Blood vessels

Arteries

Blood vessels that carry blood away from the heart.

Veins

Blood vessels that carry blood toward the heart.

Capillaries

Small blood vessels that connect arteries and veins, allowing for exchange of substances.

Tough outer layer

Resists pressure changes in arteries and veins.

Muscle layer

Contracts to control blood flow in arteries and veins.

Elastic layer

Maintains blood pressure by stretching and recoiling.

Endothelium

Smooth layer of cells that reduce friction and allow diffusion.

Lumen

The central cavity of a blood vessel through which blood flows.

Ultrafiltration

Filtration assisted by blood pressure in the capillaries.

Tissue fluid

Watery liquid containing various substances that fills spaces between cells in a tissue.

Hydrostatic pressure

The force exerted by fluids within a closed system, such as in blood vessels.

Osmosis

The movement of water across a semipermeable membrane from an area of low solute concentration to an area of high solute concentration.

Lymphatic system

A network of vessels and organs that helps maintain fluid balance, immune response, fat absorption, and waste removal.

Valves in veins

Structures that prevent the backflow of blood in veins due to low pressure.

Thicker muscle layer in arteries

Allows for control of blood flow and maintenance of high pressure.

Balanced tissue fluid return

Occurs when pressure reaches equilibrium at the venous end of capillaries.