Arteries and Veins Flashcards
What is the end of the aorta?
Abdominal Aorta
Common illiac artery
Right and left, runs vertically down the pelvic bowl
- Branches into internal + external illiac
Internal illiac supplys
Butt
External illiac runs under
Inguinal ligament
External illiac becomes –> from groin
Femoral artery
The femoral artery runs to the back to become
Popliteal artery
Popliteal –>
Posterior tibial artery
The pos tib artery runs
Down to the sole of the foot and supplies the plantar arch
What is the lower limb drainage pathway (deep)
Next to supply arteries, same names
A vein that is superficial, runs from ankle to the groin
Great Saphenous vein
Great Saphenous Vein and the femoral vein join at
Sapheno-femoral junction and goes deep as approaching the trunk
Layers of blood vessels
Tunica:
- Intima
- Media
- Adventitia (externa)
Tunica intima
*Endothelium - A simple squamous epithelium which lines the lumen of all vessels.
*Sub-endothelium - A sparse pad of loose FCT cushioning the endothelium.
*Internal Elastic Lamina (IEL)- a condensed sheet of elastic tissue, rubbery protein layer. The IEL is well developed in arteries
and less developed in veins. Barrier between this and tunica media
Tunica media, the largest layer
- Involuntary Smooth muscle
- A variable content of connective tissue fibres - mainly elastin and collagen.
- Thickness of the media is proportional to both
vessel diameter and blood pressure.
Tunica Adventitia
- Rich in Loose FCT with a high content of collagen and variable
amount of elastin (amount of elastin depends on recoil) - In larger vessels, the adventitia contains the vasa vasorum.
- Lymphatics and autonomic (sum and para for smooth vasocon + di) nerves are also found in this
region.
What is the vaso vasorum
Network of capillaries that run through the adventitia to supply Larger blood vessels as they are also organs
How is the spindle smooth muscle orientated in the blood vessel
Circumferentially
Thoracic aorta
Branches in the thoracic cavity
Abdominal Aorta
As it runs past the diaphragm
Why is thoracic Aorta elastic
Pulsatile systole and diastole
- Need smooth flow so have lot of elastin to absorb the force of the blood when ventricles push it through and then recoil to push the blood back
- P helps to close the semilun valves
- Lots of elastin found
Why is the femoral artery muscular
Primarily smooth muscle
- Diameter that optimises the fow of blood by altering it (vasocon/di)
What happens at the caps
P drops
Veins –> venules –> Vena cavae
Blood is not repressurised and travles at low P for a large volume
Function of the Arteriole
Determines the resistance of the circulation i.e determines blood pressure
What are capillaries?
Site of exchange between blood
and tissues
Smallest veins
- 1st part of the venous drainage - venules
What do veins have to prevent backflow of blood
Valves
Why does blood flow backwards in veins
Due to the low BP
Functions of veins
- Low pressure, large volume transport system
- One-way (unidirectional) flow
- Capacitance vessels i.e can hold extra blood volume if needed
Structure of the veins
Irregular, flattened shape with large lumen & thin wall, the walls collapse on itself thats why its irregular
Have spare capacity (can take up extra blood
volume) = capacitance vessels as there is pooling of blood in the veins of legs due to g.
- Intima
- Media -Much thinner than arteries as it reflects the P in them - a few layers of
smooth muscle (often in two distinct layers) eg vena cava but not as big as arteries - Adventitia -Often the thickest layer of a vein, while Media is for arteries
Why is the adventitia the largest layer in a vein
Because of the cap factor, ad at some point dont need to carry excess blood so connective tissue in Adventitia determines this i.e the collagen fibres
Why two pos tibial veins?
As the pos tibial artery pumps a high blood V and high P, but veins needs to take back the same volume of blood but can only do so under low P so need more CSA i.e more veins to take it back
What is a neurovas bundle?
Nerves that run closely with arteries and veins
How to know if a vein is superficial or deep
Deep is surrounded by skeletal muscle
What do the valves do?
Valves break up the pressure
What happens during varicose veins
Veins dilate and the leaflets dont elongate so the blood just falls back down
