Blood Vessels Flashcards
The basic structure of the blood vessels is
Endothelium - smooth lining next to the blood to reduce friction between blood and the wall
Middle Layer - contains elastic tissue
Outer layer - contains the tough, fibrous protein ‘collagen’
Explain the structure of Arteries
Thickest walls to carry blood under pressure without bursting. Have the most elastic tissue in the middle layer. They can dilate to accommodate the increase in blood volume when the ventricle contracts. They can recoil when the ventricle relaxes which helps to maintain blood pressure and helps to smooth out flow of blood to capillaries
Explain the structure of Arterioles
Relatively less elastic tissue but more muscle in their middle layer. This is to regulate the flow of blood to different parts of the body. When the muscle contracts, lumen gets narrower (constricts) reducing blood flow along the vessel. When muscle relaxes, lumen gets wider increasing blood flow.
Explain the structure of Capillaries
Wall is the endothelium only and it’s a single layer of squamous cells for a short diffusion pathway. The lumen is very narrow + RBCs can only pass one by one along the capillary this the rate of flow is very low allowing more time for exchange substances. The large capillary network provides a large surface area.
Explain the structure of Venules + Veins
Thin walls as blood flows under low pressure and is maintained by
- Valves to prevent backflow
- The effect of skeletal muscles contracting and pushing on veins
- Residual Blood pressure from the heart
What is the renal vein?
Takes blood from kidney to heart
What is the renal artery?
Takes blood from heart to kidney
What is atheroma?
A build up of fatty plaque in the arteries that can cause thrombosis and increase the risk of aneurysm and can cause a myocardial infraction if it affects the coronary arteries (heart cannot get oxygen or glucose so muscle cells cannot respire)
What is thrombosis?
A blood clot in the arteries
What is an aneurysm?
When stretchy endothelium balloons out through the muscle of an artery
What is a myocardial infraction?
A heart attack
How is the left ventricle different to the right ventricle?
- Highest blood pressure- Most cardiac muscle- Contracts with greatest force- Pumps blood to whole body
What happens to the atria during atrial systole?
They are contracted and at high pressure
What happens to the ventricles during atrial systole?
They are relaxed and at low pressure
What happens to the atrioventricular valves during atrial systole?
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