Coronary Circulation and the Vascular System

These flashcards cover key concepts related to coronary circulation, the vascular system, properties of myocardial tissue, and the differences between various conditions affecting coronary arteries.

What are the main functions of the coronary arteries?

Supply oxygen and nutrients to the myocardium (heart muscle).

What is the left coronary artery and what are its branches?

The left coronary artery (LCA) comes from beneath the aortic semilunar valves and branches into the left anterior descending (LAD) and circumflex arteries.

What does the right coronary artery supply?

It supplies blood to most of the right ventricle and right atrium, including the sinus node.

What is myocardial ischemia?

A condition characterized by partial obstruction of a coronary artery, leading to decreased oxygen supply to the tissues, often causing angina pectoris.

What is the difference between myocardial ischemia and myocardial infarction?

Myocardial ischemia is partial obstruction of a coronary artery, while myocardial infarction (MI) is a complete obstruction causing death of heart tissue.

What are the signs of Acute Coronary Syndrome (ACS)?

Unstable angina, non-ST segment elevation myocardial infarction (NSTEMI), and ST-segment elevation myocardial infarction (STEMI).

What do cardiac veins do?

They collect deoxygenated blood after it passes through the myocardium and drain into the coronary sinus, which empties into the right atrium.

What is the function of the coronary sinus?

To collect deoxygenated blood from cardiac veins and empty it into the right atrium.

What properties of myocardial tissue facilitate heart function?

Excitability, inherent rhythmicity, conductivity, and contractility.

What is the refractory period in relation to the myocardium?

A time period during which the myocardium cannot be stimulated, lasting about 250 milliseconds.

Describe the capillary system's role in circulation.

Capillaries facilitate the exchange of gases, nutrients, and wastes between blood and body cells due to their thin structure.

What is the purpose of the venous system?

To act as a reservoir for the circulatory system, holding about three-fourths of the body's blood volume and conducting blood back to the heart.

Wheres does the LCA provide blood to

The left atrium, left ventricle, majority of the inter ventricular septum, half of the inter arterial septum and part of the right atrium

Where is the right coronary artery

around the right side of the heart between right atrium and right ventricle.

How much oxygen does the heart muscle use

70% of oxygen from the blood that flows through it. the rest of the body uses about 25%. 

How does exercise affect the hearts need for oxygen

It needs more blood, only way to get more oxygen is to increase blood flow.

Hypoxia

Heart not getting enough oxygen

What happens when the heart is hypoxic

It releases adenosine that causes vasodilation so more blood can flow into the heart. 

What is adenosine

A chemical that causes vasodilation.

What is myocardial infarction

Complete obstruction of coronary artery.

Common symptoms of Myocardial Ischemia

• Chest pain (angina) squeezing, tightness, or heaviness

• Pain in near by areas: arm, neck, jaw, shoulder, or back

• Shortness of breath; feeling like you can’t catch breath

• Sweating, nausea, dizziness. 

• Sometimes no symptoms. 

Common symptoms of myocardial infarction

• Severe chest pain or pressure: crushing, squeezing or heavy, las more then a few minutes or come and go.

• Pain spreading to arm, neck, jaw, shoulder, or back

• Shortness of breath

• Sweating, nausea, or vomiting

• Lightheadedness or sudden weakness

• milder or unusual symptoms like fatigue, indigestion or no chest pain. (women older adults, people with diabetes)

Stable Angina

Angina pain develops when there is increased in the setting of a stable atherosclerotic plaque. The vessel is unable to dilate enough to allow adequate blood flow to meet the myocardial demand.

Unstable angina

The plaque ruptures and a thrombus forms around the ruptured plaque, causing partial occlusion of the vessel. Angina pain occurs at rest or progresses rapidly over a short period of time

NSTEMI

The plaque rupture the thrombus formation causes partial occlusion to the vessel subendocardial myocardium

STEMI

Is characterized by complete occlusion of the blood vessel lumen, resulting in transmural injury and infarct to the myocardium, which is reflected by ECG changes and a rise in troponin.

Thesesian veins

Drain some venous blood directly into all heart chambers, especially into the left atrium and left ventricle, bypassing the lungs, which causes a normal anatomic shunt

Excitability

The heart cells can respond when they are stimulated

Automaticity (inherent rhythmicity)

The heart can create its own electrical signals without outside help

Conductivity

The electrical signal can travel through the heart muscle

Contractility

The heart muscle can squeeze (contract) to pump blood.

Cardiac cells

Short, fat, branched and interconnected. 

Sacrolemma

The membrane that encloses individual cardiac fibers.

Myofibrils

Each fiber of muscle cells consisting of smaller units.

Systemic vasculature

begins of the aorta on left ventricle and ends in right atrium

Pulmonary vasculature

begins with pulmonary trunk out of right ventricle and ends in left atrium

Arterial system

The system of blood vessels that carries oxygenated blood away from the heart to the rest of the body.