Cellular Structure of the Nervous System

Question 1

How is the resting potential established?

Answer 1

Information is carried in electrical charges so all membranes are polarised
the charge pushes positive ions of sodium out of the membrane to create the charge of -70mV which is the resting potential

Question 2

What are the 5 stages of an action potential?

Answer 2

Stimulus
Depolarisation
Repolarisation
Hyperpolarisation
Resting state

Question 3

What happens when a dendrite is excited?

Answer 3

The resting membrane potential goes into a more positive direction a which is known as depolarising

Question 4

What happens during an action potential? (X steps)

Answer 4

1) when membrane potential reaches axon hillock, plasma membrane generates impulses conducted by the axon away from soma and dendrites toward other neurones
2) if threshold is reached by dendrites being activated, it reaches a threshold of depolarisation where the voltage gated sodium channels open
3) Sodium flows into cell and pushes membrane potential in a more positive direction which is the action potential
4) potential drops down during hyperpolarisation afterwards

Question 5

What direction is an action potential?

Answer 5

Its unidirectional

Question 6

What is an electrical synapse?

Answer 6

formed by gap junctions
current carried by transfer of ions between cells and channels
has very little delay
is bidirectional

Question 7

What is a chemical synapse?

Answer 7

Physical gap between cells
you have a presynaptic and postsynaptic side
presynaptic has vesicles with neurotransmitters and postsynaptic has receptors for those neurotransmitters

Question 8

What are the 3 classification of synapses?

Answer 8

Axodendritic - between axon and dendrite
Axoaxonic - axon to axon
Axosomatic - Axon to soma

Question 9

What are the purpose of synapses and dendrites?

Answer 9

Synapses = efficiency of transfer can be modulated
Dendrites = integrate inputs from multiple synapses

Question 10

What are coincidence detectors?

Answer 10

They are tuned to different delays at different receptors so you can perceive where sound comes from

Question 11

What does layer 4 of the cortex contain?

Answer 11

Projection neurons at different areas of the cortex

inputs from the thalamus are excitatory

Question 12

What does layer 5 of the cortex contain?

Answer 12

contains projection neurones which output to the rest of the brain, hindbrain and spinal cord

Question 13

What does layer 6 of the cortex contain?

Answer 13

projection neurones to the thalamus

Question 14

What are projection neurones?

Answer 14

They connect different areas and communicate with motor and sensory neurones

Question 15

What is neurone type determined by?

Answer 15

Locations of cell body
length
target of axon

Question 16

Afferent and Efferent neurones?

Answer 16

Afferent neurones are sensory neurones which bring information to the neurone
Efferent neurones are motor neurones which leave the CNS

Question 17

What controls the activity of smooth muscle glands and secretion?

Answer 17

The post-ganglionic neurones of the sympathetic system in the thoracic region and the parasympathetic system in cranial and sacral regions control it

Question 18

What is saltatory conduction?

Answer 18

Insulting sheaths and gaps called nodes of Ranvier allow for it and make conduction quicker
It is rapid passive conduction over high resistance membrane segments

Question 19

What are white and grey matter?

Answer 19

White = myelinated axons
grey = cell bodies, dendrites, axons

Question 20

What are glia?

Answer 20

Glia are involved in structure and support of the nervous system and are crucial for development

Question 21

What are oligodendrocytes?

Answer 21

They deposit myelin to wrap around axons in the CNS

Question 22

What are Schwann cells purpose?

Answer 22

They wrap themselves around axons to produce myelin in the PNS

Question 23

What are microglia?

Answer 23

small phagocytic cells that clear up debris

Question 24

What are astrocytes?

Answer 24

they allow contact between neurons and microcapillaries to create the blood brain barrier
they envelope synapses to clear neurotransmitters and insulate the synapse
they’re reactive during brain injury

Question 25

What are radial glia?

Answer 25

they guide the radial migration of newborn neurones from the ventricular zone to the mantle regions
they were previosuly progenitors
they signal in long axons

Question 26

Migration of neurones?

Answer 26

Neurons migrate from ventricular surface of mantle layer
migration outwards is radial migration
in other layers they can move peripherally via tangential migration

Question 27

how is cell type in the nervous system determined?

Answer 27

By the dorsoventral position of the progenitor within the neural tube