nervous system

Question 1

draw out the organisation of the nervous system

Answer 1

Question 2

draw structure of a typical CNS neuron :

Answer 2

Question 3

what are excitatory neurotransmitters - what do they do?

give some examples?

Answer 3

cause depolarisation

e.g.

acetylcholine

glutamate

Question 4

what are inhibitory neurotransmitters - what do they do?

give some examples?

Answer 4

cause hyperpolarisation

e.g.

GABA and glycine

Question 5

what is gray matter

Answer 5

nucleus - a cluster of neuron cell bodies and their dendrites

Question 6

what is white matter

Answer 6

White matter is bundles of myelinated axons that form fibre tracts connecting nuclei

Grey matter connected by white matter

Question 7

how is the spinal cord divided into grey and white matter

what are the 3 distinct regions of the spinal cord

Answer 7

• Grey matter in butterfly space
  
  • Divided into 3 distinct regions
    
    • Dorsal horn
      
      • Closest to back
    • Intermediate zone
    • Ventral horn
      
      • Closest to internal organs
• White matter surrounding
  
  • Axons of neurons in the grey matter

Question 8

describe motor neurons in the spinal cord

Answer 8

• found in ventral horn
• has single basal axon
  
  • leaves through grey matter
  • leaves through ventral root
  • coalesces with dorsal root
  • gives rise to segmental spinal nerve

Question 9

describe sensory neurons in the spinal cord

Answer 9

• found outside spinal cord but associated
• in dorsal root ganglia
  
  • neuron cell bodies are pseudo unipolar
    
    • have two projections / axons
    • one to spinal nerve
    • one to dorsal horn / passes through

Question 10

what are interneurons

Answer 10

Neurons which relay information between neurons

Question 11

types of interneurons :

Answer 11

• Local circuit interneurons
  
  • Axons remain within the nucleus
  • Carry out complex computation to integrate information
• Projection interneurons
  
  • Send their axons along fibre tracts to other nuclei
  • Can be over a metre long

Question 12

how many glial cells are there in the nervous system

Answer 12

many more than neurons

Question 13

what types of glial cells are there?

Answer 13

Three types of glial cell

• Oligodendrocytes
• Astrocytes
• Microglia

Question 14

what are oligodendrocytes

Answer 14

• myelinating cells
  
  • form myelin sheath that wraps around axons
• have processes which project from them
  
  • wrap around axons
• nodes of ranvier - ares of no myelination
• in PNS - called schwann cells

Question 15

what are astrocytes

Answer 15

Large star shaped cells

Multiple processes

Multiple functional roles

Question 16

what are the roles of astrocytes

Answer 16

• regulation of extracellular ion concentrations
  
  • essential for establishing resting potential of neurons
• Astrocyte processes enclose synapses and regulate synaptic activity
  
  • Regulate neurotransmitter uptake and degradation
• structural support
• regulation of integrity of the blood-brain barrier
• neurotrophic support/nutritive role

Question 17

how do astrocytes regulate the integrity of the blood-brain barrier

Answer 17

astrocytes have end feet which support integrity of the tight junctions

Question 18

what are microglia?

Answer 18

Small glial cells with numerous structure forms (depending on their activation state)

Play an equivalent role within the brain to white blood cells in the periphery

Immune system of the brain

Question 19

what can occur when microglia are activated?

Answer 19

can :

• Release inflammatory cytokines
• Attach disease organisms
• Phagocytose damaged cells

Question 20

what can occur when microglia are ‘inappropriately’ activated

what can this lead to?

Answer 20

Role in generation of neuropathic pain conditions

Role in some neurodegenerative diseases

• Alzheimers & parkinsons

Question 21

organisation of the peripheral nervous system

Answer 21

• Peripheral sensory neurons
  
  • The majority of the body receives sensory innervation from Dorsal Root Ganglion (DRG) neurons.
• Autonomic neurons
  
  • Neurons of the sympathetic, parasympathetic and enteric nervous systems.

Question 22

which parts of the body do not receive sensory information from the dorsal root ganglion neurons?

what are they innervated by?

Answer 22

Head, neck and some internal organs are innervated by cranial sensory ganglia that are associated with cranial nerves

Question 23

what do segmental spinal nerves carry?

Answer 23

Carry axons of

• DRG neurons
• Sympathetic neurons (postganglionic)
• Spinal cord motor neurons

Question 24

how are segmental spinal nerves formed?

Answer 24

from coalescence of the dorsal roots and ventral roots

• Ventral contain axons of
  
  • motor neurons
  • Sympathetic neurons
• Dorsal contains axons of
  
  • DRG neurons

Question 25

what are dermatomes

Answer 25

Area of skin supplied by each segmental spinal nerve * Sensory innervation

Question 26

draw mid-sagittal section of the brain and label

Answer 26

Corpus callosum * Fibre tract containing axons of neurons * Where axons cross across the hemispheres cerebellum * mostly balance

Question 27

draw coronal brain section and label

Answer 27

Question 28

function of basal ganglia

Answer 28

controlling movement * Regulate output from motor and premotor areas of the cortex * **Initiation of movement**

Question 29

what does the basal ganglia comprise of

Answer 29

Dorsal striatum = Caudate nucleus and Putamen Globus pallidus Subthalamic nucleus Substantia nigra

Question 30

what is the substantia nigra divided into?

Answer 30

2 subnuclei * substantia nigra pars reticulata * substantia nigra pars compacta

Question 31

how are the motor symptoms of parkinson's caused?

Answer 31

* substantia nigra pars compacta * contains dopeminergic neurons * these project to dorsal striatum * **degeneration of these axons and dopeminergic neurons** leads to symptoms

Question 32

how are the motor symptoms of huntington's caused?

Answer 32

Dorsal striatum contains medium spiny neurons * **Degeneration of medium spiny neurons** * = motor symptoms of huntingtons disease