Types of Blood Vessels

The cardiovascular system organs include three main types of blood vessels: arteries, veins, and capillaries. Each type has unique characteristics suited to its function:

Arteries:

• Transport oxygenated blood away from the heart (except for the pulmonary artery)
• Have thick, elastic, muscular walls to cope with high blood pressure
• Feature a small lumen, contributing to high pressure

Vocabulary: The lumen is the inner space of a tubular structure, such as a blood vessel.

Veins:

• Transport deoxygenated blood towards the heart and lungs for re-oxygenation
• Have thinner, less elastic walls due to lower pressure
• Contain valves to prevent backflow of blood

Example: The pulmonary vein is an exception, carrying oxygenated blood from the lungs to the heart.

Capillaries:

• Small blood vessels that connect arteries and veins
• One cell thick, allowing for efficient gas exchange
• Site where oxygen diffuses from the blood into tissues and carbon dioxide diffuses from tissues into the blood

Highlight: Capillaries are the type of blood vessel that directly exchanges substances with body tissues.

Functions of the Cardiovascular System

The cardiovascular system has three primary functions that are crucial for maintaining bodily health and performance:

1. Transportation: The heart pumps oxygenated blood throughout the body, delivering essential nutrients like glucose to tissues. During exercise, the heart works harder to increase oxygen levels. The system also removes waste products such as carbon dioxide and lactic acid.

2. Regulating Body Temperature: When the body is too hot, blood flow to the skin increases through vasodilation, allowing heat to dissipate. Conversely, when the body is cold, blood flow is redirected to internal organs through vasoconstriction.

3. Clotting: Platelets in the blood form clots and scabs to stop bleeding when injuries occur.

Definition: Vasodilation is the widening of blood vessels, increasing blood flow, while vasoconstriction is the narrowing of blood vessels, decreasing blood flow.

Highlight: The cardiovascular system's main function is to efficiently distribute oxygen and nutrients throughout the body while removing waste products, which is especially important during physical activity.