Cardiovascular System 1 Flashcards
Blood Vessels, Blood Components & Blood Groups
Arteries
Blood vessels which usually carry oxygenated blood away from the heart (except for pulmonary arteries)
they have thick walls and a small lumen to maintain higher pressure so it can travel further along the body
Structure of Arteries
Collagen outer layer (elastic tissue) which helps maintain a high pressure
Smooth muscle, provides control of blood flow (by contracting and relaxing)
(Folded) endothelium layer allows it to stretch a maintain a high-pressure
What do arteries branch off into?
Arterioles
Arterioles
Blood vessels which usually carry oxygenated and blood away from the heart
Structure of Arterioles
They have slightly thinner walls and lower pressure, direct blood flow to areas of the body by contracting and relaxing
What do arterioles branch off into?
Capillaries
Function of capillaries
The smallest blood vessel which has both the thinnest membrane and the smallest lumen (one cell thick) they carry out substance exchange between body cells and the blood
Structure of the capillaries
Endothelium cells which are one cell thick and the lumen allows one cell to flow through at a time
Capillary lumen in relation to substance exchange
The lumen of the capillary only allows one red blood cell to pass through at a time. This helps to drastically decrease the pressure and the speed of blood flow which allows for gas (and ion) exchange to take place more efficiently
Adaptations of the capillaries
They pass by very closely to cells to reduce the diffusion pathway and maximise diffusion rate.
The membrane is one cell thick which provides a short diffusion pathway.
There is a large number of them which increases the surface area for diffusion to take place.
What are capillary beds?
a network of capillaries in tissue
What do capillaries branch up into?
Venules
Venules
Blood vessels, which usually carry deoxygenated blood towards the heart, but do not meet the heart
Structure of Venules
They have slightly thinner walls and the lower pressure then veins
they do NOT have any valves
What do venules branch up into?
Veins
Veins
Blood vessels which usually carry deoxygenated blood towards the heart (except for pulmonary vein)
they have relatively thin walls and valves to pump blood under low pressure under the one direction
Structure of veins
The outermost muscle layer is used to control blood flow by contracting and relaxing
The endothelium inner layer is used for substance exchange by capillaries