BMC L7 Flashcards
State 4 types of sensory receptors
Temp
Mechanoreceptors
Chemical receptors
Nociceptors
State the general function of mechanoreceptros
Respond to pressure, stretch, vibration, distrotion
State the 5 types of mechanoreceptors
- Merkel cell
- Meissner corpuscle
- Pacinian corpuscle
- Free nerve endings
- Hair follicle
State the function of Merkel cells
Detect:
-Sustained pressure, static stimualtion
State the function of meissner corposcule
Detect:
light touch, slip, flutter
State the function of pacinian corposcule
Rapid vibrations
State function of free nerve endings
Touch, pressure, stretch, tickle, itch
State function of hair follicle
Detects Distortion of body hair
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
State the function of A-alpha nerve fibres
Size: Large, INSULATED
Proprioception e.g. muscle reflex
State the function of A-beta nerve fibres
Medium, insulated
Proprioception - non-painful touch e.g. pressure
State the function of A-delta nerve fibres
Small, insulated
Fast tissue damage, pin prick, intense heat
State the function of C nerve fibres
Small, UNINSULATED
SLOW TISSUE DAMAGE, SLOW BURNS, ITCH
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
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
State the 2 types of pathological pain
- Chronic
- Neuropathic
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
- Sympathetic
- 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
