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Equilibrium & Taste

Nurfitri Bustamam, SSi, MKes, MPdKed.


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Learning Objectives

Explain how the receptors in the semicircular

canals detect rotational acceleration & how

saccule & utricule detect linear acceleration

List the major sensory inputs that provide theinformation that is synthesized in the brain

into the sense of position space

Name the five major taste receptors & signal

transduction mechanisms in these receptors Outline the pathways by which impulses

generated in taste receptors reach theinsular cortex

Nurfitri Bustamam 2


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Nurfitri Bustamam 3

Equilibrium

Mendeteksi percepatan linier:

- utrikulus horizontal

- sakulus vertikal

Mendeteksi percepatan anguler:- canalis semisirkularis

horizontal (lateral)

sagital (anterior) vertikalfrontal (posterior)


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Nurfitri Bustamam 4


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Nurfitri Bustamam 5

Utriculus & Saculus


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Nurfitri Bustamam 6

Canalis Semisirkularis


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Nurfitri Bustamam 7

Canalis Semisirkularis


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Nurfitri Bustamam 8


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Nurfitri Bustamam 9


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Nurfitri Bustamam 10


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Nystagmus:refleks utk menjaga fiksasi penglihatan, tdd komponen

lambat & cepat


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Nystagmus

a) Komponen lambat (vestibulo-ocular-reflex)/VORReseptor: vestibuler

Aferen: N.VIII

Pusat: oculomotor nuclei

Eferen: N.III, N.IV, N.VI

Efektor: otot penggerak bola mata (berlawanan arah rotasi)

b) Komponen cepat (stretch reflex)

Otot bola mata teregang muscle spindle kontraksi

(searah rotasi)

Nystagmus umumnya horizontal, tetapi dpt pula vertikal

(kepala miring) atau berputar (kepala tertunduk)


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Nurfitri Bustamam15


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Vertigo: sensasi berputar tanpa ada putaran ygsesungguhnya

Caloric stimulation:

Perbedaan suhu konveksi gerakan cupula

nystagmus & nausea

Spatial Orientation

Motion Sickness

Menieres disease: fluid imbalance in inner ear

(vestibular apparatus & cochlea), simptom: vertigo,loss of hearing, ringing in the ears


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Caloric Stimulation



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Caloric Stimulation

Water 40oC (warm) & 30oC (cold) in external

auditory meatus

Temperature difference convection

currents in endolymph motion of cupula Healthy subjects COWS (Cold water

nystagmus is Opposite side, Warm water

nystagmus is Same side)

Unilateral lession in vestibular pathway

nystagmus or absent on the side of lesion



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BARANY ROTATION TEST



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BARANY ROTATION TEST

Barany introduced a routine clinical test that involves observationof the post-rotatory responses after a patient is spun around

several times in specially designed swivel chair.

post-rotatory nystagmus, abnormanalities in standing & walking,falling, and a past-pointing error can be obeserved

Nystagmus

The eyes remain fixed on their original point of focus, so thatthey must diverge slowly towards the left to compensate forrotation of the body to the right. When the limit to which the eyescan be rotated laterally is exceeded, they snap quickly back to theright and select a new point of fixation. These alternate slow andquick movements of the eyes are called nystagmus.


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FallingThe subject would be expected to fall towards the side of

flexion, which in the case of post-rotatory reflexes would be inthe same direction as the rotation. However, sinceproprioceptors in the trunk & limbs are still functioning, he mayover-correct this tendency and stagger over towards theextended side.

Past Ponting ErrorOccurs when the subject with eyes closed is instructed to

repeatedly extend his arm to touch an object directly in front ofhim, successive movement will deviate in the direction oppositeto his sensation of vertigo.

(Wiggers 1955: 171-174


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TASTE



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Taste bud tdd:

- basal cells

- Sel tipe 1&2 (sustentacular cells)

- Sel tipe 3 (gustatory receptor cells)



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Sel tipe 1, 2 & 3 memp. microvili yg menjulur kepori pengecap (taste pore)

Tiap taste bud diinervasi 50 serat saraf Tiap serat saraf menerima input dari 5 taste bud

Sel basal berdiferensiasi mjd reseptor yg baru,reseptor diganti secara continue, dg half life 10

hari Jika n. sensorik dipotong, taste bud yg

diinervasinya akan berdegenerasi. Namun, jikasaraf tsb beregenerasi sel-sel di sekitarnya akan

mjd taste bud Taste bud (fungiform & vallate papillae) tdpt pd

mucosa epiglottis, palate, pharynx & lidah



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Physiology of Taste

Pd manusia ada 4 basic taste: sweet, sour, bitter, salt

Taste bud tsb tdk berbeda dlm histologi

Asam:

- H+menstimulasi reseptor

- as.organik lbh terasa asam dari as. mineral (diduga

karena asam organik lbh cepat masuk ke sel)

Asin:

- Na+ sel

- beberapa senyawa organik juga terasa asin

Manis

- sukrosa, maltosa, glukosa, glyseral, as. aspartat

- sacharin & aspartane (pemanis buatan)



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Pahit:

quinine sulfate, nicotine, morphine, caffeine, strychnine,

magnesium, amonium & calcium

Intensity discrimination: perbedaan konsentrasi hinggalbh dari 30% baru disadari

Variation & after-effect

PTC (Phenylthiocarbamide) pd populasi Caucasian:70% merasakan asam + 30% tasteless

Miraculin (taste modifier protein) makes acid tastesweet



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Tes waktu sirkulasi: op disuntik suatu zat timbulrespons merasa pahit di lidah, mekanisme: zat disirkulasi sel kelenjar ludah sekresi rasapahit



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Taste pathways

Serat saraf sensorik dari taste bud di:

- 2/3 anterior lidah lewat n. VII- 1/3 posterior lidah lewat n. IX

- di luar lidah lewat n. X



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Abnormalities in Taste Detection

Ageusia & Hypogeusia Dysgeusia/parageusia

Altered in serotonin & Norepinephrin level (anxiety/depresionaltered taste threshold

Zinc or vit B3 deficiency

Damage glossopharyngeal nerve Neurological disorders: multiple sclerosis, bell palsy

Poor oral hygiene, smoking

Aging, drug: captoptril, cisplatin

Theraphy: improved oral hygiene & zinc supplementation

Supertaster: increased number of fungiform papillae on theirtounge



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