A&PII Exam 2 ObjectivesPower Point #1: The Chemical Senses1. 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; alsoknown as olfactory epithelium on roof of nasal cavity 3 types of cells: o olfactory receptor: millions on each side of nasal septumo supporting: surroung olfactory cellso basal: base of epithelium olfactory receptor cellso bipolar neurons: thin dendrite that ends with knob giving way to olfactory ciliao olfactory cilia: increase receptive surface area; covered in mucus that captures airborne chemicalso filaments of olfactory nerve: run superior to inferior through the cribriform plateo replaced every 30-60 dayso can distinguish 10,000 different odorso 1000 smell genes: each cell has a unique receptor protein that responds to some odorants more than otherso nasal cavity also has pain receptors that respond to irritants2. Explain the transduction of smell and its process and adaptation through the somatosenstory system.1) Odor binds to receptor2) 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 intracellular4) depolarization is caused by Na+ and Ca2+ flowing in Circuit level olfactiono olfactory cells send AP to 2nd order neurons (Mitral cells) which are inside glomeruli, which respond to different odorso 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 exposure3. 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: topo foliate papillae: lateralo 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 NT5. 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)o tip of tongue salty: inorganic salts (metal ions/NaCl)o sides bitter: alkaloids (caffeine/nicotine)o back of mouth umami: AAs (glutamate/aspartate)o pharynx6. 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 depolarizationo sour: H+ blockade of K+ channels allows cations to entero bitter/sweet/umami: receptor coupled with gustadin (G protein), which causes release of intracellular Ca2+ which opens cation channels allowing depolarization Afferent fiberso facial nerve (VII): anterior 2/3 of tongueo glossopharyngeal nerve (IX): posterior ½ of tongue and oropharynxo 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) cortex7. Define the disorders of the chemical senses. anosmia: absence of smell hyposmia: impaired sense of smell dysosmia: distorted sense of smell ageusia: absence of taste hypogeusia: decreased sensitivity hypergeusia: increased sensitivity dysgeusia: distorted sense of tastePower Point #2: Vision: The Eye Part I1. 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 commissureso 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 blinkingo have tarsal glands (in tarsal plates) to secrete oily lubrication conjunctiva: transparent mucous membrane covering eyelid lacrimal apparatus: lacrimal gland and ducts that drain secretionso gland: in orbit above lateral end of eye; releases tears (lacrimal secretions) as saline solutiono tear pathway: go through lacrimal puncta enter lacrimal canaliculi drain into lacrimal sac fall into lacrimal duct finally tears enter nasal cavity at inferior meatus2. 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 laterallyo 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 layero outermost coat of eye (connective tissue)o
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