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TAMU BIOL 320 - BIOL 320 Lab 3 Prelab Notes

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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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