Lecture 11 - Special senses Flashcards
general senses refers to sensation of (6)
Pain Temperature Touch Pressure Vibration Proprioception
Special senses (4)
Smell
Taste
Vision
Hearing and equilibrium
Olfaction + types of cells
The sense of smell
- Olfactory receptor cells
- Supporting cells
- Basal stem cells
Bipolar neurons
Sites of olfactory transduction
Respond to chemical stimulation of an odorant molecule - initiate the olfactory response
Single axons project through cribiform plate into the olfactory bulb
Olfactory receptor cells
Columnar epithelial cells which line the nose
Provide physical support, nourish, and insulate the olfactory receptor cells
Help detoxify the chemicals which come in contact with the olfactory epithelium
Supporting cells
Innervation of the supporting cells
CN VII - facial
Innervation of the olfactory receptor cells
CN I - olfactory
Lies between the bases of the supporting cells
Continually undergo cell division to produce new olfactory receptor cells
Basal stem cells
Characteristics of the basal stem cells (3)
- 1 cell lives +/- 1 month
- # decreases with age
- decreased sensitivity with age
Gustation + classes of stimuli distinguished
The sense of taste
- sour
- sweet
- bitter
- salty
- umami (savory)
Location of the taste buds
Tongue, soft palate, pharynx and larynx
Each taste bud has:
Supporting cells
Gustatory receptor cells
Basal cells
Taste buds are housed in papillae (4 types)
circumvallate (vallate)
fungiform
foliate
filiform
Cranial nerves involved in the gustatory pathway
VII, IX, X
Accessory structures of the eye
Eyelids, eyelashes, eyebrows, lacrimal apparatus, extrinsic eye muscles
Eyelids structures
Levator palpabra superioris muscle
Palpabral fissure
Lateral and medial commissure
Lacrimal caruncle
Action of levator palpabra superioris muscle
Opens up upper eyelid
Palpabral fissure
Space between upper/lower eyelid
Lateral and medial commissure
Corner where the eyelids join in each corners
Lacrimal caruncle
Contains sebaceous glands and sudoriferous glands (oil and sweat)
Layers of eyelid (superficial to deep)
Epidermis Dermis Subcutaneous tissue Orbicularis oculi muscle Tarsus Conjunctiva (palpabrae part)
Functions of eyelashes/eyebrows
Protect eyeball from foreign objects
Protect eyeball from perspiration (sweat)
Protect eyeball from direct rays from sun
Function of lacrimal apparatus
Produce and drain lacrimal fluid (tears)
Tears content
Watery solution containing:
- salts
- mucous
- lyzosyme
Function of tears
Protect, clean, lubricate/moisten
Associated structures of the lacrimal apparatus
Lacrimal glands Lacrimal (excretory) ducts Lacrimal punctum Lacrimal canals Lacrimal sac Nasolacrimal duct
Extrinsic muscles of the eye (6)
Superior rectus Inferior rectus Lateral rectus Medial rectus Superior oblique Inferior oblique
Action of superior rectus m.
Moves eyeball superiorly and medially
Action of inferior rectus m.
Moves eyeball inferiorly and medially
Action of lateral rectus m.
Abducts eyeball
Action of medial rectus m.
Adducts eyeball
Action of superior oblique m.
Moves eyeball inferiorly and laterally
Action of inferior oblique m.
Moves eyeball superiorly and laterally
3 layers of the eyeball
- Fibrous tunic
- Vascular tunic
- Retina
Superficial layer of the eyeball
Anterior cornea + posterior sclera
Fibrous tunic