Week 2 - finished Flashcards Preview

YEAR 3 SEMESTER 1 NEURO-ANATOMY > Week 2 - finished > Flashcards

Flashcards in Week 2 - finished Deck (37)
Loading flashcards...

How many neurons are there in the CNS?

Approx 100billion


Glial cells outnumber neurons in the CNS by how many to 1?



What is the function of glial cells?

Form the structural support for the neuronal network and make a massive contribution to the regulation of neuronal function.


What are the important parts/sections of the neuron? Describe briefly what each of these do.

Dendrites - receive stimuli through activation of chemically or mechanically gated ion channels. Sensory neurons produce generator or receptor potentials. Motor neurons produce excitatory (EPSP) or inhibitory (IPSP) postsynaptic potentials.

Cell body - receives stimuli and produces

Junction of axon hillock - trigger zone: integrates EPSP and IPSP and if the sum is a depolarisation threshold, it initiates an action potential.

Axon - propagates nerve impulse from initial segment (or from the dendrites in a sensory neuron) to the axon terminals in a self reinforcing manner (impulse amplitude doesn't change as it propagates along the axon)

Axons, terminals and synaptic end bulbs - inflow of Ca++ caused by depolarisation phase of nerve impulse triggers neurotransmitter release via exocytosis of synaptic vesicles


What are the 2 fundamental types of cells that contribute to the central nervous system?

Glial cells


Are dendrites myelinated?



Where do dendrites typically extend from?

The apex of the cell body


What is the soma? What does it contain? It produces proteins that do what?

The central component of a neuron and contains the nucleus.

It produces proteins for:
Electrochemical transmission
Structural maintenance of the neuron itself
Neuroimmune regulation


Where does the axon extend between?

The axon hillock and the area of the soma


What cells form myelin in the PNS?

Schwann cells


What cells form myelin in the CNS?



What are the breaks in the neuron sheath called?

Nodes of ranvier


What are the functional classifications of neurons?

Afferent: sensory
Efferent: motor
- Neither motor nor sensory
- Can be subdivided into:
Golgi type 1: long/relay (corpus callousness)
Golgi type 2: short, spinal (reflex)


What are the structural classifications of neurons?

Unipolar: autonomic ganglia
Bipolar: retina and most DRG
Multipolar: LMNs and cerebellum


What are some of the main functions of glial cells?

Ion buffering by uptake (vasomotor control, neuronal metabolic support)

Blood brain barrier

Glympatic system

Scavenger function (after cell damage)

Myelin sheathing


What are the types of glial cells? Briefly describe each of their functions.

Microglia: scavenger, clears debris. (Like a type of T cell)

- Oligodendrocytes (myelin in CNS)
- Schwann cells (myelin in PNS)
- Astrocytes (blood brain barrier)


Is there regeneration potential in the CNS?

Little to none


How does glial scarring impact CNS regeneration?

Glial cells and neural tissue have little regeneration potential. Even when this tissue does regenerate the glial cell function is impaired and organisation within that area of the CNS is impacted.


Is regeneration possible in the PNS?

Yes but it is dependant on the distance from the lesion to the soma.
Glial cells clear debris but if the myelin sheath is in tact they glial cells can secrete proteins to promote and guide axons, extension and regeneration


What are the characteristics of action all potential transmission? What are they determined by?

Electrical or chemical (NMJ or chemical)
Excitatory or inhibitory

Determined by:
Type of synapse
Type of receptors
Ions involved


What are the elements of a synapse?

Pre synaptic neuron
Synaptic cleft
Post synaptic neuron


What is the release of neurotransmitters reliant on?

The arrival of the action potential at the terminal button of the pre synaptic neuron


Describe the process of neurotransmitter release after an action potential reaches the pre synaptic neuron

Action potential reaches terminal button
Vesicles fuse to presynaptic membrane
Neurotransmitter is released into synaptic cleft
Neurotransmitter instigates a change in the neurotransmitter receptors of the post synaptic membrane
Post synaptic neuron either depolarises or hyperpolarises


What are the 2 types of post synaptic membrane receptors?

Those that form a channel through the membrane
Those that don't (eg. G- protein coupled receptor)


Describe the steps the an action potential

Influx of ions through a channel
Changes the neurons membrane potential
Na+ gives hyperpolarisatioon, neuron fires (EPSP)
Cl- gives hyper polarisation, neuron is taken further from firing (IPSP)


What will an influx of Na+ into a neuron do in terms of action potential?

It will depolarise the neuron


What will an influx of Cl- into a neuron do in terms of action potential?

It will hyperpolarise the neuron


When an EPSP is created, what does this mean?

The neuron has been sent an excitatory or depolarisation potential


What an IPSP is created, what does this mean?

The neuron has been sent an inhibitory or hyperpolarisation potential


What is a synapse?

The junction between the processes of 2 neurons by which those neurons can communicate via chemical or neurotransmitter means.