Sensory System

Question 1

Mechanoreceptors

Answer 1

detect, stimuli related to touch, pressure,
vibration, proprioception
(information about body position
and movement), hearing,
equilibrium, and blood pressure

Question 2

Thermoreceptors

Answer 2

detect changes in temperature

Question 3

Photoreceptors

Answer 3

detect light on the retina of the eye

Question 4

Nociceptors

Answer 4

detect pain,
usually as a result of physical or
chemical damage
to tissues

Question 5

Chemoreceptors

Answer 5

have the ability to sense
chemicals, whether this is taste in the mouth, smell in
the nose, or chemicals in body fluids such as oxygen,
carbon dioxide, water and glucose

Question 6

proprioceptors

Answer 6

a sensory receptor that responds to position and movement

Question 7

cutaneous sensors

Answer 7

sensory receptor found in the dermis or epidermis

Question 8

Hyposmia

Answer 8

reduced ability to smell, Free nerve endings of olfactory cells in nasal, mucosa are damaged over time

Question 9

Outer Ear The auricle (pinna)

Answer 9

Shell-shaped Cartilage covered by thick skin. Collects and
transmits sound waves to middle ear, causing tympanic membrane to vibrate.

Question 10

Outer Ear External auditory
canal

Answer 10

– Short, curved tube in temporal bone and filled with ceruminous glands Hairs and ear wax in external auditory canal prevent foreign materials entering ear

Question 11

Outer Ear Tympanic membrane
(eardrum)

Answer 11

Thin connective tissue membrane that vibrates in response to sound. Transfers sound energy to the middle ear ossicles
Boundary between outer and middle ears.

Question 12

Structure of the middle ear

Answer 12

Small, air-filled cavity in the temporal bone. Tympanic membrane separates middle ear from external ear Ov.al and round windows separate middle ear from inner ear.

Question 13

Functions of the middle ear

Answer 13

• Transmit vibrations from tympanic membrane to fluid in the cochlea (inner ear) via vibration of ossicles.
• Equalizes pressures on both sides of tympanic.
  -Middle ear provides protection from large vibrations.

Question 14

Ear Ossicles

Answer 14

• The tympanic cavity contains three small bones: the malleus (hammer), incus (anvil), and stapes (stirrup)
• Transmit vibratory motion of the eardrum to the oval window

Question 15

The inner ear structure

Answer 15

• Bony labyrinth
• Canals hollowed out of the
  temporal bone
• Contains 3 areas: the semicircular canals(equilibrium), the vestibule (equilibrium), and the cochlea (hearing)
• Filled with perilymph (similar to CSF)

Question 16

The cochlea

Answer 16

• A spiral, conical, bony
  chamber that:
  – Extends from the anterior
  vestibule
  – Contains the cochlear duct,
  which ends at the cochlear
  apex
  – Contains the organ of Corti
  (hearing receptor)

Question 17

Scala vestibuli

Answer 17

the scala vestibuli is a cochlear duct that runs along the length of the cochlea and is filled with endolymph. It is where sound vibrations from the oval window enter the cochlea and travel through the organ of Corti. It also contains the vestibular membrane which helps to regulate the pressure of the endolymph.

Question 18

Scala media

Answer 18

the scala media is the longest cochlear duct and is filled with perilymph. It contains the organ of Corti, which is made up of sensory hair cells that detect sound vibrations and send signals to the brain. These signals are then translated into meaningful auditory information.

Question 19

Scala tympani

Answer 19

the scala tympani is the shortest cochlear duct and is also filled with perilymph. It contains the basilar membrane which vibrates in response to sound waves, and this vibration helps to amplify the sound waves traveling through the duct. It also contains the tectorial membrane which helps to convert the sound waves into electrical signals. The electrical signals are then sent to the brain and are interpreted as sound.

Question 20

Vestibular apparatus

Answer 20

equilibrium receptors in the
semicircular ducts and vestibule
Maintain our orientation and balance in space

Question 21

Sclera

Answer 21

• Forms white of eye
• Tough fibrous coat
• Gives shape to eyeball
• Protects inner parts
  – It is transparent and nonvascular, covers iris, It is the principal refractive medium of the eye

Question 22

Choroid

Answer 22

• Choroid is pigmented and highly
  vascularised
• Nourishes retina
• Pigment absorbs light rays so they
  do not bounce around in the eye
• Posterior choroid continues
  anteriorly
• Anterior choroid – ciliary body and
  iris

Question 23

Iris

Answer 23

Colored part of eye.
Diaphragm between lens and
cornea
Alters pupil size

Question 24

Retina

Answer 24

• Contains nervous tissue and
  has pigment
• Contains photoreceptors
• Role in image formation

Question 25

* Macula lutea

Answer 25

– Small spot in the centre of the retina – Contains a depression called the fovea – Point of highest visual acuity – High concentration of cone photoreceptors

Question 26

Lens

Answer 26

* Transparent * Located immediately posterior to iris * Focuses light rays on retina for image formation * Part of the refractory apparatus of the eye * Enclosed by fibrous capsule * Suspensory ligaments attach lens to ciliary body

Question 27

Anterior cavity

Answer 27

– Filled with aqueous humor secreted from blood capillaries in the ciliary body – Maintains intraocular pressure – Supplies nutrients to lens and cornea

Question 28

Posterior cavity

Answer 28

– Filled with vitreous humor, jelly – like substance – Contributes to intraocular pressure – Holds retina flush against choroid

Question 29

Conjunctiva

Answer 29

* Thin mucous membrane * Lines eyelid and covers the front surface of the eyeball, except the cornea * Produces lubricant and keeps front of eyeball moist

Question 30

Describe the formation of an image on the retina.

Answer 30

Light enters the eye and passes through the cornea, aqueous humor, pupil, and lens. The light is then focused on the retina, a thin tissue layer at the back of the eye. The light is then converted into electrical signals by photoreceptor cells in the retina, which sends the signal to the brain where it is interpreted as an image.

Question 31

Rod

Answer 31

* 20 times more numerous than cones * Dim light, high sensitivity and peripheral vision receptors * Does not provide sharp images (low acuity)

Question 32

Cones

Answer 32

* Less numerous than rods * Operates in bright light, low sensitivity, mostly central receptors * Provides high clarity (high acuity) and colour vision

Question 33

Describe the pathway of the nervous impulses from the photoreceptors of the retina to the brain

Answer 33

Photoreceptors in the retina transduce light into electrical signals, which are passed through the bipolar cells and then the ganglion cells. The axons of the ganglion cells pass through the optic nerve, then the optic chiasm, before continuing through the optic tract. The optic tract then enters the thalamus, before sending impulses to the visual cortex of the brain.