Physiology 1: Final Review Flashcards
(48 cards)
cAMP Second Messenger System: Gs, Gi, Adenylate cyclase
Gs stimulate, Gi inhibit adenyl cyclase.
IP3 and DAG Second Messenger System: PLC
PLC membrane bound converts PIP2 into IP3 and DAG. IP3 moves to ER and helps release Ca++ store. DAG remains in membrane and activate PKC, this phosphorylates proteins and causes Ca++ influx
cGMP Secondary Messenger Systems
Membrane bound guanylate yclase helps form cGMP from GTP. NO activates soluble types of guanylate cyclase and increase cGMP. cGMP acts on ion channels (phospohdiesterases) and activates cGMP-dependent protein kinase.
Ca/Calmodulin complex
activates NO synthase which creates NO from argentine.
NO Synthetase
NO formed by breakdown or Arginine. NO acts on soluble guanylate cyclase.
Cholinergic Receptors: Nicotinic vs Muscarinic; #’s, types, means of action (channel vs. G-protein)
Nicotinic: N1 - skeletal muscle, N2 - ganglia. Form pore across membrane, ACh binding causes pores to open.
Muscarinic: M1,3,5 - activate PLC using Gq = increase in intracellular Ca++. M2,4 - inhibit adenylate cyclase using Gi.
Adrenergic receptors: alpha and beta receptors
Beta receptors stimulate adenylate cyclase to produce cAMP and activate PKA.
Alpha1 receptors increase IP3 and DAG or activate Ca-channels using Gq.
Alpha2 receptors inhibit adenylate cyclase by Gi.
Resting Membrane Potentials: Nerves and Muscles
-70mv Nerves, -90mv Muscles
Nernst Equation
E= (61/charge)log([ion]out/[ion]in)
Describe how the P Na/K ration affect membrane potential in a typical cell:
Higher Ratio = more Na and less negative membrane potential, easier to excite
Lower Ratio = more K and more negative membrane potential, less easy to excite
Gastrin
Increases stomach motility
Increases force of contractions
Relaxes pyloric sphincter = gastric emptying
Secreted in pyloric stomach
Motilin
Increases force of stomach contractions
Migrating Motor Complex (MMC)
GIP - Gastic Inhibiting Protein
Decreases gastric motility
Secreted in response to fats in duodenum
CCK
Secreted in small intestine
Decreases stomach motility
Increases gallbladder contractility
Results in EMZYME rich pancreatic secretions
Secretin
Decreases GI track motility
Secreted in response to acid
Results in AQUEUS pancreatic secretions rich in BiCarb
Saliva; relation to plasma, qualities
Hypotonic to plasma, proline rich = antibacterial, amalyases for starch digestion, PNS-vasodilation-increase blood flow
Parasympathetic action on GI track
ACh & Substance P = increased contractions
VIP & NO = decreased contractions
Sympathetic action on GI track
NE = inhibits ACh = blocks Alpha2 receptors, results in vasoconstriction
Nicotinic Receptors
N1: skeletal muscle, blocked by curare
N2: ganglia, blocked by hexomethonium
Muscarinic Receptors
M1 - glands M2 - heart/smooth muscle M3 - smooth muscle/glands M4 - unknown M5 - unknown
M1,3,5 - active PLC vía Gq = increase intracellular Ca++
M2,4 - inhibit adenyl cyclase via Gi
Alpha Receptors
Stimulated: Epi, NE.
Agonist: Phenylepherine
A1; post-junctional, Increase IP3 & DAG via Gq
A2; pre/post-junctional, decrease adenylate cyclase via Gi
Beta Receptors
Stimulated: Epi, NE
Agonist: Iso
B1; heart/kidneys
B2; elsewhere
B3; fat cells
All: increase adenyl cyclase, cAMP, activate PKA
Single Unit vs. Multiple Unit Smooth Muscle
Single Unit: many gap junctions, sparse innervation, slow wave potentials with spontaneous, graded oscillation in membrane potential, plasticity, and stretch induced contraction.
Multiunit: less gap junctions, higher innervation ratios, stable membrane potentials without spontaneous depolarization.
Economy and Efficiency of Smooth Muscle
Lower efficiency in smooth muscle due to 2 ATP requirement for light chain phosphorylation.
Economy is higher because ATP use is low when maintaining contraction force (latch state).