capillary
Definition
A Capillary is a microscopic blood vessel that connects an arteriole (small artery) with a venule (small vein). Capillaries are the smallest blood vessels in the body, with an average diameter of just 8 micrometres (μm). They are found all over the body, in tissues such as the skin, muscles, and organs.
The walls of capillaries are very thin, which allows the exchange of oxygen and nutrients between the blood and the cells. Oxygen and nutrients from the blood diffuse into the cells, while waste products from the cells diffuse into the blood. This process is essential for the survival of cells.
Capillaries also play a role in the immune system. They allow white blood cells to travel from the blood to the tissues, where they can fight infection.
Capillaries are so small that they can only be seen with a microscope.
The walls of capillaries are made up of a single layer of cells.
The exchange of oxygen and nutrients between the blood and the cells occurs through diffusion.
Capillaries are essential for the survival of cells.
Capillaries also play a role in the immune system.
How can the word be used?
The capillaries in the leaf allow water to move from the roots to the leaves.
Different forms of the word
Noun: Capillary.
Adjective: Capillary.
Plural: Capillaries.
Etymology
The word "capillary" comes from the Latin word "capillus", which means "hair". The Latin word "capillus" is derived from the Proto-Indo-European root *kap-, which also means "hair".
Question
What do capillaries do?
AQA Science Exam Question and Answer
Question:
Capillary beds are the sites of exchange of oxygen and nutrients between the blood and the cells. Explain how the structure of capillaries is adapted to this function.
Answer:
Capillaries are very small blood vessels with an average diameter of just 8 micrometres (μm). This small diameter is important for the exchange of oxygen and nutrients, as it allows the molecules to diffuse more easily. The walls of capillaries are also very thin, which further facilitates diffusion.
In addition, the walls of capillaries are made up of a single layer of cells. This allows the molecules to pass through the walls more easily than if they had to pass through multiple layers of cells.
The structure of capillaries is therefore well-adapted to their function of exchanging oxygen and nutrients between the blood and the cells. This allows the cells to get the oxygen and nutrients they need to function properly.