Blood Vessels: Capillaries and Veins
This page discusses the structure and function of capillaries and veins, as well as their role in the cardiovascular system.
Capillaries:
Capillaries are the smallest blood vessels in the body, serving as the interface between the blood and tissue cells.
Definition: Capillaries are microscopic blood vessels that facilitate the exchange of substances between blood and surrounding tissues.
Structure of capillaries:
- One cell thick wall for rapid diffusion
- Small internal diameter (lumen)
- No valves
Function of capillaries:
- Allow for exchange of oxygen, nutrients, and waste products between blood and tissues
- Carry both oxygenated and deoxygenated blood
Highlight: The thin walls of capillaries are crucial for their function, allowing for efficient exchange of substances.
Veins:
Veins are blood vessels that return blood to the heart from the body's tissues.
Structure of veins:
- Thinner walls compared to arteries
- Larger lumen
- Presence of valves to prevent backflow of blood
Function of veins:
- Carry deoxygenated blood back to the heart (except for pulmonary veins)
- Maintain low blood pressure
- Act as blood reservoirs
Example: The vena cava is a large vein that returns deoxygenated blood from the body to the right atrium of the heart.
Cardiovascular system anatomy and physiology:
The page also provides an overview of blood flow through the heart and major blood vessels:
-
Deoxygenated blood flow:
Vena cava → Right atrium → Right ventricle → Pulmonary artery → Lungs
-
Oxygenated blood flow:
Pulmonary vein → Left atrium → Left ventricle → Aorta → Rest of body
Vocabulary: Septum - The central wall of the heart that separates the right and left sides.
What are the 4 main arteries of the heart:
- Aorta: Carries oxygenated blood around the body
- Pulmonary artery: Takes deoxygenated blood to the lungs
- Pulmonary vein: Brings oxygenated blood from the lungs to the heart
- Vena cava: Brings deoxygenated blood from the body to the heart
Highlight: Understanding the structure and function of different blood vessels is crucial for comprehending the overall function of the cardiovascular system.
