BMC L7 Flashcards by Umar Khan

State 4 types of sensory receptors

Temp
Mechanoreceptors
Chemical receptors
Nociceptors

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State the general function of mechanoreceptros

Respond to pressure, stretch, vibration, distrotion

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State the 5 types of mechanoreceptors

Merkel cell
Meissner corpuscle
Pacinian corpuscle
Free nerve endings
Hair follicle

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State the function of Merkel cells

Detect:
-Sustained pressure, static stimualtion

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State the function of meissner corposcule

Detect:
light touch, slip, flutter

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State the function of pacinian corposcule

Rapid vibrations

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State function of free nerve endings

Touch, pressure, stretch, tickle, itch

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State function of hair follicle

Detects Distortion of body hair

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What are the 4 different nerve fibres

A-alpha nerve fibres
A-beta nerve fibres
A-delta nerve fibres
C nerve fibres

Recognise on diagram

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State the function of A-alpha nerve fibres

Size: Large, INSULATED

Proprioception e.g. muscle reflex

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State the function of A-beta nerve fibres

Medium, insulated
Proprioception - non-painful touch e.g. pressure

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State the function of A-delta nerve fibres

Small, insulated
Fast tissue damage, pin prick, intense heat

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State the function of C nerve fibres

Small, UNINSULATED
SLOW TISSUE DAMAGE, SLOW BURNS, ITCH

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Explain the incidence and purpose of fast pain

Acute “sharp” - pin prick
Removes part of the organism from harm to PREVENT FURTHER DAMAGE
FAST PAIN ADAPTS, PAIN SUBSIDES - becomes less strong

A-delta nerve fibres

MYELINATED

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Explain the incidence and purpose of slow pain

Chronic, more intense, slow burning etc

Debilitates organism until injury repais to prevent too much activity

LEADS TO HYPERALGESIA, increased sensitivity to pain, which leads to allodynia, where normal stimuli can be painful

C nerve fibres
Unmyelinated

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State the 2 types of pathological pain

Chronic
Neuropathic

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What is the severity of chronic pain?

PARTIALLY Debilitating
Destroys quality of life

What is the severity of neuropathic pain?

Pain persists in absence of tissue damage
After healing, CNS fails to rest, or pathways in CNS rewired, increased sensitivity of synapses, hyperalgesia
INJURED REGION is hypersensitive to pain

State the role of nociceptors and give an example

Detect noxious stimulus, harmful
-tissue damage, due to extreme temp

E.g. FREE NERVE ENDINGS in tissues - branching dendrites

Describe the activation of nociceptors

NOXIOUS
1. Physical distortion of membrane
2. This damages nociceptor
3. Leads to change in pH
4. Chemicals released from damaged cells: K+, ATP, mast cell secretions (histamine), Substance P, prostaglandins

Describe how damaged nociceptors release prostaglandins

Arachidonic acid in cell membranes produce arachidonate

Arachidonate is coverted into prostaglandins via COX

PROSTAGLANDINS STIMULATE SENSITISATION IN NOCICEPTORS

Describe the pain pathway

Noxious stimulus
Causes damaged tissue to rlease K+, bradykinin, causes platelets to release serotonin, causes mast cells to release histamune
These chemicals activate NOCICEPTORS
Nociceptors send signal to thalamus via spinothalmaic pathway
Thalamus sends impulse to cerebral cortex
PAIN

What is the role of substance P in the pain pathway?

Released by nociceptors
Stimulates mast cells to release histamine
Histamine activates nociceptors

Also leads to SENSITISATION OF NOCICEPTORS

What is congenital analgesia?

Inability to sense pain since birth
Patients usually die young

Mneumonic for cranial nerves

Oh Oh Oh To Touch And Feel A Girls Vagina Ah Heaven

State the cranial nerves in order

Olfactory Optic Occulomotor Trochlear Trigeminal Abducens Facial Vestibulocochlear Glossopharyngeal Vagus nerve Accessorry Hypoglossal

Cranial nerves modality pneumonic

Some Say Marry Money But My Brother Says Big Brains Matter More S - SENSORY M - MOTOR B - BOTH

State the role of the olfactory nerve and where it originates

ENTIRELY SENSORY RELATED TO SMELL ORIGNATES: OLFACTORY BULB Passes through skull at cibriform plate Terminates in olfctory mucosa of nasal cavity

State the role of the optic nerve and where it originates

Origanates: Diencephalon Passes tthrough skull at optic foramen in sphenoid bone Terminates at retina ENTIRELY SENSORY RELATED TO VISION

State the role of the oculomotor, trochlear and adbucens nerves OAT

Origanate VENTRAL AREAS OF BRAINSTEM PASS THRIGH SKULL AT SUPERIOR ORBITAL FISSURE IN SPHENOID BONE RELATED TO EYE MOVEMENTS

State the role of the trigeminal nerve OOM

3 branches: Opthalmic Maxillary Mandibular Origanate from ventrolateral surface of pons (brainstem)

State the role of the facial nerve

Originates from lateral part of pontomedullary junction Passes into internal acoustic meatus and exits through stylomastoid foramen Facial nerve gives 5 branches within th parotid gland

State the cause and symptoms of Bell's Palsy

Cause: Damage to facial nerve Facial nerve supplies muscle function + sensation to face Symptoms: Tears, salivation, taste, facial expression affected

State the role of the vestibibulocochlear nerve

2 branches: Vestibular branch (balance) Cochlear branch (hearing) AKA - ACOUSTIC NERVE RECOGNISE DIAGRAM -semi-circular canals -vesticular part -cochlear part

State the role of the glossopharyngeal nerve

Originates Medulla Oblongata Exits the skull through JUGULAR FORAMEN Motor fibres innervate the stylopharyngeus muscle of the pharynx - needed for swallowing Sensory to oropharynx and posterior tongue (supplis tongue + pharnyx)

State the role of the vagus nerve

Originates: medulla Exits skull at JUGULAR FORMAEN SENSORY TO EXTERNAL AUDITORY MEATUS + TYMPANIC MEMBRANE MOTOR FIBRES INNERVATE: -muscles of larynx -lungs -HEART -oesophagus -small intestine -most of large intestine -gall bladder

State the role of accessory nerve

Originates from: -Medulla -Spinal cord Exits skull at JUGULAR FORAMEN Supplies: -Trapezius muscles (bakc muscles) -Sternocleidomastoid muscles (involved in rotation of neck)

State the role of the hypogloassal nerve

Originates medulla oblongata Exits skull through hypoglossal canal Innervates muscle of tongue

State the two subdivisions of the ANS

1. Sympathetic 2. Parasympathetic

State the role of the sympathetic nervous system

ACTIVATES FIGHT / FLIGHT RESPONSE Blood Vessels in GI tract - VASOCONSTRICTION blood vessels in skeletal muscle: VASODILATION blood vessels in heart: VASODILATION Bronchioles in lungs: BRONCHODILATION cardiac muscle: FORCE + RATE UP Urinary sphincter: CONSTRICTION Gastointestinal peristalsis: INHIBITION SEX: ORGASM Salivary glands: Thick saliva Sweat glands: ACTIVATION

State the role of the parasympathetic nervous system

REST and DIGEST Blood vessels in GI tract Blood vessels in heart Blood vessel in skeletal muscle Bronchiols in lungs Cardiac muscle Pupils Urinary sphincter Gastrointestinal peristalsis Sex Salivary glands Sweat

Why do patients with congenital analgesia usually die young?

This is where patient is unable to percieve or sense pain since birth Therefore, they will not remove / move away from harmful stimuli. So, further damage is not prevented. Damage continues to occur and severity of damage becomes more extreme. - No activation of nociceptors -No signal send via ST pathway to thalamus -no signal sent to cerebral cortex -no sense of pain