Peters Physiology Flashcards
List the main components of neuronal structure
Dendrites Soma (cell body) Axon hillock + initial segment Axon Synapse
What is the main function of dendrites?
Receive neuronal inputs and convey graded signals towards the soma
The soma of the neurone is the metabolic centre. List the structures it contains
Nucleus Ribosomes Mitochondria Endoplasmic reticulum Nissl substance
What is Nissl substance?
Rough endoplasmic reticulum (ER with ribosomes)
Which part of the neurone is the site of initiation of an action potential?
Axon hillock + initial segment
What is the main function of an axon?
Conducts action potentials to other neurones or cells
Electrical info/material can travel from the soma to presynaptic terminal (anterograde) and vice versa (retrograde). True/False?
True
Retrograde travel can welcome infection (e.g. polio)
What is a synapse?
Point of chemical communication between 2 neurones
List the 4 main types of neurone
Unipolar
Pseudounipolar
Bipolar
Multipolar
Describe a unipolar neurone and give an example of where it may be found
No dendrite; soma only gives off axon
e.g. peripheral autonomic neurone
Describe a pseudounipolar neurone and give an example of where it may be found
Short axon bifurcates into soma and central axon
e.g. dorsal root ganglion neurone
Describe a bipolar neurone and give an example of where it may be found
Dendrite + soma + axon
e.g. retinal bipolar neurone
Describe a multipolar neurone and give an example of where it may be found
3 or more neurites attached to soma
e.g. lower motor neurone
What is the difference between Golgi type I and type II axons?
Golgi type I = long axon
Golgi type II = short axon
Which channels open in neurones when membrane polarity reaches threshold (-60mV) to cause the upstroke of the action potential?
Na channels
Which 2 factors determine the distance over which electrical current spreads in a neurone?
Membrane resistance
Axoplasm resistance
Increasing membrane/axoplasm resistance increases the distance travelled by electrical current
Increasing membrane resistance increases the distance travelled by electrical current
(less current leaks out)
A narrow axon provides high/low resistance to conduction velocity
A narrow axon provides high resistance to conduction velocity
Which insulating material can help increase conduction velocity in neurones by reducing current leak?
Myelin
Which cells produce myelin for neurones?
Schwann cells in PNS
Oligodendrocytes in CNS
Many schwann cells and oligodendrocytes surround axons. True/False?
False
Many schwann cells surround one axon but usually only one oligodendrocyte surrounds many axons
Which region does the action potential “jump” from to get between neurones in myelinated axons?
Nodes of Ranvier
What are the 3 main morphological classifications of a synapse?
Axodendritic (most common)
Axosomatic
Axoaxonic (least common)
Synapses can be excitatory or inhibitory. Respectfully, what are the main transmitters involved for each?
Glutamate for excitatory CNS
GABA or glycine for inhibitory CNS
The excitatory postsynaptic potential (epsp) is depolarizing and the inhibitory postsynaptic potential (ipsp) is hyperpolarizing. True/False?
True
If an epsp is too weak to cause synapse, how can excitation be achieved?
Converge multiple epsp’s to cause net excitation (synaptic summation)
List the sensory modalities that come under the somatosensory system
Touch Proprioception Temperature Pain Itch
What happens to the energy generated by a stimulus at a sensory nerve cell terminal?
Transduced into electrical activity which creates depolarizing (generator) potential which, if strong enough, can trigger action potential
Which receptors aid with proprioception?
Joint and muscle mechnoreceptors
Adaptation determines the firing rate of sensory neurones in response to changing stimuli. Describe the slow-adapting response
Continuous information whilst nerve being stimulated
Gives info about position, stretch, force
Adaptation determines the firing rate of sensory neurones in response to changing stimuli. Describe the rapid-adapting response
Detects change in stimulus strength and rate of movement
Adaptation determines the firing rate of sensory neurones in response to changing stimuli. Describe the very-rapid-adapting response
Responds only to very fast movement (vibration)
Primary sensory afferent fibres are grouped I-IV or Aα, Aβ, Aδ, C. Order the groups from thickest-least thickest myelination, i.e. from fastest conduction velocity to slow
Group I, group II, group III, group IV
AKA
Aα, Aβ, Aδ, C
What is meant by the receptive field of a sensory neurone?
The region which, when stimulated, produces a response in that neurone
Which type of sensory receptor do Aα primary sensory afferents conduct?
Proprioceptors