Circulatory System I

Circulatory System I

• The circulatory system comprises the heart, blood vessels, and blood.
• The cardiovascular system refers only to the heart and blood vessels.
• The circulatory system transports substances throughout the body via blood.
• Blood is the liquid medium for transporting materials.
• Blood vessels ensure proper blood routing to destinations.
• The heart pumps blood to keep it flowing.

Functions of the Circulatory System

• Deoxygenated blood enters the heart's right side.
• Oxygenated blood leaves the heart's left side.
• The AV (Atrioventricular) valve is crucial for blood flow through the heart.

Pulmonary and Systemic Circuits

• The cardiovascular system has two major divisions: pulmonary and systemic circuits.
• The pulmonary circuit carries blood to the lungs for gas exchange and back to the heart.
• The systemic circuit delivers blood to all body organs and returns it to the heart.

Blood Flow Through the Heart

• The right side of the heart receives deoxygenated blood from the body.
• The blood is pumped into the pulmonary trunk and then to the lungs.
• In the lungs, carbon dioxide is released, and oxygen is absorbed by the blood.
• Oxygenated blood returns to the left side of the heart via pulmonary veins.
• The left side of the heart pumps oxygenated blood to the rest of the body through the aorta.
• Blood is transported to tissues/organs/lungs to carry out their function.

The Heart Wall

• The heart wall has three layers: the epicardium (external), myocardium (middle/muscular), and endocardium (internal).

The Chambers of the Heart

• The heart has four chambers: two atria (receiving chambers) and two ventricles (pumping chambers).
• Right and left atria receive blood.
• Right and left ventricles pump blood.

The Valves of the Heart

• Atrioventricular (AV) valves regulate blood flow between the atria and ventricles.
• The right AV valve is also known as the tricuspid valve.
• The left AV valve is called the mitral valve.
• Semilunar valves control blood flow from the ventricles to the arteries.
• The pulmonary valve is between the right ventricle and the pulmonary trunk.
• The aortic valve is between the left ventricle and the aorta.

Pathway of Blood Flow

• Blood flow through the heart involves a specific path.
• Violet arrows indicate oxygen-poor (deoxygenated) blood.
• Orange arrows represent oxygen-rich (oxygenated) blood.

Coronary Circulation

• Coronary arteries supply blood to the heart muscle.
• Coronary veins collect the used blood from the heart.

Conduction System

• The conduction system coordinates heartbeats.
• The sinoatrial (SA) node initiates the heartbeat.
• The atrioventricular (AV) node delays the signal.

Heart Position

• The heart sits in the thoracic cavity, between the lungs, and behind the sternum.
• About two-thirds of the heart is to the left of the midline.
• The upper part is called the base
• The lower pointed tip is called the apex
• The broad, superior portion is called the base.
• The inferior end of the heart tapers down to a blunt point, called the apex.

Pericardium

• The heart is enclosed in a double-walled sac called the pericardium.
• The outer layer is the fibrous pericardium.
• The inner serous layer forms the epicardium and consists of two layers: the parietal and visceral pericardium.
• The pericardial cavity, located between these layers, contains serous fluid.