sistem sensoris pertemuan 21

Sistem Sensoris Pertemuan 21

Matakuliah : L0044/Psikologi FaalTahun : 2009

Sistem Sensoris

untuk berhubungan dengan dunia luar

kumpulan reseptor yang sensitif terhadap rangsang (reseptor sensorik) → alat indera

terdiri dari :a. alat penerima rangsang (reseptor), yaitu alat indera itu

sendirib. saraf penghubung antara reseptor dengan pusat susunan

sarafc. pusat saraf (otak), yaitu alat yang bertugas

menerjemahkan dan mengelola rangsanganPanca indera mempunyai fungsi tertentu dan peka terhadap

rangsang tertentu pulaReceptor potential : a slow, graded electrical potential

produced by a receptor cell in response to a physical stimulus

Two Categories of Receptors

• Somatic Senses: touch, pressure, temperature, and pain. Distributed throughout skin and deeper tissues.

• Special senses: smell, taste, hearing, equilibrium, vision. (more complex)

Chemoreceptors• respond to changes in chemical concentrations

Pain receptors (Nociceptors)• respond to tissue damage

Thermoreceptors• respond to changes in temperature

Mechanoreceptors• respond to mechanical forces• → proprioceptor, baroreceptor, stretch receptor

Photoreceptors• respond to light

Receptor Types

Sensations• A feeling that occurs when the brain

interprets sensory impulses• All the nerve impulses that travel away

from sensory receptors into the CNS are alike. The resulting sensation depends on which region of the brain receives the impulse.

• Semua impuls saraf dari berbagai reseptor sensorik adalah sama. Sensasi yang dihasilkan tergantung dari daerah korteks serebral mana yang menerima impuls tersebut.

• Pada saat yang sama ketika sensasi terbentuk, serebral korteks menerjemahkan darimana reeptor yang terstimulasi → seseorang dapat menunjukkan area stimulasi → PROJECTION

• Adaptasi sensorikBila reseptor sensorik terus menerus terstimulasi, membran reseptor akan menjadi kurang responsif terhadap stimuluscontoh : seseorang yang berada di pasar ikan

SPECIAL SENSES

1. Mata, merupakan indera penglihatan (organ visual) sensitif terhadap rangsangan cahaya, menerima bayangan serta kesan-kesan untuk ditafsirkan

2. Telinga, merupakan indera pendengaran (organ auditorik), di sini kesan atas suara atau bunyi diterima dan ditafsirkan

3. Hidung, merupakan indera pembau / penciuman (organ olfaktorius), sangat peka dan kepekaannya mudah hilang

4. Lidah, merupakan indera pengecapan, yang sangat peka (sensitif) terhadap rasa seperti pahit, manis, asam, dan asin

5. Kulit, merupakan indera peraba, sangat peka terhadap tekanan, suhu, sentuhan, dan rabaan

Hole, Human Anatomy & Physiology, 10th ed

Penglihatan

Apakah informasi yang kita terima dari dunia luar adalah suatu realitas ?

1. Reseptor sensorik manusia hanya dapat mendeteksi jumlah yang terbatas dari bentuk energi yang adacontoh : gelombang radio, gelombang magnet tidak dapat dideteksi oleh reseptor sensorik manusia

2. Informasi yang disalurkan ke otak manusia tidak melalui alat perekam canggih yang peka. Selama proses prekortikal dari input sensorik, beberapa stimuli ditingkatkan sedangkan yang lain dapat ditekan atau diabaikan

3. Serebral korteks selanjutnya akan memanipulasi data yang didapatkan dari reseptor sensorik, dibandingkan dengan informasi lain seperti ingatan dari pengalaman yang lalu

Sherwood, Human Physiology From Cells to Systems, 6th ed

Kanizsa’s Triangle

“Peripheral drift” by Akiyoshi Kitaoka Taken from Nationalgeographic.com

Which Line is Longer?

They are both the same.

Explanation

• This is one of the most studied illusions, and was created by a German psychiatrist Franz Müller-Lyer in 1889. It it not well understood why this illusion works, but we think it is related to the fact that the first object is simply larger, and the second object is "pointed."

• http://www.optical-illusions.biowaves.com/Perspective/MullerLyerLineLength.cfm

http://www.optical-illusions.biowaves.com/Perspective/ParallelLines.cfm

Are the Red Lines Parallel?

Spinning Effect Optical Illusion

• Move toward and away from the screen while staying focused on the red dot.

• Notice that the outer rings seem to rotate or spin when you move toward or away from the screen.

Explanation

• The eye interpretes visual cues to assist in day to day living. In this case, the visual cues mislead one to percieve motion.

• http://www.optical-illusions.biowaves.com/Misc/SpinningEffect.cfm

Disappearing Haze• Stare at the Red Dot.• Notice that the haze disappears after 20 to

30 seconds.

Explanation• The retina gradually changes senstivity to

adapt to the existing light conditions. This is what allows the eyes to work with such incredibly diverse light conditions, from bright sunlight to faint moonlight. You can learn more about this on our pages about eyesight.

• http://www.optical-illusions.biowaves.com/Color/DisappearingHaze.cfm.

Do you See Gray?• This picture is only made with black and

white. • You can see that the above picture all black

and white by covering either side of a white row with paper.

Explanation• The eye, which responds to an amazing wide

variety of light sources, from moon light to direct sunlight, tries to adjust to the present light levels. Here, the contrast is so strong and irregular, the white ends up looking gray.

• You can learn more about color perception here.

• http://www.optical-illusions.biowaves.com/Color/DisappearingHaze.cfm.

The Stacked Blocks Optical Illusion• Are the lines straight and level?• The lines are all exactly parallel.

Explanation• The eye interpretes visual cues to

assist in day to day living. In this case, visual cues mislead they eye to perceive an increased distance, therefore a narrowing where the blocks recede.

http://www.optical-illusions.biowaves.com/Distortions/StackedBlocks.cfm

Are the Boxes the Same Size? Explanation• Yes, they really are exactly the same

size. Hard to believe, isn't it. The artist is taking advantage of a very powerful three dimensional technique where all of the lines meet at one point off the edge of the canvas, thus making the mind see the picture as a 3-D model of reality, rather than just lines on a screen.. The eye then adjusts for the 3-D effect, which results in the farthest block looking much larger.

http://www.optical-illusions.biowaves.com/3D/PerspectiveBoxes.cfm

• IS THIS SPIRAL? LOOK AGAIN, THEY ARE ALL SEPERATE CIRCLES

http://www.indianchild.com/is_this_spiral.htm

Seeing is believing

MATA• analog dengan kamera• terletak di dalam rongga mata (Orbital Cavity)• 70% dari reseptor sensorik terletak pada mata• digerakkan oleh otot mata

otot lurus : m. rektus okuli superior, inferior, medial, dan lateralotot serong : m. obliquus okuli superior dan inferior

• Bagian : kornea, Iris, pupil, lensa, retina (sel batang dan kerucut) sclera, kamera okuli anterior dan posterior, humor aqueous, humor vitreous

• lateral terhadap bintik buta (tempat keluarnya pembuluh darah dan saraf), terdapat daerah lonjong disebut makula lutea, dengan cekungan kecil di pusatnya disebut fovea sentralis (hanya mengandung kerucut)

Mata manusia dapat menangkap radiasi elektromagnet dengan panjang gelombang 380 - 760 nmKecepatan Cahaya : 300.000 km/detik

Persepsi terhadap Warna ditentukan oleh :- Hue (ditentukan oleh panjang gelombang)- Brightness (intensitas)- Saturation (purity)

Neil R. Carlson, Physiology of Behaviour, 9th ed

Cornea

• Bulges forward• Transparent window of the eye (contains few cells, no blood

vessels, cells and collagenous fibers form unusually regular patterns)

• Helps focus entering light rays.• Continuous with the sclera (white portion of the eye)

Sclera

• White portion of the eye• Posterior 5/6th of the outer tunic• Opaque due to many large, disorganized collagenous and elastic

fibers.• Protects the eye and is an attachment for the extrinsic muscles

Lens• Lies directly behind the iris and pupil• Composed of differentiated epithelial cells called lens fibers.

Lens Capsule

• Surrounds the lens• Clear, membrane-like structure composed largely of intercellular

material• Elastic nature keeps it under constant tension. Can assume a

globular shape.

Human Eye – cross


Iris• The colored part of the eye• Thin diaphragm composed mostly of connective tissue and smooth

muscle fibers• Pupil – central opening of the iris

– Regulates the amount of light entering the eye during: • Close vision and bright light – pupils constrict• Distant vision and dim light – pupils dilate• Changes in emotional state – pupils dilate when the subject matter is

appealing or requires problem-solving skills

• Divides the space (anterior cavity) into the anterior chamber (between the cornea and the iris) and posterior chamber (between iris and vitreous body containing the lens)

Dim light stimulates the radial muscles of the iris to contract, and the pupil dilates. Bright light stimulates the circular muscles of the iris to contract, and the pupil constricts.


• Suspensory ligaments attached to margin of lens capsule and the ciliary muscles. Changing tension changes the shape of the capsule and lens for focusing.

• Accommodation: the ability of the lens to adjust shape to facilitate focusing. Close objects= lens thickens; distant objects= thinner, less convex

Summary of Cranial Nerves and Muscle Actions

• Names, actions, and cranial nerve innervation of the extrinsic eye muscles


Pergerakan Mata :• Vergence movement : the cooperativew movement of the eyes,

which ensures that the image of an object falls on identical portions of both retinas

• Saccadic movement : the rapid, jerky movement of the eyes used in scanning a visual scene

• Pursuit movement : the movement that the eyes make to maintain an image of a moving object on the fovea

Accomodation : changes in the thickness of the lens of the eye, accomplished by the ciliary muscles, that focus images of near or distant objects on the retina

Aqueous Humor

• Watery fluid secreted by the epithelium on the inner surface of the ciliary body into posterior chamber.

Aparatus LakrimalisConsists of the lacrimal gland and associated ducts• air mata dihasilkan oleh kelenjar lakrimalis superior dan inferior.

Melalui duktus ekskretorius lakrimalis masuk ke dalam sakus konjungtiva. Melalui bagian depan bola mata terus ke sudut tengah bola mata ke dalam kanalis lakrimalis mengalir ke duktus nasolakrimalis terus ke meatus nasalis inferior.

• Tears– Contain mucus, antibodies, and lysozyme– cleanse and protect the eye surface as it moistens and lubricates it– Enter the eye via superolateral excretory ducts – Exit the eye medially via the lacrimal punctum– Drain into the nasolacrimal duct

Retina. A.) Nerve fibers leave the eye in the area of the optic disc (arrow) to form the optic nerve. B.) Major features of the retina.


• Fovea centralis : terdapat pada macula lutea, cekungan kecil dengan lebar 1 derajad, di tengah macula luteathe region of the retina that mediates the most acute vision. Color-sensitive cones constitute the only type of photoreceptor found in the fovea.

• Macula lutea / macula retina : irregular yellowish depression on the retina, about 3 degrees wide, lateral to and slightly below the optic disc

• Optic disc :the location of exit point from the retina of the fibers of the ganglion cells that form the optic nerve ; responsible for the blind spot

The retinal consists of several cell layers.


Note the layers of cells and nerve fibers in this light micrograph of the retina.


RETINACahaya harus melewati beberapa lapisan sel yang relatif transparan sebelum mencapai sel batang dan sel kerucut.

Fotoreseptor ini berkomunikasi dengan sel-sel ganglion melalui sel bipolar.

Pengolahan informasi visual dimulai di retina itu sendiri. Akson sel batang dan sel kerucut bersinapsis dengan neuron yang disebut sel bipolar, yang selanjutnya bersinapsis dengan sel ganglion.

Campbell & Reece, Biologi, Edisi kelima jilid tiga

FOTORESEPTOR PADA RETINA

a) Fotoreseptor yang disebut sel batang sangat sensitif terhadap cahaya dan berfungsi dalam penglihatan hitam putih pada malam hari. Sel-sel kerucut bertugas dalam penglihatan warna selama siang hari.

b) Rhodopsin, pigmen visual pada membran cakram sel batang, terdiri atas molekul retinal penyerap cahaya yang berikatan dengan sejenis protein membran spesifik, opsin. Opsin mempunyai tujuh bagian heliks alfa yang menembus membran cakram.

* Fotopigmen : opsin (protein) dan retinal (lipid, disintesis dari vitamin A)


• Fotoreseptor : batang dan kerucutBatang : 120 jutaKerucut : 6 juta

• Sel kerucut banyak pada fovea sentralis, makin ke perifer makin banyak batang

• bayangan yang jatuh ke retina : lebih kecil dan terbalik


Visual Receptors

Rods• long, thin projections• contain light sensitive pigment called rhodopsin• hundred times more sensitive to light than cones• provide vision in dim light (night vision)• produce colorless vision• produce outlines of objects•Much convergence in retinal pathways Less precise images because nerve fibers from many rods converge their impulses and transmit them to the brain on the same nerve fiber.• Human eye has 125 million•More numerous in periphery

Cones• short, blunt projections• contain light sensitive pigments called erythrolabe, chlorolabe, and cyanolabe• provide vision in bright light (day vision)•produce color vision• produce sharp images•Convergence of impulses less common. Brain can pinpoint stimulation more accurately.

•Human eye has 7 million•Concentrated in foves

Visual Pigments

Rhodopsin• light-sensitive pigment in rods• decomposes in presence of light• triggers a complex series of reactions that initiate nerve impulses• impulses travel along optic nerve

Pigments on Cones• each set contains different light-sensitive pigment• each set is sensitive to different wavelengths• color perceived depends on which sets of cones are stimulated• erythrolabe – responds to red• chlorolabe – responds to green• cyanolabe – responds to blue


Nyata, diperkecil, terbalik

Stereoscopic Vision• provides perception of distance and depth• results from formation of two slightly different retinal images


Binocular vision → stereocospic vision → simultaneously perceives distance, depth height, and width of objects

The visual pathway includes the optic nerve, optic chiasma, optic tract, and optic radiations. Sherwood, Human Physiology From Cells to Systems, 5th ed

Human Visual System


JALUR NEURON UNTUK PENGLIHATAN

Karena susunan neuron dalam retina, saraf optik, dan kiasma optik, maka sisi kanan otak dapat menerima informasi sensoris mengenai benda di medan visual kiri, sementara sisi kiri otak menerima informasi dari medan visual kanan.

Masing-masing saraf optik mengandung sekitar sejuta akson yang bersinapsis dengan interneuron pada nukleus genikulata lateral.

Nukleus merelai sensasi ke korteks visual, yang diyakini merupakan yang pertama dari banyak pusat otak yang bekerja sama dalam membentuk persepsi visual kita.



(striate cortex)

• Warna primer : merah, biru, hijau• Warna komplementer

Contoh : hitam-putih, biru-kuning, merah-hijau



Photoreceptors : trichromatic coding

Retinal Ganglions Cells : Opponent-Process Coding

Red opposing GreenYellow opposing Blue



Different forms of color blindness result from lack of different types of cone pigments.

Color Blindness → 7% males, 0,4% females

Protanopia dan Deuteranopia terkait dengan kromosom X

Tritanopia : tidak terkait kromosom X. Kejadian sama antara pria dan wanita

Rainbows and Ethno-Linguistics

• http://www.missiology.org/animism/Learning/wordsandsounds.htm• “The cultural categorization of colors is the most discussed illustration in

the study of ethno-linguistics. Americans see six colors in the rainbow: red, orange, yellow, green, violet, and blue. Some cultures see eight, others four, others three. Kipsigis classify blue and black together and consider the sky tue, the word that I initially translated literally as "black." Tue, however, has a broader color range than simply black. The Malagasy speaker of Madagascar distinguishes over 100 basic categories of color (Nida 1952). The Shona of Zimbabwe and Bassa of Liberia both have fewer color categories than English speakers, and they break up the spectrum at different points (Gleason 1961, 4). ”

http://www.missiology.org/animism/Learning/wordsandsounds.htm

Color Categories of the Shona of Zimbabwe and Bassa of Liberia

Negative Afterimage

• Warna komplementer : warna yang membuat menjadi putih atau abu-abu ketika dicampurkan

• Penyebab : adaptasi pada sel ganglion retinaBila sel ganglion retina tereksitasi atau terinhibisi dalam waktu yang lama, sel ganglion akan menunjukkan rebound effect


Functions of the major Components of the Eye

Visual Fields

Rabbit Human


Gangguan Penglihatan• Mata normal : emetrop• miopi : rabun jauh• hipermetrop : rabun dekat• presbiopi : pada orang tua, berkurangnya kekenyalan lensa

sehingga daya akomodasi berkurang• astigmatisme : karena berubahnya bentuk kelengkungan lensa

Diktat Faal, Fakultas Kedokteran Universitas Tarumanagara

Amblyopia• Dim vision due to a cause other than a refractive

disorder or lesion

Amblyopia is the medical term for poor development of vision in one eye. The word comes from the Greek. [ambly- (dull) + -opia (vision)] Amblyopia is often referred to as "lazy eye." It affects just two to three percent of the population. Central vision does not develop properly, usually in one eye, which is called amblyopic. The eye is anatomically normal, but visual acuity is reduced even with glasses. Amblyopia develops sometime between birth and 8 or 9 years of age, the critical period of time when the visual system develops and matures. Amblyopia causes more visual loss in the age group under 40 than all the injuries and diseases combined.

http://en.wikipedia.org/wiki/Computed_axial_tomography

Anopia• Absence of an eye

Conjunctivitis• Inflammation of the conjunctiva

Viruses, bacteria, irritating substances (shampoo, dirt, smoke, pool chlorine), sexually transmitted diseases (STDs) or allergens (substances that cause allergies) can all cause conjunctivitis. Pink eye caused by bacteria, viruses or STDs can spread easily from person to person but is not a serious health risk if diagnosed promptly; allergic conjunctivitis is not contagious.

Diplopia• Double vision

Emmetropia• Normal condition of the eyes; eyes with no

refractive defects.

Enucleation• Removal of the eyeball

Exophthalmos• Abnormal protrusion of the eyes

Associated with hyperthyroidism and Grave’s disease. In the case of Graves Disease, the displacement of the eye is due to abnormal connective tissue deposition in the orbit and extraocular muscles (Epstein et al, 2003) which can be visualized by CT or MRI.If left untreated, exophthalmos can causes the eye lids to fail to close during sleep leading to corneal damage. The process that is causing the displacement of the eye may also compress the optic nerve or ophthalmic artery leading to blindness

http://en.wikipedia.org/wiki/Computed_axial_tomography

http://en.wikipedia.org/wiki/MRI

http://en.wikipedia.org/wiki/Cornea

http://en.wikipedia.org/wiki/Optic_nerve

http://en.wikipedia.org/wiki/Ophthalmic_artery

http://en.wikipedia.org/wiki/Blindness

Cataract• cloudy eyes → distorted view• inadequate nutrient delivery to deeper lens fibers• causes

– congenital– age-related hardening, thickening of lens– secondary result of DM

• risk factors– heavy smoking– frequent exposure to intense sunlight

Night Blindness - Nyctalopia• condition in which rod function is

impaired• most common cause : prolonged

vitamin A deficiency → leads to rod degeneration

Hemianopsia• Defective vision affecting half of the visual field

http://en.wikipedia.org/wiki/Image:Bitempvf.png

http://en.wikipedia.org/wiki/Image:Binasalvf.png

http://en.wikipedia.org/wiki/Image:Binasalvf.png

http://en.wikipedia.org/wiki/Image:Lhvf.png

Iritis• Inflammation of the iris

Also called anterior uveitis. It is the 3rd leading cause of blindness in the developed world. White blood cells are shed into the anterior chamber of the eye in the aqueous humor. These cells can accumulate and cause adhesions between the iris and the lens. Iritis is associated with over 90 different pathogens and autoimmune disorders. Some treatments include antibiotics and steroids.

Keratitis• Inflammation of the cornea

Symptoms include pain, and profuse tearing. Can be caused by infection, trauma, dry eyes, UV exposure, contact lens over-wear, degeneration.

Herpes simplex keratitis

Neuritis• Inflammation of a nerve

Optic neuritis

Optic neuritis is acute visual loss owing to demyelination of the optic nerve. It may be an isolated autoimmune condition or part of multiple sclerosis. Fortunately, vision recovers to normal or near normal in over 90% of patients within six months. No treatment improves those chances.

Retinoblastoma• Inherited, highly malignant tumor arising from

immature retinal cells

Retinoblastoma is a rare cancer of the retina (the innermost layer of the eye, located at the back of the eye, that receives light and images necessary for vision). About 300 children will be diagnosed with retinoblastoma this year. It accounts for 3 percent of childhood cancers. Treatments include surgery, radiation, chemotherapy, laser therapy, phototherapy, thermal therapy, and cryotherapy.

Trachoma• Bacterial disease of the eye that causes

conjunctivitis, which may lead to blindness

Trachoma, an infection of the eye caused by Chlamydia trachomatis, ranks worldwide as the most common preventable cause of blindness and the second most common cause of blindness after cataract. It has been estimated to cause 15% of the world's blindness.1,20 The disease is endemic in 48 countries in Latin America, Africa, the Middle East, Asia, and Australasia [see Fig. 1], and is most prevalent in poor, rural communities with lower standards of hygiene and sanitation.2 The WHO currently estimates that 6 million people are blind due to trachoma, and that an additional 146 million people have active forms of the disease.

Uveitis• Inflammation of the uvea, the region of the eye

that includes the iris, ciliary body, and choroid coat.

There are different types of uveitis, depending on which part of the eye is affected: When the uvea is inflamed near the front of the iris, it is called iritis. If the uvea is inflamed in the middle of the eye, it is called cyclitis. Cyclitis affects the muscle that focuses the lens.An inflammation in the back of the eye is called choroiditis. Eye drops, especially steroids and pupil dilators, can reduce inflammation and pain. For more severe inflammation, oral medication or injections may be necessary. Uveitis can have these complications: Glaucoma (increases pressure in the eye); Cataract (clouding of the eye's natural lens); Neovascularization (growth of new, abnormal blood vessels).

Daftar Pustaka• Campbell & Reece, Biologi, Edisi kelima jilid tiga

• Diktat Faal, Fakultas Kedokteran Universitas Tarumanagara• Hole, Human Anatomy & Physiology, 10th ed• Neil R. Carlson, Physiology of Behaviour, 9th ed• Sherwood, Human Physiology From Cells to Systems, 6th ed

sistem sensoris pertemuan 21

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