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nervous system
pages 170-182 Human Physiology, Fox
18
Physiology
Undergraduate 3
02/25/2011

Additional Physiology Flashcards

 


 

Cards

Term

The permeability of the axon membrane to NA+ and K+ depends on what?

 

and how and what is it called as ions flow?

Definition

gated channels that open in response to simulation.  Na moves in the K moves out. 

 

This flow of ions and changes in the membrane potential constitute and event called and action potential.

Term
resting membrane potential (rmp)
Definition

all cells in the body maintain a potential diffference

(voltage)

across the membrane.

this resting membrane potential where the inside is negative compared to outside.  

 

only a few cells alter their membrane potential in response to stimule..

 

Term
excitability   or   irritability
Definition

only a few types of cells react to stimuli.

this is a cental aspect of the physiology of neurone and muscle cells....to produce and conduct changes in membrane potental.   that is called excitability or irritability

Term
an increase in membrane permeability to a specific ion results in:
Definition

Diffusion of that ion down its electrochemical gradient (concentration and electrical gradients considered together)

either into or out of the cell  across places where ion channels are located.

can be measured in voltage

 

Term
depolarizatin (hypopolarization)
Definition

stimulation causes positive charges to flow into the cell  and the line will deflect upward. 

it means the potential difference between the two recording electrodes is reduced.

Term
repolarization
Definition
a return to resting membrane potential
Term
hyperpolarization
Definition

..line on oscilloscope will deflect downward

if it causes the inside of the cell to become more negative than the resting membrane potential

Term
excitatory
Definition
depolarization of a dendrite of cell body
Term
inhibitory
Definition
hyperpolarization of a dendrite or cell body
Term

the changes in membrane potential--

depolarixation, repolarization, hyprpolarization are caused by what?

Definition
changes in the net flow of ions through ion channels in the membrane   such as Na and K
Term
what makes the membrane more or less permeable?
Definition
the gated channels being open or closed
Term
What are leakage channels?
Definition
a channel that is not gated...for K+
Term
depolarization to a threshold o
Definition
depolarization below a certain level will decay and go back.  but at a certain lever depolariztion will happen and the gte will open  
Term
electochemical gradient
Definition

when the plasma membrane is freely permeal tot Na for an instant ...

the membrane potential moves rapidly toward Na+ equilibrium potential....and even though small it greatly affects the membrane potential

 

 

Term
voltage regulated  or voltage channels
Definition
gated Na and K channels stimulated by depolarization...
Term
Action Potential
Definition

explosive increase in Na permeability results is a rapid reversal of membrane potential in that region   from-7- mV to + 30 mV

 

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