special senses Flashcards
what is the largest sensory organ?
skin
what is the purpose of skin?
- covers and protects against damage from water, injury, microbes, thermoregulation
- protects against excessive loss of water and electrolytes
what is responsible for changes observed in skin and hair color?
melanin
what does pigment in skin protect against?
ultraviolet rays
when do the skin and coat color of animals change?
adapting to changes in intensity and duration of sunlight
define cutaneous
of skin
what are the two main layers of skin?
epidermis and dermis
what type of cell makes up the epidermis?
keratinocytes
how do keratinocytes form the keratin layer?
on the basal layer they multiply and differentiate to lose their nuclei
where is the dermis located?
below the epidermis
what makes up the epidermis?
fibrous and elastic tissue responsible for providing flexibility and stength
where are sweat glands, sebaceous glands, hair follicles, and nerve endings found?
dermis
what is the purpose of blood vessels in the dermis?
- provide nutrition to skin
- maintaining body temperature
- nerve endings detect pressure, pain, heat/cold
what separates the epidermis from the dermis?
basement membrane
what is the function of the basement membrane?
regulating back and forth passage of molecules between epidermis and dermis
what is the purpose of the layer of fat below the dermis?
provides insulation from varying temperatures and stores energy
The skin is enriched by ______________
sensory innervation
which type of hair provides the coat of the skin with a smooth appearance?
guard
what is the outermost “scaly” layer of hair called?
cuticle
what muscle attaches the proximal end of the follicle to the dermal papillae?
erector pili
what causes the erection of hair (goose bumps/hackles)?
involuntary contraction of erector pili
when do dogs have seasonal shedding?
spring and fall
what type of hair provides a soft undercoat?
wool hair
what is the function of wool hair?
insulation
which animal is the fleece exclusively comprised of wool hair?
sheep
which type of hair is thicker and longer, found around mouth and eyes, whiskers of cats, and associated with nerve endings responsive to touch or mechanical stimulation?
tactile
what are plantigrades?
footpads pronounced in mammals that walk on their toes and metatarsals
what are examples of plantigrades?
humans
bears
non-human primates
what are digitigrades?
animals that walk on their digits and toes characterized by the presence of digital and metacarpal pads
examples of digitigrades
dogs
cats
Nails, claws and hoofs are basically encasings of the _________ and are very similar in structure.
third phalanx
what is the main purpose of nails, claws, and hoofs?
protect tissues lying underneath, scratching, digging
where do nails grow from?
epidermis
what is the laminae of the epidermis characterized by?
folds
what structure is similar to nails but are compressed, curved, and pointed in appearance for a sharp border?
claws
what is the purpose of claws?
weapons or digging
what is the underlying dermis that is vascular and sensitive called in horses and dogs and cats?
horses = sensitive lamina
dogs and cats = quick
what are hooves?
casings of the third phalanx in ungulates
true or false: hooves continuously grow
true
where do horns grow out of?
cornual process of frontal bone
The substance of the horn resembles the hoof wall and is made up of ______________ interspersed with ______________.
‘horny’ tubules
‘intertubular horn’
true or false: antlers of deer are the same as horns
false
what are antlers?
outgrowth of the skull covered by the skin that eventually get exposed, are shed and regrown again
what is velvet?
dead skin covering antlers lost by rubbing trees
what part of the skull is the eye located?
orbit
what are the three distinct coats of the eye from superficial to deep?
sclera
choroid
retina
what is the fibrous, outermost layer of the eye that also has the cornea?
sclera
what is the cornea?
allows the light to pass through the globe of the eye
describe the middle layer of the eye
vascular layer (choroid)
describe the innermost layer of the eye
sensitive (retina) on the posterior half of the eye
why is the cornea avascular?
it would interfere with the passage of light
true or false: the sclera has sufficient blood vessels
true
what is the inside of the eye divided into?
- region in front of the lens
- region behind lens
what is the clear gel-like structure/space behind the lens occupied by?
vitreous body
what is the purpose of the vitreous body?
helps focus images on the retina
what is in front of the vitreous body that is suspended by ligaments?
lens
what divides the anterior and posterior chamber of the eye and is like the diaphragm of a camera?
iris
what is the central opening of the iris?
pupil
what are the two types of muscles that innervate the pupil?
dilators and constrictors
the constrictor and dilator muscles of the pupil have ___________ innervation
autonomic
____________ stimulation will cause the pupil to dilate and ______________ stimulation will cause the pupil to constrict.
Sympathetic
parasympathetic
what must you do in order to dilate pupils for an eye exam?
use a drug that stimulates the sympathetic system (sympathomimetic- a drug that mimics the sympathetic response) or a parasympatholytic (a drug that blocks the parasympathetic system).
what is the thin fluid in front of the lens?
aqueous humor
what may happen if the fluid from the aqueous humor doesn’t get drained properly?
increase in pressure within the eyeball leading to glaucoma which leads to blindness
what are the photoreceptor cells of the retina?
rods and cones
what is the purpose of rods and cones?
cone cells are for color and rods are for contrast
The information passes through a series of neurons in the retina and gets transmitted through the ________
optic nerve
what are the three functions of the nose?
- warms and humidifies air that is inhaled
- trap dust and particulate matter
- helps fight invading organisms by producing mucous secretion
what structures covered by the mucous membranes make olfaction possible?
dorsal and ethmoturbinate bones
what specialized cells are able to detect odor molecules?
olfactory neurons
the signals from the olfactory neurons are transmitted through nerves that pass through the ___________ of the skull at the back of the nose and reach the _______________
cribriform plate
olfactory lobe
what are the three parts of the ear?
- external
- middle
- inner
where does the external ear end?
ear drum/tympanic membrane
how does the middle ear connect the pharynx?
eustachian tube
what are the three bones of the eustachian tube?
auditory ossicles
where is the inner ear found?
petrous part of the temporal bone
what are the 2 parts of the inner ear and each of its function?
- vestibular apparatus: maintains balance and detects motion, acceleration, and gyration
- cochlea: detects waves
The vestibular apparatus has _ semicircular bony canals that are lined by a membrane and filled with a fluid
3
As the body moves, the fluid in the ear also moves and this movement is detected by specialized cells called hair cells, that are localized to certain spots (_______) within the vestibular apparatus
ampullae
Stimulation of hair cells in the ear results in nerve impulses that are transmitted along the ________ nerve to the brain.
vestibular
what structure of the ear looks like a snail shell and is a coiled bony tube divided into 3 compartments?
cochlea
what is the sensory component of the cochlea that has hair cells that detect vibrations of sound waves called?
organ of corti
The cells found at the _____ of the cochlea detect high frequencies and those at the ____ detect low frequencies
base
apex
Nerve impulses from the cochlea and the vestibular apparatus pass through the
___________________ to the brain.
vestibulocochlear nerve
what are the two purposes of the tongue?
- prehension to grab food
- gustation
what are the different types of papillae?
- filiform
- fungiform
- foliate
- circumvallate
what cells make up the taste buds?
gustatory
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