Nervous System I Flashcards
Hyperpolarization makes the membrane potential ______ polarized
More
Two types of changes in membrane potential that transmit information
- Graded potentials
2. Action potentials
True or false: the amplitude of an action potential is always the same
True
Depolarize got makes the membrane potential _____ polarized
Less
A small deviation from resting potential
Graded potentials
Threshold for action potential
-55mV
Why do action potentials propagate in one direction?
The refractory period means that action potentials cannot travel backwards
Four terms used to describe direction of changes in membrane potential relative to rest
- Depolarization
- Overshoot
- Repolarization
- Hyperpolarization
The gates of a _____________ ion channel open in response to a change in membrane potential
Voltage-gated
Velocity of action potential depends on…
Fibre diameter and myelination
Two main divisions of the efferent PNS
- Somatic nervous system
2. Autonomic nervous system
Effectors of the somatic nervous system
Skeletal muscle
The gates of ______ ion channels randomly alternate between open and closed positions
Leak
What cells assist in regeneration of damaged neurons in the PNS?
Schwann cells
Myelinated axons have a ______ propagation speed
Faster
What type of ion channels are responsible for action potentials
Voltage-gated ion channels
Four main types of ion channels
- Leak
- Ligand-gated
- Mechanically-gated
- Voltage-gated
Divisions of the autonomic nervous system
- Sympathetic nervous system
- Parasympathetic nervous system
- Enteric nervous system
The resting membrane potential of a cell at rest has a more ________ charge inside compared to the outside
Negative
_____________: the force generated by the separation of charge
Voltage
How do local anaesthetics such as noviciate and xylocaine prevent pain?
They block Na+ channels, preventing action potentials and stopping afferent pain signals reaching CNS
Effectors of the enteric nervous system (2)
Smooth muscle and glands of GI tract
The gates in a ___________ ion channel open and close in response to a specific ligand
ligand-gated channels
Effectors of the sympathetic and parasympathetic nervous systems (3)
Smooth muscle, cardiac muscle, and glands
How are graded potentials caused?
Localized ligand-gated or mechanically-gated ion channels
Two divisions of the afferent PNS
- Somatic senses
2. Special senses
When a charge/force has the ability to move charge, it is referred to as…
Potential
Concentrations of sodium and potassium inside verses outside an excitable cell
High [K+]in
High [Na+]out
_____ fibre diameter axons have faster propagation
Large
Why does myelination increase propagation speed?
Saltatory conduction
Order of voltage-gated K+ and Na+ opening as action potential is triggered
Na+ channels open as threshold is hit —> causes depolarization
K+ channels open at reversal —> causes repolarization; delayed closure causes hyperpolarization
Gates of __________ ion channels open/close in response to a mechanical stimulation (ie. touch, pressure, tissue stretching, vibration)
Mechanically-gated
Define plasticity vs repair
Plasticity: ability to change throughout life
Repair: regeneration after damage
If charge is allowed to move, it is called….
Current
How do Schwann cells assist in regeneration
Schwann cells form regeneration tube, which guides and stimulated regrow the of the axon
