Chapter 16 - The Special Senses

Question 1

Receptive field

Answer 1

• The area within which the dendritic endings of a single sensory neuron are distributed
• Small receptive field = able to identify stimulus location more precisely

Question 2

Tonic receptors

Answer 2

• Demonstrate limited adaptation
• With constant stimulus, they continuously generate nerve signals and only slowly reduced number relayed to CNS

Question 3

Phasic receptors

Answer 3

• Have rapid adaptation to a constant stimulus
• Generate nerve signals only in response to a new/changing stimulus
• Quickly decrease in number of nerve signals relayed to CNS (ex: deep pressure receptors that sense increased pressure when we sit in a chair

Question 4

Special senses are located where?

Answer 4

Only in the head

Question 5

Exteroceptors

Answer 5

• Detect stimuli in the external environment
• Ex: within skin, sensory receptors for smell, taste, vision, hearing, and equilibrium
• Type of receptor is stimulus origin

Question 6

Interoceptors

Answer 6

• Detect stimuli within the body
• Ex: within walls of viscera and blood vessels
• Type of receptor is stimulus origin

Question 7

Proprioceptors

Answer 7

• Detect stimuli within joints, skeletal muscles, and tendons that sense body or limb movements
• Type of receptor is stimulus origin

Question 8

Chemoreceptors

Answer 8

• Detect chemicals (molecules or ions) dissolved in fluid
• Type of receptor is modality of stimulus

Question 9

Thermoreceptors

Answer 9

• Detect changes in temperature
• Type of receptor is modality of stimulus

Question 10

Photoreceptors

Answer 10

• Detect changes in light intensity, color, and movement
• Type of receptor is modality of stimulus

Question 11

Mechanoreceptors

Answer 11

• Detect physical deformation of the plasma membrane due to touch, pressure, vibration, and stretch
• Type of receptor is modality of stimulus

Question 12

Nociceptors

Answer 12

• Detect painful stimuli
• Somatic nociceptors –> detect chemical, heat, or mechanical changes to body surface, joints, or skeletal muscles
• Visceral nociceptors –> internal changes within viscera
• Type of receptor is modality of stimulus

Question 13

Conjunctiva

Answer 13

• Transparent mucous membrane lining of eye and lid surfaces
• Produces a lubricating mucous secretion
• Has 3 parts (palpebral conjunctiva, bulbar (ocular) conjunctiva, conjunctival sac (fornix)

Question 14

Palpebra conjunctiva

Answer 14

• Membrane that lines underside of eyelid

Question 15

Bulbar (ocular) conjunctiva

Answer 15

• Covers sclera, but not cornea

Question 16

Conjunctival sac (fornix)

Answer 16

• Between palpebral and bulbar (ocular) conjunctiva
• Where contact lens rest

Question 17

What bones make up the orbit of the eye?

Answer 17

Roof: Frontal, sphenoid
Lateral: Frontal, zygomatic, sphenoid
Medial: sphenoid, ethmoid, maxilla, lacrimal
Floor: Palatine, zygomatic, maxilla

Question 18

Lacrimal gland

Answer 18

• Will secrete tears and secretes fluid to “wash” eyeball
• Autonomic system –> parasympathetic –> ACh –> muscarinic

Question 19

Lacrimal apparatus steps

Answer 19

1.) Lacrimal gland produces tears (lacrimal secretions)
2.) Tears enter the conjunctival sac via the excretory ducts of the lacrimal gland
3.) tears flow across the eye ball
4.) Tears enter lacrimal canaliculi at lacrimal puncta openings
5.) Tears drain into the lacrimal sac
6.) Tears empty via nasolacrimal duct into the inferior meatus of the nasal cavity

Question 20

What are the two oblique muscles that move eye in vertical plane and rotate eyeball
HINT: LR6(SO4)3

Answer 20

1.) Superior oblique
- Depresses eye and turns it laterally
- CN IV (4- trochlear)
2.) Inferior oblique
- Elevates eye and turns it laterally
- CN III (3- oculomotor)

Question 21

What are the 4 rectus muscles from the common tendinous ring
HINT: LR6(SO4)3

Answer 21

1.) Lateral rectus
- Moves eye laterally
- CN VI (6- abducens)
2.) Medial rectus
- Moves eye medially
- CN III (3 - oculomotor)
3.) Superior rectus
- Elevates eye
- CN III (3 - oculomotor)
4.) Inferior rectus
- Depresses eye
- CN III (3 - oculomotor)

Question 22

What muscles help with the eyelid?

Answer 22

1.) Orbicularis oculi muscle
- Closing eyelid
- CN VII (7- facial nerve)
2.) Levator palpebrae superioris
- Elevates and retracts eyelid
- CN III (3 - oculomotor)

Question 23

What are the 3 layers of the eyeball?

Answer 23

• Fibrous (external)
• Vascular (middle)
• Inner (retina)

Question 24

Fibrous layer

Answer 24

1.) Cornea
- Convex, transparent
- No blood vessels
2.) Sclera
- White of the eye
- Dense irregular connective tissue
Limbus: Where the cornea merges with the sclera at its outer edge

Question 25

Vascular tunic

Answer 25

1.) Iris
- Most anterior
2.) Ciliary body
3.) Choroid