Circulatory System Overview
The circulatory system is an essential organ system in complex organisms, responsible for transporting vital materials throughout the body. This system is necessary for any organism too complex for nutrients to diffuse directly to cells.
Definition: The circulatory system function is to transport materials like oxygen, nutrients, and hormones to body cells.
The animal circulatory system consists of a heart and a set of tubes. In vertebrates, it is a closed system where fluid is confined to vessels, with blood and interstitial fluid being distinct.
Highlight: The human circulatory system diagram shows three main types of blood vessels: arteries, veins, and capillaries.
The heart, a muscular pump, propels circulatory fluid through vessels to the body. It has four main chambers:
- Atria (right and left): Receive blood from veins
- Ventricles (right and left): Receive blood from atria and pump it out via arteries
Vocabulary: The sinoatrial (SA) node, also known as the pacemaker, is located in the wall of the right atrium and sets the rate and timing of heart contractions.
The SA node generates electrical impulses that spread through specialized junctions, with a slight delay at the atrioventricular node to allow the atria to empty completely.
Example: To understand how the circulatory system works, imagine the heart as a central pumping station, with arteries as outgoing pipes, veins as return pipes, and capillaries as tiny distribution channels reaching every part of the body.
