Physio Nervous System

Front 1

2 types of ion channels

Back 1

1. Not gated (always opened)

2. Gated (not open when cell is at rest)

Front 2

Stimuli that opens gated proteins

Back 2

1. Membrane voltage change

2. Ligands (binding of hormone or nt)

3. Temperature (thermal gates)

4. Mechanical deformation (e.g. touch)

Front 3

RMP

Back 3

Resting membrane potential

E.g. -70

Front 4

Electrical properties of cells are set due to

Back 4

1. Ionic concentration (more org- and K+ in cell then out)

2. Membrane permeability

Front 5

Factors establishing RMP

Back 5

1. Na/K ATPase pumps (maintain gradient)

2. Org- inside of cells that cant cross membrane

3. More non gated K proteins than N (Allow for K to diffuse out of the cell down its concentration gradient)

Front 6

What ion is the major determinant of RMP

Back 6

K+

Front 7

Electrically excitable cells types

Back 7

Muscle

Nerve

Front 8

How does a signal move

Back 8

1. Neuron stimulated

2. Gated ion channels open

3. MP changes producing a graded potential

4. Threshold is (or isnt) reached

5. If meet triggers action potential

Front 9

Graded potential

Back 9

Is a change in MP usually caused by a stimulus(created by opening gated channals) on a dendrite or cell body

Short distance signals

Can summate

Front 10

Depolarization

Back 10

More positive than RMP

Front 11

Hyper polarized

Back 11

More negative than RMP

Front 12

Critical stimulus

Back 12

A large enough graded potential or summation of GPs to hit the threshold

Front 13

Action potential

Back 13

Nerve impulse that propagates along an axon with NO change in intensity.

Initiates at trigger zone

Front 14

Trigger zone in multi vrs uni polar neurons

Back 14

Uni - just past the dendrites

Multi/bipolar - at axon hillock

Front 15

Order of events in a stimulated neuron

Back 15

1. Resting

2. Graded potential

3. Depolarization

4. Repolarization

5. Hypopolarization

6. Resting

Front 16

Depolarization phase

Back 16

1. Voltage gated Na+ channels open

2. Causeing an Increase in Na+ diffusion

3. Causes depolarization

(Na flows down its concentration gradient into the cell causes it to be less negative)

Front 17

Repolarization

Back 17

1. Na+ channels close

2. Voltage gated K+ channels open

(K+ moves down its concentration gradient and out of the cell)

Front 18

After hypoploarization

Back 18

1. K+ Channels are slow to close

2. Na channels are reactivated (but still closed) and can now respond to stimuli

Front 19

MP returns to RMP when

Back 19

K+ channels close

Front 20

Refractory period

Back 20

1. Absolute refractory (NO AP)

-all Na channels opened OR

- Na channels are inactivated

2. Relative refractory

(AP can be generated but only by a larger than normal stimuli)

-70 to -55 vrs -80 to -55

-

Front 21

Action potential propagation

Back 21

Sequence of AP triggers down a neuron, each one triggering the next as the opposite charger attract

Front 22

Rate of propagation depends on

Back 22

1. Fiber diameter (larger axon = faster)

2. Myelination (myelinated =faster)

Front 23

Why do myelinated fibers move a charge faster?

Back 23

They are insulated and lose charge slower. Requires less AP (rebooting the charge) and can spend more time moving

Front 24

Type of Fibre range

Back 24

From A-C

Type A

- larger and myelinated

- propagate APs at 130 m/sec

- sensory and motor neurons

To Type C

- smaller and unmyelinated

- propagate at 0.5m/s

- automatic NS and throbbing pain fibres

Front 25

How nerve signal passes between neurons

Back 25

1. Ap arrives at synaptic end bulb

2. Ca++ voltage gates open

3. Raise in Ca++ triggers exocytosis of vesicles containing nt

4. Nt diffuses into synaptic cleft and binds to postaynaptic membrane

5. Postsynapric receptors open ion channels (on themselves or others)

6. Gated ion channels open creating a GP

Front 26

PSP

Back 26

Postsynaptic potential

Can be

1. Excitatory = depolarization

(Due to opening of Na+/ca+ or closing of K)

2. Inhibitory = hyperpolarization

(Due to opening in of K+ or cl-

Front 27

Acetylcholine (ACh)

Back 27

Excitatory nt

ALWAYS used in neuron to muscle cell synapses

Front 28

Glutamate

Back 28

PSP

Front 29

Glycine

Back 29

Inhibitory nt

Front 30

GABA

Back 30

Inhibitory nt

Front 31

Muscle triggering

Back 31

1. Nt (Ach) is released into synapse

2. Chemical gates on motor end plate open and Na enters

3. EPP triggers sarcrolemma

Front 32

Motor end plate

Back 32

Membrane of postsynaptic muscle fibers