Unit 1 - Structure and function of arteries, veins and capillaries Flashcards
What is the order of blood circulation?
Heart → Arteries → Capillaries → Veins → Heart
What happens to blood pressure as it moves away from heart?
Decreases.
What is lumen lined with?
Lined with cells known as endothelium
What is the endothelial lining surrounded by?
Layers of tissue
Arteries?
- Carry blood away from heart
- An outer layer of tissue containing elastic fibres
- Thick middle layer with smooth muscle containing elastic fibres
- Narrow lumen
- Smooth muscle in arterioles contract and dilate to control blood flow
Capillaries?
Exchange vessels where all exchange with tissues occurs due to 1 cell thick walls
Veins?
- Carry blood back to heart
- Outer layer of connective tissue containing elastic fibres
- Thin muscular middle layer with smooth muscle
- Wide lumen
- Thinner walls due to blood being carried back to heart at low pressure
- Valves present to prevent backflow
What happens to plasma in capillaries?
Forced out due to arriving at high pressure from arteries and passes into tissue fluid
Difference between tissue and blood plasma?
Tissue contains no proteins
Tissue fluid concentration?
High conc. of soluble food, oxygen and useful ions which diffuse down a concentration gradient into nearby cells
How does tissue fluid return to capillaries?
By osmosis
What happens to tissue fluid that doesn’t return to blood?
Absorbed into tin walled lymphatic vessels. Now known as LYMPH.
What happens to lymph?
Lymph returns to the circulatory system via the lymphatic system.
