Lecture 4: Hormonal Control Of The Heart Flashcards
What is characteristic of the postganglionic neurons from the adrenal medulla?
No axon - blood used as transport
What does an inotropic agent affect?
Contractility
What does a chronotropic agent affect?
HR
What are the actions of adrenaline?
Adrenaline has positive inotropic and chronotropic action, coronary vasodilation and systemic constriction.
Where are beta 1 receptors, what is there effect and what neurotransmitter acts on them?
Nodes and heart muscle
Increase HR and contraction
Respond to adrenaline
Where are beta 2 receptors, what is there effect and what neurotransmitter acts on them?
Coronary vessels
Dilation
Respond to adrenaline
Where are alpha 1 receptors, what is there effect and what neurotransmitter acts on them?
Heart muscle
Increase contraction
Respond to noradrenaline
Where are alpha 2 receptors, what is there effect and what neurotransmitter acts on them?
Systemic Vessles
Constrict
Respond to noradrenaline
What does beta-1 do to increase contraction?
Increase calcium current, SR calcium ATPase, SR calcium release
What is the beta 1 pathway?
Gas - alpha subunit - adenylyc cyclase - cAMP -PKA activation - faster calcium transients
What is the alpha 1 pathway?
Gq beta&gamma activate PLC PIP2 - DAG & IPS PKC activated Increase pH Increase myofilament calcium sensitivity
What is the normal myocyte pH?
7.1
How much does beta stimulation increase force?
20%
How much is calcium transit increased by beta stimulation?
400%
What is endothelin 1?
21 aa peptide