L12-13 Excitable Cells CNS / PNS Flashcards
The human nervous system can be divided based on structure into the…
Central and the Peripheral Nervous Systems (CNS and PNS)
The CNS comprises…
The brain and spinal cord
The PNS comprises…
All nerves other than brain and spinal cord
The human nervous system can be divided based on function into (3)…
- Sensory receptors (sensory neurons in PNS)
- Integration (in the CNS)
- Effectors (motor neurons in PNS)
Motor neurones are also known as…
Efferent neurones (efferent meaning conduction outwards or away from something)
Interneurones and motor neurones are ( uni / multi / psuedo-uni / bi ) polar
Multipolar
meaning multiple dendrites emanating from the cell body
Motor neurones feature myelination of the axon and a cell body…
At one end
Interneurones have the cell body in the…
Middle
Sensory neurones are also known as…
Afferent neurones (afferent meaning conduction into or towards something)
Sensory neurones can be either…
Psuedo-unipolar (single process which look like 2) or Bipolar (two processes)
All types of neurone share the same basic properties:
- They conduct electrical impulses along the plasma membrane
- Communicate by synapse
- Do not divide
Which of the basic properties of neurones is responsible for neurodegenerative diseases?
They do not divide
Neurones have a ( high / low / average ) metabolic rate
High
An action potential is an ( all-or-nothing / variable ) signal
All-or-nothing
Graded potentials occur over ( the same / longer / shorter ) distances as action potentials
Shorter
Graded potentials are ( like / unlike ) action potentials in that they ( maintain / lose / gain ) strength the further they travel
- Unlike action potentials
* Lose strength the further they travel
The two types of electrical signals in neurones are…
Graded potentials and action potentials
Graded potentials ( never / sometimes / always ) generate action potentials…
Sometimes
if depolarisation at the axon hillock is sufficient
Where in the neurones do graded potentials occur?
a) Dendrites, cell body, axon terminals and axons
b) Dendrites
c) Cell body, axon terminals and axons
d) Dendrites, cell body and axon terminals
d)
graded potentials do not occur in the axon
The post-synaptic electrical impulse is a (graded / action ) potential
Graded
The post-synaptic electrical impulse in muscle cells is known as an…
End-plate potential (EPP)
Graded potentials can be (2)…
Depolarising or Hyper-polarising
Depolarising graded potentials are known as…
Excitatory Post-Synaptic Potentials (EPSPs)
Hyper-polarising graded potentials are known as…
Inhibitory Post-Synaptic Potentials (IPSPs)
IPSPs may result in the net movement of…
a) Sodium ions into the cell
b) Chloride ions into the cell
c) Potassium ions into the cell
b)
Potassium ions may also move out, which also contributes to hyper-polarisation (-)
For an action potential to occur, the threshold voltage must be reached at the axon hillock.
What is the threshold voltage?
-55mV
A graded potential that fails to reach the axon hillock above threshold is known as a…
Sub-threshold EPSP
A graded potential that successfully reaches the axon hillock above threshold is known as a…
Supra-threshold EPSP
If action potentials are all-or-nothing how do neurones transmit information about the strength and duration of the stimulus?
By varying the frequency of action potentials
The more frequent the action potentials the greater the release of neurotransmitter at the axon terminal. Information on stimulus strength and duration is therefore described as…
Frequency encoded
Frequency encoding is digital, therefore (2)…
Higher fidelity and less prone to noise (high s/n ratio)
i.e. FM vs AM radio
( Some specialised / CNS / Motor / All ) neurones can generate graded potentials AND action potentials
All
Spacial summation is the summation of EPSPs from different…
Places at the same time
Sub-threshold EPSPs may spacially summate to produce a…
Supra-threshold signal in the post-synaptic neurone.
When an IPSP spacially summates with EPSPs and diminishes them to sub-threshold levels, this is known as…
Post-synaptic inhibition
as the reduction in signal occurs in the post-synaptic neurone
Summation of multiple signals from a single neurone close together in time is…
Temporal summation
The summation of graded potentials (both EPSPs and IPSPs) is known as…
Post-synaptic Modulation (or Integration)
The summation of graded potentials, post-synaptic modulation, is ( imprecise / more precise ) in comparison to pre-synaptic modulation
Imprecise
The NMJ is known as a ? synapse…
Classical
Neurotransmitter receptors differ in (2)…
Form and mechanism
Acetylecholine (Ach) is a neurotransmitter present in the (2)…
NMJ and brain
Amine neurotransmitters (3)…
- Adrenaline
- Dopamine
- Histamine
Amino acid neurotransmitters (3)…
- Glutamate
- GABA
- Glycine
Polypeptide neurotransmitters (2)…
- Cholecystokinin
* Enkephalins
Purine neurotransmitters (2)…
- ATP
* AMP
Gaseous neurotransmitter…
Nitric oxide, NO (free radical form of N2O)
Neurotransmitter receptors have one of two mechanisms…
- Ligand-gated ion channels
(inotropic receptors) - G-Protein coupled receptors that activate 2° messengers
(metabotropic receptors, slower & longer-term)
Examples of inotropic neurotransmitter receptors are (4)…
- Acetylcholine (Nicotinic Ach)
- Glutamate
- GABA and Glycine (inhibitory)
Examples of metabotropic neurotransmitter receptors are (5)…
- Acetylcholine (Muscarinic Ach)
- Histamine
- Cholecystokinin
- ATP
- Adrenaline
Neural synapses ( are / are not ) fixed
Are not
Variation in electrical activity can cause rearrangements of synapses. This is known as…
Synaptic Plasticity
LTP
Long-term potentiation
Long-term potentiation involves…
Glutamate
Long-term potentiation results what changes in a) The pre-synaptic cell AND b) The post-synaptic cell
a) enhanced neurotransmitter release from the pre-synaptic cell
b) increase in sensitivity of the post-synaptic cell
The overall effect of LTP is to increase…
The efficacy of synaptic transmission
