how are red blood cells able to move through narrow vessels to carry oxygen through out a multicellular organism
Red blood cells are able to move through narrow vessels due to their unique structure and flexibility. They possess a biconcave shape and lack a nucleus, which provides them with greater flexibility and increased surface area for efficient gas exchange.
The flexibility of red blood cells allows them to squeeze and deform as they pass through narrow capillaries and small blood vessels called arterioles. This process is known as "plasticity" or "deformability." Red blood cells can change their shape to navigate through vessels that are smaller in diameter than their own. This ability helps them to pass smoothly through tight spaces without getting stuck or damaging the vessel walls.
Additionally, the small size of red blood cells aids their movement through narrow vessels. Their average diameter is about 7.8 micrometers, which is smaller than the diameter of most capillaries. This compact size allows them to easily navigate and flow through the intricate network of blood vessels throughout the body.
Lastly, the flow of blood through blood vessels is aided by the pumping action of the heart. The heart propels blood through the arteries, which then branches into smaller arterioles and eventually into capillaries. This continuous flow helps push the red blood cells through the narrow vessels and ensures a constant supply of oxygen to different tissues and organs in the body.