special sences Flashcards Preview

BMA1902 > special sences > Flashcards

Flashcards in special sences Deck (33):

What type of receptors do olfactory cells have?



Where are Olfactory (Chemoreceptors) located?

In the nasal Epithelium lining the nasal cavity.
The cell bodies of the olfactory cells lye between supporting cells of the epithelium.


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

converted to a gaseous state and
water soluble


Axons leaving the olfactory cells penetrate the... what?

cribriform plate (ethmoid bone)


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

Cranial nerve I


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

olfactory cortex


The sense of taste is called what?



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

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


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



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

- 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


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

 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


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

 tip - sweet, salty
 sides - sour
 back - bitter


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

Umami - amino acids, small peptides and nucleotides.

Water - water receptors in pharynx


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

Cranial Nerve VII - Facial
Cranial Nerve IX - Glossopharyngeal


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

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


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

- Anterior segment
- Cornea
- Posterior segment
- Lens


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?

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

Far vision - ciliary muscles relax flattening lens
Sympathetic constricts pupils


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?

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


Trace the pathway of sound through the ear

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


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

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.


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

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


What muscles control which eye movements?

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


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

III (oculomotor)


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

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


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?

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


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?

ciliary muscles (attached to the lens via ciliary zonule)


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

Aqueous Humor- Anterior segment
Vitreous Humor- Posterior Segment


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



What is rhodopsin and what does it do?



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?

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


What is the Optic chiasma?

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.


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

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


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

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