Special Senses I: Lecture 23

Question 1

transduction

Answer 1

physical or chemical stimulus converted into action potential that can be interpreted by brain

Question 2

pathway of sensory signals

Answer 2

first processed by sensory nuclei and transmitted to thalamus and primary cortex areas for awareness and identification

Question 3

special senses

Answer 3

convey specific stimuli from specialized sensory organs in discrete locations of head
smell, taste, vision, hearing, and vestibular sensation

Question 4

eyebrows

Answer 4

overlie the supraorbital margins of the skull; shade eye and prevent perspiration from reaching the eyes

Question 5

eyelids/palpebrae

Answer 5

separated by palpebral fissure (eyelid slit); meet at medial and lateral commissures

Question 6

lacrimal caruncle

Answer 6

at medial commissure, sebaceous and sweat glands produce oily secretion

Question 7

epicanthic fold

Answer 7

vertical fold of skin that appears lateral to nose (more common in those of Asian descent)

Question 8

tarsal plates

Answer 8

connective tissue sheets that support the eyelids; anchor to the orbicularis oculi and levator palpebrae superioris

Question 9

eye lashes

Answer 9

innervated hairs at rim of eyelid; reflex blinking

Question 10

tarsal glands

Answer 10

modified sebaceous glands embedded in the tarsal plates that prevent lids from sticking

Question 11

conjunctiva

Answer 11

transparent mucous membrane that lines the eyelids, lubricates eye; folds over the anterior surface of the eyeball

Question 12

lacrimal gland

Answer 12

medial portion of the eye that produces lacrimal secretions/tears

Question 13

lacrimal sac

Answer 13

drains the canaliculi into the nasolacrimal duct

Question 14

rectus muscles

Answer 14

superior, inferior, lateral, medial

Question 15

oblique muscles

Answer 15

move the eye vertically when eye is turned; superior and inferior

Question 16

lateral rectus innervation

Answer 16

abducens

Question 17

superior oblique innervation

Answer 17

trochlear

Question 18

oculomotor nerve

Answer 18

innervates all other eye muscles

Question 19

eye motor units

Answer 19

8-12 muscle fibers; highly precise

Question 20

fibrous layer

Answer 20

dense avascular CT; sclera and cornea

Question 21

sclera

Answer 21

toughened white portion of the eye; continuous with the dura mater of the brain

Question 22

cornea

Answer 22

transparent layer that allows light into the eye; no direct vascularization

Question 23

vascular layer

Answer 23

pupillary sphincter and dilator muscles, choroid, ciliary body, iris

Question 24

pupillary sphincter

Answer 24

contracts during parasympathetic stimulation; reduces size of pupil and restricts amount of light

Question 25

pupillary dilator

Answer 25

contracts during sympathetic activation; allows pupil to increase in size, more light enters eyeball

Question 26

choroid

Answer 26

heavily vascularized and pigmented layer; vessels supply the rest of eye

Question 27

cilliary body

Answer 27

encircles the lens; smooth muscles encircle the lens and control shape; holds lens in upright position

Question 28

iris

Answer 28

colored portion of the eye

Question 29

pupil

Answer 29

opening that allows light to enter

Question 30

neural layer

Answer 30

photoreceptor cells, macula lutea, optic disc

Question 31

photoreceptor cells

Answer 31

detect and transduce light stimuli into electrical signals; rods and cones

Question 32

macula lutea

Answer 32

yellowish central region of fovea; contains large number of photoreceptors fovea centralis allows for detailed vision and ability to focus

Question 33

optic disc

Answer 33

location where axons of optic nerve exit from retina; does not contain photoreceptors- blind spot

Question 34

anterior segment

Answer 34

filled with aqueous humor, supplies nutrients and oxygen; anterior and posterior chamber

Question 35

posterior segment

Answer 35

filled with vitreous humor; supports lens and holds neuronal layer contributes to interocular pressure

Question 36

lens

Answer 36

biconvex, transparent, flexible layer

Question 37

retina

Answer 37

develops from extension of the brain; contains millions of photoreceptors

Question 38

rods

Answer 38

dim-light and peripheral vision photoreceptors

Question 39

cones

Answer 39

bright light and high-resolution vision photoreceptors

Question 40

eye neurons

Answer 40

photoreceptors, bipolar cells, ganglion cells

Question 41

emmetropic state

Answer 41

eye is relaxed and focusing on distant objects; lens in in normal flattened shape

Question 42

accommodation

Answer 42

lens becomes more thickened, refracts light more than flattened lens so more light rays are focused on retina

Question 43

near point of accommodation

Answer 43

closest point at which eye can focus on an object; increases with age as lens becomes less flexible

Question 44

presbyopia

Answer 44

individual's near point of accommodation is 10-20 inches or great (usually in their 5th decade)

Question 45

hyperopia

Answer 45

farsightedness; eyeball is too short or cornea is too flat corrected with convex lenses

Question 46

myopia

Answer 46

nearsightedness; distance between cornea and lens is too great or cornea is too curved corrected with concave lenses

Question 47

astigmatism

Answer 47

curvature of lens or cornea is irregular; light rays are not evenly refracted

Question 48

vision information processing

Answer 48

light is converted to a graded potential, light transduction reactions, generate graded potentials

Question 49

light adaptation

Answer 49

rod system turns off, cones rapidly adapt- desensitized to bright light

Question 50

dark adaptation

Answer 50

cones stop functioning; rhodopsin accumulates

Question 51

visual pathway to brain

Answer 51

retinal ganglion exit in the optic nerve cross over that the optic chiasm, continue on to the hypothalamus sent to thalamus and midbrain, signal condensed for further processing in prefrontal cortex