Circulatory System Anatomy - Arteries and Veins Flashcards
What is the path of the arteries from the hip to the foot?
- Right common iliac artery
- External iliac artery
- Femoral artery
- Popliteal artery
- Posterior tibial artery
- Plantar arch
What is the path of the veins from the foot to the hip?
- Plantar venous arch
- Posterior tibial vein (deep)
- Popliteal vein (deep)
- Femoral vein
- External iliac vein
- Common iliac vein
Great saphenous vein is an example of a vein that is superficial and takes blood from the foot to the hip.
What are the names of the layers that make up the wall of blood vessels?
- Tunica Intima
- Tunica Media
- Tunica Adventita (Externa)
Describe the layers of the Tunica Intima
- (innermost layer of 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. the IEL is well developed in arteries and less developed in veins.
This layer should be a thin layer in a healthy vessel
Describe the make up of the Tunica Media
- Smooth muscle (circumferential so can constrict and dilate blood vessels)
- A variable content of connective tissue fibres - mainly elastin and collagen
- Thickness of the media is proportional to both vessel diameter and blood pressure (so if vessel carries higher pressure blood this layer will be thicker)
Should be the thickest layer in a healthy blood vessel
Descibe the make up of the Tunica Adventitia (Externa)
- Loose FCT with a high content of collagen and variable amount of elastin
- In larger vessels, the adventitia contains the vasa vasorum
- Lymphatics and autonomic nerves are also found in this region
Will have varying amount of elastin in this layer, depending on where it is in the body
What are vasa vasorum?
Blood vessels present in the walls of thicker blood vessels (vessels of the vessel). It supplies the wall with nutrients and removes waste when diffusion can’t get to all the tissue because its too thick.
Why do we have elastic and muscular arteries?
Elastic artery:
- Has a thicker wall if carrying blood under higher pressure. Has a LOT of elastic tissue which makes it like a rubbery pipe.
- The elastic tissue stores the energy and recoils which allows them to maintain a relatively constant pressure gradient despite the constant pumping action of the heart.
- Found closer to the heart
Muscular artery:
- Found further away from the heart and closer to the diffusion surface as they control blood flow via contraction and dilation
What are Arterioles?
- Arterioles are very small blood vessels.
- Their function is the resistance vessels of circulation and they determine blood pressure.
- If the arteriole narrows then central blood pressure increases, and if the arteriole widens then the central blood pressure lessens.
What are Venules?
The smallest veins are called venules. They are the start of the collecting (drainage) system
Describe the features of veins
- Low pressure, large volume transport system
- One-way (unidirectional flow) - with valves to stop backflow when gravity or contracting skeletal muscles around the vein try to affect the direction of blood flow
- Capacitance vessels (can take up extra blood volume at times)
Three layers:
- Intima
- Media - much thinner than arteries because lower blood pressure here - a few layers of smooth muscle (often two distinct layers)
- Adventitia - often the thickest layer of a vein so that when it takes on extra blood volume it stretches and then can tell the body when it can’t hold any more blood
Describe varicous veins and how they occur
Varicose veins occur when the vein keeps stretching until it gets so wide that the valve leaflets don’t close anymore. This means that when upright, the blood can go backwards and so you get the big veins in your legs, that are lumpy and twisted because the veins are stretched longer and wider.
