Special Senses - Lecture 2

Question 1

sensory signals are subject to extensive modification before they reach higher levels of the

Answer 1

Central nervous system

Question 2

what part of the brain plays an important rile in the control of afferent information?

Answer 2

cortex

Question 3

every cell in the CNS receives 10,000 to 40,000 synapses from other cells, some of them will be _______ and some of them will be _________

Answer 3

excitatory
inhibitory

Question 4

how do inhibitory inputs affect the response of a projection neuron to a stimulus

Answer 4

turns down or lowers the response

Question 5

T/F inhibition of painful stimulation can vary based on the situation. This is due to cortical control of sensory pathways

Answer 5

T

Question 6

all info from periphery travels to the somatosensory cortex via a

Answer 6

projection neuron

Question 7

the anterolateral system is a pathway that carries what information to where?

Answer 7

pain or hot/cold information to the somatosensory cortex

Question 8

the dorsal column system is a pathway which carries what information to where?

Answer 8

fine touch mechanoreception to the somatosensory cortex

Question 9

***see slides for mechanisms of anterolateral and dorsal systems

Question 10

Both the anterolateral and dorsal column pathways end in the somatosensory cortex on the _______ side of the body

Answer 10

contralateral

Question 11

which pathway crosses immediately and which one crosses at the level of the brainstem

Answer 11

anterolateral - immediately
dorsal column - brainstem

Question 12

all sensory information goes from the ______ to the ____________

Answer 12

thalamus
somatosensory cortex

Question 13

The smaller and more densely packed the sensory receptors are, the ______ the region in the somatosensory cortex that they will occupy

Answer 13

larger

Question 14

photoreceptors in the eye are _____ at rest and _______ when activated

Answer 14

depolarized
hyperpolarized

Question 15

the optical component (front part of the eye) is responsible for:

Answer 15

focusing the image on the receptor cells

Question 16

the neural component (back part of the eye) is responsible for:

Answer 16

transforming image into a pattern of graded potentials and AP’s

Question 17

the white part of the eye

Answer 17

sclera

Question 18

attached to the sclera; responsible for eye movements such as looking up, down or side to side

Answer 18

extraocular muscle

Question 19

where the sclera becomes clear at the very front; responsible for refracting light waves

Answer 19

cornea

Question 20

hole that allows light to pass through into back of the eye

Answer 20

pupil

Question 21

regulates the size of the pupil and the amount of light entering eyeball - colour of eye

Answer 21

iris

Question 22

parasympathetic innervation causes pupils to __________ while sympathetic innervation causes pupils to ___________

Answer 22

constrict
dialate

Question 23

is behind the iris and works the cornea to focus the image on the retina; shape and size can change

Answer 23

lens

Question 24

light passes through it and refracts a certain amount

Answer 24

cornea

Question 25

T/F the cornea is mobile and changes it's shape

Answer 25

False - it is static and stays in place

Question 26

attached to the lens and ciliary muscles

Answer 26

zonular fibers

Question 27

contact/relax to change the shape of the lens

Answer 27

ciliary muscles

Question 28

located behind the lens, against back of the eye and is where photoreceptors are found

Answer 28

retina

Question 29

what are the two types of photoreceptors, when are they activated and what type of vision are they responsible for

Answer 29

Rods: low light conditions, monochromatic Cones: more light present, colour vision

Question 30

cells activated by rods and cones; take info to brain

Answer 30

retinal ganglion cells

Question 31

leaves through the back of the eyeball towards the thalamus and cortex; made of axons and retinal ganglion cells

Answer 31

optical nerve

Question 32

a gelatinous fluid that fills the space b/w the lens and cornea

Answer 32

aqueous humour

Question 33

gelatinous fluid found behind lens

Answer 33

vitreous humor

Question 34

light waves bend once they hit they

Answer 34

cornea

Question 35

the cornea is primarily responsible for __________ and the ________ will change shape to focus the image on the ________ of the eye

Answer 35

refraction lens retina

Question 36

when an object comes very close to the eyes, what does the ciliary muscle do to focus the image on the back of the retina

Answer 36

contracts, causing the lens to get fatter and shorter; increasing the amount of refraction

Question 37

what is accommodation?

Answer 37

the process of using ciliary muscles in the lens in order to focus on objects that are very close

Question 38

loss of elasticity of the lens resulting in the inability to accommodate for near vision; due to the breakdown of the ciliary muscles; age-related

Answer 38

Presbyopia

Question 39

what is myopia or nearsightedness? when does it occur? what lens corrects it?

Answer 39

- focus on objects up close but not far away - occurs when the eyeball is too long and there is too much refraction; visual image is reconstructed at a point in front of the retina - concave lens

Question 40

what is hyperopia or farsightedness? when does it occur? what lens fixes it?

Answer 40

- see far but not close - eyeball is too short; not enough refraction and visual image is reconstructed behind retina - convex lens

Question 41

what is astigmatism

Answer 41

oblong shape of the eyeball

Question 42

glaucoma is

Answer 42

damage to the photoreceptors due to increased intraocular pressure

Question 43

cataracts are

Answer 43

clouding of the lens and is age-related

Question 44

what do bipolar cells do

Answer 44

take information from the photoreceptors and transfer to the retinal ganglion cells

Question 45

what are disks

Answer 45

- little flaps or layers of membrane in the outer segment of cones - site of actual processing of visual information

Question 46

synaptic terminals of cones make contact with

Answer 46

bipolar cells

Question 47

what enzyme converts GTP into cyclic GMP

Answer 47

guanylyl

Question 48

when no light is present, photoreceptors are relatively

Answer 48

depolarized

Question 49

**see document for phototransduction

Question 50

the disk of the cones contains a _______ which contains a chromophore called _____

Answer 50

photopigment retinal

Question 51

when light hits the photopigment what happens to the retinal? what molecule does this activate?

Answer 51

- changes conformation - cyclic GMP phosphodiesterase

Question 52

cyclic GMP phosphodiesterase is an _____ which breaks down _____

Answer 52

enzyme cGMP

Question 53

the photoreceptor is relatively ______ when light is polarized

Answer 53

hyperpolarized

Question 54

Activation of one single cone activates

Answer 54

two bipolar cells and two retinal ganglion cells

Question 55

at all times the photoreceptor is giving information via the ________ cell that says:

Answer 55

retinal ganglion yes light is hitting me or no it's not

Question 56

***see document for ON and OFF pathways

Question 57

the OFF bipolar cell is ______ by glutamate and the ON bipolar cell is _______ by glutamate

Answer 57

activated inhibited

Question 58

ON bipolar cell is inhibited by ______ being present

Answer 58

glutamate

Question 59

when light is present, the ON pathway is activated due

Answer 59

the release of inhibition on the ON bipolar cell by glutamate