ANS intro Flashcards
Exam 4
Two main neurotransmitters
- ACh
- NE
Cholinergic
-fibers that secrete ACh
Adrenergic
-fibers that secrete NE
Synthesis of ACh
- choline comes in with Na+
- choline binds to Acetyl-CoA and gets made into ACh
- calcium comes into cell and causes release of ACh into synaptic cleft
Preganglionic nerve fibers
In ANS release ACh
Postganglionic nerve fibers
- only certain release ACh
- those that activate PNS
- those that go to the somatic nervous system
- those that activate sweat glands (only somatic nervous system response activated by ACh)
Norepinephrine
released by postganglionic nerve fibers
Epinephrine
- released by adrenal medulla
- preganglionic sympathetic neurons that release ACh
- ACh acts on nicotinic receptors of adrenal gland
Dopamine
- released by postganglionic sympathetic neurons
- effect renal vascular smooth muscle
Adrenergic fibers
-only found in somatic nervous system
Synthesis of NE
- tyrosine goes through hydroxylation into dopa
- dopa goes through decarboxylation into dopamine
- dopamine is transported in a vesicle where the rest of synthesis takes place
- dopamine goes through hydroxylation into norepinephrine
- in the adrenal medulla NE goes through methylation into epi
Acetylcholine receptors
- Muscarinic
- Nicotinic
Muscarinic subtypes and location
- M1: nerves
- M2: heart, nerve, smooth muscle
- M3: exocrine glands, smooth muscle, endothelium
- M4: CNS
- M5: CNS, vascular endothelium
Nicotinic subtypes and location
- N(n) or N1: CNS, postganglionic cell body
- N(m) or N2: skeletal muscle neuromuscular junctions
Cholinergic receptors
- ACh binds equally to N & M receptors, but drugs do not
- drug that blocked primarily nicotinic receptors would affect everything
- drug that blocked muscarinic receptors would block the PNS response and sweating
Cholinergic effects - Muscarinic symptoms
- SLUDGE M
- salivation
- lacrimation
- urination
- defecation
- gastric emptying
- emesis
- miosis
Cholinergic effects - nictoinic symptoms
- MTWTF
- muscle cramps
- tachycardia
- weakness
- twitching
- fasciculation (like a tremor)
Adrenergic receptors
- bind NE and Epi at target organs of the sympathetic nervous system
- Alpha and beta
Alpha 1
- postynpatic effector cells
- smooth muscle constiriction
Alpha 2
- presynaptic adrenergic nerve terminals
- decreased sympathetic outflow
Beta 1
- postsynpatic cells in heart, lipocytes, brain
- presynaptic cells at renal tubules
Beta 2
-postynaptic effector cells of smooth muscle
Beta 3
-postsynaptic effector cells of lipocytes and heart
