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Flashcards in ToB S9 - Nerves Deck (23)
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Describe the structure of a peripheral nerve

- Cell body with nucleus, dendrites, nissl substance

- Axon Hillock

- Myelinated axon with Schwann cells and Nodes of Ranvier, Terminal buttons


What is an efferent nerve fibre?

Transports signals from the CNS to effectors Motor neurones


Which cells maintain myelination in the CNS and in the PNS?

CNS - Oligodendrocytes (1 cell per 250 axons)

PNS - Schwann cells (1 cell per axon)


What are the nodes of Ranvier?

- Gaps in the myelination of an axon

- Enable saltatory conduction


What are the three types of connective tissue sheaths found in the nervous system?

Epineurium - Covers entire nerve

Perineurium - Covers fascicles of nerve fibres

Endoneurium - Covers single cell axons


What are the consequences of demyelination?

Action potential must travel further along the axon as saltatory conduction is inhibited so action potential cannot jump between nodes of Ranvier


What makes up a neurone?

Axon, cell body, dendrites

Can be uni-polar (sensory), bi-polar (retina of eye) or multi-polar (majority)


What is white and grey matter?

White - axons

Grey - cell body


Describe the features of a nerve cell body

Nissl substance, nucleus, nucleolus, dendrite


What is the role of glial cells?

Support neurones, maintains homeostasis and form myelin/insulate neurones


List the glial cells found in the CNS, PNS and both

CNS - astrocytes, oligodendrocytes

PNS - Schwann cells, satellite cells

Both - microglia


Where are myelinated and unmyelinated neurones found?

Myelinated - Somatic

Both - Autonomic


What are ganglia?

Collections of nerve cell bodies in the PNS (swelling)


What two reciprocal components make up the autonomic nervous system?

Sympathetic and parasympathetic system


What are effectors of the ANS

Smooth muscle, cardiac muscle, glands, visceral organs


List the functions of the sympathetic NS

Involved in fight or flight response mechanism

- Increase heart rate

- Increase blood pressure

- Divert blood to muscles and heart

- Hyperventilation


List the functions of the parasympathetic NS

Involved in the resting state

- Promotes sleep

- Promotes digestion

- Promotes normal bodily functions such as bladder emptying

- Reduced heart rate and force of contraction


What neurones and receptors are involved in the sympathetic NS ?

Pre-ganglionic neurone - Cholinergic

Post-ganglionic receptors - nicotinic

Post ganglionic neurone - noradrenergic


What type of neurotransmitter and receptors are involved in the parasympathetic NS?

Pre-ganglionic neurone - Cholinergic

Post-ganglionic receptors - nicotinic

Post ganglionic neurone - cholinergic


What do excitatory and inhibitory neurones release?

Excitatory- glutamate/aspartate neurotransmitter

Inhibitory- glycine/GABA neurotransmitter


What function do astrocytes have?

- Make up the blood brain barrier

- Assist in transfer of nutrients and waste


What function do oligodendrocytes have?

Myelination of the central nervous system, myelinating up to 250 axons/cells


What function do microglia have

Immune and inflammatory functions