SENSES PDF

SENSES Doç. Dr. Güldal INAL GULTEKIN 2 The eyes & sight The E Y E 3 Photoreceptor White light stimulates specific receptors, and creates and image on the retina by changing the molecular structure of vision pigments thus creating an nervous impulse which is transmitted via the N. Opticus to the opti...

SENSES Doç. Dr. Güldal INAL GULTEKIN 2 The eyes & sight The E Y E 3 Photoreceptor White light stimulates specific receptors, and creates and image on the retina by changing the molecular structure of vision pigments thus creating an nervous impulse which is transmitted via the N. Opticus to the optic centers in the center. 1. Depth receptor Estimating the distance or the size of an object, or the speed of one object, in respect to another object. 1. Functional anatomy 4 Eye muscles set 5 Refractor power Reciprocal contraction: one side relax while the other contracts Refraction * ışığın kırılması 6  The bending of light is called refraction  The eye has two structures, the cornea and the lens, that bends light  Their surface have curvatures , they are not staigth lke glass  The lens is flexible, which provides the ability to the optics system of the eye to increase or decrease its convexity. Human Eye – cross section 7 Provides nutrition for the lens cells The eye has 2 structures that are crucial for its refractive ability : 1. Cornea 2. Lens Lens and the lens system 8     It is composed of ≅1000 layers of cells, That loose their nucleus and organelles during development And become absolutely transparent But lacks DNA, protein synthesizing machinery / thus cannot repair nor regenerate   With its ability to refract light, it helps in the formation of the image on the retina The image is formed up-side down on the retina We learn to accept the upside down image as normal 9 Infrared light (invisible) 10   Humans and most mammals can’t see infrared lights, due to LACK of receptors, However, snakes have infrared receptors, and use them to pick up on the infrared lights that is released from the prey through radiation as it Photon energy is high thermal heat. It destroys receptors Photon energy is low, and can’t create the necessary chemical change in the vision pigments Lens özellikleri 11 Light coming from 6 m is accepted as parallel converge Odak noktası diverge Focal length 12   Parallel rays that strike a convex lens are bent then light rays converge at a 'focal point' The distance between the lens and the focal point is called the 'focal distance’ Odak noktası Fokal uzunluk Odak uzaklığı 13 The acuity in respect to light 14  Light : Will have parallel rays when it’s coming from a far ( ≥ 6 m – 20 feet ) distance  But it will be oblique when coming from a near object, (a cell phone, a book)  The object has to be reflected on the retina  Fro this the eye’s OPTIC SYSTEM will have to adapt to the changes in the light ACCOMODASYON  Accommodation 15    The ability to adjust the strength of the lens is known as accommodation The strenght of the lens depends on its shape The shape of the lens is controlled by the ciliary muscles Far sight Near sight Accomodation 16 Accomodasyon 17    The cilliary muscles are attached to the lens by the Lig. suspensorium Cilliary muscles are contracted (parasympathetic stimulus) – suspensory lig. Become loose  the lens becomes more spherical due to its elastic properties (dışbükeyliği/convexity increase)  this is accommodation for for the vision of near objects Cilliary muscle relaxed / resting state (sympathetic stimulus) – suspensory lig. Become tight  the lens flattens  the refractive power decreases  accommodation for far objects 18 19 Sight problems 20 Normal view Myopia Hhyperopia Near sighted 21 Myopia Corrected Far sighted Presbyopia 22   With increasing age (40+) the lens looses its flexibility, near objects become blurry, the lens can’t accommodate thus can’t increase convexity, the objects appear behind the retina Refractive power is increased with convex lens Control of the papillae diameter 23 Parasympathetic    Sympathetic The pupillae is stimulated  The pupillae gets smaller Miosis   Radial muscles of the iris get stimulated The dilatation of the pupillae Midriasis The pupillar ligth reflex 24 25 The fovea centralis on the macula 26 Visual acuity on the retina Retina – contains melanin pigments 27 Light path Melanin inhibits the reflection of light from one retinal point to the other Nerve cells and receptors of the retina 28 29 Circuitry of the Retina Retina receptors 30 ROD CON Receptor chemicals & action potential 31    Rods – rhodopsin (black & white sight – [B/W]) Cons – cone pigment or color pigment The chemical contain Vitamin A in their structure  Avitaminosis A disrupts sight: severe conditions lead to night blindness Light energy Changes the chemical structure of Rhodopsin Creating an electrical stimulation in the receptor An impulse in generated from the retina N.Opticus carries the impulse to the centre 32 Receptor hyperpolarization and Vit A 33  w/ light the rod get hyperpolarized Na+ channels close in the outer segment  Na+K+ ATPase is active in the inner segment   Hence the rod (receptor) loses Na+ ion   Light adaptation : cGMP activation decrease  Channels close  hyperpolarization (-70-80 mV)   HYPERPOLARIZATION: receptor gets negative  This creates an nerve impulse Most of the chemicals (retinal) turn into Vit A Dark adaptation: Na+ channels open  Depolarization (-40 mV)  Vit A amount decreases Vit A is in the structure of photochemicals Directional sensitivity and retinal receptor density 34 Adaption of the receptors 35      Adaptation to light OR dark Adaptation of rods for B / W sight takes longer and is stronger then cone adaptation Adaptation goes on for minutes to an hour Color adaptation stops at one point Adaptation process initiates very fast,   Most of the adaptation will take place before the first minute has passed, But will keep increasing 36 Color view 37 Ishihara tests 38 http://fizyoloji.ege.edu.tr/index.php/lisansustu/23-sinir-pratik 39 Sinirsel ileti 40 41 Hearing İÇ KULAK 42 Çekiç Örs Üzengi Duyma organı = corti organı 43 Cochlea 44 45 46 47 48 49 50 Basilar membrane 51 52 Vibration of the basilar membrane 53   High frequency sound is a high pitched voice Low frequency sound is bass 54 Primary and secondary auditory corteces Iç kulak – vestibüler sistem 55 İşitme Doç. Dr. GÜldal İNAL GULTEKİN 56 57 Vestibular organ (denge) 58  1. 2. 3.    Denge için 3 adet komponent: 3 semi-sirkülar kanal (horizontal-anteriorposterior) Utrikül Sakkule Macula + stataconia kristalleri: receptörleri Utrikül deki makula kafanın pozisyonu yatay (horizontal) düzlemde algılar  Ayakta kafanın orientasyonu sağlanır Sakkulusdaki makula kafa pozisyonu dikey (vertikal) düzelme algılar  Yatarken kafanın pozisyonu   Üzerinlerindeki kristller ise calcium carbonate (CaCO3) tan oluşmultur Semi-circular kanallarda: crista ampullaris’leri içeri. Uazaydaki 3 boyut teşkil edilmiştir Doç. Dr. GÜldal İNAL GULTEKİN Denge resptörleri 59 Doç. Dr. GÜldal İNAL GULTEKİN R Le Parfume 60 Sense of smell Sent pathways 61 1. 2.  Old pathways: primitive scent perception area is not a learned sent , it is associated with digestion Less old pathways: especially in coordination with the hippocampus (limbic system) are the routes in which the sent gives life or death decision. There are learned events This route is the only one that bypasses the thalamus  Likes and disgusting odors  It can even cause vomiting  3. New pathways: the conscious analysis of sent. Passes by the thalamus, sent impulses to the orbitofrontal lobe Taste bundles 62      Sweet Salty Saur Bitter Umami 63