Title: Feb 20 3:31 PM (1 of 66) Special Senses Ch. 8

Transcription

1 Title: Feb 20 3:31 PM (1 of 66) Special Senses Ch. 8

2 Essential Question: How do the structures of the special senses realte to their functions? Title: Feb 20 3:33 PM (2 of 66)

3 What do you know about senses? Title: Feb 20 3:32 PM (3 of 66)

4 Special senses = smell, taste, sight, hearing and equilibrium (and touch) Receptors for senses: skin receptors photoreceptors chemoreceptors mechanoreceptors Title: Feb 20 3:34 PM (4 of 66)

5 Vision contains 70% of all body receptors requires the most learning eyes start developing about the fourth week of pregnancy not fully functional at birth eyeballs continue to enlarge lens grows throughout life all babies are far sighted at birth sees only gray tones uncoordinated eye movements by 5 mos. 20/200 vision Title: Feb 20 3:37 PM (5 of 66)

6 External eye anatomy eyelids protect eye eyelashes protect eye meibomian glandsmodified sebaceous glands, lubricate eye ciliary glandsmodified sweat glands between lashes lacrimal glandproduce tears Title: Feb 20 3:43 PM (6 of 66)

7 conjunctiva lines eyelids, covers part of surface of eyeball. secretes mucous to lubricate eyeball conjunctivitis inflammation of conjunctiva (pinkeye) Title: Feb 20 4:00 PM (7 of 66)

8 Lacrimal apparatus lacrimal glands lacrimal canals lacrimal sac nasolacrimal duct tears contain water, lysozyme, antibodies, salt Title: Feb 20 4:03 PM (8 of 66)

9 Title: Feb 20 4:06 PM (9 of 66) Extrinsic Eye Muscles

10 6 extrinsic muscles: lateral rectus moves eye laterally (abducens) medial rectus moves eye medially (oculomotor) superior rectus elevates eye (oculomotor) inferior rectus depresses eye (oculomotor) inferior oblique elevates eye and turns it laterally (oculomotor) superior oblique depresses eye and turns it laterally (trochlear) Title: Feb 20 4:08 PM (10 of 66)

11 Title: Feb 20 4:11 PM (11 of 66) Internal anatomy eyeball

12 eyeball hollow sphere has three tunics (coats): 1. sclera white of eye, thick connective tissue, aka fibrous tunic cornea is part of sclera (clear area) where light enters eye has nerve endings (pain) only transplanted tissue without rejection no blood flow Title: Feb 20 4:18 PM (12 of 66)

13 2. choroid coat blood rich tunic has dark pigment that prevents light scattering anterior forms ciliary body (muscle where lens is attached) and iris (muscle acts like diaphragm to regulate pupil opening) close vision/bright light circular muscles contract and pupil constricts distant vision/dim light radial muscles contract and dilates pupil Title: Feb 20 4:23 PM (13 of 66)

14 3. retina inner most layer white extends anteriorly to ciliary body contains photoreceptors (rods and cones) not evenly distributed rods most dense at periphery rods allow gray tones in dim light (night vision) cones allow for color vision can use an opthalmoscope to look at retina Title: Feb 20 4:31 PM (14 of 66)

15 optic nerve area of ganglion cell axons that leave the eye optic disc area of retina directly over the optic nerve does not contain any photoreceptors aka = blind spot fovea centralis area of a tiny pit that contains only cones area of sharpest vision Title: Feb 20 4:34 PM (15 of 66)

16 lens a flexible biconvex crystal like structure held in place by suspensory ligament attached to ciliary body divides anterior eye from posterior feels like hard jelly problem: cataracts hardening and clouding of lens cause hazy vision, blindness cataract surgery removal of lens and replacement with lens implant Title: Feb 20 4:39 PM (16 of 66)

17 aqueous humor (fluid) clear, watery liquid similar to blood plasma maintains ocular pressure continuously secreted by special area of cornea provides nutrients for lens and cornea reabsorbed through scleral venous sinus (Canal of Schlemm) Title: Feb 20 4:44 PM (17 of 66)

18 problem: if canal of Schlemm blocked pressure increases, depresses retina and optic nerve = glaucoma can cause blindness symptoms: halos of lights, headaches, blurred vision diagnosis; tonometer measures eye pressure treatment eyedrops increase drainage, or surgery Title: Mar 6 10:50 AM (18 of 66)

19 vitreous humor (fluid) gel like substance maintains shape, prevents collapsing maintains pressure Title: Feb 20 4:51 PM (19 of 66)

20 Rods and cones rods for night vision elongated neurons contain rhodopsin purple pigment formed from protein (opsin) and vit. A product (retinal) when light hits rods get bleaching of color due to conformational changes that causes electrical changes cause nerve impulses Night blindness inability to see at night cause deficiency of Vitamin A, deteriorates retina Title: Feb 20 4:55 PM (20 of 66)

21 cones to see color three types that are sensitive to particular wavlengths of light: blue light (blue cones) green light (green cones) green/red light (red cones) intermediate colors seen by light hitting more than 1 type of receptor Ex. blue and red cones hit = purple all three at once white Title: Feb 20 5:01 PM (21 of 66)

22 Title: Feb 23 3:22 PM (22 of 66)

23 problem: color blindness total = lack of all three types of cones partial = lack of one type most common lack red or green receptors less common blue/yellow genetic sex linked trait on X chromosome almost always in males Title: Feb 20 5:05 PM (23 of 66)

24 Pathway of light as light passes through substances, it gets refracted (bent) What parts of the eye would bend the light? greater lens convexity more it bends light Title: Feb 21 5:54 PM (24 of 66)

25 Title: Feb 21 5:57 PM (25 of 66) How a light source is focused in the eye

26 ciliary body contracts to make lens more convex accommodation = the ability for the eye to focus for close objects image on retina is called real image (reversed and upside down) Title: Feb 21 5:58 PM (26 of 66)

27 eyesight problems: emmetropia = "normal vision" lens focusing light on retina myopia = (nearsighted) light from distant objects is focused in front of retina cause eyeball too long, lens too strong, or cornea too curved correction need concave corrective lenses hyperopia = (farsighted) light from distant object focused behind retina cause eyeball too short, or "lazy lens" correction need convex corrective lenses Title: Feb 21 6:01 PM (27 of 66)

28 astigmatism =blurry images due to light that is focused as a line not a point on retina cause unequal curvature of cornea or lens Title: Feb 21 6:07 PM (28 of 66)

29 Visual Fields and pathways to brain binocular vision = vision of both eyes overlap helps with depth perception primates have this Title: Feb 21 6:09 PM (29 of 66)

30 Hemianopia = loss of same side of visual field in both eyes cause damage of visual cortex on one side only Title: Feb 21 6:11 PM (30 of 66)

31 Eye Reflexes controlled by autonomic nervous system involve ciliary body alters lens curvature iris control pupil size external muscles allow eye movement convergence= reflexive movement of eyes medially when viewing close objects photopupillary reflex pupils constricting in bright light prevents damage to photoreceptors accommodation pupillary reflex pupil constriction when viewing close objects eyestrain tired eyes when reading Title: Feb 21 6:13 PM (31 of 66)

32 Eye problems: 1. ophthalmia neonatorum newborn conjunctivitis caused by gonorrhea treatment: silver nitrate or antibiotics in eyes 2. presbyopia decreases lens elasticity cause: aging symptoms: hard to see near objects treatment: glasses Title: Feb 22 10:10 PM (32 of 66)

33 uses mechanoreceptors Ear divided into outer, middle, and inner ear outer and middle = hearing only inner ear = hearing and equilibrium Title: Feb 21 7:59 PM (33 of 66)

34 Title: Feb 21 8:03 PM (34 of 66) Ear Anatomy

35 Outer ear (External) pinna= auricle collects and directs sound external auditory canal channels the sound waves toward middle ear 1" long lined with ceruminous glands secrete cerumen (aka earwax) waxy, yellow substance functions protects ear drum from foreign materials (dust, insects, bacteria) Title: Feb 21 8:05 PM (35 of 66)

36 tympanic membrane (aka eardrum) function vibrates when sound waves hit it separates the outer and middle ear Title: Feb 21 8:13 PM (36 of 66)

37 Middle Ear aka tympanic cavity found within temporal bone laterally = tympanic membrane medially = openings called oval window and round window auditory tube connects middle ear to throat normally closed, opens when swallowing used to equalize pressure to outside ear ear popping is this area equalizing pressure Title: Feb 22 7:31 PM (37 of 66)

38 otitis media middle ear infection cause sore throats (children) because auditory tube runs horizontally symptoms: bulging and inflammed eardrum, pain treatment: antibiotics, myringotomy (lance eardrum to relieve pressure) and insert tubes articlestandard/patcare/352004/117020/p4a056opnr.jpg Title: Feb 22 7:36 PM (38 of 66)

39 Three bones found in middle ear smallest bones in body called ossicles transmit vibration from tympanic membrane to fluid of inner ear named for shapes 1. malleus (hammer) 2. incus (anvil) 3. stapes (stirrup) malleus passes vibration to incus, passes to stapes, passes to oval window of inner ear Title: Feb 22 8:08 PM (39 of 66)

40 Inner ear called osseous or bony labyrinth is a maze of bony chambers in temporal bone three sections of bony labyrinth: 1. cochlea hearing organ 2. vestibule between cochlea and semicircular canals 3. semicircular canals equilibrium area Title: Feb 22 8:16 PM (40 of 66)

41 filled with plasmalike fluid perilymph in perilymph is membranous labyrinth (membrane sacs) within this labyrinth is thicker fluid endolymph Title: Feb 22 8:28 PM (41 of 66)

42 Title: Feb 23 3:27 PM (42 of 66) inside of cochlea

43 How do we hear? Organ of Corti found in cochlea hearing receptors (Hair cells)are found here cochlear fluids move due to oval window movement cause hair cells to bend on basilar membrane due to attachment to stationary tectorial membrane on top Title: Feb 22 8:35 PM (43 of 66)

44 high pitch sounds move hairs close to oval window low pitch sounds move hairs further inside cochlea hair cells transmit impulses to cochlear nerve to auditory cortex in temporal lobe hearing is the last sense to leave our awareness when we go to sleep and first to "awaken" Title: Feb 22 8:44 PM (44 of 66)

45 How mechanoreceptors work Title: Feb 23 3:29 PM (45 of 66)

46 Title: Feb 22 8:52 PM (46 of 66) Sound waves in the ear

47 Title: Feb 23 3:31 PM (47 of 66) Cochlea straightened out

48 Hearing problems: deafness = loss of hearing of any degree conduction deafness = loss of hearing due to something interfering with conduction of sound vibrations to fluid of inner ear ex. earwax fusion of ossicles (otosclerosis) ruptured eardrum otitis media could still hear by bone conduction use hearing aids bounce sound off of skull bones Title: Feb 22 9:19 PM (48 of 66)

49 sensorineural deafness = deafness due to degeneration or damage to receptor cells in Organ of Corti, cochlear nerve or neurons to auditory cortex cause: loud noise hearing aids are less useful for this type presbycusis sensorineural deafness gradual deterioration of organ of Corti can't hear high tones and speech sounds happens with age Title: Feb 22 9:21 PM (49 of 66)

50 Mechanisms of Equilibrium vestibular apparatus = equilibrium receptors Two functional areas: 1. static equilibrium has receptors in vestibule maculae tells position of head, in relation to gravity, when not moving receptor hairs are in otolithic membrane = gel material with otoliths (stones of calcium salts Title: Feb 22 8:57 PM (50 of 66)

51 maculae when head moves otoliths orient in response to gravity, pulls hairs, sends impulse to vestibular nerve Title: Feb 23 3:32 PM (51 of 66)

52 2. Dynamic equilibrium receptors in semicircular canals canals have three orientations respond to rotation of head ex. twirling around boat rocking Title: Feb 22 9:10 PM (52 of 66)

53 in semicircular canals: crista ampullaris = tuft of hair cells with cupula (gelatinous cap) when head moves, endolymph lags behind, opposite of head stimulates hair cells and impulse travels to vestibular nerve Title: Feb 22 9:13 PM (53 of 66)

54 Title: Feb 23 3:34 PM (54 of 66) dynamic equilibrium

55 both static and dynamic equilibrium work at same time sight and propioreceptors are important too Problems with equilibrium: symptoms: nausea, dizziness, difficulty maintaining balance 1. Meniere's syndrome cause increase in endolymph that enlarges membranous labrynth symptoms: tinnitus (ringing in ear), some hearing loss, vertigo (feeling of spinning), pain, nausea, problem maintaining balance treatment:treat symptoms, ex steroids (anti inflammatory) Title: Feb 22 9:18 PM (55 of 66)

56 2. Vertigo feeling of dizziness symptom, not disease cause: problem with vestibular system treatment:anti dizziness medications Title: Feb 22 9:26 PM (56 of 66)

57 Sense of smell uses chemoreceptors (olfactory receptors) postage size area of nasal cavity ( million receptors) olfactory receptor cells = neurons with olfactory hairs stimulated by chemicals dissolved in mucus transmitted to olfactory filaments (olfactory nerve) tied to limbic system (emotions) very sensitive can pick up also fatigue Title: Feb 22 9:46 PM (57 of 66)

58 sense of smell methylmercaptan we can pick up 1/25 billionth mg/ml of this (added to natural gas) Title: Feb 23 3:35 PM (58 of 66)

59 problems: anosmias = partial or full loss of smell cause: head injuries, colds, aging, zinc deficiency olfactory auras = heightened sense of smell, epileptics before seizure Title: Feb 22 9:51 PM (59 of 66)

60 Taste (gustation) receptors are taste buds (10,000) on tongue, roof of mouth and in throat tastes: sweet sugar, saccharine, some amino acids sour acidity bitter alkaloids (nicotine, quinine, caffeine) salty metal ions in solution umami meaty, savory taste (not totally embraced by western world) amino acids Title: Feb 22 9:54 PM (60 of 66)

61 types of papillae: 1. sharp filiform entire surface of tongue taste sensation no taste 2. rounded fungiform most prominant ontip and sides of tongue 3. circumvallate forms "V" on back of tongue Title: Mar 16 8:36 AM (61 of 66)

62 taste buds (facial nerve branch) Title: Mar 13 9:00 AM (62 of 66)

63 Title: Feb 23 3:36 PM (63 of 66) taste

64 gustatory cells respond to dissolved chemicals have gustatory hairs that get stimulated, depolarize and send impulse via three cranial nerves: facial anterior tongue glossopharyngeal & vagus posterior tongue sense of taste is tied into olfactory, temperature, & texture umami enhanced by MSG spicy taste activation of taste receptors and temperature receptors Title: Feb 22 10:04 PM (64 of 66)

65 Problems: ageusia = complete inability to taste rare hypoageusia = reduced ability to taste hyperageusia = heightened ability to taste taste decreases as we age Title: Feb 22 10:00 PM (65 of 66)

66 Title: Feb 22 10:25 PM (66 of 66)