kaplan physiology notes conrad fisher

8/11/2019 Kaplan Physiology Notes Conrad Fisher

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Kaplan Physiology Notes Conrad Fisher

Chapter 1 Equilibrium and RMP

Membrane ConductanceConcentration gradient pushes K+ outside (efferent) of

the cell and Electric Gradient pushes the K+ inside via sodium potassium ATPASEpump.

If K+ leaves the cell, it is more negative.

3 main groups of channels

1.

Ungated channels passively diffuse through concentration. These channels

are always open, all cells possess ungated potassium channels, which means

there will be a net flux of potassium ions through channels unless potassium

is at equilibrium

2.

Voltage Gated Channels Depolarization is primary factor which changesdepolarization of membrane potential

a. Voltage gated sodium channels are quickly capable of being

depolarized. Sodium channels are closed under RMP but quickly

capable of activating and depolarizing and returning back to RMP

3. Ligand gated protein transporter, requires the use of a specific sub stance

(ligand). Interaction with the ligand and receptor, which regulates the

opening and closing the door.

Normal RMP potassium more inside the cell normally efflux is outside of the cell,if you lose a lot of potassium outside of the cell, makes the inside of the cell more

negative = hyperpolarization, = the pump which works with Sodium Potassium

ATPASE repolarizes the cell.

Depolarization is the rapid flux of sodium into the cell, thats a fast phase

Repolarization is based on the pump

Hyperpolarization is characterized by potassium leaving the cell (efflux)

making cell more negative

Potassium level too low, cells cause arrhythmia

Potassium levels too high also cause arrhythmia

When you remove potassium outside of the cell, leaves the interior highly negative

causing hyperpolarization. (More negativity inside the cell)

When you have increased Extracellular Ion of Potassium, concentration gradient is

changed and this causes reduction of efflux of intracellular potassium. If the


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Extracellular potassium is raised to a sever level, potassium starts to go inside the

cell and initiates depolarization.

If the potassium level suddenly goes up at severe levels, it can cause influx of

potassium inside the cell causing depolarization.

If the potassium levels outside the cell is low, the potassium inside the cells come

out and cause hyperpolarization to occur.

Sodium is higher in the plasma, lower inside the cell.

If the interior of the cell is more negative, it is resulted as hyperpolarization

Important points for Sodium

a. Sodium rushes into the cell becomes more positive, sudden positivity inside

the cell is known as depolarization.

b.

Normally cell is negative, if sodium rushes into it causes depolarizationc. Sudden rapid entry into the cell depolarizes it, RMP is not based on Sodium

because Na channels are normally closed, This is why RMP is dependent on

K+

d.

High K cause T-Waves and Low K causes U waves on EKG.

e. High and Low potassium changes RMP causing Arrhythmias

f.

High and Low potassium = Conduction Disturbances

g. Hyperkalemia is cardiologic disorders

h.

Sodium effects CNS system

Pumping Na Out of the cell

Passive diffusion is according to a concentration gradient and an electrical gradient.

The pump is to overcome the electrical gradient, its negative in a cell.

The Neuron Action Potential And Synaptic Transmission

The action potentials

a.

Motor Neuron Action Potential 2msec

b.

Skeletal Muscle 5msec

c. Cardiac Muscle 200msec

The cardiac action potential is really long because the heart needs time for blood tocompletely eject.

All action potentials start off at -70/-90 because of a natural reflux of

potassium

Potassium leaves the cell and is the most predominant ion responsible for

maintaining RMP.

Efflux of normal conductive tissue is potassium


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Action potential Theory excitable neurons stimulate to reach a threshold

before depolarization is triggered

Interior of the cell is quiet negative and

Sudden influx of sodium brings positivity inside the cell causes the cells

interior to case positive energy.

Tetrodotoxin Complete cessation of NMJ exchange, instant cardiac, peripheral,

heart, and muscle, cease to depolarize.

Overshooting or hyperpolarization has to do with potassium channels, part of

repolarization, more potassium leaves the cells. When you repolarize too much

thats when hyperpolarization occurs.

When you go more negative then-70 is when youve reached

hyperpolarization.

Ungated Potassium Channels These channels are always open and unless the

membrane potential reaches the potassium equilibrium potential. If the potassiumchannel increases inside the cell, it will leave the cell through ungated potassium

channels and based on concentration gradient, and not effected by action potential

NOT BASED ON CHARGES IS NOT ALTERED BY ACTION POTENTIAL. Action

potential is primarily, an electrical gradient event, could be created by chemical

gradient but is primarily an electrical gradient event.

Voltage Gated Channels Creates Action Potential, Changes based on charges,

voltage gated channels create the concentration differences in a lot of ways, not

continuous and affected by

Uworld Notes Physiology

Reduced Pulmonary parenchymal compliance is the hallmark of pulmonary fibrosis

kaplan physiology notes conrad fisher

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