Session 2

Question 1

What are the roles of astrocytes?

Answer 1

Structural support
Nutrition for neurones
Remove neurotransmitters
Maintain ionic environment

Question 2

Describe the glucose-lactate shuttle.

Answer 2

Glucose enters the astrocytes via GLUT1.
This in converted to pyruvate and then to lactate.
Lactate crosses the ECF to the neuron, via MCT1 and MCT2 transporters.
Lactate is then converted to pyruvate and then to ATP within the neuron.

Question 3

Do astrocytes re-uptake neurotransmitters?

Answer 3

Yes, e.g. Glutamate. This is then converted to glutamine which can then be recycles and sent back to the pre-synaptic terminal.

Question 4

Why to astrocytes take up potassium ions?

Answer 4

As this would result in depolarisation of neurones in the brain’s ECF, resulting in unwanted action potential firing.

Question 5

What are the roles of oligodendrocytes?

Answer 5

Myelination of axons in the CNS. Schwann cells myelinate those in the PNS.

Question 6

Function of microglia?

Answer 6

Immunocompetent cells which recognise foreign material and become activated. Allowing them to phagocytose debris and foreign material, forming the Brain’s main defence system. They are also able to present antigens to T-cells.

Question 7

What is allowed across the BBB and what is not?

Answer 7

Transporters present for substances such as glucose, amino acids and potassium.
Gaseous molecules and water can diffuse across freely.

Question 8

Give examples of neurotransmitters which are:

1) Amino acids
2) Biogenic amines
3) Peptides

Answer 8

AAs = glutamate, GABA, glycine
Biogenic amines = ACh, NO, dopamine, serotonin, histamine
Peptides = enkephalins, somatostatin, cholecystokinin, substance P.

Question 9

What are the 3 types of ionotropic glutamate receptors?

Answer 9

AMPA, Kainate and NMDA.

Question 10

How do glutamatergic synapses work?

Answer 10

AMPA mediate the initial fast depolarisation, and NMDA receptors are permeable to calcium ions. NMDA receptors need glutamate to bind and the cell to be polarised to allow ion flow through the channel.

Question 11

How is long term potentiation caused?

Answer 11

Due to strong, high frequency stimulation of glutamate receptors. Calcium entry through NMDA receptors is very important for this.

Question 12

How does the GABA neurotransmitter work?

Answer 12

GABA receptors have integral Chlorine channels, whereby opening of these channels causes hyperpolarisation and an inhibitory post-synaptic potential. Hence, decreased action potential firing.

Question 13

Give two classes of drugs that bind to GABA receptors

Answer 13

Barbiturates and benzodiazepines.

Question 14

Give the role of dopaminergic neurones

Answer 14

Involved in motor control, mood, arousal and rewards. Loss of dopaminergic neurones is associated with Parkinson’s disease. Release of too much dopamine is associated with schizophrenia.

Question 15

How do you treat Parkinson’s disease?

Answer 15

Give levodopa. This crosses the BBB, and is then converted to dopamine via AADC. In order to prevent conversion in the periphery, give carbidopa.

Question 16

Where does most noradrenaline come from in the brain?

Answer 16

Group of neurones in the Locus Ceruleus. These neurones are inactive during sleep and activity increases during behavioural arousal.

Question 17

Role of Serotonin (5-HT)?

Answer 17

Involved in sleep/wakefulness and mood.

Question 18

What forms the pterion and the anterior cranial fossa?

Answer 18

Pterion = Junction between temporal, parietal, frontal and sphenoid bones.
Anterior cranial fossa = Depression of skull formed by frontal, ethmoid and sphenoid bones.

Question 19

What forms the middle and posterior cranial fossa?

Answer 19

Middle = Depression formed by sphenoid, temporal and parietal bones.
Posterior = Depression formed by squamous and mastoid temporal bones, plus the
occipital bone.

Question 20

What is the difference between a linear and a diastatic cranial fracture?

Answer 20

Linear = simple break in bone, traversing its full thickness. Radiating lines away from point of impact. 
Diastatic = occurs along a suture line, widening the suture.

Question 21

Describe the two types of hydrocephalus.

Answer 21

1) Communicating = impaired CSF reabsorption in the absence of any CSF flow obstruction between the ventricles ad subarachnoid space.
2) Non-communicating = CSF flow obstruction.

Question 22

What results following tearing of the middle meningeal artery?

Answer 22

Bleeding into the extradural space (extradural haematoma).

Question 23

What are the layers of the scalp?

Answer 23

Skin
Dense connective tissue
Aponeurosis
Loose connective tissue
Periosteum

Question 24

What is the name for additional bones that can be found within sutures?

Answer 24

Wormian bones

Question 25

What is the falx cerebri?

Answer 25

A fold of the meningeal dural, which separates the two hemispheres. Its free edge contains the superior sagittal sinus, which drains into the venous circulation.