Biopsy 2 Flashcards
(28 cards)
Differences between motor neuron vs sensory neuron
- location of cell body?
- info is collected from where to where?
Motor:
- cell body at top/beginning
- down from the brain to muscles/other cells
Sensory:
- cell body is half-way/in the middle of the neuron
- from body to the brain
How is information carried from one neuron to another?
info is collected from dendrites —> carried as an electrical impulse along the axon to the terminal —> turn into chemical impulse to cross synaptic gap
- info is processed in the cell body in the beginning (motor) / half-way (sensory)
Match:
axon, cell bodies, Grey matter, White matter
Grey matter = cell bodies
White matter = axon
What are the use of the ion channels and pumps in the membranes?
control the movement of ions in and out of the cell
Types of ion channels
- resting
- voltage gated
- ligand gated
- mechanically gated
Movement of ions across neuronal membrane can cause ___ ?
electrical signals = action potential
Types of ions in intracellular and extracellular fluid?
- Sodium ion (Na+)
- Potassium ion (K+)
- Chloride (Cl-)
- Large negative ions (A-)
What forces determine the movement of ions into and out of the cells?
- Concentration
- Electrical (+/-)
Describe the Na+ & K+ channels at rest.
Na+ channels are closed
K+ channels are opened
Which side have more Na+? Intracellular or Extracellular fluid?
Extracellular
Describe K+ during resting membrane potential.
- K+ enters the cell through K+ channel and Na/K pump as the electrical force is more negative inside the cell
- K+ is also moved out of the cell through K+ channel due to a smaller K+ conc. gradient outside
- 2 forces are in equilibrium (-90mv)
At rest, is it more positive or negative outide a neuron?
Positive
Why are neurons negatively charged at rest?
In terms of Na+/K+ pumps
- Na/K pumps constantly pumping 3 Na+ out and 2 K+ into the cell
- so higher K+ conc. inside & higher Na+ conc. outside
Resting membrane potential in __?__mV?
-65 mV
more negative inside
Why is an action potential being generated?
- neuron is stimulated excitatory —> resting potential becomes action potential
- movement of ions into and out of cells —> changes in electrical activity
How is an action potential being generated?
Post-synaptic potentials are summed up —> if it‘s excitatory —> depolarise membrane at axon hillock to threshold level —> net change above threshold (-50mV) —> action potential is generated and travel down the axon
What happen to Sodium & Na+ channel when a cell is stimulated to above threshold?
Name this process.
- Na+ channel open
—> Na+ enters into the cell through Na+ channel down its conc. gradient and electrical force(negatively charged inside) —> cell becomes positive - Depolarisation
Describe Repolarisation.
Due to positively charged inside:
- Na+ channels closed
- K+ moves out of the cell to the negative outside (electrical force) and down its conc. gradient
What has happened lead to resting from Hyperpolarisaton?
- voltage-gated K+ channel shut
- K+ diffuses normally in its ‘resting open’ channel
Name the fatty substance that cover axon and the cell that produce it.
Myelin
Schwann cells
What‘s the purpose of being myelinated?
conduct action potential faster by saltatory conduction
Action potential is an _______ event.
All or Nothing
What is refractory period?
The time when membrane cannot be depolarised, and when action potential cannot be generated until preceding potential has finished
What determine the strength of stimulus?
- increased firing rate
