Cardiovascular System Flashcards
What is vasoconstriction?
Vessels get SMALLER and shrink into layers of fat for protection
What is vasodilation?
Vessels EXPAND and surface over layers of fat, nearer the skin. (red faced)
What is the structure of arteries?
Outer layer of connective tissue containing elastic fibres.
Middle layer containing smooth muscle with more elastic fibres.
Inner endothelium layer.
What is the role of the smooth muscle in the arteries?
They stretch and recoil after each contraction of the heart causing vasoconstriction or vasodilation.
Why do arteries vaso-constrict/dilate?
To control blood flow.
Structure of veins.
Same as arteries but thinner walls and larger lumen. Also contain valves.
Structure of capillaries.
1 cell thick; made from an endothelial cell.
What is the role of capillaries?
Allow exchange of substances with tissues.
Gives examples of substances that can be exchanged in the capillaries.
Water, amino acids, oxygen, CO2, waste molecules, glucose
What is the role of atrioventricular valves?
Prevent blood returning to the atria when the ventricles contract.
What are capillary beds?
Networks of capillaries which are very dense so every living cell is located close to a capillary.
What is the blood composed of?
Red blood cells; White blood cells; Plasma
What is plasma?
Composed of mainly water and other molecules such as Glucose; amino acids, respiratory gases, plasma proteins; useful ions; hormones.
What is pressure filtration?
When the blood is at high pressure arriving from the arteries, the pressure difference causes much of the plasma to be forced through the thin C walls.
What is the plasma called once it is pressure filtrated?
Tissue fluid.
