BIOL 320 Lab 3 Prelab Notes Special SensesTypes of Senses (that we are most familiar with)- Sight- Hearing- Taste- Smell- TouchBUT There are at least four other senses: body awareness, balance, thermoception, and nociceptionLocation of Receptors- Scattered throughout the bodyo Exteroceptors External stimuli receptoro Interoceptor Monitors visceral organso Proprioceptors Monitors skeletal muscles and jointsTypes of Excitation Stimulus- Photoreceptors: vision- Thermoreceptors: heat- Mechanoreceptors: cutaneous receptor, muscle spindles- Chemoreceptors: taste, smell- Nociceptors: painVision: accessory structures of eyes- Extrinsic eye muscles o Six muscles that move the eyeso Origin = orbito Also help maintain shape of eyeo There will be a muscle directly on the top and sides and under and these are the recti muscles o Recti (straight muscles): superior rectus, inferior rectus, lateral rectus, medial rectus o Oblique: superior (pulley system type muscle) and inferior; maintains shape of eye ball and not straight like rectus muscleso Know the cranial nerves and numbers of them as well as compositionCRANIAL NERVES Oculomotor nerve III (motor) Trochlear nerve IV (motor) Abducens VI (motor)- Rectio Lateral rectus: abducens nerve VIo Medial rectus: Oculomotor nerve IIIo Superior rectus: Oculomotor nerve IIIo Inferior rectus: Oculomotor nerve III- Obliqueo Superior oblique: trochlear nerve IVo Inferior oblique: Abducens nerve VIStructures of Eye- Three tunics for the wall of the eyeballo 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 passo Vascular tunic Blood vessel layero 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 photoreceptorso Macula lutea (neural layer): lateral to blind spot, center = fovea centralis, contains only cones, light passes directly tophotoreceptors, gives fine focus to small area of visiono 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 blinkingo Reflex also increases lacrimal fluid- Collagen fibers arranged to make it clear- External sheath of simple squamous epithelium Types of photoreceptors- Rodso Dim light receptorso Peripheral visiono Do not provide sharp images- Coneso Bright light receptorso High accuracy color visionIris and Pupil - Parasympathetic stimulation causes circular muscles to contracto If you want to reduce the amount of light- Sympathetic stimulation causes radial muscles to contracto Decrease amount of light or see something far from youLens- 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 systemNormal: light focuses directly on the retinaMyopia: nearsightedness – light focuses in front of the retina – corrected by contact lens Hyperopia: farsightedness – light focuses behind the retina – corrected by convex lensHearing - We have cells that respond to vibrations that come into the ear - These then send impulses to cranial nerve – vestibulocochlear nerve - Outer ear, middle ear, inner earVestibular 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 lobeEquilibrium pathway- Impulses go directly to reflex centerso Ex: stumblingo Route is to brain stem and cerebellum- Motion sicknesso Due to sensory
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