Senses

Question 0

How is the eye able to move?

Answer 0

It contains extraocular muscles

Question 1

How does light energy pass to the optic nerve?

Answer 1

Via the cornea, past the lens and toward the fovea

Question 2

What is the job of photoreceptors?

Answer 2

Converge light energy and neural activity

Question 3

What types of photoreceptors are there?

Answer 3

Rod and cone cells

Question 4

What do rod cells detect?

Answer 4

They are achromatic, so detect changes to light intensity

Question 5

What do cones cells detect?

Answer 5

The are trichromatic, so allow colour vision

Question 6

What function do bipolar cells have?

Answer 6

They create a direct pathways from photoreceptors to ganglion cells

Question 7

What do retinal ganglion cells do?

Answer 7

They leave the eye and form the optic nerve

Question 8

How is retinal change caused by rhodopsin or iodopsin?

Answer 8

They absorb the photon in the disc membrane, changing the retinal schiff base cofactor, leading to retinal change

Question 9

What does retinal change cause?

Answer 9

A series of intermediates leading to a G protein activating transducin

Question 10

What effect does transducin have in the eye?

Answer 10

Activates cGMP phosphodiesterase, converting cGMP to 5’cGMP

Question 11

Photoreceptor Na+ channels close due to what change?

Answer 11

A net decrease in cGMP concentration

Question 12

Outer segments of the photoreceptors become hyper polarised due to what change?

Answer 12

The decreased Na+ inside the cell

Question 13

Outer photoreceptors hyper polarisation causes what?

Answer 13

Ca2+ VGIC to close, so intracellular Ca2+ concentrations fall

Question 14

Low levels of intracellular Ca2+ levels in photoreceptors causes what?

Answer 14

Less glutamate to be released by exocytosis to bipolar cells

Question 15

When rod and come cells are stimulated by light, what happens?

Answer 15

They produce less NT, which can stimulate or inhibit bipolar cells

Question 16

What is included in the retinofusal projection?

Answer 16

The optic nerve, optic chiasm and optic tract

Question 17

What is the visual field?

Answer 17

The entire region of space seen by both eyes looking straight ahead

Question 18

What do optic nerve fibres do in the optic chiasm?

Answer 18

Cross over to the opposite side

Question 19

What does a 2x2mm cortex contain?

Answer 19

2 ocular dominance columns, 16 blobs and 2 complete orientation columns

Question 20

What path does a sound wave take in the ear?

Answer 20

Down the auditory meatus, to the tympanic membrane where it enters the cochlea

Question 21

What happens to the pressure waves in the cochlea?

Answer 21

They’re turned into nerve signals

Question 22

The cochlea is made up of what 3 vesicles?

Answer 22

Scala media, scala vestibuli and scala tympani

Question 23

What are the sensory receptors in the ear?

Answer 23

The hair cells that lie in the scala media

Question 24

How does vibration cause transmission?

Answer 24

Causes the organ of corti to move, the tectorial membrane distorts, so the sterocilia are disturbed producing mechanoelectrical transduction

Question 25

Endolymph of the scala media contains high concentrations of what ion?

Answer 25

K+

Question 26

Stereocilia disturbance causes depolarisation which results in...?

Answer 26

VGIC for Ca2+ to open and the NT to be released

Question 27

Where in the brain is the auditory complex located?

Answer 27

On the superior temporal gyrus in the temporal lobe of the brain

Question 28

What are the 3 senses associated with the nose and mouth?

Answer 28

Olfactory, gustatory and trigeminal

Question 29

How do odourants enter the nasal cavity?

Answer 29

They dissolve in mucus, and bind to cilia that project into the nasal cavity

Question 30

How do the cilia then produce signals?

Answer 30

Their axons project into the olfactory bulb, and signals are sent to the pyriform cortex in the temporal lobe

Question 31

There is a less direct route of olfactory signalling, what does this involve?

Answer 31

The odourants bind to cilia, activate G proteins, produce cAMP, opening Ca2+ and Na+ channels, which leads to Cl- channels opening resulting in depolarisation

Question 32

What are taste sensitive structure called?

Answer 32

Papillae

Question 33

Explain the circumuallate papillae.

Answer 33

Largest with thousands of taste buds, located posteriorly

Question 34

What characterises foliage papillae?

Answer 34

Elongated structures with hundreds of taste buds, lying along the posterior lateral edge

Question 35

What are the taste sensitive structures at the tip of he tongue?

Answer 35

The fungiform papillae, which are the smallest with only a few taste buds

Question 36

From back to front of the tongue, name the taste sensations.

Answer 36

Bitter, sour, salty, sweet

Question 37

How is the taste transduction achieved?

Answer 37

Dissolved molecules interact with receptors, depolarisation, and action potential, increased intracellular Ca2+ and release of NT, exciting nerve fibres