Cardiovascular System Module

Components of the Cardiovascular System

• The cardiovascular system consists of three main components: distribution system (vessels and blood), pump (the heart), and exchange mechanism (capillaries).
• Blood transports oxygen, metabolic substrates, CO2, and waste products around the body.
• Exchange of substances occurs between blood and cells through diffusion (98%).

Diffusion and Exchange

• Diffusion is the primary mechanism of exchange between blood and tissues.
• The cardiovascular system provides adequate conditions for diffusion to occur in each tissue.
• Oxygen diffuses from the lungs to the blood, and then to the body tissues.

Blood Flow and Regulation

• At rest, total blood flow is approximately 5 l/min, which can increase to 25 l/min during exercise.
• Blood flow must adjust to meet the body's requirements.
• Arterioles are resistance vessels that regulate blood flow by reducing the ease of perfusion to certain regions.

The Heart and Circulation

• The heart is a dual pump that supplies blood to the systemic and pulmonary circulations.
• The right heart pumps blood to the lungs, while the left heart pumps blood to the rest of the body.
• The heart pumps blood to arteries, which supply arterioles, and then capillaries, where exchange occurs.
• Deoxygenated blood returns to the heart through venules and veins.

Need for Flexibility

• The total flow in the system must be able to change, requiring a temporary store of blood that can be returned to the heart at a different rate.
• The capacitance of veins provides this temporary store, allowing them to expand and contract as needed.

Basics of the Circulation

• The circulation has low venous pressure and high arterial pressure.
• Capacitance vessels (veins) store blood, while resistance vessels (arterioles) regulate blood flow.
• Exchange occurs in capillaries.

Distribution of Blood in the CVS

• Arteries and arterioles account for approximately 11% of the blood distribution.
• Capillaries account for around 5%.
• Veins, the heart, and lungs account for around 67% of blood distribution.

This quiz covers the basics of the cardiovascular system, including its components, function, and exchange mechanisms. It introduces the heart, blood vessels, and capillaries, and explains how they transport oxygen, metabolic substrates, and waste products around the body.