An arteriole is a very small blood vessel that plays a critical role in the circulatory system. It's essentially a tiny artery.
Defining Arterioles
According to the provided reference, an arteriole (är-'tir-ē-,ōl) is:
- A small blood vessel: Arterioles are much smaller than arteries.
- A branch of an artery: They branch off from larger arteries.
- A carrier of blood: Arterioles transport blood away from the heart to the tissues and organs.
- A link to capillaries: They connect arteries to capillaries, which are even smaller blood vessels.
Function of Arterioles
Arterioles have several important functions:
- Regulating blood flow: By constricting or dilating, arterioles control the amount of blood that enters the capillaries. This is crucial for maintaining blood pressure and ensuring that tissues receive the appropriate amount of oxygen and nutrients.
- Maintaining blood pressure: Arterioles contribute to maintaining blood pressure by resisting the flow of blood.
- Distributing blood: They ensure that blood is distributed to various parts of the body, according to their needs.
Arterioles Compared to Other Vessels
| Vessel | Size | Function |
|---|---|---|
| Artery | Large | Carries blood away from the heart |
| Arteriole | Small | Connects arteries to capillaries; regulates blood flow to tissues and organs |
| Capillary | Very Small | Site of exchange of oxygen, nutrients, and waste between blood and tissues |
| Venule | Small | Connects capillaries to veins |
| Vein | Large | Carries blood back to the heart |
Key Characteristics
- Small diameter: Arterioles have a small diameter, which allows them to control blood flow through their constriction and dilation.
- Muscular walls: Arterioles have relatively thick, muscular walls that enable them to regulate their diameter.
- Pre-capillary: They are located before the capillaries, which allows them to regulate the blood that flows into the capillaries.
In summary, arterioles are crucial for controlling blood flow and blood pressure. They are small vessels that are located between arteries and capillaries.
