Unit 2: Neurophysiology Flashcards by Salina H Huy

In the nervous system of the body…

The only true afferents in reflexes are ______
____ is first integrating center in neuroendocrine reflexes

sensory neurons
Hypothalamus

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Chemical disequilibrium is largely due to ____

Na+/K+ pump

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When K+ channels open…

K+ moves _____ the cell
A net _____ charge develops inside the cell

out of
negative

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Electrochemical Equilibrium (Ei) is when concentration gradient and electrical gradient are _____ and _____

equal, opposite

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Equilibrium Potential (mV) is the membrane potential to offset an ion’s ______

concentration gradient

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Nernst Equation:

To calculate…

Vm = 61/z x log [C]outside/ [C]inside

To calculate equilibrium potential (Ei) of an ion

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Goldman Hodgkin Katz Equation:

To calculate…

Vm = PK[Kout] + PNa[Naout] + PCl[Clin] / PK[Kin] + PNa[Nain] + PCl[Clout]

*out/in except reverse for Cl

To calculate membrane potential (Vm) of a cell

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Membrane Potential Difference or Membrane Potential (Vm) is the ______ created by living cells due to uneven distribution of ions between the intracellular and extracellular fluids.

electrical potential

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Ei for a certain ion is +40 mV. The resting membrane potential of the cell is -75 mV. Is the cell membrane likely to be very permeable to this ion at rest?

No, not likely to be permeable
*Values are very different

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Membrane potential is measured with reference to _____

Is ____ in all living cells

____ approaches _____ of most _____ ion

ECF = 0 mV

negative

Vm approaches Ei of most permeant ion

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Depolarization –> Vm ____

decreases
becoming less negative, difference is getting smaller

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Hyperpolarization –> Vm ____

increases
difference getting bigger

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Ei _____ changes

NEVER
unchanging

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As permeability to an ion increases, _____ will approach _____

Vm
Ei

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Most living cells are pretty permeable to _____, which contribute to why living cells have a negative ____

potassium
RMP (resting membrane potential)

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A drug that blocks K+ leak channels is applied to a resting typical cell, what happens to the EK+ and Vm?

EK+ unchanged, Vm depolarizes (cell becomes more positive inside since K+ can’t leave)

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The main way to change the membrane potential in an average cell is to _____ by opening _____

increase permeability to ion
existing channels (channels are gated/voltage-gated)

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The goal of an electrical signal of a neuron is either continue the electrical signal (reach the _____ to initiate an action potential) OR stop the signal

To continue the electrical signal:

To stop the electrical signal:

axon hillock

To continue the electrical signal:
Depolarizing graded potential
Action potential

To stop the electrical signal:
Hyperpolarizing graded potential

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Graded Potentials

In neuron, usually _____
Variable _____
_____ or _____
_____ over time/distance
Can _____

cell body (soma)

amplitude

Hyperpolarizing or Depolarizing

Dissipates (has to travel over huge soma)

Can summate

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Below threshold and therefore does NOT initiate an action potential

subthreshold

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Reaches trigger zone, so an action potential results

suprathreshold

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Action Potential

In a neuron, usually begins at ______
Occurs only in ____
“All-or-none”: Has a _____
Uni-_____
Regenerative
No _______ or variable _____
Triggers _______

axon hillock
axon
threshold
Unidirectional
summation, variable amplitude
synaptic transmission

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Which apply or relate to graded potentials, NOT action potentials?

A. Directly involves ligand- or mechanically-gated channels
B. Regenerative
C. Summates

A and C

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Chemoreceptors are cells that have oxygen-gated channels. When oxygen is high, the K+ channels open, resulting in…

A. an increase Vm
B. depolarization of the cell
C. downregulation of respiration
D. none

A and C (hyperpolarization STOPS the signal)

If a neuron has a distribution of ions... Which ion contributes the least to Vm?

The LEAST PERMEANT ion

How does action potential trigger synaptic transmission? 1. 2. 3. 4. 5.

1. Depolarizing stimulus 2. Activate ligand-gated channels 3. Suprathreshold graded potential 4. Reaches axon hillock that initiates action potentials 5. Activates voltage-gated Ca2+ channels that then release neurotransmitters

2 ways an action potential can begin: Very beginning of the action potential? Middle the axon?

Very beginning of the action potential? Suprathreshold graded potential Middle of the axon? Local current

For action potentials... Na+ channels are _____, whereas K+ channels are ____

fast, slow

Central Nervous System: Peripheral Nervous System:

Brain, spinal cord Nerve, everything else!

4 main receptors:

thermo photo chemo mechano

Integrating center for thoughts and special senses

Cerebrum ex. thinking of danger, smelling something that reminds you of danger

Brainstem:

Pons and medulla oblongata

Where respiratory control center is

pons

where cardiovascular control center (CVCC) is

medulla

Where your emotions are if you feel excitement, heart rate kicks in

limbic system

Match responses with integrating centers Emotions: Chemoreceptor reflex: Baroreceptor reflex: Volume/osmolarity:

Emotions: limbic system Chemoreceptor reflex: pons, medulla Baroreceptor reflex: medulla oblongata Volume/osmolarity: hypothalamus

Parasympathetic has efferents out of ____ and _____ region

cervical sacral

Both sympathetic and parasympathetic innervate at some sort of _____

ganglion (collection of other neurons)

For sympathetic, all the ganglions are very ______ to the spinal cord

For sympathetic, pre-ganglions are _____, whereas post-ganglions are ____-

very short, long

The major parasympathetic nerve is called the _____

vagus nerve

For parasympathetic, pre-ganglionic nerve is ____, whereas post-ganglonic is ____

very long short

For parasympathetic, pre-ganglionic neuron releases _______. On the postganglionic neuron, _____ receptors receive that message and synapse onto organs to release ______, but bind to _____ receptors on target organ

acetycholine nicotinic acetylcholine muscarinic

For sympathetic, pre-ganglionic neuron releases ____-, which are received by _____ receptors. Postganglionic releases ______ and receptors are ____

acetylcholine nicotinic neuroepinephrine adrenergic

Afferent path or sensory/afferent live in _____ horn

dorsal

autonomic efferents (both para and symp.) --> ______ horn

lateral

Somatic motor neurons/efferents come out of ____ horn

ventral

Sympathetic is ____ and ______ regions

thoracic lumbar

Sympathetic neurons act on ______ cells in adrenal medulla to release ______

chromaffin epinephrine

The primary role of the Na/K ATPase in resting potential and action potentials is to _____

generate the gradients for K+ and Na+

K+ decreases, what happens to Vm?

Vm becomes more positive depolarizes decreases

Craniosacral division

Parasympathetic

Has GPCR on cardiac cells

Autonomic (both para and symp)

Both para and symp. _____ release neurohormones into portal system

do NOT

Adregenic receptors on targets

sympathetic

Motor neurons found in lateral horn of spinal cord

Auto

Ganglia found near targets

Parasympathetic

Has receptor-operated channels on ganglion cells

Auto