Ch 12 Flashcards
(sensory function)
- Collect info from environment, and relay it to the CNS on sensory neurons
- Respond to specific stimuli
sensory receptors
(sensory function)
- Receptors that are widely distributed throughout body
- Skin, various organs and joints
general senses
(sensory function)
- Specialized receptors confined to structures in head
- Eyes, ears, nose, mouth
special sense
A feeling that occurs when brain becomes aware of sensory info:
sensation
The way the brain interprets the sensory info:
perception
What causes change in its membrane potential?
stimulation of receptor
Ability to ignore unimportant stimuli:
sensory adaptation
(touch and pressure senses)
- Common in epithelial tissues
- Simplest receptors
- Sense itching
free nerve endings
(temperature senses)
- Sensitive to temps above 77 degrees
- Unresponsive to temps above 113 degrees
warm receptors
(temperature senses)
Sensitive to temps between 50-68 degrees:
cold receptors
(temperature senses)
- Responds to temps below 10 Celsius, produce freezing sensation
- Responds to temps above 45 Celsius, produce burning sensation
pain receptors
Visceral pain may feel as if coming from some other part of the body: (ex. heart pains feels like it’s coming from left shoulder)
referred pain
Where does sensation of pain begin?
thalamus
- Judges intensity of pain
- Locates source of pain
- Produces emotional and motor responses to pain
cerebral cortex
Regulates flow of impulses from spinal cord:
gray matter in brainstem
What are 3 pain-inhibiting substances produced in body?
- Enkephalins
- Serotonin
- Endorphins
- Stretch receptors in skeletal muscles
- Initiate stretch reflexes in which spindle stretch causes muscle contraction
muscle spindles
- Stretch receptors in tendons
- Stimulate reflexes that oppose stretch reflexes
- Help maintain posture
Golgi tendon organs
(special senses)
Olfactory organs in nasal cavity:
smell
(special senses)
Taste buds in oral cavity:
taste
(special senses)
Hearing and equilibrium:
ears
(special senses)
Sight:
eyes
(sense of smell)
Contains olfactory receptor cells and supporting epithelial cells:
olfactory organs
Once olfactory receptors are stimulated, nerve impulses travel through openings where?
cribriform plate
Olfactory nerves—–> Olfactory bulbs—–> Olfactory tracts—–>
limbic system and olfactory cortex
Center for memory and provides emotional attachment:
limbic system
Sense of taste:
gustation
(sense of taste)
- Organs of taste
- Located on papillae of tongue, roof of mouth, lining of cheek
taste buds
(sense of taste)
-Chemoreceptors
taste receptors
(sense of taste)
Modified epithelial cells that function as receptors:
taste cells
(sense of taste)
Microvili that protrude from taste cells through pores of taste buds:
taste hairs
(outer ear)
- Funnel-shaped
- Collects sound waves
auricle
(outer ear)
- S-shaped tube
- Lined with ceruminous glands
- Carries sound to tympanic membrane
- Terminates at tympanic membrane
external acoustic meatus
(middle ear)
Air-filled space in temporal bone:
tympanic cavity
(middle ear)
- Opening in wall of tympanic cavity
- Stapes vibrates against it to move fluids in inner ear
oval window
(middle ear)
-Muscle contractions that occur during loud sounds, to lessen the transfer of sound vibrations to inner ear and prevent damage to hearing receptors
tympanic reflex
(middle ear)
- Connects middle ear to throat
- Helps maintain equal pressure on both sides of tympanic membrane
- Usually closed by valve-like flaps in throat
auditory tube
(inner ear)
- Functions in hearing
- Coiled around bony core, modiolus
cochlea
(inner ear)
What is a bony shelf that coils around the cochlea?
spiral lamina
(inner ear)
Window in wall of inner ear facing the tympanic cavity, through which excess vibrations dissipate into tympanic cavity:
round window
(cochlea)
- Upper compartment
- Leads from oval window to apex of spiral
- Part of body labyrinth
scala vestibuli
(cochlea)
- Lower compartment
- Extends from apex of cochlea to round window
- Part of body labyrinth
scala tympani
(cochlea)
- Middle compartment
- Portion of membranous labyrinth in cochlea
cochlear duct
(cochlea)
Separates scala vestiboli from cochlear duct:
vestibular membrane
(cochlea)
Separates cochlear duct from scala tympani:
basilar membrane
(cochlea)
Extends partially into cochlear duct; part of the hearing receptor organ:
tectorial membrane
- Organ for sense of hearing
- Sits on upper surface of basilar membrane
- Contains hearing receptor cells, called hair cells
spiral organ
- Passes like a roof over the hair cell stereovilli
- Sound vibrations cause stereo cilia to contact and bend against the tectorial membrane
- Different frequencies of vibration move different parts of basilar membrane
basilar membrane
(hearing loss)
- Interference with conduction of sound vibrations to inner ear
- 95% of cases of hearing loss
- Caused by accusation of ear wax, hardening or injury of tympanic membrane, injury to auditory ossicles
- Diagnostic tests: Rinne test and Weber test
conductive deafness
(hearing loss)
- Damage to cochlea, auditory nerve, or nerve pathways
- Can be caused by long-term exposure to very loud sounds, such as factory noise, loud music
- Also caused by CNS tumors, brain damage resulting from a stroke
sensorineural deafness
(sense of equilibrium)
- Senses position of head when body is not moving
- Receptors are found in vestibule of inner ear
statice equilibrium
(sense of equilibrium)
- Senses rotation and movement of head and body
- Receptors are found in semicircular canals
dynamic equilibrium
Has hair cells embedded in gelatinous material, with otoliths on its surface:
macula
Gravity pulls on ___________ mass when head changes position.
gelatinous
_________ shift position, and pull on gelatinous mass and cilia of hair cells.
otoliths
This results in generation of nerve impulses in vestibular branch of vestibulocochlear nerve.
bending of hairs
A swelling of the membranous labyrinth that communicates with the vestibule:
ampulla
- Sensory organ for dynamic equilibrium
- Hair cells and supporting cells
- Located in ampulla of each semicircular canal
- Consists of hair cells whose hairs extend upward into dome-shape gelatinous mass
crista ampullaris
What are 4 accessory organs for sense of sight?
- eyelids
- eyelashes
- lacrimal apparatus
- extrinsic eye muscles
(lacrimal apparatus)
- In orbit, lateral to eye
- Secretes tears
lacrimal gland
(lacrimal apparatus)
Antibacterial component of tears:
lysozyme
(eye muscles)
Rotates eye up and medially:
superior rectus
(eye muscles)
Rotates eye down and medially:
inferior rectus
(eye muscles)
Rotates eye medially:
medial rectus
(eye muscles)
Rotates eyes laterally:
lateral rectus
(eye muscles)
Rotates eye down and laterally:
superior oblique
(eye muscles)
Rotates eye up and laterally:
inferior oblique
(outer tunic)
Cornea+Sclera:
outer tunic
(outer tunic)
- Transparent
- Helps focus light rays
- Transmits and refracts light
cornea
(outer tunic)
- White, opaque
- Protects eye, attaches muscles
- Pierced by optic nerve and blood vessels
sclera
(middle tunic)
Choroid coat+Ciliary body+Iris:
middle tunic
(middle tunic)
- Provides blood supply
- Contains melanocytes
- Melanin absorbs extra light
choroid light
(middle tunic)
- Thickest portion, pigmented
- Forms ring to hold lens
- Changes lens shape for focusing
ciliary body
(middle tunic)
- In front of lens
- Pigmented
- Controls light entering eye
iris
Between cornea and lens, filled with watery fluid:
aqueous humor
Transparent, biconvex, lies behind iris, elastic, held in place by suspensory ligaments of ciliary body; helps focus light rays, and changes shape for long distance or close vision:
lens
Forms internal ring around the front of the eye:
ciliary body
Lies just behind iris and pupil:
lens
A change in shape of lens, to view close objects:
accommodation
Lens _________ and becomes more convex when focusing on close objects.
thickens
Lens _________ and becomes flatter when focusing on distant objects.
thins
- Controls amount of light entering the eye
- Consists of connective tissue and smooth muscle
iris
Window or opening in center of iris:
pupil
Pupils dilate to:
dim light
Pupil constrict to:
bright light
- Fluid in anterior cavity
- Secreted by epithelium on inner surface of ciliary body
- Provides nutrients and maintains shape of anterior portion of eye
- Leaves cavity through scleral venous sinus
aqueous humor
- Inner tunic consists of
- Contains visual receptors
- Continuous with optic nerve in back of eye
- Ends just behind margin of ciliary body toward front of eye
- Composed of several layers
retina
(inner tunic)
Yellowish spot in retina:
macula lutea
(inner tunic)
Center of macula lutea; produces sharpest vision, only cones:
fovea centralis
(inner tunic)
Blind spot; contains no visual receptors; found where nerve fibers from retina leave eye to become optic nerve, no rods or cones:
optic disc
(inner tunic)
Thick gel that holds retina flat against choroid coat:
vitreous humor
Space enclosed by lens, ciliary body, and retina:
posterior cavity
Bending of light, which occurs when light waves pass at an angle between mediums of different densities:
refraction
(photoreceptors)
- Long, thin projections
- Contain light sensitive pigment, called rhodopsin
- Provide vision in dim light
- Produce colorless vision
- Produce outlines of objects
rods
(photoreceptors)
- Short, blunt projections
- Contain light sensitive pigments
- Provide vision in bright light
- Produce sharp images
- Produce color vision
cones
Light-sensitive pigment in rods:
rhodopsin
Erythrolabe:
responds to red light
Chlorolabe:
responds to green light
Cyanolabe:
responds to blue light
