Physiology Flashcards
what extrinsic mechanisms increase stroke volume
- sympathetic system on heart
- sympathetic system on venous return
- skeletal muscle pump
- thoracic pump
- increased activity in the RAAS
what are the molecular mechanisms by which the sympathetic system increases stroke volume
- activation of beta 1 adrenergic receptors on the ventricles
- increased cAMP
- increase in PKA
- phosphorylation of L type ca2+ channels allowing increased ca2+ entry
- constriction of veins through the activation of alpha 1 adrenergic receptors
- increases IP3 which leads to an increase in conc of Ca2+, leading to increase in Ca2+ calmodulin, activation of MLCK and phosphorylation of MLC which causes contraction of smooth muscle
name 2 systems that can regulate total peripheral resistance
- sympathetic system
- RAAS
describe the mechanism of action of the sympathetic system in regulating total peripheral resistance
- either activates alpha 1 adrenergic receptors to cause an increase in TPR
- or activates beta 2 adrenergic receptors to cause a decrease in TPR via an increase in cAMP, increase in PKA and phosphorylation of MLCK which inhibits its action so smooth muscle relax
describe the mechanism of action of RAAS in regulating total peripheral resistance
- RAAS increases TPR by the actions of AngII on AT1 receptors
- increases IP3
- increases intracellular Ca2+
- increases ca2+ calmodulin
- increases activation of MLCK
- increases phosphorylation of MLC
- increases smooth muscle contraction
which hypertensive would be frontline treatment for a black person of African or Caribbean origin
calcium channel blocker
which antihypertensive would be frontline treatment for a British Indian patient aged 45 years old with no other comorbidities
ACE inhibitors
which antihypertensive would be frontline treatment for a patient aged 45 years old with hypertension and benign prostatic hypertrophy
alpha 1 antagonist
why do ACE inhibitors cause a cough in about 20% of patients
they inhibit the breakdown of bradykinin which can then activate sensory nerves in the airways to cause the cough