Vascular Structure and Function in Hypertension Flashcards
what is the function of penyephrine?
-alpha 1 adrenergic powerful vasoconstrictor
-can constrict blood vessels in the nose to help with breathing
-alpha 1 antagonist used to be used to treat hypertension but not anymore
what happens to blood vessels as we age?
blood vessels will not be able to change diameter as much
what naturally causes vasodilation?
-release of nitric oxide by endothelial cells usually causes vasodilation of blood vessels
how does systolic BP change with age?
increases
what effect does oestrogen have on vessels?
powerful vasodilator
what does oestrogen administation do?
promotes vasodilation in humans and in experimental animals by stimulating prostacyclin and nitric oxide synthesis as well as decreasing the production of vasoconstrictor agents such as cyclooxyrgenase derived products, reactive oxygen species, angiotensin II and endothelin-1
what is the normal vascular structure (outer to inner)?
-perivascular adipose tissue
-tunica adventitia
-tunica media
-internal lamina
-tunica intima
what is the tunica adventitia?
nerves, external lamina, adventitial, fibroblasts, elastin, collagen, immune cells
what is the tunica media?
smooth muscle cells
what is the internal lamina?
between tunica media and intima
contains small holes which allow endothelial cells in tunica intima below, to communicate with smooth muscle cells in the tummy media
what is the tunica intima?
endothelial cells
how are smooth muscle cells arranged in vessels?
arranged helically like springs in the blood vessels
why is the function of smooth muscle cell structure?
blood pressure passing in these resistance vessels is dampened by these spring like smooth muscles
what is pulse wave velocity?
measurement of the effectiveness of dampening
what does high pulse wave velocity mean?
more recoiling which means blood pressure is not dampened by the springs due to stiffness of vessels
what does hypertension cause in blood vessels?
blood vessel remodelling
increased tunica media - lumen ration
thicker tunica media, narrower lumen
what are the effects of rats hindlimb unloading on their basilar artery (similar to being space)?
-if back legs raised, less blood will travel to them and instead the blood will go back to the brain
not good as brain requires constant blood supply
-basilar artery which goes to the post brain, remodels. the tunica media thickens and lumen narrows to keep blood flow to the brain constant
how does length affect flow?
flow is linearly proportional to length
doubling length doubles the time taken to pass through
how does radius affect flow?
small changes in radius have profound changes in flow
doubling radius causes time taken to pass through increase by 16 times
what is hypotrophic remodelling?
wall becomes thinner
lumen can still move inwards/narrow or outwards
what is hypertrophic remodelling?
walls become thicker
lumen can still move inwards
what is eutrophic remodelling?
material int he walls stays the same but the lumen becomes narrower or wider (happens in hypertension)
what happens to tunica intima during hypertension?
holes within the tunica intima will decrease in size
What is the most likely vascular remodelling expected in a patient with chronic hypertension?
Thickening of tunica media
Which layer of the blood vessel is the smooth muscle layer?
Tunica media
