Chapter 9- Senses (Exam 2)

Front 1

Sense

Back 1

ability to perceive stimuli

Front 2

Sensation

Back 2

conscious awareness of stimuli received by sensory neurons

Front 3

Sensory receptors

Back 3

sensory nerve endings that respond to stimuli by developing action potentials

Front 4

General senses

Back 4

- receptors over large part of body

- somatic provide info. about body and env’t

- visceral provide info. about internal organs, pain, pressure

- touch, pressure, pain, temp., and itch

Front 5

Special senses

Back 5

smell, taste, sight, hearing, and balance

(4/5 senses + balance)

Front 6

Types of Receptors

Back 6

-Mechanoreceptors

-Chemoreceptors

-OdorsPhotoreceptors

-Thermoreceptors

-Nociceptors

Front 7

Mechanoreceptor

Back 7

- detect movement

- Ex. touch, pressure, vibration-

Front 8

Chemoreceptors

Back 8

- detect chemicals

- Ex. Odors

Front 9

Photoreceptors

Back 9

detect light

Front 10

Thermoreceptors

Back 10

detect temp. changes

Front 11

Nociceptors

Back 11

detect pain

Front 12

Types of Touch Receptors

Back 12

-Merkel’s disk

-Hair follicle receptors

-Meissner corpuscle

-Ruffini corpuscle

-Pacinian corpuscle

Front 13

Merkel’s disk

Back 13

detect light touch and pressure

Front 14

Meissner corpuscle

Back 14

- deep in epidermis

- localizing tactile sensations

Front 15

Hair follicle receptors

Back 15

detect light touch

Front 16

Ruffini corpuscle

Back 16

- deep tactile receptors

- detects continuous pressure in skin

Front 17

Pacinian corpuscle

Back 17

- deepest receptors - associated with tendons and joints

- detect deep pressure, vibration, position

Front 18

Pain

Back 18

unpleasant perceptual and emotional experience

Front 19

Types of Pain

Back 19

-Localized

-Diffuse

Front 20

Localized

Back 20

- sharp, pricking, cutting pain

- rapid action potential

Front 21

Diffuse

Back 21

- burning, aching pain

- slower action potentials

Front 22

Pain Control

Back 22

Local anesthesia: - action potentials suppressed from pain receptors in local areas - chemicals are injected near sensory nerve

General anesthesia: - loss of consciousness - chemicals affect reticular formation

Front 23

Referred Pain

Back 23

- originates in a region that is not source of pain stimulus - felt when internal organs are damaged or inflamed

- sensory neurons from superficial area and neurons of source pain converge onto same ascending neurons of spinal cord

Front 24

Olfaction

Back 24

- sense of smell - occurs in response to odorants - receptors are located in nasal cavity and hard palate - we can detected 10,000 different smells

Front 25

How does olfaction work?

Back 25

1. Nasal cavity contains a thin film of mucous where odors become dissolved.

2. Olfactory neurons are located in mucous. Dendrites of olfactory neurons are enlarged and contain cilia.

3. Dendrites pick up odor, depolarize, and carry odor to axons in olfactory bulb (cranial nerve I). 4. Frontal and temporal lobes process odor.

Front 26

Taste

Back 26

Taste buds:

- sensory structures that detect taste

- located on papillae on tongue, hard palate, throat

- Inside each taste bud are 40 taste cells

- Each taste cell has taste hairs that extend into taste pores

Front 27

How does taste work?

Back 27

1. Taste buds pick up taste and send it to taste cells.

2. Taste cells send taste to taste hairs.

3. Taste hairs contain receptors that initiate an action potential which is carried to parietal lobe. 4. Brain processes taste.

Front 28

Types of Tastes

Back 28

-Sweet

-Sour

-Salty

-Bitter

-Umami

-Certain taste buds are more sensitive to certain tastes.

-Taste is also linked to smell.

Front 29

Vision- Accessory Structures

Back 29

Eyebrow:

- protects from sweat

- shade from sun

Eyelid/Eyelashes:

- protects from foreign objects

- lubricates by blinking

Conjunctiva: thin membrane that covers inner surface of eyelid

Lacrimal apparatus: produces tears

Extrinsic eye muscles: help move eyeball

Front 30

Anatomy of Eye

Back 30

-Hollow, fluid filled sphere

-Composed of 3 layers (Tunics: Fibrous, Vascular, & Nervous Tunics)

-Divided into chambers

Front 31

Fibrous Tunic

Back 31

-Outermost layer

Sclera:

- firm, white outer part

- helps maintain eye shape, provides attachment sites, protects internal structures

Cornea:

- transparent structure that covers iris and pupil

- allows light to enter and focuses light

Front 32

Vascular Tunic

Back 32

-Middle layer

-Contains blood supply

Choroid:

- black part (melanin)

- delivers O2 and nutrients to retina

Ciliary body: helps hold lens in place

Suspensory ligaments: help hold lens in place

Lens:

- flexible disk

- focuses light onto retina

Iris:

- colored part -

- surrounds and regulates pupil

Pupil:

- regulates amount of light entering

lots of light = dilated

little light = constructed

Front 33

Nervous Tunic

Back 33

-Innermost tunic

Retina:

- covers posterior 5/6 of eye

- contains 2 layers

1. Pigmented retina:

- outer layer

- keeps light from reflecting back in eye ( dark/ black pigment makes it difficult for light to reflect back)

2. Sensory retina:

- contains photoreceptors (rods and cones)

- contains interneurons

Rods:

- photoreceptor sensitive to light

- 20 times more rods than cones

- can function in dim light

Cones:

- photoreceptor provide color vision

- 3 types blue, green, red

Front 34

Nervous Tunic

Back 34

Rhodopsin: photosensitive pigment in rod cells

Opsin: colorless protein in rhodopsin

Retinal:

- yellow pigment in rhodopsin

- requires vitamin A

Front 35

Effects of Light on Rhodopsin

Back 35

1. Light strikes rod cell

2. Retinal changes shape

3. Opsin changes shape

4. Retinal dissociates from opsin

5. Change rhodopsin shape stimulates response in rod cell which results in vision

6. Retinal detaches from opsin

7. ATP required to reattach retinal to opsin and return rhodopsin to original shape

Front 36

Retina Structures

Back 36

-Rods and cones synapse with bipolar cells of sensory retina

-Horizontal cells of retina modify output of rods and cones

-Bipolar and horizontal cells synapse with ganglion cells

-Ganglion cells axons’ converge to form optic nerve

Front 37

Fovea centralis

Macula

Back 37

Macula: small spot near center of retina

Fovea centralis:

- center of macula

- where light is focused when looking directly at an object

- only cones

- ability to discriminate fine images

Optic disk:

- white spot medial to macula

- blood vessels enter eye and spread over retina

- axons exit as optic nerve

- no photoreceptors

- called blindspot

Front 38

What are the three chambers of the eye?

Back 38

Anterior chamber:

- located between cornea and lens

- filled with aqueous humor (watery)

- aqueous humor helps maintain pressure, refracts light, and provide nutrients to inner surface of eye

Posterior chamber:

- located behind anterior chamber

- contains aqueous humor

Vitreous chamber:

- located in retina region

- filled with vitreous humor: jelly-like substance

-vitreous humor helps maintain pressure, holds lens and retina in place, refracts light

Front 39

Functions of Eye

Back 39

Light Refraction

- bending of light

Focal point

- point where light rays converge

- occurs anterior to retina

- object is inverted

Front 40

Focusing Images on Retina

Back 40

Accommodation:

- lens becomes less rounded and image can be focused on retina

- enables eye to focus on images closer than 20 feet

Front 41

Neuronal Pathway for Vision

Back 41

Optic nerve:

leaves eye and exits orbit through optic foramen to enter cranial cavity

Optic chiasm:

where 2 optic nerves connect

Optic tracts:

route of ganglion axons

Front 42

Eye Defects

Back 42

Myopia: - nearsightedness - image is in front of retina

Hyperopia: - farsightedness - image is behind retina

Presbyopia: - lens becomes less elastic - reading glasses required

Astigmatism: - irregular curvature of lens - glasses or contacts required to correct

Colorblindness: - absence or deficient cones - primarily in males

Glaucoma: - increased pressure in eye - can lead to blindness

Front 43

Hearing and Balance

Back 43

External (Outer) Ear - Extends from outside of head to eardrum

Auricle: fleshy part on outside

External auditory meatus: canal that leads to eardrum

Tympanic membrane: - eardrum - thin membrane that separates external and middle ear

Front 44

Middle Ear

Back 44

Air filled chamber (nothing but air)

Malleus (hammer): bone attached to tympanic membrane

Incus (anvil): bone that connects malleus to stapes

Stapes (stirrup): bone located at base of oval window

Oval window: separates middle and inner ear

Eustachian or auditory tube: - opens into pharynx - equalizes air pressure between outside air and middle ear

Front 45

Inner Ear

Back 45

Set of fluid filled chambers

Bony labyrinth:

- tunnels filled with fluid

- 3 regions: cochlea (perilymph and ends lymph), vestibule, semicircular canals

Membranous labyrinth:

- inside bony labyrinth

- filled with endolymph

Endolymph: clear fluid in membranous labyrinth

Perilymph: fluid between membranous and bony labyrinth

Cochlea:

- snail-shell shaped structure

- where hearing takes place

Front 46

Inner Ear

Back 46

Scala vestibuli:

- in cochlea

- filled with perilymph

Scala tympani:

- in cochlea

- filled with perilymph

Cochlea duct:

- in cochlea

- filled with endolymph

Front 47

Inner Ear

Back 47

Spiral organ: - in cochlear duct - contains hair cells

Tectorial membrane: - in cochlea - vibrates against hair cells

Hair cells: attached to sensory neurons that when bent produce an action potential

Front 48

Inner Ear

Back 48

Vestibular membrane: wall of membranous labyrinth that lines scala vestibuli

Basilar membrane: wall of membranous labyrinth that lines scala tympani (hair)

Front 49

How do we hear?

Back 49

1. Sound travels in waves through air and is funneled into ear by auricle.

2. Auricle through external auditory meatus to tympanic membrane.

3. Tympanic membrane vibrates and sound is amplified by malleus, incus, stapes which transmit sound to oval window.

4. Oval window produces waves in perilymph of cochlea.

5. Vibrations of perilymph cause vestibular membrane and endolymph to vibrate.

6. Endolymph cause displacement of basilar membrane.

7. Movement of basilar membrane is detected by hair hairs in spiral organ.

8. Hair cells become bent and cause action potential is created.

Front 50

Balance (Equilibrium)

Back 50

Static equilibrium: - associated with vestibule - evaluates position of head relative to gravity

Dynamic equilibrium: - associated with semicircular canals - evaluates changes in direction and rate of head movement

Front 51

Balance (Equilibrium)

Back 51

Vestibule: - inner ear - contains utricle and saccule

Maculae: - specialized patches of epithelium in utricle and saccule surround by endolymph - contain hair cells

Otoliths: - gelatinous substance that moves in response to gravity - attached to hair cell microvilli which initiate action potentials

Front 52

Balance (Equilibrium)

Back 52

Semicircular canals:

- dynamic equil.

- sense movement if any direction

Ampulla: base of semicircular canal

Crista ampullaris: in ampulla

Cupula:

- gelatinous mass

- contains microvilli

- float that is displaced by endolymph movement