Lecture 2 - Circulation Flashcards
Do peripheral arteries have a higher elastic or smooth muscle content?
Arteries close to the heart are more elastic in nature, as this allows them to dampen out the pulsatility of blood flow.
Arteries towards the peripheries have more smooth muscle, as this allows them to control the distribution of blood flow.
In histology, what tissue is black, and what is red/purple?
Black = Elastic tissue
Red/purple = Collagen
Describe how the benefits of having more elastic tissue in the arteries closer to the heart
During systole elastic arteries distend and store the potential energy from blood flow. During diastole this energy is exerted on the blood to dampen the pulsaility, in the ascending aorta this causes peak coronary perfusion to occur during diastole, and helps to close the aortic semilunar valve.
Name the layers of an artery from inner to outermost
- Tunica intima
- Tunica media
- Tunica adventitia
What makes up the tunica intima?
One layer of endothelial cells, which are supported by an internal elastic lamina.
The endothelial (simple sqaumous epithelial cells are in direct contact with the blood).
What makes up the tunica media?
And is it thicker in arteries or veins?
Smooth muscle
Thicker in arteries than veins (thicker the media, the higher the pressure)
What makes up the tunica adventitia?
It’s a tensile outer sheath, which consists of lots of elastic tissue and collagen.
The tunica adventitia enables veins to act as capacitance vessels, and allows venous pooling to occur.
This outer tensile sheath limits the expansion of the veins, allowing us to use them as a conduit
The thickest layer in a vein is the tunica adventitia
Make sure you know the difference between nerve, artery and vein.
You can tell it’s a nerve since you can see the fasciles of axons, and for an artery the wall is thicker, and often in post mortum the vein wall is collapsed.
What do venous valves prevent? (bicuspid valves)
They prevent the back flow of blood.
Muscle contraction surrounding the vein act as a pump and assist in venous return.
When these valves stop working you get varicose veins, especially in the superficial veins in the hypodermis, as there is little muscle to act as a pump.
How can you tell the difference between cardiac muscle/smooth muscle cells and skeletal muscle?
Skeletal muscle has peripheral nuclei, whereas smooth and cardiac muscle has a central nucleus
What are the ways substances can be moved from the lumen of a capillary to the interstitial space?
- Direct diffusion
- Diffusion through an intercellular cleft
- Diffusion through pore
- Vesicles
How do we access the right atrium for a procedure?
Via right internal jugular vein
How does the great saphenous vein join to the femoral vein, and how does the small saphenous vein join to the popliteal vein?
Great saph. forms saphenofemoral junction to join femoral vein.
Small saph. forms saphenopopliteal junction to join popliteal vein.
What does the redundency of venous drainage in the lower limb allow us to do?
Use the veins there (most of the time great saphenous vein) for grafts (e.g. bypasses)
