BUT There are at least four other senses body awareness balance thermoception and nociception Types of Senses that we are most familiar with BIOL 320 Lab 3 Prelab Notes Special Senses Sight Hearing Taste Smell Touch Location of Receptors Scattered throughout the body o Exteroceptors o Interoceptor o Proprioceptors External stimuli receptor Monitors visceral organs Types of Excitation Stimulus Monitors skeletal muscles and joints Photoreceptors vision Thermoreceptors heat Mechanoreceptors cutaneous receptor muscle spindles Nociceptors pain Chemoreceptors taste smell Vision accessory structures of eyes Extrinsic eye muscles o Six muscles that move the eyes o Origin orbit o Also help maintain shape of eye o There will be a muscle directly on the top and sides and under and these are the recti muscles rectus o Recti straight muscles superior rectus inferior rectus lateral rectus medial o Oblique superior pulley system type muscle and inferior maintains shape of eye ball and not straight like rectus muscles o Know the cranial nerves and numbers of them as well as composition CRANIAL NERVES Oculomotor nerve III motor Trochlear nerve IV motor Abducens VI motor Recti o Lateral rectus abducens nerve VI o Medial rectus Oculomotor nerve III o Superior rectus Oculomotor nerve III o Inferior rectus Oculomotor nerve III o Superior oblique trochlear nerve IV o Inferior oblique Abducens nerve VI Oblique Structures of Eye Three tunics for the wall of the eyeball o Fibrous tunic Outermost layer Protective structure that protects it from external structure Two regions Sclera white of the eye tendon like protection Cornea transparent anterior 1 6 and allows for light to pass o Vascular tunic Blood vessel layer o Sensory tunic Retina which is made up of photoreceptor cells Innermost tunic Two layered retina outer pigmented layer of melanin and inner neural layer Neural layer o transparent out pocketing of brain with millions of photoreceptors o Macula lutea neural layer lateral to blind spot center fovea centralis contains only cones light passes directly to photoreceptors gives fine focus to small area of vision o Detached retina pigmented and nervous layers separate causes blindness if not reattached by laser surgery Optic disc exit area for optic nerve no photoreceptors blind spot Cornea Supplied with nerve endings for reflex blinking o Reflex also increases lacrimal fluid Collagen fibers arranged to make it clear External sheath of simple squamous epithelium Types of photoreceptors Rods o Dim light receptors o Peripheral vision o Do not provide sharp images Cones o Bright light receptors o High accuracy color vision Iris and Pupil Lens Parasympathetic stimulation causes circular muscles to contract o If you want to reduce the amount of light Sympathetic stimulation causes radial muscles to contract o Decrease amount of light or see something far from you Biconvex flexible structure changes shape for focusing Enclosed in thin elastic capsule Ciliary body needs to relax for lens to pull something and look at something far I think Controlled my nervous system Normal light focuses directly on the retina Myopia nearsightedness light focuses in front of the retina corrected by contact lens Hyperopia farsightedness light focuses behind the retina corrected by convex lens Hearing We have cells that respond to vibrations that come into the ear Outer ear middle ear inner ear These then send impulses to cranial nerve vestibulocochlear nerve Vestibular equilibrioception Three semicircular canals detects rotation Utricle linear acceleration and head tilts in horizontal plane Saccule linear acceleration and head tilts in vertical plane up and down Auditory pathways Impulses sent to thalamus Thalamus to auditory complex in temporal lobe Equilibrium pathway Impulses go directly to reflex centers o Ex stumbling o Route is to brain stem and cerebellum Motion sickness o Due to sensory mismatch