blood vessels

what are the 3 types of blood vessels?

- arteries

- veins

- capillaries

what are the 4 types of arteries?

- large elastic (conducting) arteries

- medium muscular (distributing) arteries

- arterioles

- metarterioles

what are the 3 layers of large and medium arteries?

- tunica intima

- tunica media

- tunica adventitia

what are the 3 components of the tunica intima?

- endothelium

- subendothelium

- internal elastic lamina

what are the 3 components of the tunica media?

- myocytes

- elastin

- collagen

what lies in between the tunica media and tunica adventitia?

external elastic lamina

what are the 3 components of the tunica adventitia?

- fibres

- fibroblasts

- vasa vasorum (neurovascular bundle)

which layers do arterioles not have?

- internal elastic lamina

- external elastic lamina

how is smooth muscle arranged in metarterioles?

rings called precapillary sphincters

what are the 2 layers of capillaries?

- endothelium

- basement membrane

what are 3 types of capillaries?

- continuous

- fenestrated

- sinusoidal

where are continuous capillaries found? (2)

muscles and skin

what can pass through continuous capillaries? (2)

- water

- some ions

where are fenestrated capillaries found? (2)

kidneys and small intestine

what can pass through fenestrated capillaries?

slightly larger molecules

where are sinusoid capillaries found? (3)

spleen, liver and bone marrow

what are the features of sinusoid capillaries? (2)

- intercellular gaps in endothelium

- incomplete basement membrane

what can pass through sinusoid capillaries? (2)

cells and proteins

what are the 3 types of veins?

- post-capillary venules

- venules

- veins (small, medium and large)

what is the structure of post-capillary venules? (2)

- similar to capillaries but with pericytes

- slightly more permeable

what is the structure of venules? (2)

- endothelium associated with pericytes (smooth muscle cells)

- contain valves to prevent backflow

what are the 4 layers of a vein?

- endothelium (and valves)

- basement membrane

- smooth muscle

- adventitia

what are venae comitantes?

- deep paired veins wrapped together with an artery in one sheath

- pulsations of the artery promote venous return of paired veins