A PII Exam 2 Objectives Power Point 1 The Chemical Senses Objective 1 Define and identify the anatomy of the olfaction receptor cells and epithelium Olfactory Epithelium Olfactory Receptor Cells o Pseudostratified epithelium 1 layer of cells giving the false impression of multi layer o Located on the roof of the nasal cavity o Three types of cells Olfactory Receptor Supporting and Basal o Millions on each side of nasal septum o Bipolar Neurons thin dendrite that ends with a knob giving way to olfactory cilia o Olfactory Cilia Serve to increase receptive surface area These lie flat on epithelium and are covered by mucus that is produced by the supporting cells The mucus captures airborne chemicals o Filaments of the Olfactory Nerve run superior to inferior through the cribriform plate o Replaced every 30 60 days by differentiation of basal cells o These cells can distinguish about 10 000 different odors o Receptors are stimulated by at least 1 000 smell genes active in the nose Unique receptor protein Each cell has only 1 TYPE of receptor protein Each protein responds to some odorants more than others o Nasal cavity contains pain receptors that respond to irritants Objective 2 Explain in detail the transduction of smell and its process and adaptation through the somatosenstory system 1 Odor binds to a receptor 2 G protein signaling molecule is activated which activates the enzyme adenylate cyclase to synthesize cAMP o cAMP is a secondary messenger 3 cAMP allows a cation membrane channel to open from the extracellular to intracellular space 4 Na and Ca2 flow in causing depolarization Objective 3 Describe and locate the types of taste buds associated with gustation Taste Buds Our sensory receptors for taste 1 1 o Tongue cheeks soft palate pharynx epiglottis Taste buds primarily on the tongue housed in papillae Abrasive Feel o Fungiform Papillae Top Mush room shaped elevations scattered over the entire tongue surface most are near the anterior tip Innervated by CN VII o Foliate Papillae Lateral o Circumvallate Papillae Back Located on lateral borders of the tongue and taste buds are in folds on the sides of the papillae Largest in size but fewest in number Inverted v shaped row at the back of the tongue Innervated by CN VII and IX Objective 4 Describe the gustatory cells Each bud has 50 100 cells of which there are 2 types o Gustatory Cells and Basal Cells replaced 7 10d Gustatory Cells Gustatory Hairs o Project through at taste pore into saliva Like Olfactory Cilia and Mucus Dendrites in each cell take signal from receptor cell to the brain o 2 Types of Gustatory cells one releases its neurotransmitter serotonin and the other uses ATP Objective 5 Name the major types of taste stimuli and where they most commonly occur o Salty Inorganic salts metal ions Nacl Sour Acids acidic H Sweet Receptors Tip of Tongue o Elicited by organics sugars salts Salty and Sour Sides Bitter Back o Alkaloids caffeine nicotine Umami Pharynx o AAs Glutamate Aspartate However all taste can come from all areas these are just primary regions Objective 6 Describe the physiology and transduction of gustation including the afferent fibers that are involved Physiology o Chemicals dissolved in saliva contact gustatory hairs 2 2 o Binding of chemical to gustatory cell induces depolarization o At highest change in membrane voltage neurotransmitter released from synapse o Binding of NT to the associated afferent fiber dendrite moves information to the 1st Receptor coupled w gustducin G Protein Gustducin causes the release of intracellular calcium which opens cation channels allowing for depolarization order neurons Chemical Depolarization o Salty Na influx through Na channels Causes depolarization o Sour H blockade of K channels Allowing cations to enter o Bitter Sweet Umami Gustatory Pathway Afferent Pathways Origination o Facial Nerve VII Anterior 2 3 of tongue o Glossopharyngeal Nerve IX Posterior 1 3 of tongue and the oropharynx o Vagus Nerve X Throat region Epiglottis Lower Pharynx o Solitary Nucleus of Medulla 2nd order neurons o Thalamus 3rd order neurons o Taste Gustatory Cortex Objective 7 Define the disorders of the chemical senses Smell Taste o Anosmias Absence of smell o Hyposmia Impaired sense of smell o Dysosmia Distorted sense of smell o Ageusia Absence of taste o Hypogeusia Decreased sensitivity o Hypergeusia Increased sensitivity o Dysgeusia Distorted sense of taste Elicit digestive reflexes through PNS on the way saliva into mouth Power Point 2 Vision The Eye Part I Objective 1 Locate and describe the accessory structures of the eye in detail along with the path through the lacrimal apparatus Eyebrows Overlie supra orbital margins of skull Shade the eyes from sunlight and prevent perspiration from reaching eyes o Contraction of Orbicularis Oris OR Oculi 3 3 Eyelids Palpebrae Separated by the palpebral fissure meet at the medial and lateral commissures of the eye o Function Protect the eyes Blink 3 7 sec and prevent drying through blinking Lacrimal caruncle In medial commissure fleshy elevation that contains sweat glands Tarsal Plates Connective Tissue Sheets support eyelid Eyelashes Projecting follicles of which a touch prevents reflex blinking o Has tarsal glands in tarsal plates to secret oily lubrication Conjunctiva transparent mucous membrane covering the eyelid Lacrimal Apparatus o Lacrimal Gland and ducts that drain o Lacrimal Gland In orbit above lateral secretions end of the eye Releases lacrimal secretion tears as a saline solution o As you blink tears are spread downward to the following pathway o Go through Lacrimal Puncta Enter Lacrimal Canaliculi Drain into Lacrimal Sac Then fall into Lacrimal Duct Finally tears enter Nasal Cavity at Inferior Meatus Objective 2 Describe the actions of the extrinsic eye muscles and how they may relate to one another Rectus Muscles Originate from annular ring which surrounds optic canal Oblique Muscles Move eyeball in vertical plane when the eye is already looking medial Superior oblique and Inferior oblique rotate eye opposite their name and also laterally Superior and inferior recti naturally turn the eye medially when they depress and elevate it thus the superior and inferior oblique muscles are essentially to pull eye laterally o This counteracts medial pull allowing eye to depress and elevate vertically Objective 3 Describe each of the three layers of the eye in detail Fibrous Layer Outermost coat of the eye o Essentially connective tissue 4 4 o
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