Arteries and Veins Flashcards
Lower limb supply path
Supply path begins at the end of aorta and branches into the left and the right limb. Right common iliac artery branches to form external iliac artery and passes into the limb to femoral artery, from groin down to behind the knee to popliteal artery, below knee branches into posterior tibial artery which runs into sole of foot into plantar arch
Lower limb drainage path
Plantar venous arch is beginning of the venous drainage path. The posterior tibial vein is deep as it runs next to the posterior tibial vein. Runs up popliteal vein, up femoral vein, up to external iliac vein which extends into common iliac vein which goes to the inferior vena cava
What is the great saphenous vein?
The great saphenous vein is superficial (sits just underneath the skin) runs from the ankle to the groin which joins onto the femoral vein and goes deep into the external iliac vein and so on
What are the three layers of blood vessel walls?
Tunica Intima (inner most layer)
Tunica Media (middle layer)
Tunica Adventitia (outer/external layer)
What is the Tunica Intima?
Inner most layer of blood vessel wall lined by endothelium (epithelium which separates blood vessel wall and blood) sitting on sub-endothelium which provides support and cushioning. Sub-endothelium rests on internal elastic lamina which is a sheet of elastic tissue
What is tunica media?
Smooth muscle cells surrounded by connective tissue. A vein that has low pressure blood will have a relatively thin tunica media whereas an artery that has high pressure blood will have a relatively thick tunica media
What is the tunica adventitia?
Outer layer of connective tissue that surrounds blood vessels as loose and richly arranged FCT with variable amounts of elastic tissue where elastic recoil is required
What does this image show?
This compares the thoracic aorta (as it comes off the heart in the thoracic cavity) and femoral artery (artery deep in the thigh). Thoracic aorta is an elastic artery and femoral artery is a muscular artery.
Pink/red staining shows collagen. Media is thicker in aorta than femoral artery
What is the thoracic aorta?
Thoracic aorta is an elastic artery as it has lots of layers of elastic tissue layered up inside the tunica media, making it a very rubbering hose, between the elastic tissue is smooth muscle cells. There is lots of alternating pressure in the aorta as the pump is contracting and relaxing hence the pressure is very pulsatile
What is the femoral artery?
In the femoral artery there are fine strands of elastic tissue, the media is dominated by the muscle component as in capillaries we don’t want pulsatile flow we want smooth flow. Less pulsatile flow = less elastic tissue than in thoracic aorta and more muscular tissue in femoral artery
What is an arteriole?
Found at the end of the supply path (smallest arteries) and drain into the capillaries and exchange surfaces. They resist vessels of the circulation - determine blood pressure. Depending on the rate of contraction you supply more or less restriction for the amount of blood you want to push into the network
What is a venule?
Oxygen depleted carbon dioxide rich blood exchange surfaces into smallest veins, venules. Venules are the first part of the venous drainage once you leave the capillary beds. Blood travels in the direction of the venous valve which ensures the blood only goes in one direction
What are veins?
Veins act as a low pressure system but a large volume transport network, unidirectional from capillaries to the heart. Capacitance vessels - ability to hold additional volume if needed
What is the structure of a vein?
Veins look irregular, flattened, large lumen diameter, thin wall causing surrounding tissue to fall on top of itself post-mortem
They can hold additional blood volume - venous network can only do this
What are the three layers of veins?
Three layers (same names as the arteries), media thinner than in arteries often only few layers of smooth muscle and sometimes in two distinct layers. The adventitia is often the thickest layer due to veins having a capacitance function - controls how much blood volume a vein can have
