exam #2: chapter 10

Question 1

three common steps associated with any sense

Answer 1

-a physical stimulus
-sensory transduction (input)
-formulation of “perception”

Question 2

6 sensory systems

Answer 2

-somatosensory (touch, proprioception, temperature, pain)
-visual
-auditory
-vestibular (balance)
-olfactory (smell)
-gustatory (taste)

Question 3

four basic types of information conveyed by each sensory system

Answer 3

-modality of stimulus (waves)
-intensity of stimulus (volume)
-time course of stimulus (duration)
-location of stimulus

Question 4

sensory cells
-what types?

Answer 4

-some are neurons themselves
-most are specialized epithelial cells that synapse on adjacent sensory neurons

Question 5

four functional class of sensory receptors

Answer 5

-mechanoreceptors
-chemoreceptors
-thermoreceptors
-photoreceptors

Question 6

sensory receptors at the protein level
-two types

Answer 6

-channels (physically gated)
-GPCR

Question 7

mechanoreceptors
-stimuli
-location

Answer 7

-pressure, movement
-skin, muscles, ears

Question 8

photoreceptors
-stimuli
-location

Answer 8

-light
-eyes

Question 9

chemoreceptors
-stimuli
-location

Answer 9

-chemicals
-nose, mouth

Question 10

thermoreceptors
-stimuli
-location

Answer 10

-temperature
-skin

Question 11

nocireceptors
-stimuli
-location

Answer 11

-pain
-skin

Question 12

modalities: the five senses
other somatic senses?
other sense?

Answer 12

taste, touch (somatic sense), smell, sight, sound
pain, temperature, itch, proprioception
sense of balance

Question 13

sensory receptors
-are they specific or non-specific?
-transduce the external stimulus into what?

Answer 13

-each sensory receptor responds to a particular modality
-changes in membrane potential

Question 14

how is stimulus intensity encoded in sensory neuron?

Answer 14

by action potential frequency

Question 15

when intensity of a stimulus increases

Answer 15

amplitude/frequency increases = action potential firing increases

Question 16

generator proteins
-produced in?
-what kind of receptor?

Answer 16

-produced in specialized dendritic processes of primary sensory neuron
-sensory receptor

Question 17

receptor potentials
-produced in
-what kind of receptor?
-communicated to?

Answer 17

-produced in specialized epithelial cells
-sensory receptor
-communicated to associated primary sensory neuron

Question 18

sensory adaptation/duration
-two types of receptors
-how do sensory systems work?

Answer 18

duration of sensory is in part encoded by adaptation of receptors
-phasic receptors (most) = fast-adapting
-tonic receptors (constant event) = slow-adapting
-sensory systems detect contrast

Question 19

receptive field
-comprised of what?

Answer 19

receptive field of a sensory neuron encodes the location of the stimulus
-a center and a surround

Question 20

activity of cortical neuron:
-increase frequency
-decrease frequency
-steady frequency

Answer 20

-increase: apply pressure to center, but not to surround
-decrease: apply pressure in surround, but not in center
-steady: tonic firing rate

Question 21

somatosensory receptor types: cutaneous (skin) receptors

Answer 21

-touch/pressure (mechano)
-hot/cold (thermo)
-nociceptors (pain)

Question 22

somatosensory receptor types: proprioceptors

Answer 22

-muscle spindles
-golgi tendon organs
-joint receptors

Question 23

cutaneous receptors: types of touch receptors

Answer 23

-free nerve endings
-merkels’s discs*
-ruffini corpuscles (endings)**
-meissner’s corpuscles*
-pacinian corpuscles**
*superficial in skin
**deeper in skin

Question 24

four attributes of touch
-modality
-location
-intensity and time course

Answer 24

-superficial or deep in skin
-focused or larger receptive field
-frequency and amplitude of stimulus

Question 25

8 parts of the eye

Answer 25

cornea iris pupil lens retina fovea optic nerve virtuous humor

Question 26

left eye: left visual field v.s right visual field

Answer 26

left: crosses over right: stays ipsilateral

Question 27

right eye: left visual field v.s right visual field

Answer 27

left: stays ipsilateral right: crosses over

Question 28

where is the point of crossover in the eye?

Answer 28

optic chiasma

Question 29

optic info goes from ____ to _____

Answer 29

thalamus ; occipital lobe

Question 30

rods v.s cones -what kind of light? -greater what? -what are the light receptors?

Answer 30

rods: dim light, greater sensitivity to light, and rhodopsin is light receptor cones: color vision (bright light), greater visual acuity (sharp image), photopsins are light receptors

Question 31

retina v.s fovea v.s optic nerve

Answer 31

retina: where light rays are projected fovea: center of retina/field of vision, cones here optic nerve: sensory, cranial nerve that carries info from retina to CNS

Question 32

cornea v.s pupil

Answer 32

cornea: light hits here first pupil: light goes through here after

Question 33

optic disk

Answer 33

blind spot because no photoreceptors here

Question 34

autonomic control of pupil diameter: sympathetic v.s parasympathetic -which muscles are stimulated via which receptors -excitatory or inhibitory?

Answer 34

s: radial muscles stimulated via a1-adrenergic receptors p: circular muscles stimulated via muscarinic receptors -both excitatory/both muscles contract

Question 35

photoreceptor cells (PCRs) of the retina transduce what?

Answer 35

electromagnetic energy in the form of photons

Question 36

vertical pathway within the retina

Answer 36

PRCs --> bipolar cells --> ganglion cells (optic nerve)

Question 37

anatomy of the retina -what kind of epithelium? -where are PRCs (rods/cones)? -bipolar cells do what? -ganglion cells do what? -interneurons do what?

Answer 37

-pigmented epithelium -PRCs sit at the back of the retina -bipolar cells receive input from PRCs -ganglion cells receive input from bipolar cells -interneurons mediate lateral information flow

Question 38

how cells communicate in the retina: two pathways

Answer 38

-vertical pathway of info flow (PRCs to bipolar cells to ganglion cells) -horizontal pathway of info flow

Question 39

visual transduction in the retina -controlled by what? -photocreptors are what what kind of receptors? -photopigment is what? -G-protein is what?

Answer 39

-rods and cones -GPCRs -retinal -transducin

Question 40

"dark current" -PRCs in light v.s dark -dark Vr -light Vm

Answer 40

-hyperpolarized in light and depolarized in dark -Vr=-40 mV -Vm down to ~ -65 mV

Question 41

phototransduction in a rod (7 steps) -gamma (photon) activates _____ -_____ activates Gt (transducin) -__ (__) activates cGMP-dependent phosphodiesterase (PDE) -PDE increases or decreases [cGMP]I -increases or decreased [cGMP]i closes __ channels -decreased ___ influx ___ the rod cell -___ means decreased __ release at PRC/BPC synapse

Answer 41

-gamma (photon) activates rhodopsin -rhodopsin activates Gt (transducin) -Ga (GTP) activates cGMP-dependent phosphodiesterase (PDE) -PDE decreases [cGMP]i -decreased [cGMP]i closes Na+ channels -decreased Na+ influx hyperpolarizes the rod cell -hyperpolarization means decreased NT release at PRC/BPC synapse

Question 42

NT released by rod cell -excitatory or inhibitory?

Answer 42

glutamate -acts as inhibitory because of nature of bipolar cells

Question 43

rods: rhodopsin, 1 type cones: photopsin, 3 types

Answer 43

rods: absorbs blue/green cones: S cones (blue), M cones (green), L cones (red)

Question 44

convergence in rods v.s cones in fovea

Answer 44

rods experience convergence and cones in fovea experience no convergence

Question 45

information flow in receptive fields (5 steps)

Answer 45

PRCs --> BPCs --> ganglion cells --> thalamic neurons (LGN) --> cortical neurons

Question 46

ganglion cell receptive fields detect what? -"on center" GCs stimulated by? -"off center" GCs stimulated by?

Answer 46

contrast -"on center" are most stimulated by central illumination and darkness in the surround -"off center" are most stimulated by surround illumination and darkness in the center