Lecture 7 02/17/2014
Neurotransmitter: norepinephrinesmall derived from an amino acid; also derived from a pathway that other
neurotransmitters could come from.
Peripheral actions of norepinephrine in flightorfight:
NT on the peripheral can have different targets and actions (muscle and organs) ▯caused by stress or any
real threat to homeostasis; it can be moderate or severe, the magnitude can change
Heart: cardiac, increase function; rate or strength of contraction
Beta 1 norepinephrine receptorsincrease contractilitystrength of contraction. Beta 1 adrenergic receptor
and together it can increase cardiac output which is proportional to blood pressure. Hypertension: high
blood pressure, so you would want to prevent norepinephrine from acting on Beta 1 receptors, so:
Block with an antagonist: betablockers (first treatment)
Smooth muscle: involuntary muscletends to surround structures that can expand and collapsestomach,
bladder, blood vessels.
Blood vessels: Beta2 receptors: results in dilation, vasodilator.
Stomach and kidneys have alpha receptors and norepinephrine binds to alpha receptors and it results in
vasoconstriction, narrowing of blood vessels.
Same tissue, same vascular structure, yet the muscle knows it’s going to skeletal muscle with the different
receptors. Skeletal muscle will have beta receptors.
The signals for fight or flight go to the hypothalamus and the cortex.
Pulmonary smooth muscle: Beta2 receptors, results in bronchodilatoin. Beta2 is related to cAMP and to
Asthma and hypertension: use betablockers, but with asthma?