L10;C3 Flashcards
What is the resting membrane potential? What is it permeable to and impermeable to?
Resting membrane potential is (-70mv)
It is impermeable to sodium. Once it’s outside the cell it needs a channel to get back in
It is permeable to potassium. This can leak into concentration gradient
Overall, the cell inside is ______ and outside is ______
Negative, positive
Why si the resting membrane potential -70mv?
Due to there being a high [na] outside the cell and medium [k] inside the cell.
Explain what occurs during:
Depolarization
Hyperpolarization
Depolarization- occurs when inside the cell becomes less negative, (-70-0mv) more Na channels open and Na enters the cell. This is required for nerve impulse to occur
Hyperpolarization- when the inside of the cell becomes more negative, (-70–90mv) more K channels open and leave the cell, makes it harder for them to come back in. And harder for nerve impulse to occur.
Explain the following with respect to Na and K in/eflux:
Inhibitory signal
Excitatory signal
Inhibitory Signal= K efflux—> hyperpolarization
Excitatory signal= Na influx—> depolarization
Explain the difference between temporal summation and summation
More rapid stimuli= temporal summation
Many stimuli in different point= summation
What are the five events during action potential?
- Resting state
- Depolarization
- Propagation of AP
- Repolarization
- Return to resting state with help from Na-K pump
What are the two refractory periods? What happens during them?
Absolute refractory period= when a given segment of an axon is generating AP, it’s Na gates are open and its unable to responded to another stimulus
Relative refractory perid= when Na gates a closed and K are open, it is hyperpolarizing and needs to have greater than normal stimulus to activate
The velocity of an action potential is determined by three things, list nad describe them
Myelinated fibres—> AP is fastest in Salatory conduction. It travels from one node of ranvir to the next.
Diameter of nerve—> larger diameter of the neuron conducts a faster impulse due to less resistance to current flow
Group C neurons—> these are afferent and deal with temperature and are unmyelinated slow in conductivity.
What does the enzyme Cholinestrase do?
This breaks down Ach into choline and acetic acid
Small molecules, _____ acting
Big molecules, ____ acting
Fast, slow
What system is Ach used for with respect to its neurotransmitter pre and post function?
Norepinephrine?
Ach is used as the neurotransmitter for the motors neurns that innervate skeletal muscles in the para sympathetic system
Norepinephrine is the post neurotransmitter for the sympathetic system as well as Ach as pre
Explain what happens with EPSPs and IPSPs
Excitatory Postsynaptic Potential (EPSP)- depolarizes, excitatory, and promotes AP. Has summation which is multiple EPSPs and leads to more depolarization.
Inhibitory Postsynaptic Potential (IPSP)- hyperpolarizing, inhibitory, prevents AP. More summation of this means more inhibitory
How are neurotransmitters destroyed?
Enzymes, they remove them and reap take into terminal.
Four major sites of CNS?
Cerebrum—> mind and intellect
Diencephalon—> thalamus, hypothalamus, sensory integration
Cerebellum—> coordinations of movement
Brian stem—> midbrain, pons, medulla and connects brain to spine
