Scheme for Past Year Qs 2009

Jan 14, 2011


  1. 1.     Referred pain:

·        Def: Pain felt away from its original site or you can answer it like visceral pain which is felt at a somatic structure or a dermatome which may be a distance away from the diseased viscus.
·        Examples:

    Cardiac pain is referred mainly to retrosternal region as well as left shoulder and inner side of left arm.

     Gall bladder pain is referred to tip of right shoulder and right scapulae.
     *Renal pain is referred to?
     -try to answer this urself :P
    *Inflammed appendical pain is referred to?
    -try to answer this urself :P
     *just additional questions I added myself, wasn’t in the past year Questions.

·        Theories of explanation:
Convergence theory
Facilitation Theory
§  Pain impulses from diseased viscus and a particular somatic structure developed from same embryonic segment as the diseased viscus are transmitted by sensory fibers that enter the spinal cord at the same level.

§  CONVERGE on the SAME cells of substantia gelatinosa of Rolandi(SGR)àtravel along lateral spinothalamic tract to sensory areas of the cortex.

§  Since somatic pain is much more common than visceral pain, the sensory areas of the cortex are more accustomed to somatic pain.  

§  Therefore, visceral pain is MISINTERPRETED by the brain and projected to the corresponding somatic structure.
§  Input from visceral afferents thru collateral branches lowers the threshold of spinothalamic neurones receiving afferents from somatic areas.

§  Any minor activity in somatic area, which would normally die away in spinal cord passes to the brain and is perceived as pain.

  1. 2.     Factors affecting RAS:

·        Impulses from sensory pathways
·        Impulses from motor cortex
·        Stress
·        Sympathomimetic drugs
·        Caffeine
·        Thyroid hormones

  1. 3.     Spinal reflexes in UMNL:

·        Superficial reflexesàabsent on the affected side
·        Deep reflexesàexaggerated with appearance of clonus bcoz of there are sparing of some supraspinal facilitatory discharge to the musle.
·        Babinski’s sign is positive

  1. 4.     Vertigo; False sensation of counter rotation of the individual or the surroundings on stop of rotation

Neural pathway
§  On stop of rotation
§  Inner ear disease
§  Motion sickness
§  Overdose of streptomycin
§  Errors of refraction
§  Chronic alcoholism
§  Caloric or galvanic stimulation of SCC
§  Crista ampullaris discharge impulses to
àvestibular nerve fibers
àvestibular ganglion
àvestibular nucleus in medulla
ànerve fibers extend up and thru ICP
àrelay in folliculonodular lobe of cerebellum
àdentate nucleus of same cerebellar hemisphere
àdentato-thalamo-cortical pathway
àcross midline to relay in
àthalamus, then terminate in
àsuperior temporal gyrus of cerebral cortex of opposite side

  1. 5.     Compare:

REM Sleep(paradoxical sleep)
Non-REM Sleep(slow wave sleep)
 §  Occurs in episodes of 5-30 mins which recur about every 90 min.     
 §  Active dreamingàremember dreams.
 §  Muscle tone is extremely depressed
 §  Irregular HR & RR
 §  Rapid eye movement
 §  EEG pattern shows beta waves indicating high level of activity in the brain

 §    Decrease in
         -Peripheral vascular tone
         -bp by 10-30%
         -Respiratory rate(RR)
 §  Dreams are not remembered bcoz not consolidated in memory
 §  EEG pattern is typically theta and delta waves
*the Non-REM sleep is the more restful sleep where dreams are not remembered.

  1. 6.     Role of both hypothalamus and limbic system in control of emotions:

·        Fear can be produced by stimulation of :
-hypothalamus as well as
-amygdaloid nucleus which is concerned with memories that evoke fear.
    ·        Rage can be produced by stimulation of the rage center in the :
-lateral hypothalamic nuclei
-also by stimulation of amydaloid nucleus.

  1. 7.     Role of retinal receptors in color vision:

  •     Function of cones only~! Coz rods only appreciate all chromatic series of shades of gray
  •           The retina has 3 kinds of cones, each containing different photopigment that are maximally sensitive to one of the primary colors of vision; red, green, blue.
  •     Blueàshort wave lengthàabsorbs light maximally in the blue-violet portion of the spectrum, 445mu.
  •     Greenàmiddle wave pigmentà absorbs maximally in the green portion at wave length of 535 mu.
  •     Redàlong wave pigmentàabsorbs maximally in the yellow portion of the spectrum at 565 mu but its spectrum extends far more enough into long wave lengths to sense red.
  •     Each of the 3 phtochemical pigments is affected most by its specific wave length, but is also affected to a carrying extent by other wave lengths of the chromatic series.
  •     Equal stimulation  of all 3 types of conesàwhite is perceived
  •     Unequal stimulation of all 3 types of conesàany of the chromatic series of colors may be perceived depending on relative frequency of impulses from each of the cone system.

  1. 8.     Impedance matching function of middle ear:

·        Lever action of malleus and incus:
- malleus and incus joint act as a lever
-malleus arm is longer than incus arm by a ratio of 1.3:1
- force of movement at incus and foot plate of stapes by increase by 1.3 times.
·        Areal ratio of tympanic membrane and oval window:
-force exerted over the large tympanic membrane(55sq mm) is concentrated on the tiny foot plate of stapes (32 sq mm) wth a gain of pressure equals the surface area of the larger divided by the smaller
-     Increased force, decrease in area results in increase in pressure.

1.     D- Left sup temporal gyrus
2.     B-Analytic mental process
3.     ...
4.     B-reduced hearing on both sides mainly contralateral
5.     D-somatosensory area 1
6.  vibration sense

1.     A-loss of supraspinal facilitation
2.     B-spared facilitatory vestibulospinal tracts in UMNL
3.     D-under supra spinal control
4.     C- dissociated anesthesia below level of lesion bilaterally
5.     D- dt different conduction velocities of sensory nv fibers
6.     D

1.     D-Left optic tract
"Usaha Sehabis Daya"

Scheme for Past year's Qs 2010

Jan 11, 2011

Problem 1
1- A
2- B
3- C
4- D
5- B

Problem 2
1- A
2- C
3- A
4- B

Problem 3
1- C
2- D
3- A
4- B

Short essay questions

1. weber-fechner law:
- num.  of nerve impulses in the sensory nerve fiber directly proportionate to the amplitude of the receptor potential, directly proportionate to the log intensity of the stimulus.
- wide variation in the strength of the stimuli will result in only restricted (small) variations in the amplitude of the receptor potential and frequency (impulse) of action potentials discharged along the sensory fibers.

2. Static stretch reflex:
Maintained weak steady passive stretch
Nuclear chain
Flower spray
Alpha motor neurons in AHC
Thick myelinated axons of alpha motor neurons
Extrafusal fibers
Muscle tone (neurogenic,  maintained, subtetanic muscle contraction)

3. Declarative memory
A) short-term memory
-change the sensitivity of synaptic transmission btw neurons.
-presynaptic facilitation or inhibition at synapses
-lasts for seconds up to several minutes
-new or facilitated pathways = memory traces
B) long-term memory
-structurally changes occur in synapses such as
         i.            Increase num of  vesicles release sites for secretion of transmitter
       ii.            Increase num of transmitter vesicles released
     iii.            Increase num of presynaptic terminals
    iv.            Change structure of dendrites – transmit stronger signals

4.  A) photoreceptor potential
       I.            cGMP gated channels open
    II.            Na n Ca enter outer segment
 III.            Na accumulate in outer—go to inner segment—pump out
 IV.            Ca also pump out
    V.            Inward current keeps the receptor depolarized near -40mv
 VI.            Synaptic transmitter (glutamate) is continually released.
                       i.  Structurally change from kinked form to straight form of retinal
                      ii. Conformational change of metarhodopsin of photopigment
                      iii.  Activation of transducin
                      iv.  Activation of PDE
                       v.    Decrease intracellular cGMP
                       vi  Closure of Na channel
                      vii. Hyperpolarization
         viii. Decrease of synaptic transmission
                        ix.    Response in bipolar cells (depolarization) and other neural elements.

B) role of cGMP
        i.            cGmp bound wif Na channel ptn—causes splints (open state)
      ii.            Na influx
    iii.            depolarized
                      I.    metarhodopsin 2 activate transducin
                      II. active transducin activate PDE—breaks cGMP into 5 GMP
                     III.   no more splinting –Na channel close up
                      IV.    decrease Na influx
                       V.       hyperpolarized