Cardiovascular System: Heart & Systemic Circuit

Cardiovascular System Overview

• The cardiovascular system has three main parts: the heart, blood vessels, and blood.
• The system includes the pulmonary and systemic circuits, with the coronary circuit as part of the systemic circuit.
• The cardiovascular system transports blood, delivers oxygen, removes carbon dioxide, transports nutrients, removes waste, and protects against infections.

Heart

• The muscular pump at the center of the circulatory system is the heart.
• It is electrically stimulated to move blood throughout the body.

Systemic Circuit

• Blood travels between the heart and peripheral tissues through the systemic circuit.
• Arteries transport oxygen, nutrients, and hormones to tissues, while veins return deoxygenated blood to the lungs for gas exchange.
• Oxygen-rich blood enters the left atrium, moves to the left ventricle, and is pumped into the aorta for systemic circulation.
• At the tissues, oxygen and nutrients are delivered, and carbon dioxide and waste enter the blood.
• Deoxygenated blood returns to the right atrium through the superior and inferior vena cava.

Pulmonary Circuit

• The pulmonary circuit moves blood between the heart and lungs.
• Deoxygenated blood goes from the right side of the heart to the lungs for oxygen and carbon dioxide exchange, then oxygenated blood returns to the left side of the heart.
• Oxygen-deprived blood flows from the superior and inferior vena cava into the right atrium, then to the right ventricle and through the pulmonary arteries to the lungs.
• Oxygenated blood returns to the left atrium via the pulmonary veins.

Coronary Circulation

• The coronary circulation is part of the systemic circulation.
• Coronary arteries supply oxygenated blood to the heart, and cardiac veins drain deoxygenated blood.

Blood Vessels

• The three primary types of blood vessels are arteries, veins, and capillaries, categorized by their histological structure.
• Arteries narrow into arterioles and then capillaries; venules arise from capillary beds and enlarge into veins.

Arteries

• Arteries have thick, muscular walls and a small internal lumen.
• They can withstand high-pressure blood and typically carry oxygenated blood, except for the pulmonary artery.

Veins

• Veins carry blood to the heart.
• They have thin walls, a larger internal lumen, and contain blood under low pressure.
• Valves prevent backflow.
• Veins typically carry deoxygenated blood, except for the pulmonary veins.

Capillaries

• Capillaries form a microscopic web of vessels with walls one endothelial cell thick.
• The walls are thin and fenestrated.
• They are found in the tissues and can only tolerate slow-moving, low-pressure blood.
• The exchange of gases, nutrients, water, and waste occurs in the capillaries.

Blood

• Blood consists of plasma, red blood cells, white blood cells, and platelets.

Plasma

• Plasma makes up 55% of blood volume, is the blood's liquid component, and facilitates the transport of carbon dioxide, hormones, and metabolic waste.
• Plasma is clear and straw-like in color.

Red Blood Cells (Erythrocytes)

• Red blood cells comprise 45% of blood volume, are formed in bone marrow, and carry oxygen

White Blood Cells

• White blood cells are created in bone marrow and are part of the immune system.

Platelets

• Platelets are small cells that help clot blood.

Coronary Artery Disease

• Narrowing of the arteries supplying the heart causes coronary artery disease as a result of atherosclerosis
• Atherosclerosis involves the buildup of fatty cholesterol plaque inside a vessel.
• Atherosclerotic buildup narrows blood vessels, reducing oxygen delivery to the heart tissue.
• It leads to angina and myocardial infarction.

Angina

• Angina is painful spasming of the coronary arteries due to diminished blood flow.
• Angina is not life-threatening but can warn of a heart attack or stroke.

Myocardial Infarction (Heart Attack)

• A myocardial infarction occurs when an artery is completely blocked by a blood clot or dislodged plaque.
• Complete occlusion of the anterior interventricular artery results in a "widowmaker" myocardial infarction
• A "widowmaker" myocardial infarction, can be particularly lethal because this artery supplies a large portion of the heart.

Coronary Artery Disease Treatment

• Stent placement, also known as percutaneous transluminal coronary angioplasty.
• Coronary artery bypass graft surgery (for severe disease).

Overview of the cardiovascular system, including the heart, blood vessels, and blood. Focus on the systemic circuit, detailing how oxygen-rich blood circulates from the heart to tissues and returns deoxygenated blood.