lecture 1 : cells of the nervous system

Question 1

what is a neurone?

Answer 1

this is a highly organised metabolically active cell involved in cells signalling

Question 2

what are the features of the cell body?

Answer 2

• large nucleus with a prominent nucleolus
• there is abundant Rough endoplasmic reticulum
• there is a well developed golgi
• abundant mitochondria
  highly organised cytoskeleton
• numerous lysosomes

Question 3

what are the features of dendrites?

Answer 3

• they receive incoming information
• dendrites have protrusion called dendritic spines that receive the majority of synapses
• they increase the surface area of the neurone

Question 4

what cells does the cerebellum have a large number of?

Answer 4

the cerebellum has a large number of purkinje cells

Question 5

what are
primary dendrites ?
secondary dendrites ?
tertiary dendrites?

Answer 5

from vertices of pyramid
form primaries
form secondaries

Question 6

what is the axon hillock?

Answer 6

this is where the action potential is generated

Question 7

what are axons organised into?

Answer 7

• node - sodium channels are found here
• paranode - ends of the myelin are bound to the axon to form tight junctions
• juxta paranode - area adjacent to paranode where potassium and calcium channels are found

Question 8

what are unmyelinated sections called?

Answer 8

the nodes of ranvier

Question 9

where are the terminals located?

Answer 9

they are close to the target

Question 10

what are the two forms of axon terminals?

Answer 10

boutons - this is a standard synapse
varicosities - this is when axons may synapse with many smooth muscle cells so there are many swellings containing neurotransmitters

Question 11

what are prominant features in axons?

Answer 11

microtubules and neurofilaments

Question 12

what feature is present in the post synaptic neurone?

Answer 12

• there are lots of mitochondria present

- this is due to large amounts of ion pumping and synaptic transmission

Question 13

what are the two types of synaptic inputs ?

Answer 13

• they can be excitatory

- they can be inhibitory

Question 14

how do neurones interact together?

Answer 14

the competing inputs are integrated in the postsynaptic neurone - this is neuronal integration

Question 15

what are the types of synapse?

Answer 15

1. axon dendritic (excitatory)
2. axon somatic (inhibitory)
3. axon anoxic (modulatory)

Question 16

what is anterograde transport?

Answer 16

this is the transport of materials needed for neurotransmission away from the soma

Question 17

what are the two types of anterograde transport and what do they consist of ?

Answer 17

• fast anterograde:
  consists of synaptic vesicles, transmitters and mitochondria
• slow anterograde:
  this is the bulk cytoplasmic flow of soluble constituents

Question 18

what is retrograde transport?

Answer 18

• this is the transport of materials towards the soma

Question 19

what is fast retrograde?

Answer 19

• transport of substances happens from the EC space
• trophic growth factors
• uses different molecular motors

Question 20

what happens in multiple sclerosis?

Answer 20

this is a restriction on the axon which causes swellings to occur due to accumulation of vesicles of neurotransmitter at the restricted point

Question 21

what is a pseudo unipolar ?

Answer 21

• these neurones have two fused processes that are axonal in structure
• they are normally sensory neurones
• the signal received passes directly to the axon terminal without going through the soma

Question 22

what is a bi polar neurone?

Answer 22

• this is involved in the white matter of the cerebral cortex
• the soma is in the same line of action as the axon

Question 23

what is a golgi type 1 multipolar?

what are examples

Answer 23

• these have highly branched dendritic trees
• the axons extend for large distances
• pyramidal cells (cerebral cortex)
• purkinje cells
  (cerebellum)
• anterior horn cells
  (spinal cord)

Question 24

what are golgi type 2 multipolar cells?

what are examples

Answer 24

• they are highly branched dendritic trees
• they have short axons
• glutamate transmitters
• stellate cells (found in the cerebellum and cerebral cortex)

Question 25

what are the three main types of neurone?

Answer 25

- sensory - motor - interneurone

Question 26

what are sensory neurones?

Answer 26

they are normally pseudo uni polar with one process that divides into two branches - one branch to the CNA - one branch to the sensory receptor

Question 27

what are motor neurones?

Answer 27

- they conduct signals form the CNA to the effectors | - they are generally multipolar with large somas

Question 28

what are interneurones?

Answer 28

- these are neurones whose somas and processes remain inside the CNS - they can be large multipolar neurones or small bio polar circuit neurones

Question 29

what is a nucleus?

Answer 29

- this is a group of un-encapsulated neuronal cell bodies within the CNS

Question 30

what is a lamiae?

Answer 30

these are layers of neurones of similar type and function

Question 31

what is a ganglion?

Answer 31

these are groups of neuronal soma in the peripheral nervous system that are encapsulated to form a ganglion

Question 32

what are fibre tracts?

Answer 32

these are groups or bundles of axons in the CNS

Question 33

what are nerves?

Answer 33

nerves are discrete bundles of axons outside of the CNS

Question 34

what are neuroglia? | what are the different neuroglia?

Answer 34

these are the support cells of the CNS - astrocytes - oligodendrocytes - microglia - ependymal cells - immature progenitors - Schwann cells - Satellite cells

Question 35

what is the structure of astrocytes?

Answer 35

- multi processed star like shape - most numerous cell in the CNS - there are gap junctions present

Question 36

what are the functions of astrocytes?

Answer 36

- they are a scaffold for other cell types and aid the growth of axons - the formation of the blood brain barrier - transport of substances from the blood to the neurones - the removal and the degradation of neurotransmitters - the synthesis of neurotrophic factors - potassium buffering - scar tissue formation - glioma formation

Question 37

what are oligodendrocytes?

Answer 37

they are the myelin forming cells of the CNS

Question 38

what are the types of oligodendrocytes what is the structure of oligodendrocytes?

Answer 38

- the main types are interfascicular and perineuronal - they have small and spherical nuclei - they have thin process - there are prominent golgi - they are highly metabolically active

Question 39

what are the functions of oligodendrocytes?

Answer 39

- the maintenance of the myelin sheaths (much smaller than schwann cells) - they produce many myelin internodes

Question 40

what are the diseases concerning myelin?

Answer 40

- multiple sclerosis (this is the loss of myelin due to an autoimmune disease) - adrenolebukodystrophy (this is a progressive loss of myelin)

Question 41

what are microglia and whats the structure?

Answer 41

- they are the immune cells of the CNS - they are derived from the early development of the blood monocytes that invade the brain - they have dense lysosomes, lipid droplets and residual bodies

Question 42

what are the functions of the microglia?

Answer 42

- macrophage population for the brain - they are antigen presenting - they are needed for tissue presenting - they are synapse stripping

Question 43

whats the structure of ependymal cells? and what are ependymal cells?

Answer 43

- they are epithelial cells that line the ventricles of the brain and the central canals of the brain - they have apical microvilli and cilia - there are gap junctions - there are no tight junctions

Question 44

what are schwann cells?

Answer 44

- any axons outside the CNS are myelinated by the schwann cells - one schwann cell myelinated one axon - they can also perform the functions of astrocytes and promote repair

Question 45

what are satellite cells?

Answer 45

- each soma in a spinal ganglion (PNS) is surrounded by metabolically active supportive satellite cells