Week 3- Body and Chemical Senses

Question 1

What is the force that brings us downwards

Answer 1

Gravity

Question 2

How many semicircular canals are there per side

Answer 2

3

Question 3

How are the three semicircular canals oriented?

Answer 3

At right angles to each other

Question 4

What are the three semicircular canals called

Answer 4

Posterior, anterior and lateral

Question 5

What are the other two little organs

Answer 5

The otoliths

Question 6

What are the two otoliths called?

Answer 6

Utricle and saccule

Question 7

What do the semicircular canals have in common with the otoliths

Answer 7

Each are filled with fluid which moves slightly as you change your orientation and a small patch of sensory hair cells which is what does the transduction

Question 8

What happens when you move around the world?

Answer 8

The fluid moves which displaces the hair cells and leads to sensory responses. Hair cells connected to neural units which then fire when they deflect and send their signals upwards in the system

Question 9

How many axes can the body move linearly along?

Answer 9

3- x, y and z

Question 10

How many planes can the body rotate within?

Answer 10

Frontal (roll- rotate around x axis), median (pitch- rotate around y axis), and transverse (yaw- rotate around z axis)

Question 11

Where does the z axis go?

Answer 11

Straight through your spine and out through your head

Question 12

Where does the y axis go?

Answer 12

Through each of ears and out other side

Question 13

Where does the x axis go?

Answer 13

Back of head out through nose

Question 14

How many possible ways can the body move in independent of the others?

Answer 14

6

Question 15

What is the bundle of hair cells projecting across the canal called?

Answer 15

Cupula

Question 16

Where is the cupula located?

Answer 16

In the ampula

Question 17

How is the utricle and the saccule different to the cupula?

Answer 17

Cupula is a little bundle of hair cells projecting across canal, utricle and saccule contain hair cells that are laid out like a carpet with all the hair cells sticking in the same direction.

Question 18

What is endolymph?

Answer 18

The fluid around the semi-circular canal within the cavity

Question 19

What does rotational acceleration cause?

Answer 19

Fluid movement relative to the canals, as the fluid ‘lags behing’ the head/canal due to inertia

Question 20

What causes neural firing

Answer 20

When the body moves, which moves the endolymph along the cavity, causing it to brush the cupula which causes the neurons to fire

Question 21

Essentially, what does the semi-circular canal sense?

Answer 21

Changes in rotation

Question 22

What is the specific stimulus for the otoliths?

Answer 22

A linear excelleration or a static tilt and change in orienation compared to being aligned with gravitational vertical

This is because its putting the same forces on your otoliths

Question 23

How are receptors arranged in the utricle?

Answer 23

Horizontal otolithic membrane

Question 24

How are receptors arranged in the saccule

Answer 24

Vertical membrane

Question 25

Why are receptors arranged differently for the utricle and saccule

Answer 25

Because between the 4 organs, they will respond to linear acceleration or tilt along any axis

Question 26

What is the jelly in the otoliths called

Answer 26

otholithic membrane

Question 27

Where do sensory nerve fibres from the hair cells project to in transduction?

Answer 27

The vestibular nuclei of the brainstems, then signals go 4 ways.

Question 28

What are the 4 routes from the vestibular sensory organ to the cortex

Answer 28

Vestibulo-cerebellar, thalamic, spinal and ocular

Question 29

What is Vestibulo- cerebellar

Answer 29

Some direct projections from vestibular organs to cerebellum, for movement feedback and posture

Question 30

What is Vestibulo-thalamic

Answer 30

Projects to cortex for balance perception

Question 31

What is Vestibulo-spinal?

Answer 31

Reflexive balance, including limb movements

Question 32

What is Vestibulo-ocular

Answer 32

Compensatory and stabilising eye movements - like blair witch project

Question 33

What is the oculogyral illusion

Answer 33

Spin round repeatedly, then stop. Illusory movement of the body and of stationary objects occurs. Due to inertia, fluid in the semicircular canals decelerates more slowly than the canals when spin stops. The resulting shear is in the opposite direction to that produced by the original rotation.

Question 34

What is the oculogravic illusion?

Answer 34

When the body undergoes linear acceleration, an illusory impression of body tilt occurs. Linear acceleration and static head tilt both trigger responses in the otoliths. Responsible for plane crashes during take-off from aircraft carriers.

Question 35

What body parts can humans smell their gender on?

Answer 35

Breath and hands

Question 36

If something is released into a gas, what is it called?

Answer 36

volatiles

Question 37

If the chemical compound smells, what are they called?

Answer 37

odourants. Mostly an organic compound/carbon chains

Question 38

What is a chemoreceptor?

Answer 38

An olfactory receptor cells

Question 39

Where are chemoreceptor found?

Answer 39

In the roof of the nasal cavity, in the olfactory epithelium

Question 40

Where are odorant recepters found?

Answer 40

On hairs protecting from receptor cells.

Question 41

How many olfactory receptors types are they and how often are they renewed

Answer 41

500-1000 different receptor types and renewed every 2 months

Question 42

Where do receptor cells project to?

Answer 42

Mitral cells

Question 43

Where do mitral cells live

Answer 43

In the olfactory bulb

Question 44

Where do receptor cells synapse

Answer 44

In spherical bundles called glomeruli

Question 45

What do glomeruli take?

Answer 45

Projections from 200 receptor cells of the same type

Question 46

How many mitral cells are they in the human olfactory bulb

Answer 46

50000

Question 47

What are free nerve endings responsible for?

Answer 47

sensations of coolness, tingling and burning

Question 48

What is selectivity

Answer 48

When receptors respond preferentially to a particular ordorant chemical . This receptor may respond at a lower rate to similar chemical e.g. ones with a slightly longer/shorter carbon chain.

Question 49

What is adaptation

Answer 49

When responses fall rapidly after ordorant exposure. At the same time your perception of the intensity of the smell decreases. Detection of the molecule becomes more difficult.

Question 50

After the olfactory receptors are released, where do they go?

Answer 50

Into the Olfactory Bulb

Question 51

Where do all senses besides Olfactory go for a relay station?

Answer 51

The Thalamus. Signals go there before they go anywhere else.

Question 52

What sense do the mitral cell axons go straight to the primary .... cortex?

Answer 52

Olfactory

Question 53

Why is there a strong emotional impact of smell?

Answer 53

Because of the direct connection of the Primary olfactory cortex and the amydala

Question 54

How many odours can humans recognise

Answer 54

10000

Question 55

How is it possible that humans can smell 10000 odours when they only have 500-1000 different receptor types

Answer 55

Population coding- Stimulus information is encoded not simply by which cell is firing most, but by the pattern of firing throughout the entire neural array. Each olfactory mixture is represented by a different pattern of activity across receptors/mitral cells

Question 56

What is the difference between analysis and synthesis?

Answer 56

Analysis is the process of breaking down into separate components. Synthesis The combination of components forms a new perceptual whole that cant be broken down.

Question 57

What happens when smells are repeatedly presented together

Answer 57

They acquire properties of each other

Question 58

Why was gustation evolved?

Answer 58

To determine what is nutritious food and to avoid poisoning

Question 59

What is chemicals for gustation?

Answer 59

Molecules dissolve in saliva and bind with receptors

Question 60

Where are chemoreceptors found in gustation?

Answer 60

On the tips of microvilli projecting from the end of taste receptor cells

Question 61

How many receptor cells is in a taste bud?

Answer 61

50-150

Question 62

How many taste buds do we have

Answer 62

5000-10000

Question 63

How long do taste receptor cells last?

Answer 63

10 days

Question 64

What are the four categories found for selectivity?

Answer 64

Sugars, salts, acids, plant alkaloids (bitter)

Question 65

What is cross fibre theory

Answer 65

Taste signalled by overall pattern of firing over all 4 channels

Question 66

Where do gustatory nerve axons terminate

Answer 66

In the brainstem.

Question 67

where do projections from the brainstem in gustation go

Answer 67

Travel to the cortex via the thalamus, and to the amgydala

Question 68

What is the insula cortex?

Answer 68

The primary gustatory cortex

Question 69

Where does the insula cortex project to?

Answer 69

The orbitofrontal cortex

Question 70

How does adaptation affect taste

Answer 70

Reduces intensity

Question 71

What is cross adaptation

Answer 71

A sweet taste causes water to taste sour and a sour taste causes water to taste sweet and reduces the intensity of some bitter tastes

Question 72

What is the difference between flavour and taste

Answer 72

Flavour is a multi-sensory taste. It is gustatory, olfactory and texture etc.

Question 73

Where is flavour processed?

Answer 73

Orbitofrontal cortex