Cardiovascular System 1

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

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

Arterioles

Blood vessels which usually carry oxygenated and blood away from the heart

They have slightly thinner walls and lower pressure, direct blood flow to areas of the body by contracting and relaxing

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

Endothelium cells which are one cell thick and the lumen allows one cell to flow through at a time

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

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.

a network of capillaries in tissue

Venules

Blood vessels, which usually carry deoxygenated blood towards the heart, but do not meet the heart

They have slightly thinner walls and the lower pressure then veins they do NOT have any valves

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

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

They help prevent blood back flowing as the blood is flowing much slower due to the low pressure

Blood flow is assisted by contraction of muscle cells near the veins

Plasma Platelets Red Blood Cells White Blood Cells

A pale straw coloured substance which carries (mainly) waste products away from cells to where they’re disposed of (e.g. CO2 to the lungs)

Carbon Dioxide Urea

amino acids glucose proteins RBC WBC hormones electrolytes

aka platelets