how an AP travels through the heart.

A
  • 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.
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8
Q

What does the P wave show?

A

Atrial depolarization

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9
Q

What does the QRS complex show?

A

Ventricular depolarization and atrial repolarisation

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10
Q

What does the T wave show

A

Ventricular repolarization

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11
Q

What is end diastolic volume?

A

The maximum amount of blood in the ventricles

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12
Q

What is systolic volume?

A

Amount of blood remaining in heart after ventricular contraction

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13
Q

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

A

An increase in coronary blood flow.

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14
Q

What is heart O2 consumption principally required for?

A

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

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15
Q

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

A

Control of coronary blood flow is mainly metabolic - main metabolic vasodilator is ADENOSINE.
-Also β-adrenergic vasodilation (via ANS)

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16
Q

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

A

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

17
Q

On and ECG, what suggests myocardial ischemia?

A

S-T segment depression (see ECG for visual)