A&P 15: The Special Senses Flashcards
Special senses
vision, taste, smell, hearing, and equilibrium
Special sensory receptors
distinct receptor cells confined to the head region and are highly localized, either housed within complex sensory organs or in distinct epithelial structures (taste buds and olfactory epithelium)
Eye
in adults, a sphere with a diameter of about 2.5cm; only the anterior 1/6 of the surface is visible; rest is enclosed and protected by a cushion of fate and the walls of the bony orbit
Accessory structures of the eye
eyebrows, eyelids, conjunctiva, lacrimal apparatus, & extrinsic eye muscles
Eyebrows
short, coarse hairs that overlie the supraorbital margins of the skull; help shade the eyes from sunlight and prevent perspiration trickling down the forehead from reaching the eyes
Eyelids
anteriorly, the eyes are protected by these mobile structures; AKA palpebrae
Palpebral fissure
the eyelids are separated by this slit and meet at the medial and lateral angles of the eye
Medial and lateral commissures
the medial and lateral angles of the eye
Lacrimal caruncle
the medial commissure supports this fleshy eleveation; contains sebaceous and sweat glands and produces the whitish oily secretion (eye sand) that collects, especially during sleep
Tarsal plates
the eyelids are thin, skin-colored folds supported internally by these connective tissue sheets; support the orbicularis oculi and levator palpebrae superioris
Eyelashes
projecting from the free margin of each eyelid are these; the follicles of these are richly innervated by nerve endings so anything that touches them triggers reflex blinking
Tarsal glands
glands embedded in the tarsal plates; their ducts open at the eyelid edge just posterior to the eyelashes
Conjunctiva
transparent mucous membrane; major function is to produce a lubricating mucus that prevents the eyes from drying out
Palpebral conjunctiva
transparent mucous membrane that lines the eyelids
Bulbar conjunctiva
transparent mucous membrane that reflects (folds back) over the anterior surface of the eyeball; covers only the white of the eye, not the cornea; very thin; blood vessels are clearly visible beneath it
Conjunctival sac
when the eye is closed, a slitlike space occurs between the conjunctiva-covered eyeball and eyelids; where a contact lens lies; eye medications are often administered into its inferior recess
Lacrimal apparatus
consists of the lacrimal gland and the ducts that drain lacrimal secretions into the nasal cavity
Lacrimal gland
lies in the orbit above the lateral end of the eye and is visible through the conjunctiva when the lid is everted
Lacrimal secretion
the lacrimal gland continually releases this dilute saline solution (tears) into the superior part of the conjunctival sac through several small excretory ducts
Lacrimal canaliculi
blinking spreads the tears downward and across the eyeball to the medial commissure, where they enter these paired structures
Lacrimal puncta
“prick points;” tears enter the paired lacrimal canaliculi through these 2 tiny openings on the medial margin of each eyelid
Lacrimal sac
from the lacrimal canaliculi, tears drain into here
Nasolacrimal duct
from the lacrimal sac, tears drain into here, which empties into the nasal cavity at the inferior nasal meatus
Lysozyme
tears contain mucus, antibodies, and this enzyme that destroys bacteria