Sensory Transduction

Question 1

how do we hear - brief overview

Answer 1

sound > vibration of air > vibrate the eardrum, the malleus, the incus, the stapes > vibration spreads to cochlea > vibration of air is converted to movement/vibration of fluids in the cochlea > vibration in the cochlea is captured by hair cells > transduction > perceived in the auditory cortex

Question 2

what is transduction

Answer 2

physical vibration is transduced to neural energy

Question 3

what makes up the middle ear

Answer 3

malleus
incus
stapes

Question 4

what does the stapes connect to

Answer 4

the oval window of the cochlea

Question 5

what does the inner ear contain

Answer 5

cochlea - part of auditory system

labyrinth - part of vestibular system

Question 6

what are the 3 fluid filled cavities of the cochlea

Answer 6

scala vestibuli
scala media
scala tympani

Question 7

what separates the cavities of the cochlea

Answer 7

Reissner’s membrane separates s.v. from s.m

Basilar membrane separates s.m. from s.t

Question 8

what plays a role in the cochlea in transduction

Answer 8

organ of Corti hair cells, basilar membrane to tectorial membrane

Question 9

where do the s.t. and s.v meet

Answer 9

helicotrema

Question 10

what does the s.t. and s.v. connect with respectively

Answer 10

s. t. = oval window

s. v. = round window

Question 11

what fluid is present in the cavities

Answer 11

endolymph - scala media

perilymph - scala vestibuli and typmani (continous with the two cavities)

Question 12

what do the hair cells do in the ear

Answer 12

auditory receptors with sterocilia

synapse on bipolar neurons with cell body in the spiral ganglion

Question 13

where are the hair cells located

Answer 13

between basilar membrane and reticular lamina

Question 14

how do the hair cells contribute to transduction

Answer 14

• tectorial membrane vibrates
• hair cells’ cilia bend
• depending on how they bend, the hair cells release neurotransmitter
• the neurotransmitters released in the hair cell are captured in nerve fibers.
• neural energy sent to the brain

Question 15

what is odd about hair cell cell channels

Answer 15

K+ current is inwards due to endolymph

Question 16

what is the function of the vestibular system

Answer 16

Provides information concerning gravity, rotation and acceleration

allows for:

• gaze & postural stability
• sense of orientation
• detection of linear & angular acceleration

Question 17

how does the vestibular system work

Answer 17

Head angular acceleration (semicircular canals)
- Head rotation.

Head linear acceleration (saccule and utricle)

• Translational motion.
• Gravity (and by extension head tilt).

Question 18

what does the movement of cells towards and away the crystals cause

Answer 18

towards = depolarisation

away = hyperpolarisation

Question 19

what is the structure of the semicircular canals

Answer 19

3 fluid-filled canals, right angles to each other

1 for each major plane

Question 20

what fluid is in the semicircular canals

Answer 20

endolymph

Question 21

what are the otolith organs

Answer 21

saccule and utricle

Question 22

what are the 3 major vestibular reflexes

Answer 22

Vestibulo-ocular reflex
Vestibulo-colic reflex
Vestibular-spinal reflex

Question 23

what does the vestibulo-ocular reflex do

Answer 23

keep the eyes still in space when the head moves.

Question 24

what does the Vestibulo-colic reflex do

Answer 24

keeps the head still in space – or on a level plane when you walk.

Question 25

what does Vestibular-spinal reflex do

Answer 25

adjusts posture for rapid changes in position.

Question 26

what is the cupula and where is it located

Answer 26

structure in the vestibular system, providing sense of spatial orientation

located within the ampullae of each of the three semicircular canals

Question 27

what is the overview of how vision works

Answer 27

1 - pattern of the object must fall on the vision receptors (rods and cones in the retina)&raquo_space; accommodation
2 - amount of light entering the eye must be regulated
3 - energy from the waves of photons must be transduced into electrical signals
4 - brain must receive and interpret the signals

Question 28

direct pathway for signal transmission

Answer 28

photoreceptors&raquo_space; bipolar cells&raquo_space; ganglion cells

Question 29

what is the function of photoreceptors

Answer 29

Converts electromagnetic radiation to neural signals

Question 30

what are the 2 types of photoreceptors

Answer 30

rods and cones

Question 31

what are the 4 main regions of a photoreceptor

Answer 31

Outer segment
Inner segment
Cell body
Synaptic terminal

Question 32

what is the basis for phototransduction

Answer 32

1 - Vertebrate Photoreceptors have a depolarized rmp
2 - With light exposure, Vm hyperpolarizes
3 - A cGMP-gated Na+ channel that is open in the dark and closes in the light
4 - change in Na+ with light is the signal that enables the brain to perceive objects in the visual field

Question 33

when is the dark-current channel open and closed

Answer 33

opens in the dark

closes in the light

Question 34

what opens the dark-current

Answer 34

cGMP

Question 35

what vitamin is needed for sight

Answer 35

vitamin A

Question 36

why is the dark-current channel important

Answer 36

Keeps photoreceptor Vm more positive than most neurons

→ Steady release of neurotransmitter

Question 37

what do rods and cones see

Answer 37

Rods – seeing in dim light

Cones – seeing in normal daylight

Question 38

what are features of rods

Answer 38

achromatic
peripheral retina
high convergence
high light sensitivity
low visual acuity

Question 39

what are features of cones

Answer 39

chromatic
central retina (fovea)
low convergence
low light sensitivity
high visual acuity

Question 40

what is the function of horizontal cells

Answer 40

Receive input from photoreceptors and project to other photoreceptors and bipolar cells

Question 41

what is the function of amacrine cells

Answer 41

Receive input from bipolar cells and project to ganglion cells, bipolar cells, and other amacrine cells