3.2 Flashcards
What is the outermost layer of the artery and what is its function?
Connective tissue and collagen which strengthen the outer wall to protect the artery from over-stretching and the pressure exerted by other organs.
What is the middle layer of the artery and what is its function?
Smooth muscle cells ( lined with endothelium cells- squamos epithelial cells) can contract and relax to control the lumen diameter- controlling b.p.
What is the inner layer of the artery and what is its function?
Elastin allows arterys to stretch at high pressures and recoil at lower pressures.
What are arterioles?
Arterioles are small blood vessels that distribute the blood from an artery to the capillaries.
What rings around the arterioles and what is this for?
Rings of smooth muscle contract and relax to control the blood flow, directing it to certain parts of the body (typically parts which require more oxygen).
What are the adaptations of capillaries?
- Very narrow diameter slows the blood flowing allowing more efficient diffusion between blood and surrounding cells
- Walls = one cell thick to shorten diffuion pathway- increasing rate
-leaky walls allow the diffusin of plasma and dissolved substances to leave the blood
Name the key thing about capillary beds
Precapillary sphincters open and close to control blood flow. When sphincters are open, the blood is diverted and travells in a matrix of capillaries. When the sphincters are closed, the blood is unable to travel into a closed capillary and is directed to an area of higher demand.
What is a venule and what is it made of?
Venules receive blood from the capillaries in the capillary bed and transport it to the veins. The venule walls consist of collagen and elastin.
What is the outermost layer of the vein and what is its function?
Collagen provides strength to the outer wall of the veins. This protects the vein from over-stretching and from high pressure exerted by other organs.
What is the inner layer of the vein composed of and what is its function?
Only a small amount of elastin and smooth muscle. There’s no pulse in the veins so they do not need to strech and recoil.
explain the function of pocket valves in the veins
Skeletal muscles nearby the vein (that it runs through) contract, opening the valves and pushing the blood forward towards the heart. When these skeletal muscles relax, the valves close, preventing the backflow of blood.
What is hydrostatic pressure?
The pressure exerted on any liquid (the liquid will always flow from high to low pressure)
What is oncotic pressure?
The osmotic pressure exerted on water caused by dissolved solvents. (e.g plasma proteins)
