Introduction:
The sense organs are highly specialized structures that receive information from the environment. These organs contain special sense receptors ranging from complex structures, such as eyes and ears, to small localized clusters of receptors, such as taste buds and olfactory epithelium (receptors for smell).
Smell and taste are chemical senses, which contain chemoreceptors that respond to chemicals in solution. Food chemicals dissolved in saliva stimulate taste receptors in taste buds. The nasal membranes produce fluids that dissolve chemicals in air. These chemicals stimulate smell receptors in olfactory epithelium. The chemical senses complement each other and respond to many of the same stimuli.
Photoreceptors, which include rods and cones, in back of the eye respond to light energy. Rods provide dim-light, black-and-white vision, and are the source of peripheral vision. Cones operate in bright light and provide color vision. Cones are most concentrated at the back center of each eye. Rods are more numerous than cones, and surround the cones. Information from the rods and cones travels via the optic nerve into the brain for interpretation.
The ear has two specialized functions: sound wave detection and interpretation of the head position in space. Sound waves enter the outer ear through the external auditory canal (ear canal) and strike the tympanic membrane (eardrum). Vibration of the eardrum moves three ossicles (small bones) inside the middle ear, which in turn stimulate the organ of Corti (hearing receptor in the inner ear). Impulses travel from the organ of Corti through the vestibule cochlear nerve to be interpreted by the brain.
The ear also contains equilibrium (sense of balance) receptors. The vestibular apparatus, a group of equilibrium receptors in the inner ear, sense movement in space. Maculae receptors in the vestibule monitor static equilibrium (head position with respect to gravity when the body is still). Cristae receptors in the semicircular canals monitor dynamic equilibrium (movement). Impulses from the vestibular apparatus travel along the vestibulocochlear nerve to appropriate brain areas. These centers start responses that fix the eyes on objects and stimulate muscles to maintain balance.
Mechanoreceptors respond to mechanical energy forces: touch, pressure, stretching, and movement. Ranging in complexity from free nerve endings beneath the skin to more complex tactile receptors at the bases of hair, mechanoreceptors change shape when pushed or pulled.
Different types of skin receptors sense different environmental stimuli. Free nerve endings sense pain. Specialized receptors such as Merkel’s discs and Meissner’s corpuscles sense touch. Pacinian corpuscles sense deep pressure. Naked nerve endings are thought to be responsible for sensing temperature.
Other types of sensory receptors provide the brain information on the body. Interreceptors in body organs inform the CNS about internal conditions such as hunger and pain. Proprioceptors in joints, tendons, and muscles detect changes in position of skeletal muscles and bones. This information allows humans to be aware the positions of their trunk and limbs without having to see them.
Senses:
1-Sence of touch:
Found area have receptor
2-Tow point test:
The density of touch receptors is measured by the two-point threshold test. The two points of a pair of adjustable calipers are simultaneously placed on the subject’s skin with equal pressure, and the subject is asked if one or separate contacts are felt. If two, the points of the divider are brought closer together, and the test is repeated until only one point of contact is felt The minimum distance at which two points of contact can be felt is the two-point threshold Starting with the calipers wide apart and the subject’s eyes closed, determine the two-point threshold on the back of the hand. (Randomly alternate the two-point touch with one-point contacts, so that the subject will not try to second guess the examiner)Repeat this procedure with the palm of the hand, fingertip and the back of the neck.
3-Sense and temperature:
Found the area have receptor to hot and receptor to cold in arm .
4-Adaptation :
Many of our sense receptors respond strongly to acute changes in our environment and then cease responding when these stimuli become constant This phenomenon is known as sensory adaptation. Our sense of smell, for example quickly adapts to the odors of the laboratory, and our touch receptors soon cease to inform us of our clothing until these stimuli change.
A- Touch receptor:
Put one coin in hand and determine the time needed to to don’t sense for this ,then put 4 other coin and determine again .
B-Temperature receptors:
Place right hand in warm water (about 40 degrees) and the left in cold water, and leave them in the water for about 3 minutes. Then place both hand in lukewarm water (about 22-25 degrees).
4-Referred pain:
Referred pain is the phenomenon of perceiving pain in one area of the body when another area is actually receiving the painful stimulus. This can result when there is convergence of afferent (sensory) fibers onto the dorsal horn relay cells in the spinal cord. We say that the pain is referred to the other area. Have the subject place their elbow in a pan or shallow bucket of ice their arm should be relaxed with the forearm and hand out of the water.
Taste bud:
1-Determination of threshold volume of sucrose:
determine the threshold needed to sense to sucrose in taste buds in tongue
2-Localization of bud:
Taste buds contain the receptors for taste. They are located around the small structures on the upper surface of the tongue, soft palate, upper esophagus, the cheek, epiglottis, which are called papillae. These structures are involved in detecting the five elements of taste perception: salty, sour, bitter, sweet and umami; through the combination of these elements we detect “flavors.” A popular myth assigns these different tastes to different regions of the tongue; in reality these tastes can be detected by any area of the tongue. Via small openings in the tongue epithelium, called taste pores, parts of the food dissolved in saliva come into contact with taste receptors. These are located on top of the taste receptor cells that constitute the taste buds. The taste receptor cells send information detected by clusters of various receptors and ion channels to the gustatory areas of the brain via the seventh, ninth and tenth cranial nerves.
Reflex:
1-Tendon reflex (knee jerk reflex)(patellar reflex):
Sudden kicking movement of the lower leg in response to a sharp tap on the patellar tendon, which lies just below the kneecap. One of the several positions that a subject may take for the test is to sit with knees bent and with one leg crossed over the other so that the upper foot hangs clear of the floor. The sharp tap on the tendon slightly stretches the quadriceps, the complex of muscles at the front of the upper leg.
2-Ciliospinal reflex:
Pinch the skin on one side of the nope of your neck and note the dilation of the pupil of the eye on the psilateral side.
3-Labyrinthine reflex:
A-Post rotatory nestigmas:
‘ Head forward 30” then turn to right 12 turn and note the direction of eye movement.
‘ Head in right Shoulder then turn to right 12 turn and note the direction of eye movement.
‘ Head and body forward 90” then turn to right 12 turn. Observe in which direction he appears to fall.
B-Post pointing:
‘ Head forward 30” then turn to right 12 turn. With his eyes opened have the subject extend his arm to touch the finger of the operator.
‘ Head forward 30” then turn to right 12 turn. With his eyes closed have the subject extend his arm to touch the finger of the operator.
C-Equilibrium:
‘ Head forward 30” then turn to right 12 turn. Observe in which direction he appears to fall.
‘ Head in right Shoulder then turn to right 12 turn . Observe in which direction he appears to fall.
‘ Head in left Shoulder then turn to right 12 turn . Observe in which direction he appears to fall.
‘ Head to back 90” then turn to right 12 turn. Observe in which direction he appears to fall.
4-Proprioception:
Have the subject hold her arms stretched forward with index fingers pointed toward each other and then try to bring the fingertips together. Test this reaction first with the subject’s eyes open and then with the eyes closed. Record the results Have the subject stand with feet together and arms outstretched. Observe body sway and the corrective motions required to maintain balance, and then test the subject first with her eyes open and then with the eyes closed. Then have the subject stand first on one foot and then on the other. Again perform the test with the eyes closed and open. These tests evaluate the static equilibrium of the person and point out the contribution made by the eyes to static equilibrium.
Have the subject look at the ceiling and stand on E one foot. Again have her stand on one foot, with her head in the same position as before, but this time with the eyes closed.
5- Pupillary reflex:
In this exercise you will determine the response obtained in various common human reflexes. Reflexes that result in contraction of skeletal muscles are called somatic reflexes. Those that cause contraction of cardiac r smooth muscle or secretion by glands are known as visceral (autonomic) Study the characteristics of a reflex are and reflex behavior which are discussed in your textbook.
Hearing:
1-Acuity test:
This should be performed in a quiet room. Have the subject close one ear with cotton and close his eyes. Hold a watch in line with his open meatus. Gradually move the watch away from his ear until he just loses the ability to hear the ticking. Measure the distance between watch and ear and record. Move the watch farther away and then begin moving it nearer the subject’s ear until he first hears the ticking
2-Sound localization test:
with the subject seated and blindfolded, bring a watch within hearing range from several different angles around his head(The clicking oftow coin to gether can used in place of the watch in this test) the subject to point to the direction from which What each he hears the sound. Is his judgment better in the median plane or at the side of the head? the median plane, is he more accurate with sound above the head or in front of it?
3-Tuning fork test (Weber and Rinne ):
A complete hearing evaluation involves several other tests as well. In order to determine what kind of hearing loss is present, a bone conduction hearing test is administered. In this test, a vibrating tuning fork is placed behind the ear, on the mastoid process. When the patient can no longer feel/hear the vibration, the tuning fork is held in front of the ear; the patient should once more be able to hear a ringing sound. If they cannot, there is conductive hearing loss in that ear. Additionally, the tuning fork is placed on the forehead. The patient is then asked if the sound is localized in the center of the head or whether it is louder in either ear. If there is conductive hearing loss, it is likely to be louder in the affected ear; if there is sensor neural hearing loss, it will be quieter in the affected ear. This test helps the audiologist determine whether the hearing loss is conductive (caused by problems in the outer or middle ear) or sensor neural (caused by problems in the cochlea, the sensory organ of hearing) or neural – caused by a problem in the auditory nerve or auditory pathways/cortex of the brain.
Vision:
A-Visual activity:
The visual acuity test is used to determine the smallest letters you can read on a standardized chart (Snellen chart) or a card held 20 feet away. Special charts are used when testing at distances shorter than 20 feet.
B-Astigmatism:
Cover one eye with your hand and look at the image. Take your hand away after a few seconds, repeat the test covering the opposite eye.
C-Blind spot determination:
Wright + and point in paper and put it in 1 meter and focus in + and nearing that to the point that don’t see the point and determine the distance between eye and paper.
D-Pupillary reflex:
Focus the visible light in eye and note what happened to pupil.
E-Distance accommodation:
Result and discussion:
Senses:
1-Sence of touch:
* * * * *
* * * *
* * * * *
* * * * *
* * * * *
2-Tow point test:
Finger tip 4mm
Palm 20mm
Forearm 33mm
In one point the tow tips of caliper in the same receptive field and in tow the tow tips in different receptive field and the receptive field of fingertip is more small than palm and forearm.
3-Sense and temperature:
H C
C C
H
C C
C H C
C:cold H:hot
4-Adaptation :
A-Touch receptor:
The first coin needed 15sec
The other 4 coin needed 39sec
The adaptation to one coin needed less time than other 4 coins because the stimulus in 4 coin is more than one coins then needed more time.
B-Temperature receptors:
Right hand fell cold and left fell hot then you fell pain in right hand then adaptation to hot and cold temperature and I do not sense any thing
c-Referred pain:
The location of sensation changes from elbow to the inner side of the hand and the little finger.
Is pain perceived at a location other the site of the painful stimulus.
Taste bud:
1-Determination of threshold volume of sucrose:
Threshold occurred at [sucrose] = 2%
The stimulus of sucrose occurred(threshold point) then action potential will occur .
2-Localization of bud:
Reflex:
Reflex:
1-Tendon reflex (knee jerk reflex)(patellar reflex):
In reaction these muscles contract, and the contraction tends to straighten the leg in a kicking motion. Exaggeration or absence of the reaction suggests that there may be damage to the central nervous system. The knee jerk can also be helpful in recognizing thyroid disease.
2-Ciliospinal reflex:
Expanding pupil
3-Labyrinthine reflex:
A-Post rotatory nestigmas:
‘ Head forward 30” eyes move right and left
‘ Head in right Shoulder eyes move up and down
‘ Head and body forward 90”eyes move angularly
B-Post pointing:
‘ Head forward 30” With his eyes closed you can’t touch the finger of the operator.
‘ Head forward 30” With his eyes openedyou can touch the finger of the operator but in hardly
C-Equilibrium:
‘ Head forward 30”fall to right
‘ Head in right Shoulder fall to forward
‘ Head in left Shoulder fall to back ward
‘ Head to back 90” fall to left
“Doll’s eyes”
The poorly named “doll’s eye” maneuver is a simple mechanical test that is particularly useful in the patient with depressed consciousness. More appropriately called the oculocephalic maneuver, it is composed of a rapid passive rotation of the head laterally, which causes an inertial flow of the horizontal canal endolymph in the opposite direction of the head rotation. the eyes are driven in a direction opposite the head rotation.
If the patient is awake, the hemispheric checking component (this has the same substrate as the fast component of the nystagmus) keeps the eyes from deviating from midposition and actually may drive the eyes beyond the midposition toward the direction of turning. If the patient is in a coma due to bilateral hemispheric suppression, such as with toxic or metabolic disease (e.g., sedative overdose or uremia), the checking component (also the fast component of nystagmus) is lost. In this case, the eyes deviate away from the direction of head rotation in an unchecked manner (the reflex response is not inhibited by cerebral cortical input). Of course, if dysconjugate gaze is produced during the maneuver, damage to the brain stem in areas that control brain stem extraocular function must be assumed.
Conditions affecting vestibular function
There are a large number of conditions that can affect the vestibular apparatus. Broadly, these can be divided into peripheral causes and central causes. These two types of causes can often be distinguished on clinical grounds . Peripheral causes include conditions damaging the inner ear or the vestibulocochlear nerve while central causes affect the brain stem, vestibulocerebellum or, in rare cases, the cortex.
The most common cause of peripheral vertigo has been termed acute labyrinthitis or vestibular neuronitis. While there may be subtle distinctions between these conditions, the presumed etiology is inflammation. In this condition the vertigo comes on quickly and patients often have severe nausea and can’t walk. They are at their worst in a matter of hours and then there is slow improvement over days to weeks. There is usually no hearing loss. If it comes on very rapidly (and particularly if there is hearing loss), you should consider that the condition might result from infarction due to occlusion of the labyrinthian artery. Meniere syndrome is not uncommon. It is believed to result from obstructed drainage of endolymph, resulting in increased pressure due to continued production. The pressure damages the delicate hair cells (both vestibular and auditory) with loss of sensitivity. The clinical course is punctuated by paroxysms of sudden vertigo (often with worsened tinnitus), lasting hours with spontaneous resolution. This is believed to occur due to sudden puncture of the membranes, with resolution of symptoms dependent on sealing the puncture and reestablishment of the normal equilibrium between the fluid compartments of the inner ear. These attacks of vertigo (which can occasionally be triggered by loud noises) can be violent enough to throw the patient to the ground, though, in between attacks, there may be little residual other than some low-tone hearing loss.
Perilymph fistula is another cause of peripheral vertigo that is due to leakage of fluid. This condition is often precipitated by barotrauma (abrupt pressure changes) and individual attacks can occasionally be precipitated by pressure changes (including Valsalva maneuver, coughing, sneezing, airplanes, scuba diving, etc). Fluid usually leaks around the round window into the middle ear (and can occasionally be seen there).
Acoustic neuroma (actually a neurolemmoma) is a common tumor that grows on the vestibular nerve. Ironically, despite the fact that it damages vestibular nerve fibers, it is a rare cause of vertigo. This is because it progresses slowly, with ample time for compensation of deficits.
Positional vertigo will be discussed.
Central causes of vertigo include damage to the brain stem or vestibule cerebellum. Stroke, usually involving the posterior inferior cerebellar artery (which supplies the lateral brain stem and part of the cerebellum) often produces severe vertigo (along with diminished pain and temperature sensations in the face). Isolated infarction or hemorrhage in the cerebellum can produce vertigo. These are particularly important to recognize because they can produce swelling and mass effect that can occasionally be fatal due to brain stem damage. Both of infarction and hemorrhage often produce occipital headache (particularly common with hemorrhage). It is important to consider this before attributing vertigo to vestibular neuronitis, which shouldn’t produce headache.
Neoplasms of the cerebellum and brain stem usually don’t produce much vertigo (for the same reason of slow growth with compensation that we invoked with acoustic neuroma). Inflammatory disease (such as MS or rare conditions such as neurosarcoid) can produce vertigo although this is usually not severe. Paroxysmal vertigo can result from the aura of migraine or seizure. This is presumed to result from activation of the part of the sensory cortex that perceives motion. If vertigo is the only symptom, it is difficult to diagnose seizure or migraine until or unless more characteristic features arise.
4-Proprioception:
In tow feet open eyes 68 sec
In tow feet close eyes 33 sec
In one feet 5 sec
5- Pupillary reflex:
Decrease in pupil size.
Hearing:
1-Acuity test:
The distance in right ear = 80cm
The distance in left ear = 66cm
2-Sound localization test:
The subject pointed to the direction from which he hears the sound.
3-Tuning fork test (Weber and Rinne ):
Vision:
A-Visual activity:
we see all line at 6m.
B-Astigmatism:
I can see all line
If some lines seem grey and others darker, you likely have a visual impairment. You need to have your sight checked out by an ophthalmologist.
C-Blind spot determination:
You will don’t see the point in39cm; because the image of point in bind spot
D-Pupillary reflex:
The pupil will decrees in high concentration of light
We are all familiar with the pupil constricting to light and dilating when that stimulus is removed. This phenomenon also occurs physiologically when you go from a lighted environment to a darker one. There are rare cases in which the pupil constricts to darkness. The mechanism is not well understood. This response was first proposed as a sign of retinal disease such as congenital stationary night blindness and congenital achromatopsia. However, it has also been reported in albinism, Best’s disease, optic nerve hypoplasia, retinitis pigmentosa, and Leber’s congenital amaurosis.
E-Distance accommodation:
The pupil will decrees when we look to near thing
The pupil will increase when we look to far thing
Reference:
1. http://www.britannica.com/EBchecked/topic/320239/knee-jerk-reflex
2. http://www.nlm.nih.gov/medlineplus/ency/article/003396.htm
3. http://www.optical-center.co.uk/astigmatism-test
4. http://www.patient.co.uk/health/otosclerosis-leaflet#
5. http://www.dartmouth.edu/~dons/part_1/chapter_6.html
6. Yueh, B; Shapiro N; MacLean CH; Shekelle PG (April 2003). “Screening and management of adult hearing loss in primary care: scientific review”. Journal of the American Medical Association (American Medical Association) 289 (15): 1976’1985. doi:10.1001/jama.289.15.1976. PMID 12697801. Retrieved 2007-11-10
7. http://nortonhealthcare.adam.com/pages/guide/reftext/html/nerv_sys_fin.html