NBSS: (neuroscience) Main sensory organs and their function

Question 1

what is sensory transduction and what does it contain

Answer 1

specialised cells (often neurons) that can convert information about external world into a signal that our brain can understand.

These are our sense organs:
eyes, ears, tongue and nose

Question 2

What are 5 types of sensory receptors?

Answer 2

• Thermoreceptors
• Painreceptors
• Mechanoreceptors
• Chemoreceptor
• Electromagnetic receptors

Question 3

How do chemoreceptors work for smell?

Answer 3

1. Odorants bind to receptors
2. Olfactory receptor cells are activated and send electrical signals.
3. The signals are relayed via converged axons.
4. The signals are transmitted to higher regions of the brain.

Question 4

How is vision mediated?

Answer 4

Mediated by electromagnetic receptors also known as photoreceptors.

Question 5

where are photoreceptors located, and what are the 2 types?

Answer 5

These are located in the retina - 2 types of photoreceptor: rods and cones.

Question 6

what are the differences between rods and cones?

Answer 6

DIFFERNCES:

• Rods are very sensitive and can be triggered by a single photon of light. So rods allow us to see in low light.
• Cones allow us to see colour but require much brighter light.

SIMILARITIES:

• Both rods and cones have outer segments with an array of membranous discs.

Question 7

What does the rod contain that has photosensitive pigments, what is this called?

Answer 7

The rod disc contains the critical photosensitive pigments, rhodopsin

Question 8

how is rhodopsin made?

Answer 8

made from a combination of opsin and retinol which comes from vitamin A.

Question 9

what does rhodopsin do?

Answer 9

absorb light photons in visual range leading to protein conformational change

Question 10

in the dark, are ion channels in rods open or closed?

Answer 10

open

Question 11

what pigment do cones contain?

Answer 11

photopsins

Question 12

what is the most common cause of Retinitis Pigmentosa?

Answer 12

rhodopsin gene mutations

Question 13

what is this blindness due to?

Answer 13

photoreceptor death - rods and cones

Question 14

what are mechanoreceptors used for?

Answer 14

hearing

Question 15

where are the mechanoreceptors converting sound energy into nerual signals located?

Answer 15

cochlea - inner ear

Question 16

what is the cochlea? what is the central one, running all the length of the cochlea called?

Answer 16

sprial tube with interior divided into 3 sections

the central one running all length of cochlea is called the organ of Corti

Question 17

where is the receptor hearing cells specifically found?

Answer 17

organ of Corti

Question 18

what are their receptor cells called in the organ of corti?

Answer 18

hair cells or stereocilia (hair-like part extended from surface)

Question 19

what do sound waves do?

Answer 19

make membrane that hair cells sit on vibrate, causes hairs/stereocilia to bend

Question 20

what does the bending of hairs/stereocilia do?

Answer 20

• opening of ion channels
• depolarisation of hair cell
• neurotransmitter released at synapse between hair cells and sensory neuron
• so action potentials get fired in sensory neuron

Question 21

what does hair cell damage/problems result in?

Answer 21

hearing loss/deafness

Question 22

what is the intensity of the stimulus reflected by?

Answer 22

amplitude of receptor potential

stronger stimulus = bigger receptor potential

Question 23

how can action potentials be described?

Answer 23

all or nothing - so have relatively fixed strength

Question 24

what does a bigger receptor potential mean?

Answer 24

more neurotransmitter release → higher rate of action potential firing

Question 25

what is it called when different types of receptor cells detect sweet/salty

Answer 25

labelled lines principle of coding

Question 26

how many different odorant receptor types do we have?

Answer 26

100-200

Question 27

how do we see colour?

Answer 27

cones with topsin pigment

Question 28

what are the 3 different types of photopsin?

Answer 28

blue, green and red - so we have blue, green and red cones

Question 29

how can we distinguish colour?

Answer 29

combinations of cones - blue, green and red

ie to see the colour orange, the red cones activated a lot and green a bit, to specific levels so combination of this tells brain it is orange

Question 30

what focuses image in visual field?

Answer 30

image of visual field focused onto retina by LENS

Question 31

what are lateral parts of hemifield called?

Answer 31

temporal

Question 32

what can the nasal part of hemifield be called?

Answer 32

medial

Question 32

where are images from temporal part of left visual field focused onto?

Answer 32

nasal/medial retina of left eye, and to some extent the right eye

Question 33

where are images in the nasal part of right hemifield focused onto?

Answer 33

temporal retina of left eye, and to some extend right eye

Question 34

frequency of sound wave is roughly equivalent to pitch of sound, what is this coded for by?

Answer 34

position along cochlea

Question 35

where is the highest frequency of sound heard?

Answer 35

Hair cells at the base of the cochlea will detect high frequency sounds, so there will be high pitched sounds. This gradually decreases as you go along the length of the cochlea to a lower frequency sounds and low pitch sounds.

This is a position code for hearing.