Neuro Block 9: Overview

list the 2 main cell types of neuro:

1. neurones → excitable, can generate signals and transmit signals over long distances and emit neurotransmittera

2. glial cells → supportive, non-excitable cells

draw the structure of a neuron

What is the axon hillock?

• decision point → initiates action potential

A neuron receives a signal: list the flow of information

dendrites → soma → axon hillock → axon → synapse with other neuron

List the 3 types of neurones

1. multipolar; many dendrites, one axon

2. pseudo-unipolar; single process splitting into 2

3. bipolar; one dendrite, one axon

draw the 3 types of neuron and name their main function:

List the 4 types of glial cell:

1. Astrocyte

2. Microglia

3. Oligodendrocyte

4. Schwann Cell

What is the function of astrocytes?

• support neurones

• maintain bbb

• regulate ion + nutrient levels

What is the function of microglia?

• immune cells (phagocytose pathogens and debris, mediate immune repsonse

What is the function of oligodendrocytes?

• form myelin sheath in CNS

• increase signal conduction speed

• provide structural support

What is the function of Schwann cells?

• form myelin sheath in PNS axons (one cell → one segment)

Describe the structure of the blood brain barrier:

• tight junctions between endothelial cells

• astrocyte end-feet surrounding vessels

• basement membrane

What is the function of the BBB?

• separates blood in systemic circulation from extracellular fluid of brain

• highly selective → protects CNS

What does the BBB limit entry of?

• large molecules

• hydrophilic compounds

• toxins e.g. bacteria, fungi and viruses

• water soluble ions and electrolytes

What can pass though the BBB?

• lipid soluble small molecules

What causes a vasogenic oedema?

• breakdown of BBB

• proteins leak through barrier

• water follows and causes swelling

Describe the structure of peripheral nerves:

• individual nerve fibres grouped into fascicles

• surrounded by perineurium

• multiple fascicles form a nerve

• surrounded by epineurium

What is the composition of peripheral nerves?

• motor and sensory

• autonomic

• myelinated and unmyelinated

List 5 peripheral nerve fibre types:

1. A alpha

2. A beta

3. A gamma

4. A delta

5. C

What is the function of large A alpha nerve fibres?

• motor

• proprioception

What is the function of A beta nerve fibres?

• touch

• pressure

What is the function of A gamma fibres?

• muscle spindle

What is the function of A delta nerve fibres?

• pain

• temperature

What is the function of C nerve fibres?

• slow chronic pain

• temperature

List the grey matter structures in the spinal cord:

• dorsal horn

• ventral horn

List the white matter structures in the spinal cord:

• dorsal columns

• anterolateral spinothalamic system

• corticospinal tract

What is the function of the Cerebellar cortex?

• Refines motor movement (not direct control), specifically fine motor control

• Uses feedforward mechanism

• Compares intended vs actual movement

• Enables error correction for any discrepancy between that

List the 3 layers of the cerebellar cortex:

1. Molecular layer

2. Purkinje cell layer

• Main output neurones

3. Granular layer

• Input neurones

What do the Purkinje cells in the cerebellum act as?

• output neurone from cerebellum

What do the granule cells in the cerebellum act as?

• input neurons

List the lobes of the cerebral cortex:

1. frontal → motor

2. parietal → sensory

3. occipital → vision

4. temporal → auditory and memory

How many layers of the cerebral cortex?

• 6

What is the retina?

• part of the eye containing photoreceptors

• is part of the CNS as it is derived from CNS tissue and contains neurones