Exam 2 Flashcards
Proteins that form gap junctions
Connexins
Gap junctions
Channels that allow direct communication between neighboring cells.
How many connexins assemble to form a connexon.
6
Electrical synapse
Direct conduction of electricity between two cells through gap junctions allowing for fast communication.
Chemical synapse
Release of neurotransmitters into synaptic cleft which selectively activate receptors on the post synaptic cell surface resulting in change in the post synaptic cell
What is the functional role of vesicles at the synapse?
Vesicles at the synapse play a role in release of neurotransmitters
How is vesicle release at the synapse coordinated?
Depolarization, calcium entry, and SNARE proteins.
Down regulation
Describes a decrease in the number of receptors on the surface of target cells –> this makes cells less sensitive to a hormone/NT
If a change in PNa on a post synaptic neuron caused hyperpolarization, did PNa increase or decrease?
Hyperpolarization –> decrease
What ion plays the most direct role in fusion of vesicles to presynaptic membrane and release of NT?
Calcium
If mitochondria are carried from the cell body to synapse via fast axonal transport, what protein is most likely involved?
Kinesin
A hyperpolarizing graded potential is…
inhibitory to the generation of an action potential
Which ion gradient typically provides the energy for uptake of a neurotransmitter into vesicles in the presynaptic nerve terminal?
Hydrogen ion gradient
Opiate drugs activate on which receptor
Metabotrophic receptors
Do all metabrotropic receptors have the same effects?
No, they have different effects. May be depolarizing or hyperpolarizing.
Naloxone is sometimes used to reverse heroin overdose because…
it is a receptor antagonist that attaches to opioid receptors w/o activating them. It binds w/ a higher affinity than heroin and prevents heroins attachment to the receptor.
If overtime the sensitivity of a synapse has diminished due to repetitive stimulation what is the most likely reason?
The number of postsynaptic receptors is increased.
A drug like cocaine slows the neurotransmitter dopamine from the synaptic cleft. Under normal conditions, what ion gradient provides the driving force for dopamine reuptake?
The sodium gradient across the presynaptic membrane
Botox…
decreases fusion events
cAMP increase leads to activation of…
protein kinase A
Which subunit of heterotrimeric G protein is released when the receptor is activated?
Alpha
What is a TEER?
Trans epithelial electrical resistance is an indicator of the tightness of the epithelium
Aquaporins
Amphipathic integral membrane proteins that form water channels
What is an estimate for the thickness (apical-basolateral dimension) of an enterocyte cell layer?
25-30 um
The selective permeability of tight junctions is primarily influenced by…
claudin proteins associated with the tight junction complex
