Week 8 - Blood & Blood Vessels Flashcards
What are the main types of bv
Arteries
Arterioles
Capillaries
Venules
Veins
Define vascular tone
Ability of muscle in vessels to contract + maintain a state of partial contraction.
– Important in maintaining vessel pressure + efficient bf.
Where does microcirculation occur
Arterioles
Capillaries
Venules
List the Tunics of a bv
Tunica interna / intima
Tunica Media
Tunica Externa / Adventitia
Whats on the inner most layer of the tunica interna / intima
Endothelium – Thin layer of flattened cells
What on the the tunica interna facilitates efficient bf by ⬇️ surface tension?
Smooth luminal surface
What is deep to the endothelium on the tunica intima / interna
Basement membrane
What does the basement membrane of the tunica interna do?
Provides physical support for the epithelial layer.
Anchors endothelium, to underlying connective tissue
+ regulates molecular movement.
What is the most outer part of the tunica interna?
Internal elastic lamina
= Thin sheet of elastic fibres w/ a no. of window like openings to facilitate diffusion.
Describe the tunica media
Muscular + connective tissue of mainly smooth muscle + lots of elastic fibres.
What is the role of the smooth muscle in the tunica media
Reg. diameter of lumen via vasoconstriction/dilation.
Also contracts when a small artery or arteries are damaged to help limit loss of blood.
What does the tunica externa consist of
Elastic + collagen fibres.
Nerves, tiny bv + lymphatics
What are the vasa vasorum
Small vessels that supply blood to the tissues of the tunica externa.
What are the 2 types of arteries
Elastic
Muscular
Examples of elastic arteries
Aorta + pulmonary trunk
Both conducting arteries
What is the function of the aorta + pulmonary trunk in being elastic arteries
Propel blood onward while ventricles are relaxing.
What is meant by the elastic arteries functioning as a pressure reservoir
Their walls stretch to accommodate surge of blood = elastic fibres momentarily store mechanical energy.
Fibres recoil + convert pot. energy into KE of the blood
If elastic arteries are known as conducting arteries, what are muscular arteries known as?
Distributing arteries
– Distribute blood to arterioles
Tunica interna of arterioles
Thin
Fenestrated internal elastic lamina that disappears distally.
Tunica media of arterioles
1-2 layers of circular smooth muscle
– Form precapillary sphincters at distal end
Tunica externa of arterioles
Loose collagenous connective tissue
Unmyelinated sympathetic nerves
What part of the arteriole has the precapillary sphincters
Metarteriole
Where the metarteriole-capillary junction is formed
Function of arterioles
Regulate blood flow into cap. networks
What causes resistance to blood flow in bv
Friction between blood + inner walls of bv.