AUTONOMIC NERVOUS SYSTEM Flashcards
where is the control center of the ANS
-no true pinpoint of control center but hypothalamus is heavily involved
-hypothalamic neurons project into brainstem down spinal cord to synapse with autonomic neurons
where are parasympathetic neurons located
travel through cranial/vagus nerves out through brainstem to innervate organs
where are sympathetic neurons located
-travel through thoracic nerves + some lumbar nerves to innervate same organs + kidney
-some cause adrenal gland (on top of L/R kidney) to release epinephrine into bloodstream which will travel to organs (hormone)
sympathetic/parasympathetic innervates the kidney
sympathetic only
sympathetic neurotransmitter
norepinephrine
-epinephrine as the sympathetic hormone
parasympathetic neurotransmitter
ACh
name of receptors for nor/epi
adrenergic receptors
-for sympathetic
name of receptors for ACh
muscarinic cholinergic receptors
-for parasympathetic
general pathway of hypothalamic neurons to ANS neurons
neurons in limbic system (emotional center, gray matter) synapse with hypothalamic neurons ->
hypothalamic neurons synapse with sympathetic/parasympathetic neurons
metabotropic
initiate a G-protein pathway
muscarinic cholinergic receptors initiate what pathway
G-protein pathway (metabotropic)
-when ACh binds, initates G-protein pathway that will illicit parasympathetic response
adrenergic receptors initiate what pathway
G-protein pathway (metabotropic)
-when epi/nor binds, initiate G-protein pathway that will illicit sympathetic response
how do nicotinic cholinergic receptors work
-ionotropic- open up for ions to travel through
-these are the ACh receptors at NMJ -> located on fibers, allow sodium to enter + depolarize to generate AP
can muscarinic + adrenergic receptors be both cAMP + IP3/DAG pathways
yes- just not on the same organ
-this is so that we can produce different responses from those organs
cAMP pathway
neurotransmitter binds to receptor ->
alpha swaps out GDP for GTP + disassociates away from beta/gamma ->
alpha activates adenylate cyclase, which converts ATP to cAMP ->
cAMP activates kinases which phosphorylates things
IP3/DAG (PIP2) pathway
-neurotransmitter binds to receptor -> alpha swaps out GDP for GTP + disassociates away from beta/gamma -> alpha activates phospholipase C, which converts PIP2 into IP3 + DAG
-IP3 opens SR channels so calcium can spill out + cause contraction of SMOOTH MUSCLE (not an actin/myosin interaction)
-DAG activates protein kinases, which phosphorylate things
classes of adrenergic receptors
Alpha
* Alpha 1: IP3/DAG
* Alpha 2: cAMP
Beta
* Beta 1: cAMP
* Beta 2: cAMP
* Beta 3: cAMP
adrenergic receptor on smooth muscle lining of blood vessels
alpha 1
describe alpha 1 receptor pathway on blood vessels
-nor/epi binds to adrenergic receptor -> IP3/DAG pathway occurs -> IP3 goes to SR + releases calcium, causing smooth muscle to contract -> blood vessels narrow
-blood vessels narrow in response to sympathetic nervous system -> important so that blood can be shunted to areas needing it
adrenergic receptor on smooth muscle lining of lungs
beta 2
describe beta 2 receptor pathway on lungs
-nor/epi binds to adrenergic receptor -> cAMP pathway occurs -> increase in cAMP activates protein kinases, which inhibit smooth muscle contraction
-smooth muscle relaxation causes lungs to dilate + diameter of bronchioles will increase so more air can come in/out
-sympathetic nervous system does this to oxygenate blood + blow out CO2 during exercise
