Exam 2: Vasodilators/Angina Flashcards
(35 cards)
Types of vascular tone
Arteriolar, capillary, venous tone
Describe venous tone and how it’s composition is advantageous
2-3 times larger than arteries. Lack of musculature allows veins to have increased capacitance
Blood vessel diameter relationship to resistance of vessel
The larger the diameter the less the resistance.
Doubling the diameter has resulting in 1/16 of the initial resistance. Larger diameter greater flow. Doubling the diameter increased flow by 16 times.
Steps in Blood vessel contraction
Contraction thru trigger calcium influx. Calcium binds to calmodulin (calcium modulator).
Ca and calmodulin activate MLCK. MLCK attaches Phosphate to Myosin light chain. MLC causes contraction.
What blocks MLCK from activating MLC
cAMP causes a phosphorylation cascade. MLCK is inactivated when phosphorylated. Therefore cAMP blocks contraction of blood vessels.
Venous system functions
Return blood to heart and acts as reservoir for blood volume (veins contain 70% of blood volume).
Angina pectoris definition
Chest pain
Hearts preferred source of energy
Fatty acid oxidation
Classic angina is also referred to as
Angina of effort
List causes of variant angina
Coronary vasospasm
Aka Vasospastic
Aka prinzmetal angina
Unstable angina is also referred to
Angina at rest
Which form of angina is a medical emergency
Unstable angina/angina at rest aka Acute coronary syndrome.
Treatment for classic angina
Reduction of demand.
Meds: can give nitro
Treatment for variant angina
Potent vasodilators, nitrates. Calcium ch blockers can be given prophylactically.
Coronary Blood Flow is Inversely proportional to
coronary vascular bed resistance
Coronary blood flow is directly related to what
Perfusion pressure and duration of diastole.
Myosin light chains active and inactive forms
Myosin light chains are activated when phosphorylated.
MLC are inactive without this phosphorylation
Myosin light chain kinase active and inactive forms
MLCK is active when it is not phosphorylated.
MLCK is inactive when it is phosphorylated.
What inactivates MLCK
cAMP. cAMP causes phosphorylation cascade.
What activates or phosphorylates MLC
MLCK
Nitrates/nitrites impact of vasculature
Increases venous capacitance of large veins. Also decreases force, and wall stress which improves myocyte perfusion. This is the drugs best response.
Large arteries will dilate with large doses.
Nitric oxide activates guanylyl cyclase which activates cGMP. What is cGMPs role in reducing contraction
cGMP strips PO4 from MLC rendering it inactive, leading to relaxation.
What breaks down cGMP
PDE- phospodiesterase
How can we prolong cGMP, thereby increasing duration of relaxation?
PDE can be blocked thru phosphodiesterase inhibitors. This prolongs cGMP presence therefore prolonging relaxation.
