Circulatory System I Overview

Circulatory System I

• The circulatory system comprises the heart, blood vessels, and blood.
• The cardiovascular system is also known as the circulatory system.
• The circulatory system transports substances throughout the body.
• Blood is a liquid medium carrying materials.
• Blood vessels route blood to different destinations.
• The heart pumps blood.

Functions of the Circulatory System

• The system has a fundamental purpose to move materials from one place to another.
• It transports substances in the blood.
• Deoxygenated blood travels to the right side of the heart, then to the lungs. Oxygenated blood comes from the left side back to the rest of the body.
• AV (Atrioventricular) valves control blood flow.

Pulmonary and Systemic Circuits

• The circulatory system has two major circuits.
• The pulmonary circuit carries blood to the lungs for gas exchange and back.
• The systemic circuit transports oxygenated blood to the rest of the body.
• It delivers oxygen to each organ and removes its waste products (carbon dioxide and other waste products.)

The Right Half of the Heart

• The right side receives blood that has circulated through the body.
• It pumps the blood into the pulmonary trunk.
• Blood is sent to the lungs (oxygen-poor).
• The blood returns to the left side of the heart through pulmonary veins.

The Left Half of the Heart

• The left side of the heart sends blood to the aorta, which delivers it throughout the body.
• Oxygen-rich blood is supplied to every organ.
• Deoxygenated blood returns to the right side of the heart.

Position, Size, and Shape of the Heart

• The heart rests in the thoracic cavity's mediastinum, in between the lungs and behind the sternum.
• Two-thirds of the heart is on the left side of the median plane.
• The heart's broad upper portion is called the base, where major blood vessels connect.
• The heart's pointed bottom is called the apex.

The Pericardium

• The heart is surrounded by a double-walled sac called the pericardium.
• The outer layer is the fibrous pericardium, and the inner layer is the serous pericardium.
• The serous pericardium has a parietal layer and a visceral layer (epicardium.)
• The space between the parietal and visceral layers is called the pericardial cavity.

The Heart Wall

• The heart wall has three layers.
• The outer layer is the epicardium.
• The middle layer is the myocardium (muscular layer.)
• The inner layer is the endocardium.

The Chambers of the Heart

• The heart has four chambers: two atria, and two ventricles.
• The atria receive blood.
• The ventricles pump blood out.
• The heart's superior portions are called atria. Two inferior chambers are called ventricles.

The Valves

• The atrioventricular (AV) valves regulate the flow of blood between the atria and ventricles.
• The right AV valve is also known as the tricuspid valve.
• The left AV valve is also known as the mitral valve.
• Semilunar valves regulate blood flow from ventricles to the great arteries (pulmonary and aortic).
• Pulmonary and aortic valves regulate the exit of blood from the right and left ventricles, respectively.

The Pathway of Blood Flow

• Blood flows from the body to the right atrium, into the right ventricle, to the lungs, to the left atrium, to the left ventricle, and finally, to the rest of the body.
• Violet arrows indicate oxygen-poor blood; orange arrows indicate oxygen-rich blood.

Coronary Circulation

• The coronary arteries supply blood to the heart muscle (myocardium).
• The coronary sinus collects blood from the heart muscle and empties into the right atrium.

The Conduction System

• The cardiac conduction system regulates the timing and coordination of heart contractions.
• The SA (sinoatrial) node initiates the heartbeat.
• The heartbeat begins at the SA node in the right atrium.

This quiz covers the essential components of the circulatory system, including its structure, functions, and the roles of the heart and blood vessels. Explore the dynamics of the pulmonary and systemic circuits and their significance in overall health.