Circulatory System Flashcards
Arteries
They carry blood away from the heart to the tissues.
It is the thickest vessel and has a quite thick elastic layer.
It has a thin endothelium with no valves.
Veins
Carry blood back to the heart from the tissues. It is a thin muscle with an elastic layer with no valves.
Arterioles
They carry blood under lower pressure to the tissues.
Quite a thick muscle, a thick elastic layer (in proportion), a thin endothelium and no valves.
Capillaries
Exchange metabolic materials between cells. They are high in numbers and branched. They have no valves. A narrow lumen. The walls mainly consist of mainly of the lining layer They have a narrow diameter.
What to mention when relating the structure of a blood vessel to its function
Muscular walls. Elastic tissue. Epithelium.
Artery structure related to its function
The function of the arteries is to transport blood rapidly under high pressure from the heart to the respiring tissues. The muscle layer is thick compared to the veins. Means they can be constricted and dilated to control blood flow. The elastic layer is relatively thick compared to veins. This maintains the high pressure of the blood. There are no valves. The overall thickness of the wall is great which prevents the vessel bursting.
Arteriole structure related to its function
Its function is to carry blood, under lower pressure than the arteries, from arteries to capillaries. They also control the blood flow between the two. Arterioles have a muscle layer that is relatively thicker than in the arteries. This controls the flow of blood into the capillaries. The elastic layer is relatively thinner than in the arteries. This is because the blood pressure is lower.
