Sensory System

Question 1

Does pressure activate an ionotropic or metabotropic receptor?

Answer 1

ionotropic

Question 2

does taste/smell activate an ionotropic or metabotropic receptor?

Answer 2

metabotropic

Question 3

does light/vision activate an ionotropic or metabotropic receptor

Answer 3

metabotropic

Question 4

what is a receptor potential

Answer 4

a change in mem pot of a sensory cell in response to a stimulus

Question 5

function of merkel discs

Answer 5

at surface, adapt slowly, provides cont info

Question 6

function of meissner’s corpuscles

Answer 6

at surface, very sensitive and adapt rapidly

Question 7

function of Ruffini corpuscles

Answer 7

deeper, adapt slowly, sense low freq vibrations

Question 8

function of pacinian corpuscles

Answer 8

deeper, adapt quickly and sense high freq vibrations

Question 9

where are hair cells in the ear found and what is their function

Answer 9

cochlea; respond to vibration induced by sound

Question 10

function of rhodopsin

Answer 10

• highly conserved among animals and some plants
• a family of photo receptors
• composed of retinal pigment bound to opsin protein (a 7 transmembrane domain protein)
  - opsin is sim to GPCR, but ligand is the conformational change of retinal in light

Question 11

detail conformational change of retinal

Answer 11

light induces retinal to change from 11-cis to All-trans form which induces a change in conformation of opsin
photo-excited rhodopsin triggers cascade that changes membrane pot of photoreceptor cells

Question 12

function of ommatidium

Answer 12

• optical units found in compound eyes of invertebrates
• each has a lens that directs light onto photoreceptor cells called retinula cells
• retinula cells contain rhodopsin and their axons comm. w/ nervous system
• the smaller, the better the resolution

Question 13

functions of rods

Answer 13

• in vertebrates
• modified neuron w/ outer segment, inner segment, and synaptic terminal
  
  • inner segment: nucleus & mito
  • outer segment: photoreception in membrane-bound discs packed w/ rhodopsin
• hyperpolarizes in light
• depolarizes in dark
• more sensitive to low intensities of light–> high sensitivity B&W vision

Question 14

detail how vision works in vertebrates?

Answer 14

in dark, rod cells are depolarized to steady state (~-35mv)
when rhodopsin absorbs light, it gets photoexcited and activates a G protin called TRANSDUCIN
when transducin is active, cGMP phoshphodiesterase is active so cGMP–> GMP
in dark, cGMP keeps Na+ open, and in light, less cGMP = closed Na+ -> rod cell now hyperpolarized

Question 15

which cell are the input and output to bipolar cells in the retina?

Answer 15

input from photoreceptor cells, output to ganglion cells

Question 16

What do the depolarized photoreceptors release as a NT to the bipolar cells in the dark

Answer 16

glutamate

Question 17

What happens to glutamate when there is light?

Answer 17

PR hyperpolarize and stop releasing NT

Question 18

What happens to glutamate in the dark once released from PR cells?

Answer 18

some bipolar cells have metabotropic receptors that open Cl- channels–> Cl- enters so hyperpolarized

Question 19

What happens in the light when glutamate is not released?

Answer 19

Cl- remain closed, depolarized bipolar cell to threshold, and fires AP to ganglion cells which fires another AP to optic nerve to brain

Question 20

T/F: depolarization of PR cells release bipolar cells from inhibition

Answer 20

F: hyperpolarization

Question 21

What happens to the shape of the lens as it is looking at an object close vs far away

Answer 21

close: lens round out
far: lens stretches out

Question 22

what is the most sensitive area for resolution and has the highest density of PR?

Answer 22

fovea

Question 23

what causes poor vision

Answer 23

change in eyeball shape that puts focal length outside the range the lens is able to focus

Question 24

what is presbyopia

Answer 24

lens becoming less elastic w age–> reading glasses

Question 25

what is presbyopia

Answer 25

lens being less elastic with age–> reading glasses

Question 26

function of cones

Answer 26

respond to diff wavelengths of light for color vision...provide sharpest vision
many in fovea
-3 kinds
     1) absorbs violet & blue
     2) absorbs green
     3) absorbs red and yellow

Question 27

T/F: fovea has only cone cells

Answer 27

T

Question 28

What are the 3 kinds of cone cells?

Answer 28

red, green, blue