Week 4-Nervous system pt2 Flashcards
What is a resting membrane potential (RMP)?
charge difference across the plasma membrane AT REST
Neg inside
pos outside
What charges are inside and
outside of the cell at rest?
I-negative
O-Positive
Why is it necessary to have a RMP in neurons?
RMP exists because of unequal electrolyte
distribution between extracellular fluid
(ECF) and intracellular fluid (ICF)
How does a resting membrane potential exist in a cell—describe the processes occurring and ions involved that result in a resting membrane potential
potassium ions leak out
Na/k pump- pumps 3 na out and 2 k in (losing positive-helps make more negative)
Negatively charged proteins stay inside cell
Level of Na and K inside/outside of cell
Na
I-small
o-large
K
I-large
o-small
action potential
electrical signal sent down axon
Describe how an action potential is generated starting with a stimulus—describe
the processes involved
1- dendrite takes in stimulus to cell body
2-allows na to enter
2-goes into depolarization
Followed by repolarization
a. What could act as a stimulus?
chemical or sensory stimuli
b. Describe what occurs during depolarization phase—describe flow of specific ions and how the membrane potential changes
A Stimulus causes membrane to become more positive
(toward zero) by letting Na+ into the cell
-Allows Na in
-Causes sodium channels to open-causing more sodium to roll into cell
-Each specific channel opens based on its specific threshold-goes down the line, has to get to a specific positivity to open
Makes inside more positive
Threshold
Amount of positivity it takes to open the channel
. Describe what occurs during repolarization phase—describe flow of
specific ions and how the membrane potential changes
occurs when the inside of the cell becomes
a certain positive number
-Na channels close at a certain positivity
-once they close, k channels open
-allow for k to escape out of cell, making cell more negative
Differentiate between continuous conduction and salutatory conduction of an action potential
c- Continuously polarizing and repolarizing until you reach the end of the axon-action potentials - Na and K gates opening and closing
s-Uses myelin- essentially get to skip over the places that are myelinated, makes polarization and depolarization faster
Give location of cell bodies of preganglionic neurons of sympathetic divisions
T1-T12
L1-L2
Give location of cell bodies of preganglionic neurons of
parasympathetic divisions
C.N. III, VII, IX, X (3,7,9,10)
in spinal cord in S2 – S4
In general—where are the ganglion located in the sympathetic versus the
parasympathetic division?
S-Generally very close to spinal cord (Pre-short and post-longer)
P-closer to tissues- (pre-longer and post-short)
What does it mean if a tissue has “dual innervation” by the autonomic motor division?
(both sympathetic and parasympathetic innervate the tissue)
Which tissues ONLY receive sympathetic simulation/innervation (meaning they
do not have dual innervation)?
Smooth muscle in blood vessels
Sweat glands
Adrenal gland
May be alternate receptors (alpha and beta) to allow for alternate response
Name neurotransmitters normally released by pre and post ganglionic neurons in both sympathetic and parasympathetic divisions (not the exceptions)
ACH and N.E
Where are cell bodies of lower motor neurons located?
Brain stem
any part of spinal cord
Name neurotransmitter released by lower motor neurons
ACH
Somatic motor pathway
Upper motor neuron ->
Lower motor neuron ->
LMN releases ACH ->
ACH binds to Nicotinic receptors in skeletal muscle
Parasympathetic pathway
Parasympathetic Preganglionic-> Releases ACH
Bind to nicotinic receptors in ps post
Parasympathetic postganglionic -> Releases ACH
Binds to Muscarinic receptors in cardiac, smooth and glands
Sympathetic Pathway
sympathetic Preganglionic-> Releases ACH
Binds to nicotinic receptor on post
sympathetic postganglionic ->Releases NE
Binds to adrenergic receptors of cardiac, smooth and glands
Differentiate between adrenergic and cholinergic neurons
A-Release Norepinephrine
c-Release ACH
