Circulatory System Quiz

Circulatory System I

• The circulatory system comprises the heart, blood vessels, and blood.
• The cardiovascular system refers solely to the heart and blood vessels.
• Its primary function is transporting substances throughout the body via blood.
• Blood is a liquid medium carrying various materials.
• Blood vessels direct blood flow to specific destinations.
• The heart acts as a pump, keeping blood circulating.

Functions of the Circulatory System

• The circulatory system's function is to transport substances throughout the body.
• Blood is the medium for this transport.
• Blood vessels ensure proper routing of blood.
• The heart pumps blood.

Pulmonary and Systemic Circuits

• The cardiovascular system has two divisions: pulmonary and systemic circuits.
• The pulmonary circuit carries blood to the lungs for gas exchange, returning it to the heart.
• The systemic circuit supplies blood to every body organ, including parts of the lungs and the heart wall itself.

Pathway of Blood Flow

• The right side of the heart processes deoxygenated blood, sending it to the lungs.
• The left side handles oxygenated blood, distributing it to the body.
• Oxygen-poor blood is indicated by violet arrows, while oxygen-rich blood is shown with orange arrows.

Heart Chambers

• The heart has four chambers.
• The atria are the upper chambers (singular: atrium) receiving blood.
• The ventricles are the lower chambers, pumping blood.
• The right and left ventricles are crucial pumps pushing blood.

Heart Valves

• Atrioventricular (AV) valves control blood flow between atria and ventricles.
• The right AV valve is called the tricuspid valve.
• The left AV valve is called the mitral valve.
• Semilunar valves (pulmonary and aortic) regulate blood flow from ventricles into arteries.
• The pulmonary valve controls blood outflow to the lungs.
• The aortic valve regulates blood flow from the left ventricle to the aorta.

Position, Size, and Shape of the Heart

• The heart is located within the thoracic cavity, mediastinum.
• It's positioned between the lungs and behind the sternum.
• About two-thirds of the heart lies to the left of the median plane.
• The base (top) is where major blood vessels attach.
• The apex is a blunt tip situated above the diaphragm.

The Pericardium

• The heart is enclosed in a double-walled sac called the pericardium.
• The outer wall (parietal pericardium) has a tough fibrous layer and a thin serous layer.
• The inner layer (visceral pericardium, or epicardium) coats the heart surface.
• The space between these layers is the pericardial cavity.

The Heart Wall

• The heart wall comprises three layers:
• Epicardium: thin outer layer.
• Myocardium: thick, muscular middle layer.
• Endocardium: thin, inner layer lining the chambers.

Coronary Circulation

• Immediately after leaving the left ventricle, the aorta branches, supplying blood to the heart via coronary arteries.
• The coronary sinus, a significant vein on the heart's posterior surface, collects blood from various sources and returns it to the right atrium.

The Conduction System

• The heart's conduction system initiates and regulates its rhythmic contractions.
• Specialized cardiac muscle cells form a network of pathways that conduct impulses throughout the heart.
• The sinoatrial (SA) node sets the pace of heartbeat (pacemaker).
• At 1 month of fetal development, the heart begins its rhythmic contractions.