Topic 3 - NERVOUS SYSTEM I (Neuronal Physiology - Electrically Excitable Cells | GP to AP) Flashcards
electrically excitable cells
- ONLY muscle and nerve cells
- capable of producing departures from RMP in response to stimuli (=changes in the external or internal environment)
electrically excitable cells:
when a neuron is stimulated
name 3 things that happen
- gated channels open
- membrane potential changes, producing a graded potential. If the threshold potential is reached
- triggers an action potential
Graded potential
- stimulus causes what? located where? how?
- stimulus causes a small change in membrane potential, usually on dendrite or cell body (no longer at rest) by opening gated channels (changes membrane permeability)
what are the 2 possible results of graded potentials?
- more positive than RMP = depolarization
- e.g. -70mV to -65mV (closer to 0)
- more negative than RMP = hyperpolarization
- e.g. from -70mV to -75mV
name 1/4 characteristics of graded potentials
1
- graded potentials are short distance signals - die away quickly (short-lived)
- magnitude and distance traveled by potential varies directly with the strength of the stimulus
- graded potentials can summate - 1st graded potential present when 2nd stim occurs ⇒ these add (sum) to create the resulting larger graded potential
ions move passively (unlike charges attract (+ & -) = current flow, causing depolarization or hyperpolarization on adjacent membrane
name 1/4 characteristics of graded potentials
2
- ions move passively (unlike charges attract (+ & -) = current flow, causing depolarization or hyperpolarization on adjacent membrane
- magnitude and distance traveled by potential varies directly with the strength of the stimulus
- graded potentials can summate - 1st graded potential present when 2nd stim occurs ⇒ these add (sum) to create the resulting larger graded potential
graded potentials are short distance signals - die away quickly (short-lived)
name 1/4 characteristics of graded potentials
3
- ions move passively (unlike charges attract (+ & -) = current flow, causing depolarization or hyperpolarization on adjacent membrane
- graded potentials are short distance signals - die away quickly (short-lived)
- graded potentials can summate - 1st graded potential present when 2nd stim occurs ⇒ these add (sum) to create the resulting larger graded potential
magnitude and distance traveled by potential varies directly with the strength of the stimulus
example:
larger stimulus ⇒ larger graded potential that travels further across the membrane
name 1/4 characteristics of graded potentials
4
- ions move passively (unlike charges attract (+ & -) = current flow, causing depolarization or hyperpolarization on adjacent membrane
- graded potentials are short distance signals - die away quickly (short-lived)
- magnitude and distance traveled by potential varies directly with the strength of the stimulus
4.
graded potentials can summate - 1st graded potential present when 2nd stim occurs ⇒ these add (sum) to create the resulting larger graded potential
what happens after a graded potential occurs?
repolarization = return to RMP after depolarization or hyperpolarization
Graded potential to Action Potential
- Graded potentials are essential in what?
- IF
- essential in initiating a nerve impulse (action potential)
- IF it is depolarized and IF it is large enough or multiple GPs sum to be large enough (if there is a critical stimulus) ⇒ leads to an action potential
what are the 3 steps from GP to AP
- critical stimulus
- Graded potential reaching threshold
- action potential
GP to AP
the story so far (draw diagram)