Transcript 1. Taste
RECEPTORS GENERAL RECEPTORS •Receptors for touch, pressure, pain & temperature •Located throughout the body •Found in the Dermis layer of the skin -- pain receptors also called NOCICEPTORS SPECIAL RECEPTORS •Photoreceptors for Vision (sight) -- On the Retina 1. RODS -- dim light & motion 2. CONES -- color •Mechanoreceptors --for Hearing, Position, & Balance 1. Hearing -- located in the Cochlea of the inner ear 2. Baroreceptors -- monitoring of Blood Pressure --located in the arch of the Aorta & in the carotid sinuses 3. Proprioceptors --Located in muscles, tendons, joints & the semicircular canals of the inner ear --Provide information on position, balance & movement of limbs •Osmoreceptors 1. Located in the digestive tract & in the hypothalamus 2. Monitor for changes in the concentration of body fluids (Electrolytes) •Chemoreceptors -- for Taste, Smell, O2 & CO2 levels 1. Taste --taste buds located on the tongue fissures --4 types (Bitter, Sour, Salty, & Sweet) 2. Smell --olfactory cells located in roof of the nasal cavity 3. Receptors for O2 & CO2 located in arch of the Aorta & carotid sinuses DEFINITIONS ADAPTATION -- Receptors adjust themselves so that they no longer respond to the stimulus as they did in the beginning. REFERRED PAIN -- Some neuron connect impulses from the skin & the viscera to send to the brain -- The brain cannot differentiate, so assign pain to the skin Gallbladder pain may be felt in in the shoulder Kidney pain may be felt in the lumbar (flank)region EYE Clear, transparent, anterior coat of the eye Part that is replaced in a corneal transplant Cornea Lens Watery fluid & helps maintain curve of cornea & carries nutrients to the cornea & lens thickness is adjusted Aqueous to focus light humor -- lens thins or flattens out for distance Ciliary Suspensory -- lens thickens or body ligament rounds up for near -- hold Lens in place & vision help it to change shape Refraction -- the change of direction of a light ray as it passes from one medium to another (bending) Accommodation -- coordinated eye changes to enable us to focus on on objects Jelly-like substance that give the Vitreous eye shape & aids in refraction humor If lost cannot be replaced causing blindness as retina falls forward Cornea Removal of the eyeball is called Enucleation absorbs stray light Retina rays & nourishes Choroid the retina opaque back portion of Sclera the Cornea Rods -- functions in dim light & senses motion Cones -- functions in bright light & is sensitive to 3 colors Red Green Light blue Fovea centralis Retinal artery & vein Optic nerve Optic disc -- Cranial Nerve II carries visual impulses from the rods & cones to the Occipital Lobe Papilledema --swelling & inflammation of the optic nerve (Blind Spot) -- area in which there is no rods or cones Area where the vascular bed can be directly examined -- area that contains a large amount of cones, so it is the point of most acute vision Muscles of the Eye Intrinsic muscles -- inside the eye Lens Iris Colored portion of the eye Pupil -- regulates amount of light entering the eye -- rounds up or flattens to view objects Myopia -- nearsightedness Hyperopia -- far-sightedness Astigmatism -- distortion of the curvature of the cornea Presbyopia -- old-sightedness Extrinsic Muscles 6 muscles attach to the skull bones & the sclera to allow for coordinated movement Nerves for the Extrinsic Muscles Trochlear & -- supplies one extrinsic muscle each Abducens Oculomotor -- supplies 4 extrinsic muscles Protection of the Eye -- Skull bones -- Eyelid & eyelashes --eyelashes sense particles -- sebaceous glands help lubricate the eye (Sty -- inflammation of one of these glands) Produces tears Lacrimal Conjunctiva Tears film across the eye gland in the direction of the nose Lacrimal ducts Keeps the eyeball moist Lines the eyelid & cornea Destroys pathogens EAR External Structures Also called the Auricle Pinna Made of cartilage Helps collect sound waves Not necessary for hearing which captures foreign material & protects the ear Sound vibrations are first picked up here In small children, it is chiefly made of cartilage Tympanic Membrane External Auditory Canal Middle Ear It’s a cavity filled with air Incus & containing Ossicles Connects middle ear to the throat Stapes Equalizes pressure Malleus Easy route for infection Lies between the tympanic membrane & Incus Shaped like a hammer Shaped like an anvil & lies between Eustachian Tube the Malleus & Stapes Attaches to the Oval window, which is the dividing line between Middle & Inner ear These bones are joined in such a way that sound waves are amplified 20x by the time they reach the oval window Inner Ear Osseous Labyrinth Semicircular canal -- vibrations enter here Vestibulocochlear through the Oval window nerve Functions in hearing Contains Organ of Corti, the site for the sensory receptor cells (Hair Cells) Vestibule Cochlea Impulses are picked up here and sent to the 8th Cranial nerve Vestibulocochlear Base of the canal contains 2 sacs with hair cells that deal with head position & equilibrium Within the Bony Labyrinth is a Membranous Labyrinth Membranous Labyrinth The inner ear contain fluid Between the Bony labyrinth and the Membranous labyrinth is a fluid called: Perilymph Endolymph -- is the fluid inside the Membranous Labyrinth bone membrane perilymph endolymph Balance & Equilibrium Senses eye movement & head position Also send impulses to Vestibulocochlear nerve & then to the Cerebellum Organ of Corti Endolymph Hair Cells Basilar Membrane Tectorial Membrane Sound Waves Vibration of the Tympanic Membrane Vibration of Middle Ear bones Vibration of Oval Window Fluid Movement within Cochlea Vibration of the Basilar Membrane Bending of Hairs of Receptor Cells of Organ of Corti starts the Electrical Stimuli Vibration of Round Window Dissipation of Energy Electrical Stimulus picked up by the Vestibulocochlear Nerve Impulse sent to the Temporal Lobe of the Cerebral Cortex HEARING LOSS Conductive Deficit --Causes: Cerumen (ear wax) Foreign bodies Perforation of the tympanic membrane Otitis Media -- inflammation or infection of the middle ear Otosclerosis -- immobility of an ossicle usually the stapes Treatment is a Stapendectomy Treat underlying cause Nerve Deficit -- Damage to the 8th Cranial Nerve --Causes: Prolonged exposure to loud noises Drugs like Streptomycin; Neomycin Cochlear atrophy German measles in the first trimester Mumps Cilia (hair cells) on the receptors have worn away is the most frequent cause of nerve deafness