Chu MP and AP

How is RMP found

Difference in elextric potential between interior and exterior of a cell memb at rest

How is Graded potential found

Change in membrane potential that vary in size, as oppose to being a nal-or none

Types of GP potentials

synaptic potentials, end plate potentials, receptor potentials, pacemaker potentials, and slow-wave potentials

What sets the resting membrane potential

K+ mostly

What state are K+ channels in at rest

open

What causes RMP to be negitive

K2P channels

What is RMP

Baseline elextrical potential across the cell membrane when the cell is not firing

Physiological role of RMP

Keeps cell in a ready state, force for ion movement, cell excitability, cell volume and homeostasis

What are the differences between K+ leak and voltage gated

Closed at RMP, open after depol, open slowly

What is the nernst equation

(61/z)Log (Ion0/inoi)

What is Depol GP

A stimulus that causes the cell to be less negativly charged

What is repol GP

Causes cell to be more negitively charged

Step one of synaptic poten

Action potential reaches axon terminal and depolarizes membrane

What is step 2 of synaptic potentials

Voltage gated Ca2_ is open and Ca flows in

Step 3 of synaptic potentials

Ca triggers release of neurotransmitter

Step 4 of synaptic potential

Neurotransmitter binrds to receptors on the target cell

What kind of neurons use ESPS

Glutaminergic and cholinergic

What channels does EPSP open?

Na, Ca, K

What neuron uses IPSP

GABA or glycine-ergic neurons

What ions are used with IPSP

Cl

What is the spike-initiation zone?

Axon Hillock

First AP stage

Resting memb poten

Second AP stage

RMP to threshold

3rd stage of AP

Threshold to top

4th stage AP

Top to RMP

5th stage of AP

RMP to bottom

What happens in resting stage

K+ leak channels let out K+

What happens in RS to threshold

EPSPs in, or IPSPs out

What are the EPSPs in rs to threshold

Na+ or Ca2+

What are the IPSPs in RS to threshold

K+ or Cl

What happens during Depol

VG Na+

What happens during Repol

K+

What happens during hyperpol

K+ slowly closes

What does ion conductance describe?

How easily specific ions can move across a cell membrane

What impacts ion conductance

number of open channels, type of channel, probability that channel is open

At rest, what is high conductance

K+ high, Na low

At depol, what is high

Na conductance

What is high for Repol?

K+ conductance

What is high for hyperpole

K+

Significance of ion conductance: MP

Relative conductance of different ions dictates membrane voltage

Significance of ion conductance: AP generation

Rapid, regulated changes in Na⁺ and K⁺ conductance allow excitable cells (neurons and muscle) to fire APs.

Significance of ion conductance: Excitability

Altered ion conductance can make cells more or less likely to fire (e.g., increased K⁺ conductance reduces excitability)

Significance of ion conductance: Unidirectional signaling

Time-dependent changes underlie absolute refrectory periods

Significance of ion conductance: Muscle and cardiac

Proper ion donductance is required for skeletal, cardiac, and smooth muscle

Significance of ion conductance: Clinical

Abnormal conductance can cause epilepsy, arrhythmias, and muscle weakness

What is MS

Chronic autoimmune disease of the CNA

What does myelin do

Insulates axons

What is AP jumping between nodes of ranview called?

Saltatory conduction

How does the loss of Myelin impact this?

Formes sclerotic plaques

What does MS do to saltatory conduction

Conduction is slowed/fails

Where are Na+ channels normally

Nodes of ranvier

Where are K+ channels?

Hidden under myelin

What does MS do to K+

K+ channels are exposed

What does exposer of K+ channesl cause?

Membrane hyperpolarization, reduced ability to threshold, AP failure

Why is increased Na distributed in MS

To fix membrane potential

What does increased Na in MS cause

More channel activity, and reverses Na Ca

What does reversal od Na/Ca cause?

Accumulation of Ca in axon

What does increased Ca in cell cause?

Protease activation, and damages cytoskeleton and mitochondria

Ratio of Na to Ca

3:1

What molecules are involved in inflammatory molecular signaling

Cytokines, ROS< autoantibodies

What do cytokines do

amplify inflammation

What do ROS do

damage lipids, proteins, and DNA

What do autoantibodies do?

target myelin proteins

What do the molecular signals do?

Disrupt ion channel, impair synaptic transmission, prevent remyelination

What does MP allow cells to do?

Generate and propagate APs

What does Hypoklemia cause

what does excessive Hyperpolarization cause

Muscle weakness

What does hyperkalemia cause

depolarization

What does excessive depol cause

arrhythmias

What does high sodium serum typically present as?

Water deficit relative to sodium

Causes of hypernatremia

Water loss/reduced intake, or excess sodium

What does hypernatremia result in?

More plasma osmoarity, water shifts out of brain cells, cellular dehydration

Clinical manifestation of hypernatremia

Thirst, confusion, irritability, muscle twitching, seizures

Management of hypernatremia

Gradual correction with hypotonic fluids

What can rapid correction of hypernatremia cause

Cerebral edema

What is D5W

5% dextrose in water

What is the osmolarity of D5W

252 mOsm/L

How does hypernatrmia effect RMP

Minimally

Why is the RMP minimally affected by Hypernatremia

K+ permeability instead of Na

Effect of hypernatremia on AP

Increased AP amplitude

What does hypernatremia affect directly

Cell volume and brain function

What does hypernatremia not effect directly

Excitability

What is mild hyponatremia

130 - 134

What is moderte hyponatremia

125 - 129

What is severe hyponatremia

125

Why does hyponatremia matter?

Sodium controls water balance and cell volumer

What can celling of cells via hyponatremia cause?

Headache, confusion, seizures, or coma

Does hyponatremia effect RMP

No it does not

What does Hyponatremia do to AP

Reduces AP amplitude and nerve conduction velocity

What does moderate hyponatreimia cause

mild symptoms like nausea and headache

What does severe hyponatremia casue

Neurological symptoms (confusion, seizures, coma)

What is used to treat hyponatremia

Hypertonic saline (3% NaCL)

At what rate should Na be increased

8-10 mEq/L every 24 hours

Causes of hyperkalemia

Decreased renal excretion; cellular shift of K+ out of cells, Excess intake, medications

What does Hyperkalemia do?

Reduces RMP

What is a clinical manifestation of Hyperkalemia

Muscle weakness ore paralysis, paresthesia, Cardiac arrhythmias

What is the effects of hyperkalemia on RMP

Reduces K+ gradient, and makes RMP less negative

Effect of hyperkalemia on RMP and AP

Cells are closer to threshold

What is the range for early/mild hyperkalemia

5.1 to 5.9

Range for moderate to severe hyperkalemia

6.0 - 6.5