Basic Neurosciences

Question 1

What is a neuron?

Answer 1

• Basic functional unit of the nervous system
• A specialised cell transmitting nerve impulses

Around 100 billion, originate from ectoderm

Question 2

Cell body/soma

Answer 2

Site of major metabolic activity and contains cellular organelles

Question 3

Dendrites

Answer 3

Receive signals from other neurons and transmit back to the cell body of their own neurones

Question 4

Axon

Answer 4

Conducts action potentials away from the cell body to the axon terminus.

Axon hillock = initial segment of the axon as it moves from the soma

Question 5

Classification of neurones:

Functional (sensory, motor, interneuron)
Structural (unipolar, bipolar, multipolar)

Answer 5

Functional:

Majority have a sensory (afferent) function
All unipolar or bipolar are sensory in function

Motor (efferent) neurones are the largest

Interneurones are found entirely in the CNS.

Structural:

Unipolar (single process) brush cell cerebellum

Bipolar (2 processes with a single axon and dendrite from the cell body; many are specialised for transmission of sense)

Multipolar - 1 axon and multiple dendrites (majority of neurones in CNS, include motor and inter- neurones)

Question 6

Glial cells

• Astrocytes
• Oligodengrocytes
• Schwann cells
• Microglia
• Ependymal cells

Answer 6

Provide a supportive function to maintain the action of neurones. 10-50 times more glial cells than neurones.

Also regulate the extracellular environment, uptake of neurotransmitters at synapses, secrete neurotrophic factors.

May be able to communicate with each other electrically

Question 7

Glial cells

Astrocytes

Answer 7

LARGEST glial cell
-Help formation of the blood-brain barrier
- structural support and repair, regulate K+ in
extracellular fluid

They proliferate when brain tissues is damaged and form a dense network, glial scar

Question 8

Oligodendrocytes

Answer 8

Formation and maintenance of myelin sheath around axons in the CNS

Question 9

Microglia

Answer 9

Primary immune cells of the CNS; resident macrophages and aid phagocytosis

Question 10

Schwann cells

Answer 10

Derived from the neural crest and only found in PNS.

Myelination of the PNS

Question 11

CNS glial cells vs PNS glial cells

Answer 11

CNS; astrocytes, microglia, oligodendrocytes, ependymal cells

PNS; schwann cells, satellite cells

Question 12

Cerebral cortex: overall structure

Answer 12

• Most of cerebral cortex in neocortex (divided into 6 layers) and is the top layer of cerebral hemisphere.

Allocortex = paelocortex and archicortex, both interconnected with the limbic system

Paelocortex = includes entorhinal cortex and piriform lobe

Archiocortex = hippocampus dealing with memory and spatial function

Question 13

The neocortex

Answer 13

• Covers >90% of the cerebral cortex
• Consists of 6 layers
• 2 main types of cell are pyramidal and stellate cells

Other cells: fusiform cells, horizontal cells of cajal and cells of Martinotti

Question 14

Which are the largest neurones found in the brain

Answer 14

Betz cells

Question 15

Cerebellar cortex

Answer 15

Consists of 3 layers
Purkinje cells, granule cells, stellate cells, basket cells and Golgi cells

All are inhibitory cells, apart from granule which are excitator

Purkinje cells are the main course of output from the cerebellum

Question 16

What are the principle cells of the hippocampus?

Answer 16

Pyramidal cells

Question 17

What are the principle cells of the dentate gyrus?

Answer 17

Granule cell

Question 18

Senile plaque composition vs neurofibrillary tangles

Answer 18

Senile plaque = amyloid beta, extracellular in grey
matter
Neurofibrillary tangles = hyperphosphorylyaed tau protein

Question 19

CSF site of formation

Answer 19

Ependymal cells in the choroid plexus of the lateral, third and fourth ventricle

Question 20

Ependymal cells

Answer 20

Line the ventricular system and are involved with CSF circulation and fluid homeostasis in the brain.

Specialised choroid plexus cells produce csf

Question 21

Dopamine hypothesis and schizophrenia

Answer 21

Negative symptoms = reduced dopamine activity in the frontal lobe

Positive symptoms = increased dopamine activity in the striatum

Question 22

Neurotransmitters:

Acetylcholine

Answer 22

• Excitatory neurotransmitter
• Small molecule, class 1
• Synthesised in the Basal nucleus of Meynert
• Involved in learning and memory
• Increased in Parkinson’s disease
• Decreased in Alzheimer’s and Huntington’s

Question 23

Neurotransmitters:

Serotonin

Answer 23

• Class II, small molecule
• Excitatory neurotransmitter
• Ligand-activated and metabotropic
• Synthesised in the raphe nucleus
• Implicated in depression/anxiety

Question 24

Neurotransmitters:

GABA

Answer 24

Small molecule, class III
Inhibitory 
Ligand-activated and metabotropic 
Synthesised in the nucleus accumbens
Decreased in anxiety and Huntington's

Question 25

Types of interneuron

Lugaro cells
Basket cells
Satellite cells

Answer 25

Lugaro cells = cerebellum
Basket cells = cortex and cerebellum
Spindle cells = connect the widely separated areas of the 🧠

Question 26

CSF AD biomarker

Answer 26

Elevates total tau, 181-phosphorylated tau and low beta amyloid

Question 27

ASD neuropathology

Answer 27

Hypoplasia of cerebellar vermin

Lower purkinje count

Question 28

Pituitary gland

Answer 28

Anterior - glandular, ingrowth of ectoderm

Posterior - magnocellular cells from partaventricular and supraoptic nuclei of hypothalamus

Question 29

Posterior pituitary

Answer 29

Oxytocin

ADH

Question 30

Anterior Pituitary

Answer 30

ACTH (Corticotropin release hormone +ve)
TSH (Thyrotropin release hormone +ve)
Prolactin (Dopamine -ve)
Growth Hormone (GH release hormone +ve)
FSH/LH (gonadotrophin release hormone)

Question 31

Hirano bodies

Answer 31

Eosinophillic intracytoplasmic inclusions, non-specific sign of neuronal degeneration.

Found commonly in hippocampi:

Alzheimer's Disease 
ALS
Bv FTD
Creutzfeldt Jacob 
Alcoholism