CNS 2 Flashcards
Pacinian corpuscles
Joint receptors
Stretch receptors in muscle
Hair cells in auditory & vestibular system
Mechanoreceptors
Rods and cones of retina
Photoreceptor
Olfactory receptors
Taste receptors
Osmoreceptors
Carotid body O2 receptors
Chemoreceptors
Extreme of temperature and pain
Nocireceptors
Onion-like structure in subq area
Sensation: vibration & tapping
Adaption: rapidly
Pacinian corpuscle
Present in non-hairy skin
Sensation: velocity
Adaption: rapidly
Meissner’s corpuscle
Encapsulated
Sensation: pressure
Adaptation: slowly
Ruffini’s corpuscle
Transducer is on epithelial cells
Sensation: location
Adaptation: slowly
Merkel’s disk
Most sensitive nerve fiber to LA
Fast pain, temp, touch, & pressure
A-delta (III)
Nerve fiber resistant to LA
Slow pain and temp (unmyelinated)
C (IV)
2 pathways of sensory information
Dorsal (posterior) column tract
Anterolateral tract
. Lateral spinothalamic tract
. Ventral (anterior) spinothalamic tract
Dorsal column system responsible for?
Fine touch (2 point), pressure, proprioception, tactile localization, & vibration
Anterolateral system responsible for?
Pain, temperature, light touch (feather), tickling & sexual sensations
_____ crosses the midline in the brain stem while the _____ crosses the midline in the spinal cord
Dorsal column tract; anterolateral system
He major somatosensory areas of the cerebral cortex are?
S1 & S2
The “map” of the body is called?
Sensory homunculus
The largest area of somatosensory cortex (sensory homunculus) represent the ______, where ______ is most important
Lips, face, hands, and fingers; precise localization
Loss of somatic sensory area 1 results in:
1) loss of discrete localization ability
2) inability to judge the degree of pressure
3) inability to determine the weight of an object
4) inability to determine the shape or form of objects (astereognosis)
5) inability to judge texture
2 functional brain systems:
Limbic system
Reticular formation
Structures located on medial aspect of cerebral hemispheres & diencephalon (rhinencephalon, amygdala, hypothalamus, & anterior nucleus of thalamus)
Important in emotions
Puts emotional response to odors
Responsible for F activities- feeding, fleeing, fighting, feeling, & sex
Limbic system
Deals with anger, danger, and fear responses
Amygdala
Plays a role in expressing emotions via gestures, and resolves mental conflict
Cingulate gyrus
Indirect route for sensory information reaching to sensory strip
Maintains alert/awake state
OFF when sleeping
Complete loss of this activity is coma
Reticular activating system (RAS)
General anesthetics produce sedation and hypnosis by depressing _____
RAS
Ability to discriminate tactile sensation
Important role in perception of pain & temp
Information form diff. parts of body is arranged somatotopically
Destruction of these nuclei result in loss of sensation on contralateral side of body
Thalamus
What does the paraventricular nucleus in the hypothalamus do?
Oxytocin release
Water conservation
Satiety
What does the supraoptic nucleus in the hypothalamus do?
Vasopressin release
If the right lateral spinothalamic tract is severed at C3, what sensations are lost where?
Pain and temperature on left side
What sensations are blocked in the lateral column by epidural or spinal anesthesia?
Pain and temperature
Lamina __ & __ is substantia gelatinosa
II, III
Free (naked) nerve endings Myelinated Diameter= 1-4 mc m Fast/sharp pain (stinging, pricking); 6-30 m/sec Well localize, can point to pain
A-delta fibers
Free (naked) nerve endings Unmyelinated Diameter= 0.4-1.2 mc m Transmit slow/chronic pain; 0.5-2m/sec Diffuse, burning, aching, throbbing sensation
C fibers
Where do cell bodies of A-delta and C fibers lie?
Dorsal root ganglia (DRG)
Fibers ascend or descend 1-3 segments in?
Track of Lissauer
A-delta fibers terminate in laminate __ & __ of dorsal horn & cross to the contralateral lateral spinothalamic tract and ascend to brain
I, V
C fibers terminate in laminate __ & __
II, III (substantia gelatinosa)
For A-delta fibers, the NT is _____ which binds to AMPA and NMDA receptors on postsynaptic membrane
Glutamate
For C fibers, the NT is _____ which binds to NK-1 receptor on postsynaptic membrane
Substance P
Slow onset and long duration analgesia
No early depression of ventilation bc uptake by systemic circulation is minimal
Late (6-12hrs) depression of ventilation occurs due to rostral (towards head) spread of morphine in CSF
Intrathecal (spinal) placement of hydrophilic opioid
Slow onset and long duration of analgesia
Early depression of ventilation (w/in 2 hrs) due to increased uptake by systemic circulation (rapid transportation)
Late depression of ventilation occur due to rostral spread in CSF
Epidural placement of Hydrophilic opioid
Rapid diffusion out of CSF
Rapid onset and short duration of analgesia
Early depression (w/in 2 hrs) of ventilation d/t significant uptake by systemic circulation
D/t rapid diffusion out of CSF, little left in CSF for rostral spread so late depression of ventilation does NOT occur
Intrathecal and Epidural placement of lipophilic opioids
Effects of mu-1 receptors
Supraspinal & spinal analgesia Euphoria Low abuse potential Meiosis (PPP) Bradycardia Hypothermia Urinary retention-C/I in BPH Pruritus
Effects of Mu-2 receptors
Spinal analgesia
Respiratory depression (decreased sensitivity of resp. center to CO2)
Addiction
Constipation (marked) decreased motility & tone of GI muscles
Increased CSF pressure (cerebral edema) C/I in head injury
Effects of kappa receptors
Supraspinal & spinal analgesia
Dysphasia, sedation
Low abuse potential
Diuresis
Effects of delta receptors
Supraspinal & spinal analgesia
Respiratory depression
Physical dependence
Constipation (minimal)
Pain do to stimulus that does not normally provoke pain
Allodynia
Increased sensitivity to pain
Hyperalgesia
Destruction of thalamic nuclei
Thalmic syndrome
Severe facial pain
CN V & IX
Tic Douloureux (trigeminal neuralgia)
Light focuses behind the retina & is corrected w/ a convex lens
Hypertropia- farsighted
Light focuses in front of retina & corrected w/ biconcave lens
Myopia-nearsighted
What deficiency causes night blindness?
Vitamin A
Cutting the optic nerve causes?
Blindness in ipsilateral eye
Cutting the optic chiasm causes?
Heteronymous bitemporal hemianopia (tunnel vision in pituitary adenoma)
Cutting the optic tract causes?
Homonymous contralateral hemianopia
Cutting the geniculocalcarine tract causes?
Homonymous hemianopia with macular sparing
Auditory ossicles
Malleus, incus, & stapes
Membrane b/w middle ear and inner ear
Oval window
The scala vestibuli & scala tympani contain ______ & have a high __
Perilymph; Na
The scala media contains _____ & has high ___
Endolymph; K
The base of basilar membrane responds best to which frequencies?
High
The apex of basilar membrane responds best to which frequencies?
Low
Defects in external or middle ear
Defects in transmission of sound to inner ear d/t was, foreign body, destruction of auditory ossicals, thickening of ear drum d/t repeated ear infection
Bone conductance > Air conductance
Conductive deafness
Defects in inner ear or vestibulocochlear nerve
Both bone & air conductance are reduced
Adverse effect of aminoglycosides
Nerve deafness
Receptor for pain
Free nerve endings in the skin, muscle, & viscera
