L87- Physiology of hypertension 2 Flashcards
What is the volume during cardiac output at rest?
5.8L/min
What is the volume during cardiac output at vigorous exercise?
25.6L/min
What is the flow of blood like during vasoconstriction?
slower flow
what happens to pressure and resistance during vasoconstriction?
increases
what is the 3 layers in arteries and veins?
Tunica intima – innermost, includes the endothelium -
squamous cells
Tunica media – middle, mainly circular smooth muscle and elastin
Tunica adventitia –fibrous connective tissue, rich in collagen and elastin
what are the structure of cardiac, smooth and skeletal muscles cells?
- cardiac= branched
- skeletal= in fibres
- smooth= not always contractile cells
how does muscle contraction occur in smooth muscles?
- Intracellular Ca2+ concentrations increase when Ca2+ renters the cell and is released from the sarcoplasmic reticulum.
-Ca2+ binds to calmodulin
-Ca2+ –calmodulin activates myosin light chain kinase (MLCK)
-MLCK phosphorylates light chains in myosin heads and increase myosin ATPase activity
-Active myosin cross bridges slide along actin and creates
muscle tension
How many Ca2+ molecules can calmodulin allow to bind to itself?
4
what is wall shear stress?
is a frictional force parallel to the wall at the surface of the endothelium directly related to blood flow velocity.
what does shear stress cause to happen?
stimulates Nitric oxide production
What is eNOS?
NITRIC OXIDE SYNTHASE
How is NO produced and what happens next?
- eNOS synthesises NO which is readily diffused across the plasma membrane into smooth muscle cell
- where it activates guanylyl cyclase cGMP
- this leads muscle relaxation and blood vessels dilating
what are the 3 variables that resistance depend on?
- blood viscosity
- vessel length
- vessel radius
