Neuronal Tissues Flashcards by Alfie Wain

What is the Broadmann Area of the Primary Visual Cortex?

Broadmann Area 17

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What is the Broadmann Area of the Primary Motor Cortex?

Broadmann Area 4

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What Are the Broadmann Areas of the cerebral cortex?

Regions of the cerebral cortex with their own distinct function

52 in total

Each area has its own particular inputs and outputs

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What are the components of a typical neurone?

Cell body (containing the nucleus)

Dendrites

Axon hillock

Axon

Axon collaterals

Axon terminals

Myelin sheath

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What are the functions of neurones?

Receive and integrate incoming information from sensory receptors or other neurones

Chemically transmit information to other neurones or effector organs

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What are dendrites?

Branched protoplasmic extensions

They propagate the electrochemical input from other cells to the cell body of a neurone

They branch off from the cell body to receive incoming action potentials from other neurones

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How much of a neurone can a dendrite occupy?

Up to 95%

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What is the role of the cell body in a neurone?

Houses the organelles (nucleus, cytoplasm, mitochondria, ribosomes, etc.)

Produces neurotransmitters which are subsequently stored in synaptic vesicles

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What is the role of the axon hillock?

It is a part of the cell body with a high density of voltage gated Na channels

Is the sight at which action potentials are triggered due to the high density of voltage gated Na channels

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Myelinated axons

Have a diameter greater than 1 micrometer

Myelination allows saltatory conduction

Action potential passes between nodes of ranvier

This is very rapid (up to 120m/s)

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What is the role of a sensory neurone?

Sends information from the sensory organs (receptors) into the CNS

Therefore also called Afferent neurones

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What is the role of a motor neurone?

Carry messages from the CNS to operate muscles and glands

Also referred to as efferent neurones

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What is the role of an interneurone?

These carry messages from one set of neurones to another

Bring information from different sources into one location In the CNS

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What are neuronal pathways?

These are used to link separate neurones

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What is the role of oligodendrocytes?

Oligodendrocytes are responsible for producing and maintaining the myelin sheath in the CNS to create white matter

Each oligodendrocyte can myelinate multiple axons

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What are the components of myelin?

Myelin basic protein and proteolipid protein make up approximately 80% of myelin

Other proteins include myelin associated glycoprotein (which facilitates the interactions between the axon and myelin

What are the benefits of myelinated axons?

Increases the nerve conduction and velocity

Decreases the size of nerves as a result

What is the role of microglia in the CNS?

Act as the macrophages of the CNS essentially

Begin inactivated but become activated by pathogens

Comprise 5% of the cells in the brain

They are phagocytic and immune cells but also promote repair

Apoptotic clearance

What are the roles of Astrocytes in the CNS?

Provide structural support to the CNS

Supply glucose

Maintain the ionic environment via removal of K

Uptake leftover neurotransmitters in the synaptic clefts

Repair the CNS

Form the blood brain barrier

What are the developmental functions of Astrocytes?

Regulate neuro and gliogenesis (they’re stem elements of the CNS)

Neuronal pathfinding

Regulate synaptogenesis

What are the structural functions of astrocytes?

Form the scaffold of the CNS, therefore defining the functional architecture of the brain and spinal cord

Astrocytes form a continuous syncytium and integrate other neural cells into this syncytium

What are the blood brain barrier related functions of Astrocytes?

Form the glial-vascular interface

Regulate the cerebral microcirculation

What are the metabolic functions of astrocytes?

Provide energy substrates for neurones

Collect neuronal waste

What are the homeostatic functions of astrocytes?

Control the microenvironment of the CNS

Regulate the concentrations of K following the fluctuations which occur after neuronal activity

Regulate extracellular pH

Remove neurotransmitters from the extracellular space

What are the signalling functions of astrocytes?

Modulate synaptic transmission Metabolise and synthesise neurotransmitters Release neurotransmitters

What are the 2 subtypes of astrocytes and how do they differ?

Fibrous astrocytes are located in white matter areas Protoplasmic astrocytes are located in grey matter

What is the role of astrocytes in the glutamate-glutamine shuttle?

They take up approximately 80% of glutamate released at the synapse They then convert this to glutamine and release it so the presynaptic terminal can uptake it It is then converted back to glutamate

What are the roles of ependymal cells in the CNS?

They line the ventricles of the brain and the central canal of the spinal cord Aid in homeostasis of the CSF due to the close contact with it as well as the Brain parenchyma Also contribute towards the formation of CSF and assist in its circulation via cilia movement

What is the blood brain barrier?

Highly selective permeability barrier which has evolved to determine substances can enter the brain and provides immune privilege to the CNS

What cells are present in the blood brain barrier?

Astrocytes Peri yes Blood endothelial cells These are arranged in neurovascular bundles

How does the permeability of the blood brain barrier change with age?

Decreases Dysregulation of the blood brain barrier is evidenced in Alzheimer’s disease and delirium, as well as other neurodegenerative disorders

What are the roles of Schwann cells and how do they differ from oligodendrocytes?

They are the Neuroglia of the PNS Aren’t present in the CNS Important for regeneration and they provide substrate for the axon to grow along Myelinates a single axon

What are Satellite cells?

Located exclusively in the peripheral ganglia (sensory, parasympathetic and sympathetic) Wrap around neuronal cell bodies forming a complete envelope Function isn’t 100% clear but considered to support neurones, supply nutrients, regulate exchange of materials between the interstitial fluid and neurones Similar to what astrocytes do in CNS

How are Neuroglia different to neurones?

Do not generate any action potentials Are able to divide Form the myelin sheathes

What are gliomas?

Tumours derived from glial cells Highly malignant and grow rapidly Difficult to access surgically so radiotherapy is the go to treatment option Usually inside the cranium so also referred to as intra-axial tumours

What is a neuroblastoma?

Rare tumour Outside of the cranium, typically the adrenal glands, abdomen, thoracic cavity, neck and spine Derived from the neural crest cells from the nervous system Survival rates vary depending on the subtype Initial prognosis is typically good However survivors often develop neurological problems approximately 30 years later Treatment depends on the subtype