sensory organs Flashcards
name the sensory organs
eyes
ears
tongue
nose
skin
eyelids represent ___________ of skin
folds
eyelashes act as ________
filters
oily gland found in both eyelids
sebaceous glands
- helps keep tears off the face
conjunctiva
- special inner lining of the eyelids
- special mucus membrane
- palpebral conjunctiva
- bulbar conjunctiva
- can check here for jaundice, anemia, conjunctivitis
palpebral conjunctiva
- where the conjunctiva attaches to the inner (caudal) surface of the eyelid
- helps keep it in place
bulbar conjunctiva
- the conjunctiva that attaches to the eyeball
where is the nictitating membrane located?
medial canthus (inner corner of the eye)
canthus
junction of the upper and lower eyelids at either corner of the eye
what is the nictitating membrane composed of?
cartilage partially covered in conjunctiva
hardner’s gland
gland found at the base of the nictitating membrane
lacrimal apparatus consists of:
- lacrimal gland
- lacrimal sac
- lacrimal puncta
- lacrimal and nasolacrimal ducts
lacrimal duct
conducts tears from the medial corners to the nasal cavity
tears drain through the ___________
into the ________
via the ________
lacrimal duct
nasal cavity
nasolacrimal duct
sclera
- tough, white, fibrous connective tissue
- outermost covering
- entrance site of blood vessels and the optic nerve
- attachment site for ocular muscles (control eye movement)
- near the eyelids, the sclera is covered in bulbar conjunctiva
cornea
- clear ‘window’ covering the cranial eyeball
- no blood vessels
- receives nutrients from lacrimal secretions, aqueous fluid, and scleral blood vessels
- multiple layers
what is damage to the cornea called?
ulcer
iris
- the muscle part
- posterior to the cornea
- anterior to the lens
- regulates the amount of light that gets into the eye
- contractile membrane
- may be colored
- attached to the sclera and the ciliary body
pupil
- hole
- is not a structure
lense
- gelatinous center surrounded by a capsule
- bi-convex
- focuses light on the retina
- held in place by zonules extending from the ciliary body
ciliary body
- thickening on the inner wall of the eyeball
- connect the iris and the ciliary processes
- encircles the inside of the eyeball
- attached by zonules to the lense
- changes the shape of the lens
- produces aqueous fluid
choroid
vascular layer between the tough outer sclera and sensitive inner retina
retina
- light-sensitive nervous tissue layer that houses photoreceptors (rods and cones)
- extends along the inner aspect of the eyeball
tapetum lucidum
- a reflective layer of cells
- between the retina and the choroid
- reflects light back through the retina
clear liquid fluid in the eye
aqueous fluid
- drains and is replaced
glaucoma
- increased intraocular pressure in the anterior cavity
- caused by overproduction of aqueous fluid and failure of aqueous ducts to drain properly
cataracts
- cloudiness/opacity in the lens
- must be distinguished from nuclear sclerosis in dogs (grey-blue haze on the lens that rarely causes blindness)
the degree of light refraction in the eye depends on (2)
- the angle of incidence
- the index of refraction for each media within the eye
rods respond to what
dim light
- more are present in nocturnal animals
- black and white sight
what do cones respond to?
- bright light
- color
the retina sits on the _________
choroid
what part of the ear is the tympanic membrane?
outer ear
where does the middle ear extend from?
the tympanic membrane to the (air-filled) petrous temporal bone, creating a cavity
what separates the middle and inner ear?
the coverings of the round and oval windows
where are the auditory ossicles located?
middle ear
what are the auditory ossicles in order:
- malleus
- incus
- stapes
what do the auditory ossicles do?
amplify vibrations of the eardrum to the oval window
where is the cochlea located?
inner ear
what is housed in the inner ear
- cochlea
- semi-circular canals
where are the semi-circular canals located
inner ear
describe the inner ear and where it is
- fluid-filled
- excavated in the porous temporal bone and bordered by the round and oval windows
what are the 2 parts of the inner ear?
- cochlear division
- vestibular division
describe the cochlear division of the inner ear
- sensory for SOUND
- snail-shaped
- houses the organ of Corti (hearing receptors)
- fluid-filled
- includes special hair cells that are connected to the cochlear part of the vestibule-cochlear nerve (are stimulated by the movement of fluid)
describe the vestibular division of the inner ear
- sensory for BALANCE
- series of 3 canals perpendicular to each other (x,y,z) called semi-circular canals
- contains nerve receptors for the perception of balance
- connected to the vestibular branch of the CNVlll
nerve deafness
- the malfunction of receptors or auditory nerves
- genetic
transmission deafness
- malfunction in the transmission of sound waves from the outer ear to the inner ear
The nose plays a role in both:
- sensory
- respiration
nares aka:
nostrils
What breathing strategy do cats and dogs use to help prevent the dilution of sents?
they breathe in through the large hole openings at the front of the nose and earth out of the side flaps
what are the 2 specialized tissues in the nose
- olfactory epithelium
- vomeronasal organ
olfactory epithelium
- found high in the nasal passage
- sensory cells are mixed with support cells
- dendrites of sensory cells project into nasal mucus membranes
vomeronasal organ
- accessory olfactory tissue (not in all species)
- found on either side of the nasal septum
- responsible for pheromone detection
pheromones
- chemical substances that affect social and reproductive communication
- are externally excreted
- are detected by sensory cells of the vomeronasal organ
hormone level fluctuations cause
subtle changes in pheromone production
flehmen response
physical set of movement that encourages the flow of pheromone-containing air into the vomeronasal organ
- commonly called stink face in cats
