Cell Physiology Cont'd Flashcards
Types of Receptors:
what are 3 other ex of ligand-gated receptors?
5-HT3
GABAa
Glutamate
Types of Receptors:
what are receptors that control membrane bound enzymes called?
metabotropic receptors
Types of Receptors: Metabotropic receptors
how do they work
when a ligand attaches to its receptor , an enzyme on the cytoplasmic surface (inside) of the membrane is activated a reaction inside the cell is accelerated by the enzyme
Types of Receptors: Metabotropic receptors
what are the most common type of receptors that control membrane bound enzymes
G-protein coupled receptors
Types of Receptors: Metabotropic receptors
what are examples of the receptors
GPCR 7-transmembrane Serpentine Muscarinic ACh receptors (are GPRC) most adrenergic receptors
Types of Receptors:
what type of receptors are integral plasma membrane proteins that when activated by a ligand are either enzymes themselves or part of an enzymatic complex.
Catalytic receptors
Types of Receptors:
what are ex of catalytic receptors
Insulin
EPO
ANP
Types of Receptors:
what type of receptors are proteins located in the cytosol or nucleus, are ligand-activated transcription factors.
Nuclear (intracellular) receptors
Types of Receptors:
how do Nuclear (intracellular) receptors work
link extracelular signals to gene transcription in the nucleus of the cell
Types of Receptors:
what type of drugs exert their cellular effects via the nuclear receptors
Steroid hormones
What spans the thickness of the lipid bilayer
channels
Proteins that span the membrane are called what?
integral or transmembrane proteins
Chemicals that attach to the receptors of the cell membrane are called _____
ligands
Ligands act as what (first or second messengers)?
first messengers
Receptor sites are usually located where?
outside the cell
membrane enzymes are generally anchored where?
inside the cell
Chemicals generated inside the cell by enzymes facing inward from the cell membrane are called what? (1st or 2nd messengers)
Second messengers
what is the 1 exception to the 2nd messengers. All second messengers are released into the cell except this one?
Acetylcholinesterase
-projects outward into the synaptic cleft so it can metabolize ACh
take home message about receptors:
A membrane receptor usually either operates as a _____ or controls an ______
Channel
Enzyme
Signal transduction:
what is it
the relaying of a message from the exterior to the interior of the cell
Signal transduction:
Signal transduction using receptors involves the action of an intermediary protein messenger, which transfers the signal from the receptor to an enzyme. ___ Proteins are the best known proteins for relaying messages from receptors to enzymes
G proteins
what is the name of the membrane stimulatory protein
Gs
What is the name of the membrane inhibitory protein
Gi
on the exterior the 1st messenger attaches to the receptor and Gs or Gi relays or shuttles information to an enzyme. What is the enzyme that it is usually shuttled to?
adenylate cyclase
what is the function of the Na+ K+ pump ATPase pump
keep intercellular K+ high and Intracellular Na+ low
The Na+ K+ pump uses energy derived from the breakdown of ATP to go through a series of shape changes , ultimately moving __ Na+ ions out of the cell in exchange for __ K+ ions that are transported into the cell
3 Na+
2 K+
Remember
How many Na+ And K+ are exchanged
3 Na+ extruded
2 K+ imported
An ____ fits into a receptor and then makes something happen.
Agonist
A _____fits into a receptor but has no direct effect. it prevents the agonist from attaching to the receptor so nothing happens
Antagonist (competative)
Resting Potential:
where are leaky K+ channels located
lipid bilayer
Continuosly open (Leaky) K+ channels are located in the lipid bilayer and permit what?
outward diffusion of K+ down the concentration gradient
What controls the RMP
K+
with acute hyperkalemia the diffusion gradient for K+ in reduced, b/c the rate of diffusion out of the cell is decreased what happens to the RMP?
the resting potential is diminished aka the cell depolarizes (RMP goes from -70 to -60)
With hypokalemia the diffusion gradient for K+ is enhanced, b/c the rate of diffusion out of the cell is increased, what happens to RMP?
The resting potential is increased the cell hyperpolarizes
– RMP goes from -70 to -80
with polarity the (-) negative sign in front of the numerical value for the Resting potential indicated the what?
Polarity
thus hyper polarized is MORE neg
and Hypo or depolarized is more Positive
State the steps of an Action potential
A) RMP at -70mV when the nerve axon depolarizes to threshold the FAST Na+ VOLTAGE GATED CHANNEL snaps open
B) a massive and abrupt depolarizations occurs as Na+ influxes ( RMP +30mV)
C) the fast voltage gated Na+ channels quickly shits in the inactivated state and the voltage gated K+ channels open the diffusion ok K+ out causes repolarization and restoration of the RMP at -70mV
D) the Na+ K+ pump extrudes Na+ that entered the cell a d recaptures the K+ that was lost thus restoring ionic balance
** the leaky K+ channels constantly leak K+ out of cell)
See page 8 in sweat book for a diagram
in the neuron the voltage gated Na+ channels are located princiably where?
the axon and concerted in the nodes of ranvier
what is the term for the period when the gated sodium channel is in the inactivated state?
absolute refractory period
Know this!!!
When are 3 important clinical example r/t the absolute refractory period (inactivated state)
1) cardioplegia
2) SCh administration
3) LA administration
Memory master pages
IA3a-b
