BSC2086 Anatomy Physiology II Exam 1 Study Guide Lesson 2 Special Senses Special Senses There are five 5 special senses o Olfaction Smell o Gustation Taste o Vision Sight o Equilibrium Balance o Hearing Olfaction Smell Olfactory organs provide sense of smell Located in nasal cavity on either side of nasal septum Two 2 layers o Olfactory Epithelium Contains Olfactory Receptor Cells Highly modified neurons Supporting Cells Basal Stem Cells Regenerate olfactory receptor cells Olfactory reception involves detecting dissolved chemicals as they interact with odorant binding proteins on cell membrane of olfactory receptor cell Olfactory Pathways Axons leaving olfactory epithelium Collected into 20 or more bundles Penetrate cribiform plate of ethmoid Reach olfactory bulbs of cerebrum where first synapse occurs Axons leaving olfactory bulbs travel along olfactory tract to olfactory cortex hypothalamus and portions of limbic system Arriving information reaches information centers WITHOUT first synapsing in thalamus o Lamina Propria Contains Areolar tissue Blood vessels Nerves Olfactory Glands Form mucus o Secretions coat surfaces of olfactory organs o Olfactory discrimination Can distinguish thousands of chemical stimuli CNS interprets smells by the pattern of receptor activity o Olfactory receptor population Considerable turnover Receptor cells replenished by basal cells Number of olfactory receptors sense of smell decline with age 1 BSC2086 Anatomy Physiology II Exam 1 Study Guide Gustation Taste Gustation provides information about the foods liquids consumed Taste Receptors Gustatory Receptors 2 BSC2086 Anatomy Physiology II Exam 1 Study Guide o Distributed on tongue portions of pharynx and larynx o Taste Buds Clusters of taste receptors Associated with epithelial projections lingual papillae on superior surface of tongue Three 3 types of lingual papillae Filiform Papillae Don t contain taste buds provide friction Fungiform Papillae Contain five 5 taste buds each Circumvallate Papillae Contain one hundred 100 taste buds each Taste buds contain Basal cells Gustatory cells o Extend taste hairs through taste pore o Survive 10 days then replaced Monitored by cranial nerves that synapse within the medulla oblongata then on to thalamus primary sensory cortex Gustatory discrimination o Four 4 primary taste sensations Sweet Salty Sour Bitter nucleotides o Other human taste sensations Umami Receptors sensitive to amino acids small peptides and Detects characteristics of beef chicken broths parmesan cheese 3 BSC2086 Anatomy Physiology II Exam 1 Study Guide Water Detected by water receptors in the pharynx o Dissolved chemicals contact taste hairs o Bind to receptor proteins of gustatory cell o Salt and sour receptors Chemically gated ion channels Stimulation produces depolarization of cell o Sweet bitter and umami stimuli Bind to membrane receptor protein to activate G proteins o End result of taste receptor stimulation release of neurotransmitters by receptor cell Generate action potentials in afferent fiber o Taste sensitivity Significant individual differences 1000x more sensitive to acids sour taste 100x more sensitive to bitter o Adaptive sour bitter foods are often poisonous Some conditions are inherited Ex 30 of Caucasians cannot taste phenylthiocarbamide PTC Number of taste buds begins declining rapidly by age 50 Vision Sight Accessory Structures of the Eye Accessory structures of the eye provide protection lubrication and support o Palpebrae Eyelids Continuation of skin Blinking keeps surface of eye lubricated free of dust and debris Tarsal Glands Secrete lipid rich product that helps keep eyelids from sticking together o Superficial Epithelium of Eye Lacrimal Caruncle Contains glands producing thick secretions Contributes to gritty deposits that appear after a good night s sleep 4 BSC2086 Anatomy Physiology II Exam 1 Study Guide Conjunctiva Epithelium covering Inner surfaces of eyelids palpebral conjunctiva Outer surface of eye ocular conjunctiva Conjunctivitis Pinkeye Inflammation of the conjunctiva redness caused by infection allergy chemical irritation o Lacrimal Apparatus Produces distributes and removes tears Lacrimal Gand Tear Gland Secretions contain lysozyme Tears collect in the lacrimal lake at the medial canthus antibacterial enzyme Pass through o Lacrimal puncta o Lacrimal canaliculi o Lacrimal sac o Nasolacrimal duct o Then reach inferior meatus of nose The Eye Eyeball hollow divided into two cavities o Posterior Cavity Larger filled with vitreous humor o Anterior Cavity Smaller filled with aqueous humor Anterior chamber before the iris Posterior chamber after the iris 5 BSC2086 Anatomy Physiology II Exam 1 Study Guide Three 3 layers of the eye o Fibrous Layer outer Cornea Transparent anterior region Sclera White of the eye Cornal Limbus Border between cornea and sclera o Vascular Layer Uvea intermediate Functions 6 BSC2086 Anatomy Physiology II Exam 1 Study Guide Provides route for blood vessels lymphatics that supply tissues of the eye Regulates the amount of light entering eye Secretes reabsorbs aqueous humor that circulates within chambers of eye Controls shape of lens essential to focusing Components Iris Contains pupillary muscles o Sympathetic AND parasympathetic innervation change the o Sympathetic stimulates pupillary dilator pupils get diameter of the pupil bigger dilate o Parasympathetic stimulates pupillary constrictor pupils get smaller constrict Ciliary Body Contains ciliary processes ciliary muscle that attaches to suspensory ligaments of lens o Control lens position and shape Choroid Delivers oxygen nutrients to retina o Inner Layer deep Pigmented Part outer layer Absorbs light that passes through neural part Prevents rebounding of light Neural Part Retina inner layer Contains visual receptors and associated neurons Photoreceptors o Rods Don t discriminate light colors highly sensitive to light Used in low light nighttime o Cones Provide color vision Densely clustered in fovea at center of macula 7 BSC2086 Anatomy Physiology II Exam 1 Study Guide 8 BSC2086 Anatomy Physiology II Exam 1 Study Guide Bipolar Cells Neurons that allow rods and cones to synapse with ganglion cells Horizontal Cells Extend across outer portion of retina Amacrine Cells Where bipolar cells synapse with ganglion cells o Comparable to horizontal cell layer Horizontal amacrine cells alter sensitivity of the retina Optic Disc Circular region just medial to fovea where the optic nerve
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