lecture 2- Receptors Flashcards
Nicotinic receptors 1. (Nn) mechanism/response
2. NM mechanism/response
3. Nn in adrenal medulla
4. what NT?
opens Na+/K+ channels which leads to depolarization/
skeletal muscle contraction or depolarization of postganglionic (synaptic) neuron or depolarization of medullary cells (release of catecholamines- mostly Epi); ACh
M1 receptors: M stands for? PSNS or SNS? Nuerotransmitter? location? response? mechanism?
Muscarinic - G protein PSNS ACh autonomic ganglion depolarizes postsynaptic neurons (slow EPSP- depolarization below threshold) ^PLC, ^IP3, DAG Ca++ (G q response)
M2 receptors: M stands for? PSNS or SNS? Nuerotransmitter? location? response? mechanism?
Muscarinic (G protein)
PSNS
ACh
Heart
Response:
dec. Heart rate (chronotropy)
dec. conduction velocity at AV node (dromotropy)
dec. I-f aka: dec. funny current,
dec. I-CaL L type Ca current,
Inc I-K-ACh (K+ leaves-hyperpolarizes)
dec. ATRIAL contractile force (inotropic)
Gi- dec. Adenlyl cyclase, dec. cAMP;
inc. K+ channel efflux, dec. Ca++ channel influx
M3 receptors on smooth muscle: M stands for? PSNS or SNS? Neurotransmitter? location? response? mechanism? also M3 on secretary glands. response? innervated by
- Muscarinic (G protein)
- PSNS
- ACh
- smooth muscle of eyes, bronchioles, GI tract, Urogenital system
- contraction
- Gq: activates Phospholipase C, inc. IP3, inc. DAG, inc. Ca++
- increase secretion
- sympathetic
M3 receptors on vascular endothelium: M stands for? PSNS or SNS? Nuerotransmitter? location? response? mechanism?
- Muscarinic (G protein)
- Parasympathetic NS
- ACh
- vascular endothelium (NOT smooth muscle)
- dilation
- atypical Gq: Ca++/CaM activates eNOS, inc. in NO, inc. cGMP which leads to relaxation
Adrenergic A1 receptors on smooth muscle:
location
response
mechanism
- smooth muscle- eye, vascular, urogenital, hair follicles
- contracts smooth muscle
- Gq: PLP, inc. IP3, inc. DAG, inc. Ca++
Adrenergic A2 receptors:
locations (4)
response (4)
mechanism (2)
1-axon terminals- dec. NE - Gi- inc. K+ release
2-pancreatic beta cells- dec. insulin
3-vascular smooth muscle- contracts -Gq
4-platelets-aggregation
mechanism: Gq or Gi
Adrenergic B1 receptors (2):
location (2)
response (2)
mechanism
All B adrenergic receptors are Gs
-heart- inc. HR (chromo), inc. conduction velocity thru AV
node (dromo), inc. contractility (inotropic)-Gs- inc. Ca++
-kidney juxtaglomerular cells- inc. renin release-Gs inc. Ca+
Adrenergic B2 receptors (2)
location
response
mechanism (1)
All B adrenergic receptors are Gs
smooth muscle (eye, bronchioles, GI, urogenital, vascular)-relaxes smooth muscle- Gs/MLCK
heart- inc
what adrenergic receptors does the liver have?
A1-
- INC gluconeogensis, glycogenolysis (glycogen splitting)
- Gq: PLP, inc. IP3, inc. DAG, inc. Ca++
B2-
-INC gluconeogensis, glycogenolysis (glycogen splitting)
Gs- inc. cAMP, inhibition of MLCK
what adrenergic receptors does skeletal muscle have?
lipocytes?
skeletal muscle:
B2-INC gluconeogensis, glycogenolysis (glycogen splitting)
Gs- inc. cAMP, inhibition of MLCK
lipocytes:
activates lipolysis- inc. adenyly cyclase, inc. cAMP
D1 receptors- neurotransmitter location response mechanism
dopamine (DA)
vascular smooth muscle- especially renal vasculature
dilates renal vasculature
Gs- inc. in cAMP
D2 receptors- neurotransmitter location response mechanism
dopamine (DA)
axon terminals (autoreceptors), cholinergic neurons in the gut
decrease DA release, decrease GI motility
Gi- dec. in cAMP, dec. in Ca++
Eye- pupil diameter
1-iris circular muscle
-receptors? effects?
2-iris radial muscle
-receptors? effects?
1- iris circular sphincter muscle
M3-muscle constriction- miosis
B2-slight relaxation (mydriasis)- small effect
2-iris radial dilator muscle
A1-muscle contraction- mydriasis (biggest pupil dilator)
Eye- lens shape
cilliary smooth muscle
M3-muscle contraction-relaxes ligaments-increased lens diameter- accommodation for near vision
B2-muscle relaxation- stretches and pulls ligament-thinner lens- far vision (slight effect)
