Circulatory System Overview

Circulatory System I

• The circulatory system comprises the heart, blood vessels, and blood. Cardiovascular system refers exclusively to the heart and blood vessels.
• The circulatory system's main function is transporting substances throughout the body via blood.
• Blood serves as the liquid medium for these transported materials.
• Blood vessels direct blood flow to specific destinations.
• The heart acts as the pump, keeping the blood flowing.

Functions of the Circulatory System

• The circulatory system conveys substances from one place to another within the body.
• Blood is the liquid medium that carries these substances.
• Blood vessels carry blood to appropriate destinations.
• The heart propels blood through the system.
• Without valves, the body would need more effort to propel blood to distant areas.

Pulmonary and Systemic Circuits

• The circulatory system is divided into two main parts: the pulmonary and systemic circuits.
• The pulmonary circuit carries blood to the lungs (for gas exchange) and then back to the heart.
• The systemic circuit distributes oxygenated blood to all body organs and tissues and returns deoxygenated blood to the heart.

The Right Half of the Heart & Pulmonary Circuit

• The right side of the heart receives deoxygenated blood from the body.
• The right side pumps this blood into the pulmonary trunk.
• The oxygen-poor blood is then distributed to the lungs to release carbon dioxide and absorb oxygen.
• The oxygenated blood returns to the left side of the heart via pulmonary veins.

The Left Half of the Heart & Systemic Circuit

• The left side of the heart receives oxygenated blood from the lungs.
• The left side pumps this blood into the body's largest artery, the aorta.
• The aorta branches to deliver oxygen throughout the body.
• After exchanging gases, the deoxygenated blood returns to the right side of the heart via two large veins, the superior vena cava and inferior vena cava.

Position, Size, and Shape of the Heart

• The heart is located in the thoracic cavity, within the mediastinum, situated between the lungs and deep to the sternum.
• Approximately two-thirds of the heart lies to the left of the median plane.
• The broad superior part of the heart is called the base, where large vessels connect.
• The pointed inferior end is termed the apex of the heart, residing slightly above the diaphragm.

The Pericardium

• The heart is encased in a double-walled protective sac called the pericardium.
• The outer layer (parietal pericardium) is tough and fibrous.
• The inner layer (visceral pericardium or epicardium) adheres to the heart's surface.
• The space between these layers is the pericardial cavity, containing lubricating fluid.

The Heart Wall

• The heart wall has three layers: epicardium (outermost), myocardium (middle, muscular), and endocardium (inner lining).

The Chambers of the Heart

• The four chambers include two atria (receiving chambers) and two ventricles (pumping chambers).
• The atria receive blood from vessels, and ventricles push blood into arteries.
• The right and left ventricles are the major pumping chambers.

The Valves

• Atrioventricular valves (AV valves) regulate blood flow between atria and ventricles.
• Semilunar valves control the flow from ventricles to arteries.

Pathway of Blood Flow Through the Heart

• Blood flows through the pulmonary circuit from the right side of the heart to the lungs and returns to the left side.
• Blood flows through the systemic circuit from the left side of the heart throughout the body and back to the right side.

Coronary Circulation

• The coronary arteries supply blood to the heart muscle.
• The coronary veins drain blood away from the heart muscle.
• The coronary sinus collects blood and drains it into the right atrium.

The Conduction System

• The heart's conduction system coordinates the rhythmic contraction of heart chambers.
• Specialized tissues initiate and spread electrical impulses that trigger contraction.

This quiz covers the fundamental aspects of the circulatory system, including its components such as the heart and blood vessels. It explores the major functions of this system and explains the difference between the pulmonary and systemic circuits. Test your knowledge on how blood circulates and its vital role in transporting substances throughout the body.