Sensories Organ (Taste, Smell,

Hearing) By :

Drh. Aulia Firmawati, M.Vet

Reseptor Stimuli (Rangsangan) Reseptor

(Organ Indera)

Sistem Saraf

Mampu mengubah energi panas, mekanik, kimia menjadi potensial aksi

*Potensial aksi berasal dari ketidak seimbangan Na+ dan K+

Reseptor Organ Penginderaan :

1. Indera Perasa/Pengecap Kemoreseptor

2. Indera Penciuman Kemoreseptor

3. Indera Pendengaran Mekanoreseptor

4. Indera Penglihatan Fotoreseptor

Letak Reseptor :

• Eksoreseptor >> didekat permukaan tubuh dan berfungsi peneruskan perubahan yang berasal dari lingkungan luar

• Enteroreseptor >> didalam tubuh yang berfungsi meneruskan perubahan didalam tubuh

Taste

Pengecap (TASTE)

• Indera pengecap merupakan indera yang paling penting yang dimiliki oleh hewan untuk dapat mencicipi makanan.

• Reseptor pada indera perasa/pengecap (Taste) adalah TASTE BUD

Terdapat empat macam papila lidah:

1. Papila foliate, pada pangkal lidah bagian lateral,

2. Papila fungiformis, pada bagian anterior.

3. Papila sirkumfalata, melintang pada pangkal lidah.

4. Papila Filiformis, terdapat pada bagian posterior. Pada foliate tidak terdapat kuncup-kuncup pengecap.

TASTE BUD :

• Taste bud receptors detect gustatory stimuli. Receptors signal the five qualities of taste : sweet, salty, sour, bitter, umami (savory).

• Taste buds are located on several kinds of papillae on the tongue and in the pharynx and larynx. Taste buds contain chemoreceptor cells arranged around a taste pore.

• These cells are innervated by taste afferent fibers of cranial nerves VII, IX, X.

Sub-Modalities of Taste

• Sour taste - The stronger the acid, the more sour the taste – proportional to pH. Warns against potentially noxious/poisonous chemicals.

Compound Index

HCl 1

Formic 1.1

Chloroacetic 0.9

Lactic 0.85

Acetic 0.55

Citric 0.46

Carbonic 0.06

Sub-Modalities of Taste

• Salt taste - cations and anions of ionized salts. Ensures proper dietary electrolyte balance.

Compound Index

NaCl 1

NaF 2

CaCl2 1

NH4Cl 2.5

KCl 0.6

Sub-Modalities of Taste

Sweet taste –

• Organic compounds, sugars, glycols, amino acids etc.

• Identifies energy-rich nutrients.

Compound Index

Sucrose 1

p-4000 5000

Saccharin 675

Chloroform 40

Fructose 1.7

Glucose 0.8

Lactose 0.3

Sub-Modalities of Taste

• Bitter taste - long chain organic substances and alkaloids.

• Taste threshold is lowest for bitter substances.

• Warns against potentially noxious/poisonous chemicals.

Compound Index Quinine 1 Strychnine 3.1 Nicotine 1.3 Caffeine 0.4 Atropine 0.13 Cocaine 0.02 Morphine 0.02

Sub-Modalities of Taste

• Umami taste – allows the recognition of amino acids.

• Glutamate

• Monosodium glutamate (MSG)

• Aspartate

Variation in Taste Receptors Among Animals

• No relationship exists between the number of taste buds in different animals and their ability to perceive a tastant.

Chicken 24 Pigeon 37

Starling 200 Duck 200

Parrot 380 Kitten 473

Bat 800 Dog 1,706

Human 9,000 Pig, Goat 15,000

Rabbit 17,000 Calf 25,000

Catfish 100,000

Anatomy of a Taste Bud

• Found on dorsal and lateral surfaces of tongue, buccal mucosa, soft palate, epiglottis, wall of pharynx and larynx

• 40 supporting cells, 5-18 taste cells, 35-22 basal cells

• Life span – 10-14 days

Anatomy of a Taste Bud

• Innervation - secondary receptor cells

• Each taste bud innervated by ~ 50 nerve fibers

• Each nerve fiber receives input from ~ 5 taste cells

• Taste receptors adapt rapidly

Models of encoding of taste qualities at the periphery

*

Salt

Sour

TRP ion channel

TRP ion channel

Sweet

T1R2 + T1R3 G-protein coupled receptor

Bitter

T2R G-protein coupled receptor

Umami

T1R1 + T1R3 G-protein coupled receptor

Transmission to CNS

• Rostral 2/3 of tongue - facial (VII) nerve (cell bodies in geniculate ganglion)

• Caudal 1/3 of tongue - glossopharyngeal (IX) nerve (cell bodies in petrosal ganglion)

• Pharynx and larynx - vagus (X) nerve (cell bodies in nodose ganglion

• Efferent fibers to salivatory (gustatory) nuclei in the NTS, then thalamus, etc; also to vomiting centers in reticular formation

SMELL

Reseptor Penciuman (Smell)

• Aroma dideteksi oleh reseptor penciuman

• Reseptor ini biasanya dikhususkan sebagai Saraf bipolar

• Pada Mamalia >> Reseptor penciuman terletak di jaringan epithelium pada bagian atas rongga hidung dan disekeliling sel basal dan sel penyokong

Olfaction

• Associated with selection of food

• Social behavior

• Avoiding predators – predator odors trigger freezing or flight responses in mice.

• Reproduction (pheromones) – odors from potential mates (conspecifics) elicit innate sexual responses in many animals.

Summary - Olfaction

• Mammalian olfactory receptors are all G-protein coupled receptors.

• Odorant receptor genes vary by species: mice – 900, humans – 350.

• Species vary in the density of olfactory receptors/cm2: dogs 100X that of humans

• Odors are detected by olfactory chemoreceptor cells in the olfactory mucosa. A few dozen mammalian odorant receptors have known ligands.

• Proses ini dimulai ketika seorang G-protein dirangsang. Hal ini memicu aktivasi adenylyl adenilat , enzim yang mempercepat konversi ATP untuk cAMP , seorang utusan kedua . adenosin siklik monofosfat, atau cAMP, kemudian mengikat ke saluran tindakan di membran silia. Hal ini menyebabkan saluran untuk membuka dan Ca + + untuk memasuki silia. Masuknya Ca + + saluran klorida mengaktifkan untuk membuka dan Cl-daun melalui saluran ini. Hal ini menyebabkan biaya membran menjadi lebih positif, atau depolarize , dan potensial aksi dibuat. Yang potensial aksi turun ke akson dari sel reseptor penciuman, akhirnya bertemu dengan akson dari sel-sel reseptor penciuman lainnya untuk membentuk saraf penciuman (saraf kranial 1). (Bear dkk., 1996)

HEARING

Reseptor : Suara (mekanoreseptor)

Mekanisme penghantaran mekanoreseptor :

Mekanoreseptor Telinga bagian luar (auricula) Membran timpani Telinga bagian dalam (Malleus, Incus,Stapes)

Eustacius Tekanan Gelombang dideteksi oleh membran labirin Spiral

choclea Kanal Vestibulum

STRUKTUR TELINGA

TERIMAKASIH