Neurology - basics Flashcards by Alice Harsant

What is the morphological classification of the NS?

CNS - brain and spinal cord
PNS - everything else incl cranial and spinal nerves

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Direction of flow classification?

Afferent/sensory system - information toward from CNS/PNS

Efferent/motor system - information away from CNS/PNS

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Physiological classification?

Somatic/voluntary - coordinates voluntary control

Visceral/involuntary - involuntary activities such as digestion

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What is grey and white matter?

Grey matter - cell bodies
White matter - axons

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What is the blood supply to the brain?

Via the carotis arteries, which pools in cerebral arterial circle before distributed to the brian.

Brain requires rich blood supply.

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What is the ventricular system of the brain?

A system of cavities through the brain, which contain ependymal cells. These secrete cerebrospinal fluid from the choroid plexus.

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What is cerebrospinal fluid?

Its ultra-filtrated blood, containing glucose and minerals for nutrition and provides shock support.

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What are the layers that protect the brain?

Skull bone
-Epidural space
-Dura mater
-Subdural space
-Arachnoid layer
-Subarachnoid space
-Pia mater

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What is the epidural space?

Loose connective tissues, veins and lymphatics. This cusions the brain.

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What is the dura mater?

Thick, dense fibrous tissue fused with bone

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What is the subdural space?

Contains lubricating fluid

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What is the arachnoid layer?

Has cerebrospinal fluid and blood vessels providing nutrition and cushioning

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What is the subarachnoid space?

Cerebrospinal fluid leaking from the ventricular system with varying thickness

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What is the pia mater?

A thin layer on the brain with many tiny blood vessels.

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What are the elevations and depressions called?

Folds - gyri
Grooves - sulci

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What is the peripheral NS?

links the environment with the central nervous system using efferent and afferent fibres.

All spinal nerves are a mix of sensory and motor.

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What are cranial nerves?

Sensory
I - olfactory
II - optic
VIII - vestibulocochlear

Motor
III - oculomotor
IV - trochlear
VI - abducten
XI - accessory
XII - hypoglossal

Mixed
V - trigeminal
VII - facial
IX - glossopharyngeal
X - vagus

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What is the anatomy of the neurones?

Cell body/soma - converts signal to membrane potential, contains nucleus

Dendrites/receptor segment - conducts impulse and recieves information

Axon/neurone fibre - relays impulses to other neurones and effector organs. Myelinated for insulation by Schwann cells in PNS and Oligodendrocytes in CNS

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What are the protein molecules on the nerve membrane?

Receptor proteins - bind to neurotransmitters
Channel proteins - acts as pores for ion movements
Transport proteins - transfer ions

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What are the different classifications of neurones?

Multipolar - most common. Multiple dendrites and one axon e.g. motor neurones
Bipolar - one dendrite and one axon e.g. olfactory, retina and ear. Cell body in middle.
Pseudopolar - sensory information from skin and organs to spinal cord e.g. sensory neurones

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What makes up the support matrix?

Neuroglia surrounds neurones and supports it all. Capable of mitotic activity.

Fibrillary and protoplasmic astrocytes - nourishment and metabolic support

Oligodendrocytes - insulate the cells of CNS

Microglia - macrophages of the CNS and 10-15% of the brain cells

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Action potential formation?

Resting potential - usually -75mV, due to electrical difference across the membrane. Maintained due to selective permeability (readily in to K+ and slightly to Na+) and sodium-potassium pump (Na+ out and K+ in)

Action potential - voltage gated Na+ channels open, Na+ floods in. Up to +30mV.

Repolarisation - Na+ gates close and K+ open, removing K+ from inside and bringing back down to -90mV.

What happens when the AP reaches the end?

Voltage gated Ca2+ channels open, leading to an influx of Ca2+
This causes vesicles with neurotransmitters to fuse to membrane, releasing contents into synapse.
The neurotransmitters diffuse across the synapse and bind to the post-synaptic receptors
Neurotransmitters are then either recycled or broken down by an enzyme

What happens when the AP reaches the end?

Voltage gated Ca2+ channels open, leading to an influx of Ca2+
This causes vesicles with neurotransmitters to fuse to membrane, releasing contents into synapse.
The neurotransmitters diffuse across the synapse and bind to the post-synaptic receptors
Neurotransmitters are then either recycled or broken down by an enzyme

What are the types of neurotransmitters?

Peptides that are either excitatory, inhibitory or modulatory. Two main types: -ACh, Acetylcholine - released at neuromuscular junctions and ANS. >Nicotinic receptors - preganglionic neurones in neuromuscular junctions and autonomic nS >Muscarinic receptors - pre- and post-ganglionic in parasympathetic and pre-ganglionic sympathetic -NAd, Catecholamines - in sympathetic nervous system on post-ganglionic neurones. >Adrenoreceptors, B1 in heart excitatory, B2 smooth muscle relaxatory Also glutamine (brain), glycine (SC inhibitor), GABA (CNS inhibitor), dopamine, serotonin

What can block neurotransmitters?

Agonists - make transmission more likely e.g. preventing reuptake of neurotransmitters (prozac/cocaine), trigger the receptor itself (nicotine) or making receptor more responsive (anti-anxiety) Antagonists - make transmission less likely. e.g. blocking receptor site (snake venom) or preventing release of neurotransmitter (anti-psychotic drugs)

What makes up the autonomic nervous system?

Parasympathetic - slows down Sympathetic - speeds up

What makes up the somatic nervous system?

Sense organs and voluntary muscles Afferent - toward CNS Efferent - away from CNS

What makes up the peripheral nervous system?

The somatic nervous system and the autonomic nervous system

Whats an example of a reflex arc?

Organ>Sensory receptor>Visceral afferent>Integrating centre>Pre-/Post-efferent>visceral efector

What is the efferent 2-neurone system?

1. Pre-ganglionic in CNS - longer in parasympathetic, shorter in sympathetic. Typically uses ACh 2. Post-ganglionic in PNS - > Longer in sympathetic and shorter in parasympathetic. Located very near, if not in the walls of the effector organs > Parasympathetic uses ACh and sympathetic uses NAd

Does the somatic nervous system have 2 neurone system?

No it is just one neruone from CNS to skeletal muscle

What is the nerve distribution of sympathetic system?

They originate in the lateral horns of T1 - 12 and L2-3 of spinal cord (thoracolumbar)

What is the nerve distribution of the parasympathetic system?

Originates in brainstem (II, VII, IX and X) and in S2-4. The most important is X which arises from the medulla oblongata.

What is the somatic nervous system??

Makes up part of peripheral nervous system involving voluntary movement.

What makes up the SNS?

1. Afferent nerves - reception of internal and external stimuli 2. Processing centre - somatomotor cortex and cerebellum down to spinal cord 3. Efferent nerves - from CNA to skeletal muscle to move the limb Only one neuronal pathway with ACh.

What is a neuromuscular junction synapse/

Between nerve and muscles. Its grooved to fit the surface of skeletal muscle and increase surface area. It contracts a muscle completely (all or nothing)

What does a Golgi receptor do?

Measures muscle tension via tendons

What do muscle spindles do?

Measure muscle length

What do meisner corpuscles do?

Measure light touch

What do merkels disks do?

Measure deep touch

what do pacinan corpuscles do?

Measure pain/deep pressure

What do ruffini corpuscles do?

Measure stretch

What do free nerve endings do?

Measure pain

What is a reflex arc?

Does not pass the brain to allow quick movement. Brain does eventually recieve sensory input while the action is occuring. Receptor > sensory neurone > spinal cord > interneuron > motor neurone > effort organ

What is the patella reflex?

1. Tapping patella stretches quad 2. Sensory neurones fire to spinal cord 3. Spinal cord detects signal and sends a response via interneurone. L4-L6 for femoral nerve leads to stifle extension 4. Motor neurone carries response to muscle contracting the quads

What is the withdrawal reflex?

1. Forceps pinch web between toes 2. Pain receptors fire to spinal cord 3. Spinal cord detects signal and sends reponse via interneurone. L6-S1 via sciatic nerve. 4. Flexor muscles and limb is protracted (hamstring)

What other reflexes are there?

-Cranial tibial reflex via peroneal nerve (L6-7) -Perineal reflex via pudendal nerve (S1-3)

What is the largest foramen?

Foramen magnum - passage for the centra nervous system, connecting brain and SC

What are the intervertebral space and foramina?

Intervertebral foramen is the root of spinal nerves, arteries and ligaments. Vertebral foramina - vertebral canal Transverse foramen - holes by big hole, occupied by veins/arteries

What is the antlo-occipital joint?

Base of head, where it joins the vertebrae

How far do the nerves go down the spine?

To L1-2 and then spread to cauda equina

What is the dorsal root ganglia?

A collection of nerves that emergy from the dorsal root of spinal nerves

What are the four main nerves in the forelimb?