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anp 1111 > lect 14,15,16, 17: neuroanatomy & neurophysiology > Flashcards

lect 14,15,16, 17: neuroanatomy & neurophysiology Flashcards

1
Q

7.1 describe the structural organization of the CNS

A
  • includes brain and spinal cord

subdivision:
cerebral hemispheres
diencephalon: thalamus, hypothalamus, epithalamus

brainstem: midbrain, pons, medulla, cerebellum

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2
Q

7.1.1 define gray matter, white matter, nucleus, ganglion

A

gray matter: non-myelinated, dendrites, nuclei: intense inter/synaptic communication

white matter: has been myelinated, axons with myelinated sheets around them

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3
Q

7.1.1 define gray matter, white matter, nuclei (spinal cord)

A

spinal cord: butterfly shape central cavity with grey matter, white matter outside

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4
Q

7.1.1 define gray matter (cerebral cortex)

define: type of thought, contralateral, lateralization

A
  • conscious thoughts

3 functional areas: motor, sensory, association

contralateral: each hemisphere handles sensory and motor functions of opposite side of body

lateralization: largely symmetrical but not 100% equal in function

no functional area acts alone, all conscious behaviour involves entire cortex

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5
Q

7.1.2 describe the lobes, gyri and sulci of cerebral hemisphere

A
  • gyrus: hill
  • sulcus: valley, anatomical land marks

longitudinal fissure: (left and right)

transverse fissure: (cerebrum and cerebellum)

  • lobes: frontal, parietal, occipital, temporal, insular, central sulcus: pre central/postcentral gyrus, parieto-occipital sulcus, lateral sulcus
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6
Q

7.1.2.1 location and function of motor areas

A

location: posterior part of frontal lobes, primary motor cortex, premotor cortex, Broca’s area and frontal eye field

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7
Q

7.1.2.1 location and function of motor areas: PRIMARY MOTOR CORTEX

A

(BA 4): pre central gyrus of frontal lobe of each hemisphere

  • contains pyramidal cells (large neutrons) allow control of skeletal muscles
  • body represented spatially = somatotopy
  • digits require precise motor control
  • motor innervation is contralateral
  • no overlap between muscles involved unrelated movements
  • stroke: damage to area of right hemisphere paralyzes body muscles of left, only voluntary movement lost, reflex contraction still possible
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8
Q

7.1.2.1 location and function of motor areas: PREMOTOR CORTEX

A
  • anterior to primary motor cortex
  • helps plan movements (basic motor movements into complex tasks)
  • coordinates movements of multiple muscle groups simulataneousy (referred to as muscle memory)
  • can control voluntary actions that depend on sensory feedback (feeling for something in the dark)

damage to premotor cortex: can have some movement but do not know where to put them

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9
Q

7.1.2.1 location and function of motor areas: Broca’s area + Frontal eye field

A

Broca’s area:
- region of BA 44

  • present in one hemisphere only (usually left)
  • originally thought to be ONLYYY a motor speech area
  • prepares when we are about to yap/ organize sounds into words

Frontal eye field:
- close to BA 8
- controls voluntary eye movement

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10
Q

7.1.2.1 location and function of sensory areas (PSC + SAC)

A

primary somatosensory cortex (PSC):

  • in postcentral gyrus of parietal lobe (BA 1-3)
  • receives info from somatic sensory receptors (skin)
  • & info from proprioceptors (joints + muscles –> spatial discrimination)

somatosensory association cortex:

  • posterior to PSC (BA 5-7)
  • integrate + analyze somatic inputs ( temp + pressure)
  • interpret size, texture, relationship of parts based on prior experience (feeling for something in your pocket)
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11
Q

7.1.2.1 location and function of association areas (VISUAL)

A

primary visual cortex: map of visual space on retina

visual association area: surround PVC, interprets visual image based on prior experience (recognize face, ) + movement (see if something is moving or stationary)

damage to this area: blindness, some visuality but cannot understand what we’re seeing

visual agnosia: inability to understand what you’re seeing

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12
Q

7.1.2.1 location and function of association areas (AUDITORY, VESTIBULAR)

A

primary auditory cortex: sound for pitch, rhythm, loudness

auditory association area: interpretation based on memory (speech, words, music)

vestibular (equilibrium) cortex:
- not visible at surface, deep in lateral sulcus, posterior to insular, adjacent to parietal cortex
- awareness of balance

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13
Q

7.1.2.1 location and function of association areas (OTHERS)

A

olfactory:
- medial temporal lobes = uncus
- small in humans, tissue forms limbic system,(emotions/memory)
- conscious awareness of different odours

gustatory:
- insula
- aware of diff tastes

visceral sensory cortex:
- posterior to gustatory cortex
- conscious perception of visceral senses: (upset stomach, full bladder)

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14
Q

7.1.2.1 Multimodal association area

A
  • receives input and sends output from multiple different areas

sensory receptor –> primary sensory cortex –> sensory association cortex –> multimodal association area

example
1. anterior association area (prefrontal cortex):
most complicated cortical area, intellect, complex learning, recall, personality (working memory)
- abstract areas, judgment, reasoning, concern
- matures slowly: depends on feedback from social environment
- closely linked to limbic system: involved in mood

  1. posterior association area (temporal, occipital, parietal lobes):
    - stores complex memories
    - linked to sensor input (feel/see)
    - localization of self and surroundings in space
    contralateral neglect: recognize one part of body and not the other
    - recognize patterns, faces
    - understanding language (written + spoken - wernicke’s area)
  2. limbic association area
    - emotional impact (aware of danger in a situation based on prior learning/experience)
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15
Q

7.1.2.2. Explain hemispheric lateralization

(commissural, associating, projection fibres)

A
  • each hemisphere has abilities not completely shared by other hemisphere
  • cerebral dominance: hemisphere that is dominant for language
  • 90% of people: left hemisphere dominant for math, logic, language e
  • right hemisphere: creativity, visual-spatial skills, intuition, emotion, artistic, musical skills
  • left cerebral dominance: right handed
  • right cerebral dominance: left handed/ambidextrous
  • communicate with each other b/w cortex & lower CNS centres

commissural fibers: connect corresponding areas b/w 2 hemispheres, largest is corpus callosum,

associating fibers: connections within hemisphere w gyrus + lobes, diff parts of same hemisphere

projection fibers: to or from cortex and rest of nervous system, run vertically (lower brain)

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16
Q

7.1.2.3. Describe the locations of the basal nuclei and the limbic system

A
  • caudate nucleus, putamen and globus pallidus
  • inputs from entire cerebral cortex + other subcortical nuclei
  • no direct access to motor pathways: project to premotor + prefrontal cortices to influence muscle movement directed by primary motor cortex
  • precise roles elusive ( difficult to access, some overlap with cerebellum)
  • start/stop/monitor intense movements (arm swing)
  • inhibit antagonistic/unnecessary actions by only sending best response to cortex
  • associated with cognition and emotion (filter)
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17
Q

7.1.2.3. Describe the locations of the basal nuclei and the limbic system (DISEASE)

A

Huntington - too much movement
- Huntington protein increases, degenerates nuclei, connections to frontal lobe lost, unable to control feeling/thought/movement

Parkinson’s- too little movement
- degeneration of dopamine releasing neuron’s of substantia nigra (mid brain)
- overactivity, tremors, loss of facial expression, difficulty walking/writing

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18
Q

7.1.2.4. Describe the structural components of the diencephalon (thalamus)

A

thalamus, hypothalamus, epithalamus: enclose 3rd ventral

  • thalamus:
  • INFO RELAY STATION, GATEWAY TO CEREBRAL CORTEX
  • 2 masses of grey matter held by midline (inter thalamic adhesion)
  • different nuclei named after position (lateral, medial etc)
  • afferent impulses from all senses and of body converge here, gateway to cerebral cortex
  • sorts & edits info, direct impulses to region of cortex
  • crude recognition of senses as pleasant or unpleasant
  • inputs emotion and visceral function from hypothalamus
  • mediating senses, arousal, learning, memory
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19
Q

7.1.2.4. Describe the structural components of the diencephalon (hypothalamus - 7 functions )

A

hypothalamus:
- below thalamus

  1. autonomic control centre: bp, heart, respiration,
  2. emotion response: heart of limbic system
  3. body temp regulation
  4. food intake regulation: hunger, satiety (satisfied)
  5. water balance regulation: release ADH, thirst centre
  6. sleep-awake cycle
    regulation: suprachiasmatic nucleus (biological clock)
  7. control of endocrine system: release supraoptic and paraventricular nuclei which produce hormones, ADH and oxytocin

hypothalamic disturbances:
disorders in body homeostasis: obesity, sleep, emotion imbalance, dehydration

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20
Q

7.1.2.4. Describe the structural components of the diencephalon (epithalamus)

A

epithalamus:
- dorsal part, forms roof of 3rd ventricle

  • pineal gland extends from dorsal border (secrete melatonin)
  • also has choroid plexus (CSF forming structure)
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21
Q

7.1.2.5. Describe the structural components of the brainstem

(midbrain)

A
  • midbrain:
  • 2 cerebral peduncles carry large motor tracts (motor response)
  • hollow cerebral aqueduct runs through midbrain

-periaqueductral gray matter: for pain suppression

  • corpora quadrigemina (4 paired twin bodies)
  • superior colliculi: visual reflex, follow moving object
  • inferior colliculi: auditory relay, startle reflex

midbrain slice:

  • level of cerebral aqueduct
  • substantia nigra: high melanin content (communicate via dopamine as neurotransmitter), degeneration of this leads to parkinsons

red nuclei: rich vascular supply, have iron pigment, relay pathways for outgoing pathways and limb flexion, some associated with reticular formation

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22
Q

7.1.2.5. Describe the structural components of the brainstem

(pons)

A

pons: 4th ventricle level

  • bridge, connection tracts
  • cranial nerve V (trigeminal), VI (abducens), VII (facial)
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23
Q

7.1.2.5. Describe the structural components of the brainstem

(medulla oblongata)

A

medulla oblongata:
- pons to spinal cord

  • pyramids (large motor tracts) decussation of which: crossing neural information
  • olivary nuclei: relay sensory info re muscles and joints to cerebellum
  • cranial nerves: XII hypoglossal, IX glossopharyngeal, X vagus
  • *vestibulochoclear nerve fibers (VIII) for auditory and balance relay
  • corresponding hypothalamus centres. hypothalamus CONTROLS through sending info through centres in medulla:
  • cardiovascular
  • respiratory
  • vomit, hiccup, swallow, cough, sneeze
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24
Q

7.1.2.7. Describe the main structures of the cerebellum

A
  • not under conscious control
  • processes info from cerebral motor cortex (proprioceptors - planning movement)
  • repetitive movements where we do not have to think (eg. driving)
  • bilateral symmetry:
  • connected by vermis
  • fine transverse fissures called folia
  • hemisphere divided into 3 lobes: anterior, posterior, flocculondular (smallest)
  • anterior complete map, posterior, complete map per side
  • sensory and motor map overlap
  • medial: trunk + girdle
  • intermediate: skilled movements
  • lateral: input from association areas of cortex (planning movement)
  • flocculondular lobes: input from equilibrium sensors; balance and some eye movements
25
Q

7.1.2.7. Localize the cerebellar peduncles

A
  • connect cerebellum to brain stem
  • innervation is same side (ipsilateral)
  • superior (outgoing)
  • via midbrain, to thalamus to motor cortex
  • middle (incoming)
  • via pons, info coming to cerebellum from motor association cortex
  • informs of motor activities
  • inferior (incoming)
  • via medulla, proprioceptor information (position of body/joints) and vestibular info (balance and equilibrium)
26
Q

7.1.2.3. Describe the locations of the limbic system

A
  • emotional visceral brain
  • amygdala: fear, anger, danger
  • hippocampus: memory, emotions
  • anterior cingulate gyrus (gestures, body language, resolve conflicts when frustrated)
  • link between odours, memories and emotions
  • link with hypothalamus provides stress to have affect on BP, GI, heart rate
  • link with cortex allows awareness to information and allows to react emotionally / ignore
27
Q

7.1.2.6. Briefly explain the role of the reticular formation/ reticular activating system

A
  • parts of medulla, pons, midbrain
  • neuron project to hypothalamus, cortex, cerebellum

RAS does 2 things

  • lets in enough info (too little - coma, too much - cannot respond)
  • filters signals, disregards 99% if sensory stimuli so incoming info in manageable
28
Q

7.1.3.Describe the external and internal anatomy of the spinal cord

A
  • extends from foramen magnum to 1st/2nd lumbar vertebrae
  • 2 way conduction system (incoming sensory, outgoing motor)
  • major reflex centre
  • initiates complex patterns of motor activity: 31 pair of spinal nerves

held in place by:

  • denticulate ligaments: pia matter shelves
  • filium terminate: pia mater-covered conus extension
  • cauda equina: horses tail, loose arrangement of terminal neurons, do not go straight down
29
Q

7.1.3.1. Describe how spinal nerves are connected to the spinal cord

A

gray matter, all neurons are multipolar
- organized like butterfly wings

  • paired anterior _ posterior horns connected by gray commissure
  • lateral horns in thoracic and superior lumbar: autonomic regulation
  • opening is central canal
  • anterior: somatic motor neurons, exist via ventral roots
    in cervical and lumbar regions (due to upper/lower limbs)
  • lateral horns: autonomic motor neurons to visceral organs

dorsal root ganglion:
afferent fibres from peripheral sensory receptors form dorsal roots
- house cell bodies of sensory neurons axons enter cord to
1) travel to higher cord/brain centres

2) synapse with interneurons in posterior horns
- spinal nerve = fused dorsal + ventral roots

  • roots and nerves part of PNS
30
Q

7.1.3.1. Describe how spinal nerves are connected to the spinal cord

A

white matter:
myelinated + un-myelinated fibres
- comm between diff parts of cord, cord/brain

  • ascending, descending, transverse commissural tracts (direction of fibres)

properties of spinal tracts:
- path ways cross over (decussation)
- consist of a chain of 2-3 neurons
- exhibit somatotopy
- all pathways/tracts are paired

31
Q

7.1.4.Briefly summarize how the brain and spinal cord are protected

(meninges / meninx)

A

protection:
1- bones
2- meninges
3- cerebral spinal fluid
4- blood brain barrier

meninges: 3 CT membranes that
1- cover + protect CNS
2- protect BV + enclose venous sinus
3- contain cerebral spinal fluid
4- form partitions with skull

1) dura mater: outermost covering
- outer periostea layer + inner meningeal layer
- spinal cord only has meningeal layer
- 2 layers fused except where dural sinuses present

dura septa: partition and anchor
- falx cerebri (longitudinal fissure)
- falx cerebelli (vermis)
- tentorium cerebelli (transverse fissure)

2) arachnoid mater
- loose covering separated by subdural space
- subarachnoid space (bigger) between arachnoid mater and Pia mater: BV + CSF found here
- CSF reabsorbed back to bloodstream at arachnoid granulations

3) Pia mater:
- delicate CT + tiny BV, clings tightly to brain
-follos convolutions (gyrus, sulcus)

32
Q

7.1.4.1. Describe the turnover of cerebrospinal fluid

A
  • liquid cushion to give buoyancy to CNS tissue
  • protective, supportive, nutritive roles
  • similar to plasma but less protein more vitamin C, Na, Cl, Mg, H, less K and CA
  • choroid plexuses: roof of ventricles, source of CSF
  • clusters of permeable capillaries enclosed by layer of ependymal cells (modify it, only needed ions go in)
  • around 150 mL, turned over every 8 hours
  • hydrocephalus : more CSF in head than absorbed

pathway:
- choroid plexus: 3rd/4th ventricles
- median + lateral apertures
- subarachnoid space
- arachnoid granulations + dural issues

33
Q

7.1.4.2. Describe the blood-brain barrier

A

why:
hormones act as NT
some ions increase the rate of neuronal firing

composed of 3 layers:

  • continuous epithelium of capillary wall (impermeable tight junctions)
  • thick basal lamina (enzymes that destroy chemicals)
  • feet of astrocytes, muscle cells pericytes: maintain cells + stimulate formation of tight junctions

what gets in: glucose, amino acids, electrolytes,(FD-speciifc transport)
- fat solubles (drugs like alcohol, nicotine affect brain)

not completely uniform in:

choroid plexus, ependymal cells then control what gets in

very permeable near vomiting centre +
hypothalamus (sense water balance + body temp) incomplete in newborns/premature infants

34
Q

7.2. Describe the structural organization of the peripheral nervous system

A
  • 12 pairs of cranial nerves pass through foramina of skull
  • first 2 pairs teach to forebrain, rest originate from brain stem
  • all except vagus nerve serve only head + neck
  • most cranial nerves are mixed, except those for special sense organs
  • “on occasion, our trusty truck acts funny, very good vehicle anyhow”

sensory/motor/both:
“some say marry money but my brother says(minimal motor) its bad business to marry money”

35
Q

7.2.1.Identify the 12 pairs of cranial nerves by name, number and type (sensory, motor, both)

nerves I and II

A

1) olfactory: S

  • afferent sensory fibers for smell
  • nasal mucosa to olfactory bulbs

-fibres from olfactory bulb neurons extend to make olfactory tract to primary olfactory cortex

2) optic: S

  • afferent sensory fibres for occipital cortex
  • retina fibres form optic nerve which pass through optic foramen of orbit
  • converge to form optic chiasma (where fibres cross over)
  • optic tracts to thalamus, optic radiation to occipital cortex
36
Q

7.2.1.Identify the 12 pairs of cranial nerves by name, number and type (sensory, motor, both)

nerves III and IV

A

3) oculomotor nerves M

  • eye mover
  • 4/6 extrinsic movement muscles (mixed motor nerves)
  • superior, medial, inferior rectus + inferior oblique muscles
  • parasympathetic fibres to iris; lens (some sensory proprioceptive to support motor function)

4) trochlear nerves (pulley) M

  • innervates 1 pair of extrinsic eye muscle (superior oblique)
  • loops through pulley shaped ligament in orbit
37
Q

7.2.1.Identify the 12 pairs of cranial nerves by name, number and type (sensory, motor, both)

V

A

5) trigeminal nerves B

  • both motor + sensory
  • largest of cranial nerves
  • 3 divisions:
  • ophthalmic: eyes
  • maxillary: upper jaw
  • mandibular: lower jaw
  • sensory fibres from face and motor fibres for chewing (mandibular division)
  • dentists; maxillary or mandibular
38
Q

7.2.1.Identify the 12 pairs of cranial nerves by name, number and type (sensory, motor, both)

VI

A
  1. abducens M
  • motor
  • controls extrinsic eye muscle that abducts eye
  • primarily motor to lateral rectus muscle
39
Q

7.2.1.Identify the 12 pairs of cranial nerves by name, number and type (sensory, motor, both)

VII

A
  1. facial nerves B
    - large nerve with 5 major branches for
  • mixed nerve (primarily motor for facial expression
  • parasympathetic to lacrimal glands and 2 pairs of salivary glands (submandibular + sublingual)
  • sensory: taste from anterior 2/3 of tongue
40
Q

7.2.1.Identify the 12 pairs of cranial nerves by name, number and type (sensory, motor, both)

VIII

A
  1. vestibulocochlear nerves:
    - sensory nerve for hearing + balance
  • cochlear (hearing) and vestibular (balance) branches that fuse
41
Q

7.2.1.Identify the 12 pairs of cranial nerves by name, number and type (sensory, motor, both)

IX

A
  1. glossopharyngeal B
  • both sensory + motor
  • tongue and pharynx
  • motor: swallow + gag reflex, parasympathetic to parotid glands
  • sensory ( taste, pressure, touch, pain) from pharynx + posterior tongue e
  • sensory info from carotid sinus (chemoreceptors + baroreceptors –> bp, bPh)
42
Q

7.2.1.Identify the 12 pairs of cranial nerves by name, number and type (sensory, motor, both)

X *IMPORTANT**

A
  1. vagus nerve B
    - mixed nerves
  • wanders beyond head + neck region
  • parasympathetic motor to: heart, lungs, abdominal viscera, somatic to pharynx and larynx
  • sensory from carotid sinus: general sensory from pharynx and posterior tongue, proprioceptive information from muscles of pharynx and larynx
43
Q

7.2.1.Identify the 12 pairs of cranial nerves by name, number and type (sensory, motor, both)

XI and XIII

A
  1. accessory nerve M
  • motor output to pharynx, larynx, soft palate
  • motor output to trapezium + sternocleidomastoid (head/neck movement)
  • supports vagus nerve
  1. hypoglossal nerve M
  • beneath tongue, primarily motor
  • mixes food on tongue, swallow, speech
44
Q

7.2.2.Describe the structural organization of spinal nerves; distinguish between a ramus and a root

A
  • 31 pairs: all mixed nerves, name according to point of tissue
  • 8 cranial
  • 12 thoracic
  • 5 lumbar
  • 5 sacral
  • 1 coccygeal

roots: sensory information from dorsal, motor from ventral (1 way)

-converge to form nerve and ramus for (2 way traffic)

  • spinal nerve branches into dorsal and ventral ramus

rami: 2 way traffic, carry both sensory motor fibres (different destinations)

45
Q

7.2.2.1. Define plexus and list the principal plexuses of the peripheral nervous system

A
  • interlacing nerve networks/ bundle of intersecting nerves
  • all ventral rami branch (except t2-t12) and make lateral connections outside spinal cord (nerve plexus)
  • fibers in ventral rami redistribute in plexuses

1) each branch of plexus contains fibres from various different spinal nerves

2) fibres travel from vernal ramus to body periphery using different roots and different peripheral nerves

  • each muscle in a limb receives nerve supply from more than one spinal nerve –> damage to 1 spinal segment/root canont completely paralyze limb/muscle
46
Q

7.2.2.1.1 Describe the origin and distribution of the cervical plexus

A

origin: deep in neck under sternocleidomastoid
c1-c4
distribution:
- cutaneous nerve: most branches (skin areas)
- phrenic nerve: single most important nerve, motor and sensory fibres to diaphragm (breathing)

47
Q

7.2.2.1.2. Describe the origin and distribution of the brachial plexus (5)

A
  • c5-c8: nerve supply under upper limbs

1) axillary nerve: to/from shoulder (esp deltoid)

2) musculocutaneous nerve: to/from biceps brachia and brachial to flex arms

3) median nerve: flexor muscles in anterior forearm + palm, pronate forearm, flex wrist/fingers, oppose thumb

4) ulnar nerve: medial to elbow (funny bone) follows ulna along medial forearm –> wrist and finger flexion, adduction abduction of medial fingers

5) radial nerve: to humerus and dorsal part of hand –> elbow extension, forearm supination, extension of wrist fingers, abduction of thumb

48
Q

7.2.2.1.3. Describe the origin and distribution of the lumbar plexus

A
  • to abdominal wall muscles + anterior muscles in thigh

1) femoral nerve: anterior thigh; thigh flexor + knee extensor

2) obturator nerve: medial thigh; adductor muscles

49
Q

7.2.2.1.4. Describe the origin and distribution of the sacral plexus (4)

A

L4-S4: branches to buttocks, lower limbs, pelvis

1) siatic nerve: posterior thigh diverges into tibial and fibular

2) tibial nerve: behind knee joint to posterior calf + sole of foot

3) common fibular nerve: to knee joint, calf and dorsum of foot

4) superior + inferior gluteal nerves: to butt

5) pudendal nerve: muscles + skin of perineum (erection /voluntary urination)

50
Q

7.2.3.Describe the membranous wrappings of a nerve; define dermatome

A

area of skin innervated by cutaneous branches of single spinal nerve

endoneurium: loose CT around SINGLE nerve fibre + associatie

perineurium: wraps around group of nerve fibres (fascicle)

epineurium: wraps around faiscle to make a nerve

most nerves 2 ways: handle sensory + motor info

51
Q

7.3. Describe the physiology of sensation and sensory receptors

A
  • classified according to types of stimuli, their location and structural complexity

sensory receptors according to stimulus detected:

1) mechanoreceptors: touch, pressure

2) thermoreceptors: temp

3) photoreceptors: light

4) chemoreceptors: chemicals

5) nociceptors: pain

sensory receptors according to locations:

1) extero: surface of body, from outside, special senses

2) intero/visero: within body (visceral organs) (thirst, hunger, full bladder)

3) proprioceptors: skeletal muscles, tendons, joints, ligaments, CT covering, respond to stretch

sensory receptors according to structural complexity:

1) non encapsulated (free) nerve endings
- epithelia + CT
- esp in pain, temp and pressure
- vanilloid receptor: ion channel opened by heat, low pH, chemicals such as capsaicin (peppers)
- itch receptor: inflammatory chemicals (histamine)
- epithelial tactile complex: junction of dermis + epidermis, light pressure, merkel discs
- hair follicle receptors

2) encapsulated nerve endings
- enclosed in CT capsule, usually mechanoreceptors

  • tactile corpuscles/ meissner: discriminative touch, surrounded by Schwann cells dermal papillae (nipple, finger tips, sole of feet)
  • lamellar/pacinian: single dendrite, when pressure first applied (on/off - vibration)
  • bulbous/ruffini: continuous and deep pressure
  • muscle spindles: proprioceptors, muscle stretch
  • tendon organs: proprioceptors, muscle relax
  • joint kinesthetics: combination, monitor joint position
52
Q

7.3.1.Define sensation and discuss the underlying processes (sensory process)

A

3 levels of processing:

1) receptor level
- specific: stimulus energy must match receptor

  • in receptive field
  • transduction: conversion of stimulus into graded potential EPSP or ISP

2) circuit level
- get into to proper area of cortex so one is aware and can localized source of stimulus

chain of 3 neurons

1st order: cell bodies in dorsal root ganglion, bring info to CNS (spinal cord)

2nd order: go to thalamus or cerebellum, cell body in dorsal horn

3rd order: cell bodies in thalamus, take info to sensory area of cerebral cortex

3) perceptual level
- info has to get to right place to be understood + localized

53
Q

7.3.2.1. Explain signal transduction; distinguish between generator and receptor potentials

A
  • transduction: conversion of stimulus into graded potential EPSP or ISP
  • potentials must reach threshold
    generator potentials: free or encapsulated dendrites
    receptor potentials: special senses
54
Q

7.3.2.2. Explain the concept of adaptation; describe phasic and tonic receptors

A
  • reduction in sensitivity (electrical activity) in the presence of a constant stimulus, can occur quickly for stimuli that are not painful
  • peripheral adaptation: at level of receptor, reduces how much info sent to CNS
  • central adaptation: at level of neural pathway to brain, involves brain nuclei
  1. phasic receptors: adapt quickly, provide info on rate of change of stimulus

(eg, lamellae, tactile corpuscles + special senses going from dark to bright light)

  1. tonic receptors: sustained response with little to no adaptation, info on strength of stimulus
    (nociceptors + proprioceptors)
55
Q

7.3.4.1. Describe the chain of neurons in the ascending pathways + 7.3.4.2. Describe the principle ascending pathways

A
  1. dorsal column-medial lemniscal pathway:
    - target is thalamus
    - handles info from single receptor or few related types
    - gives precise info
    - decussation at medulla
    eg (vibrations, discriminative touch, some proprioceptor)
  2. spinothalamic pathways:
    - target is thalamus
    - info from several types of receptors
    - not as precise
    - decussation at spinal cord
    - eg (pain, temp, pressure, coarse touch)
  3. spinocerebellar pathways:
    - target is cerebellum
    - info about muscle or tendon stretch for skeletal muscle activity
    - ipsilateral no decussation
56
Q

7.3.5.Processing of sensation at the perceptual level

A
  • info has to get tor right place to be understood and localized using correct neural pathway

notion of sensation : awareness of changes in internal/external environment

perception: conscious integration of changes, determine how you will response

57
Q

7.3.5.2. Describe and discuss the principal features of perceptions

A

perceptual detection: being aware of it

magnitude estimation: intensity of stimulus, by action potential frequency

spatial discrimination: localize stimulus, precise localization

feature abstraction: each neuron tuned to one property of stimulus (dimensions of touching)

quality discrimination: subdmodalities of particular sensation (sweet and salty, both at once)

patter recognition: recognize face, songs

sharp pain: myelinated, A delta fibers
burning pain: non myelinated c fibers
pain transmitted by: neurotransmitters glutamate + substance P

  • pain suppression: endorphins + enkephalins,
58
Q

7.3.3.3. Describe the properties and location of nociceptors; compare somatic and visceral pain; explain the concept of referred pain

A
  • pain threshold: amount of stimulus needed to generate pain; same for everyone
  • tolerance: ability to withstand pain, influenced by genetics, gender, etc
  1. somatic pain: musculoskeletal, localized easily (aches, throbbing, cramping) l
  2. visceral pain: organs of thorax + abdominopelvic area, extreme stretching of tissues, chemicals, muscle spasms (burning)
  3. referred pain: pain from one part of body seems to appear somewhere else (heart attack)
59
Q

7.3.2.3. Classify the sensory receptors according to their structure, location and function

7.3.3.1. Describe the properties and location of tactile receptors

7.3.3.2. Describe the properties and location of thermoreceptors

7.3.3.4. Describe the location and functions of proprioceptors

7.3.3.Somatic sensation

A

tactile receptors: respond to touch
location: upper dermis, Merkel’s disks, Meissner’s corpuscles, Ruffini endings, and Pacinian corpuscles

thermoreceptors: react to temp, free nerve endings
location: the dermis, skeletal muscles, liver, and hypothalamus

propioceptors: feedback about body/limb position,
location: all over body

somatic sensation: bodily sensations of touch, pain, temperature, vibration, and proprioception

anp 1111 (3 decks)

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