A PII Exam 2 Objectives Power Point 1 The Chemical Senses 1 Define and identify the anatomy of the olfaction receptor cells and epithelium pseduostratified epithelium layer of cells giving false impression of more than one layer also known as olfactory epithelium on roof of nasal cavity 3 types of cells o olfactory receptor millions on each side of nasal septum o supporting surroung olfactory cells o basal base of epithelium olfactory receptor cells o bipolar neurons thin dendrite that ends with knob giving way to olfactory cilia o olfactory cilia increase receptive surface area covered in mucus that captures airborne chemicals o filaments of olfactory nerve run superior to inferior through the cribriform plate o replaced every 30 60 days o can distinguish 10 000 different odors o 1000 smell genes each cell has a unique receptor protein that responds to some odorants more than others o nasal cavity also has pain receptors that respond to irritants 2 Explain the transduction of smell and its process and adaptation through the somatosenstory system 1 Odor binds to receptor 2 G protein signaling molecule is activated which activates enzyme adenylate cyclase to synthesize cAMP secondary messenger 3 cAMP allows cation membrane channel to open from extracellular to intracellular 4 depolarization is caused by Na and Ca2 flowing in Circuit level olfaction o olfactory cells send AP to 2nd order neurons Mitral cells which are inside glomeruli which respond to different odors o mitral cells send info down olfactory tracts to thalamus or to hypothalamus amygdala or limbic system sympathetic emotional responses to smells olfaction has low threshold so only a few molecules need to be present receptors adapt by 50 in first second or so and slowly after that complete adaptation occurs 1 minute after exposure 3 Describe and locate the types of taste buds associated with gustation taste buds sensory receptors for taste cheeks soft palate tongue pharynx epiglottis stratified squamous taste buds on tongue housed in papillae abrasive feel o fungiform papillae top o foliate papillae lateral o circumvallate papillae back largest least 4 Describe the gustatory cells each taste bud has 50 100 cells two types gustatory cells and basal cells basal cells stem cells most dynamic because they replace every 7 10 days gustatory cells gustatory hairs that project through at the taste pore into saliva dendrites in each cell take signal from receptor to brain two types of gustatory cells one releases NT serotonin and other uses ATP as NT 5 Name the major types of taste stimuli and where they most commonly occur sour acids acidic H o sides of mouth sweet elicited by organics sugars salts salty inorganic salts metal ions NaCl o tip of tongue o sides bitter alkaloids caffeine nicotine o back of mouth umami AAs glutamate aspartate o pharynx 6 Describe the physiology and transduction of gustation including the afferent fibers that are involved dissolved chemicals in saliva contact gustatory hairs chemicals bind to gustatory cells induces depolarization NT released from synapse at highest change in membrane potential NT binds to associated afferent fiber dendrite and moves info to 1st order neuron chemical depolarization o salty Na influx through Na channels causes depolarization o sour H blockade of K channels allows cations to enter o bitter sweet umami receptor coupled with gustadin G protein which causes release of intracellular Ca2 which opens cation channels allowing depolarization Afferent fibers o facial nerve VII anterior 2 3 of tongue o glossopharyngeal nerve IX posterior of tongue and oropharynx o vagus nerve X throat region epiglottis lower pharynx o solitary neurons of medulla 2nd order elicit digestive reflexes through PNS on the way saliva into mouth o thalamus 3rd order neurons o taste gustatory cortex 7 Define the disorders of the chemical senses anosmia absence of smell hyposmia impaired sense of smell dysosmia distorted sense of smell hypogeusia decreased sensitivity hypergeusia increased sensitivity dysgeusia distorted sense of taste ageusia absence of taste Power Point 2 Vision The Eye Part I 1 Locate and describe the accessory structures of the eye in detail along with the path through the lacrimal apparatus 70 of all sensory receptors are in eyes vision dominant sense eyebrows overlie supra orbital margins of skull shade eyes from sunlight and prevent perspiration from reaching eyes contraction of oculi eyelids palpebrae separated by palpebral fissure meet at medial and lateral commissures o protect eyes blink 3 7 secs prevent drying through blinking lacrimal caruncle in medial commissure fleshy elevation that contains sweat glands tarsal plates connective tissue sheets that support eyelids eyelashes protect follicles of which a touch prevents reflex blinking o have tarsal glands in tarsal plates to secrete oily lubrication conjunctiva transparent mucous membrane covering eyelid lacrimal apparatus lacrimal gland and ducts that drain secretions o gland in orbit above lateral end of eye releases tears lacrimal secretions as saline solution o tear pathway go through lacrimal puncta enter lacrimal canaliculi drain into lacrimal sac fall into lacrimal duct finally tears enter nasal cavity at inferior meatus 2 Describe the actions of the extrinsic eye muscles and how they may relate to one another rectus originate from annular ring which surrounds optical canal faster than any other muscle very precise oblique muscles move eyeball in vertical plane when eye is looking medially superior oblique and inferior oblique rotate eye opposite their name and also laterally superior and inferior recit naturally turn eye medially when they depress and elevate it thus superior and inferior oblique muscles are essential to pull eye laterally o counteracts medial pull allowing eye to depress and elevate vertically Stimulation PNS SNS o PNS bright close vision circular muscles contract sphincter pupillae o SNS dim distant vision radial muscles contract dilator pupillae 3 Describe each of the three layers of the eye in detail Fibrous layer o outermost coat of eye connective tissue o sclera posterior portion of eye white of eye posterior articulates with dura mater of brain through optic nerve o cornea anterior 1 6 of fibrous layer covered in stratified squamous epithelium most susceptible to damage pain receptors Vascular layer o middle coat of eyeball 3 regions choroid membrane forming posterior 5 6 of this layer
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