The Senses ST 110

Special Senses Organs and accessories related to: Vision Hearing Taste Smell Equilibrium

Types of Receptors Chemoreceptors Nociceptors Thermoreceptors Mechanoreceptors Photoreceptors

Sensations vs Perceptions Sensations- Feelings that occur when the brain receives sensory impulse from PNS. Perceptions-conscious awareness of sensation after interpretation.

Somatic Senses Involve the receptors associated with skin, muscles, joints and visceral organs.

Senses Touch- tactile receptors located in the skin or just beneath it. Pressure- stimulation of receptors in deeper tissue

Receptors Touch and Pressure Free ends of sensory nerve fibers Meissner’s corpuscles Pacinian corpuscles

Senses Cont. Thermal- perceptions of degrees of warmth and coolness Temperature- free nerve endings located beneath skin Heat receptors Cold receptors

Senses Cont. Pain- free nerve endings that are stimulated when tissues are damaged. Acute Chronic

Acute Pain Occurs very rapidly Not felt in deeper tissues Sharp/stabbing pain

Chronic Pain Slower onset Builds slowly in intensity (sec. or min.)

Visceral Pain AKA referred pain Pg 194 fig 9-1

Stretch Receptors Sensations of lengthening and stretching muscles Golgi tendon organs Muscle spindles

Sensation of Sight Eye-sensory and receptor organ that receives images and transmits them to the brain.

Eye Terminology Optic Ocular Extraocular Intraocular OD OS

Accessory Organs Lacrimal apparatus Eyelids Extrinsic muscles

Lacrimal Apparatus Produce and drain lacrimal fluid (tears) from eye Lacrimal gland Excretory lacrimal ducts

Eyelids Palpebrae 4 layers Skin Muscle tissue Connective tissue Conjunctiva Protection

Extrinsic Muscles Rectus Oblique Pg 196 tbl 9-2

Conjunctiva Thin mucous membrane Stratified columnar epithelium Conjunctivitis

Structure of Eye Fluid filled hollow sphere 3 layers (tunics) Outer Middle inner

The Eye Cornea Iris Pupil Lens

The Eye Presbyopia Retina Fovea centralis Aqueous humor

The Eye Vitreous Humor Optic disc Sclera Choroid

Actions of Eye Accommodation Convergence Emmetropia

Visual Acuity 20/20 Snellen Chart 1 st number-distance from the chart (20ft) 2 nd number- deviation from the norm based on ability to read chart

Pathology of Eye

Glaucoma Increase IOP Loss of vision/blindness

Keratoplasty Corneal transplant

Inflammation Keratitis Iritis Conjunctivitis

Strabismus “cross eyed”

Cataract Lens loses transparency “milky”

Xerophthlamia Dry eye

Procedures Blepharoptosis Drooping of upper eyelid

Sensation of Hearing Ear-pick up and amplify sound waves for interpretation Equilibrium 3 regions External Middle Internal

External Ear Pinna External Auditory Canal Cerumen

Middle Ear Eustachian Tube Tympanic Membrane Mastoid Sinus Ossicles

Transmit and amplify sound waves Malleus (hammer) Incus (anvil) Stapes (stirrup)

Inner Ear AKA labyrinth Cranial Nerve VIII- transmits info from inner ear to brain

Normal Ear Actions Air Conduction Bone Conduction Sensorineural Conduction

Ear Pathology

Outer Ear Impacted cerumen Otalgia Otitis Otorrhagia

Middle Ear Eustachitis Mastoiditis Myringitis Otosclerosis Otitis Media

Inner Ear Labryinthitis Meniere’s Syndrome Tinnitus Vertigo

Procedures Otoplasty Mastoidectomy Myringotomy Stapedectomy

Hearing Loss Deafness Conductive Hearing Loss Noise-Induced Hearing Loss Sensorineural Loss Presbycusis

Sensation of Taste Taste bud-modified epithelial cells that function as receptors Contain microvilli Types Sweet Salty Sour Bitter

Sensation of Smell Olfactory receptors Nasal cavity Olfactory pathways- Nerve impulses travel through olfactory tract and enter brain Interpreted as specific odors Closely associated with areas of brain important in memories and emotion