special sences

Question 1

What type of receptors do olfactory cells have?

Answer 1

Chemoreceptors

Question 2

Where are Olfactory (Chemoreceptors) located?

Answer 2

In the nasal Epithelium lining the nasal cavity.

The cell bodies of the olfactory cells lye between supporting cells of the epithelium.

Question 3

In order to stimulate olfactory cells for us to smell something the substance must be two things. What are they?

Answer 3

converted to a gaseous state and

water soluble

Question 4

Axons leaving the olfactory cells penetrate the… what?

Answer 4

cribriform plate (ethmoid bone)

Question 5

The fibers from the olfactory nerve travel to the brain via which cranial nerve?

Answer 5

Cranial nerve I

Question 6

sensations of smell are experienced when impulses reach the…… in the temporal lobe.

Answer 6

olfactory cortex

Question 7

The sense of taste is called what?

Answer 7

gustation

Question 8

What cells are responsible for taste and where are they located?

Answer 8

Gustatory epithelial cells.

Located in taste buds mainly on the surface of the tongue in projections called lingial papillae.

Question 9

Gustatory cells have fine projections called what that function as the actual taste receptors?

Answer 9

Microivilli

Question 10

What are the three different types of lingual papillae, where are they located and how many taste buds to they have?

Answer 10

- Filiform papillae
    provide friction
    do not contain taste buds
    located to the back on the sides 
- Fungiform papillae 
    contain 5 taste buds each
    located on the front
- Circumvallate papillae 
    contain 100 taste buds each
    located towards the back

Question 11

There are 4 primary taste sensations. What are they and what are they stimulated by?

Answer 11

sweet - stimulated by sugars, saccharin
sour - stimulated by H+ (acids)
salt - stimulated by metallic salts, eg. Na+, K+
bitter - stimulated by alkaloids, e.g. quinine,
nicotine, morphine

Question 12

In which regions of the tongue are the 4 primary taste sensations detected?

Answer 12

tip - sweet, salty
sides - sour
back - bitter

Question 13

There are two additional taste sensations other than sweet, sour, bitter and salty. What are they?

Answer 13

Umami - amino acids, small peptides and nucleotides.

Water - water receptors in pharynx

Question 14

Impulses from taste receptors travel into the medulla in a number of cranial nerves. What are the two primary ones?

Answer 14

Cranial Nerve VII - Facial

Cranial Nerve IX - Glossopharyngeal

Question 15

Trace the pathway of light through the eye and to the visual cortex

Answer 15

cornea –> Anterior segment (aqueous humor) –> Pupil –> Lens –> Posterior segment (vitreous humor) –> Retina (rods and cones) –> Optic nerve –> optic chiasma –> optic tract –> Primary visual cortex

Question 16

Which structures of the eye bend (refract) light rays?

Answer 16

• Anterior segment
• Cornea
• Posterior segment
• Lens

Question 17

You have been reading your text book for a while and your eyes are beginning to tire. What changes occur within your eyes as you stare thoughtfully into the distance and what division of the nervous system controls these changes?

Answer 17

Close vision - ciliary muscles contract causing the lens to bulge
Parasympathetic dilates pupils

Far vision - ciliary muscles relax flattening lens
Sympathetic constricts pupils

Question 18

You are watching the gorillas and your friends taps you on the shoulder to ask a question. As you turn to look at your friend what changes would your eyes undergo and what division of the nervous system controls these changes?

Answer 18

• Increased refraction
• Eyeballs converge
• Ciliary muscles contract causing the lens to bulge
• Pupils constrict
• Controlled by the Parasympathetic

Question 19

Trace the pathway of sound through the ear

Answer 19

external acoustic meatus –> Tympanic membrane –> Malleus, Incus and Stapes –> Oval window –> Round window –> cochlear –> basilar membrane –> spiral organ –> hair cells –> cochlear nerve –> Auditory cortex

Question 20

Explain how sound is transmitted through the ear to the auditory cortex of the brain

Answer 20

1- sound waves entering the ear arrive at the tympanic membrane.
2- movement of the tympanic membrane causes the auditory ossicles to move. Sound is transmitted and amplified to the oval window
3- Movement of the stapes against the oval window creates pressure waves within the perilymph of the vestibular duct.
4- Pressure waves distort the basilar membrane of the cochlear duct as they move from the oval window to the round window.
5- Vibration of the basilar membrane pushes the hairs of receptor cells against the overlying factorial membrane. This bends the hairs and stimulates the receptor cells.
6- Once stimulated, the receptor cells transmit impulses along the cochlear nerve to the auditory cortex for interpretation.

Question 21

What mechanisms does the body have of maintaining balance and equilibrium?

Answer 21

Saccule and utricle - linear movements - jelly with otoliths
Semicircular canals - dynamic movement - fluid with hair cells

Question 22

What muscles control which eye movements?

Answer 22

Lateral rectus - Moves eye laterally
Medial rectus - Moves eye medially
Superior rectus - Elevates eye and turns it medially
Inferior rectus - Depresses eye and turns it medially
Inferior oblique - Elevates eye and turns it laterally
Superior oblique - Depresses eye and turns it laterally

Question 23

Which nerve id the most important in relation to eye movement?

Answer 23

III (oculomotor)

Question 24

What are the two types of receptors of the retina and what do they detect?

Answer 24

Rods - receptors for dim light

Cones - receptors for bright light, colour and visual acuity (blue, green and red cones)

Question 25

Light rays passing from one transparent medium to another change direction according to the density of the substance. This is called refraction. The pathway of light in the eye involves four such changes of medium. What are they?

Answer 25

air to cornea cornea to aqueous fluid in anterior cavity aqueous fluid to lens (controlled by iris) lens to vitreous body in posterior eye cavity

Question 26

Objects that are nearer than 6 m give rise to light rays that are on divergent paths. These require greater refraction to bring them into focus at the fovea, hence the lens (the only adjustable component) is thickened to provide the extra refraction = accommodation. This is achieved through contraction of which muscles?

Answer 26

ciliary muscles (attached to the lens via ciliary zonule)

Question 27

What is the name of the two types of fluid in the eye and in which areas are they located?

Answer 27

Aqueous Humor- Anterior segment | Vitreous Humor- Posterior Segment

Question 28

What colour in perceived if all (blue, red and green) cones are stimulated

Answer 28

white

Question 29

What is rhodopsin and what does it do?

Answer 29

h

Question 30

When moving from a bright to a dark area, some time must be allowed for adaptation of the eye. Why is this? What is happening?

Answer 30

Light promotes the breakdown of rhodopsin causing depolarisation.
Rhodopsin is then regenerated from its components, preparing the rod for its next stimulus.
In bright light, the rhodopsin in rods is largely broken down.
Moving from light to dark take time to adjust because time is required for rhodopsin regenerate

Question 31

What is the Optic chiasma?

Answer 31

This is apart of the brain where the optic nerves from each eye cross. Some fibres from each side pass to the opposite side while others remain uncrossed.

Question 32

Which portion of each retinal field cross at the optic chiasma?

Answer 32

Note that fibers from the lateral portion of each retinal field do not cross at the optic chiasma.

Question 33

Which areas of the brain process visual information and what type of information to they process?

Answer 33

primary visual cortex -
Processes contrast information and object orientation
visual association areas -
Processes form, colour, and motion from p.v.c.