Chapter 16: Sense Organs Flashcards
sensory receptor
a structure that detects a stimuli
transduction
the conversion of one form of energy to another
stimulus energy to nerve signal
sensation
an awareness of the stimulus
most ____ signals delivered to the CNS produce no ____ sensation
sensory; conscious
What are the 4 types of info transmitted by sensory receptors?
- modality
- location
- intensity
- duration
modality
type of stimulus or the sensation it produces
vision, hearing, taste
What does the brain use to interpret what modality a signal represents?
labeled line code
Why does the body have a labeled line code?
because all action potentials are the same
location
encoded by which nerve fibers are issuing signals to the brain
area that detects stimuli for a sensory neuron
receptor field
intensity
encoded in 3 ways
- which fibers are sending signals
- how many fibers are doing so
- how fast these fibers are firing
duration
how long the stimulus last
phasic receptors
generate a burst of action potentials when first stimulated, but then dull down after the stimulus adapts QUICKLY even though the action potential continues
tonic receptors
adapt slowly, generate nerve signals more steadily
an example of a tonic receptor is?
proprioceptors
How can receptors be classified? (3)
- by modality
- by distribution
- by origin of the stimuli
Classification of receptor?
thermoreceptors, photoreceptors, chemoreceptors, mechanoreceptors, nocireceptors
by modality
Classification of receptor?
exteroceptors, interoceptors, proprioceptors
by origin of the stimuli
Classification of receptor?
general (somoesthetic) senses: widely distributed
by distribution
What are 4 types of encapsulated nerve endings?
- tactile corpuscles
- krause end bulbs
- lamellar corpuscles (phasic)
- bulbous corpuscles (tonic)
From receptors to final destinations, most signals travel by way of _____ neurons
3
first order neuron (somatosensory projection pathways)
afferent (toward CNS)
first order neuron
from body, enter the __ ___ of the spinal cord
from heard, enter ___ and the ____ via cranial nerves
dorsal horn
pons; medulla
Touch, pressure, and proprioceptors are on _______; while heat & cold are on _____
large myelinated axons; small unmyelinated axons
second order neurons (somatosensory projection pathways)
interneurons the decussate to opposite sides in the spinal cord
Where do second order neurons end up?
in the thalamus except for proprioceptors (cerebellum)
third order neurons (somatosensory projection pathways)
thalamus to primary cortex of cerebrum (postcentral)
pain
discomfort caused by tissue injury
nociceptors
provide different pain sensations
somatic pain
skin, muscle, joins
visceral pain
viscera organs
____ is the most potent pain stimulus known. ___ are released to stimulate pain fibers.
bradykinin; chemicals
What are the 2 projection pathways for pain?
the head, and from the neck down
Pain signals from the head
1st neuron: cell bodies in the dorsal root ganglion
2nd neuron: decussate & send fibers up spinothalamic tract
3rd neuron: thalamus to post central gyrus
Somatic pain travels via _____
Visceral, Emotional travels via _____ (reticular formation) or _____ (thalamus)
spinothalamic tract
spinoreticular tract; gracile fasciculus
referred pain
pain in the viscera often mistakenly thought to come from the skin or other superficial site; BRAIN IS CONFUSED
analgesic
pain relieving
neuromodulators can block what?
transmission of pain signals and produce feelings of euphoria
spinal gating
stops pain signals at the posterior horn of the spinal cord
gustation
taste (chemoreceptors)
taste pores
pit in which the taste hairs project
taste hairs are ____ not neurons
epithelial cells
to be tasted what must happen
molecules must dissolve in saliva and flood the taste pore
5 primary taste sensations
bitter, sweet, sour, umani, salty
2 mechanisms of action for taste
second-messenger system
depolarize cells directly
olfaction
sense of smell
are neurons
taste vs. smell
smell is are neurons not epithelial cells
what is the order of the olfactory projection pathway?
- olfactory bulb
- primary olfactory cortex
- hippocampus
hearing
a response to vibrating air molecules
hearing and equilibrium reside in what part of the ear?
inner ear
outer ear
funnel for conducting vibrations to the tympanic membrane
middle ear
located in the air filled tympanic cavity in the temporal bone (enclosed air space)
auditory tube connects _____ to ____
middle ear cavity to nasopharynx
otitis media
middle ear infection common in children due to angle
inner ear (2)
filled with fluid sacs (endolymph and perilymph)
responsible for equilibrium
cochlea
organ of hearing
long tube
what are the 3 fluid filled chambers of the cochlea?
scala vestibuli (superior) cochlear duct (middle chamber) scala tempani inferior)
inner hair cells vs outer hair cells
provides for hearing (inner) increases precision (outer)
static equilibrium
perception of the orientation of the head when the body is stationary
dynamic equilibrium
perception of motion of acceleration
oval window send _____ vs the round window
frequencies
neuromodulators can block what?
transmission of pain signals and produce feelings of euphoria
spinal gating
stops pain signals at the posterior horn of the spinal cord
gustation
taste (chemoreceptors)
taste pores
pit in which the taste hairs project
taste hairs are ____ not neurons
epithelial cells
to be tasted what must happen
molecules must dissolve in saliva and flood the taste pore
cones
color and day vision
2 mechanisms of action for taste
second-messenger system
depolarize cells directly
olfaction
sense of smell
are neurons
taste vs. smell
smell is are neurons not epithelial cells
what is the order of the olfactory projection pathway?
- olfactory bulb
- primary olfactory cortex
- hippocampus
hearing
a response to vibrating air molecules
hearing and equilibrium reside in what part of the ear?
inner ear
outer ear
funnel for conducting vibrations to the tympanic membrane
middle ear
located in the air filled tympanic cavity in the temporal bone (enclosed air space)
auditory tube connects _____ to ____
middle ear cavity to nasopharynx
otitis media
middle ear infection common in children due to angle
inner ear (2)
filled with fluid sacs (endolymph and perilymph)
responsible for equilibrium
cochlea
organ of hearing
long tube
what are the 3 fluid filled chambers of the cochlea?
scala vestibuli (superior) cochlear duct (middle chamber) scala tempani inferior)
inner hair cells vs outer hair cells
provides for hearing (inner) increases precision (outer)
static equilibrium
perception of the orientation of the head when the body is stationary
dynamic equilibrium
perception of motion of acceleration
oval window send _____ vs the round window
frequencies
calcium carbonate protein granules that add to the weight and inertia to enhance sense of gravity
otoliths
movement in semicircular canals?
direction of motion
optic disc
blind spot
farsightedness
eye is too short
nearsightedness
eye is too long
rods
help with night vision
rods contain visual pigmented ______
rhodopsin
2 major parts of rhodopsin
opsin (protein portion)
retinal (vit A derivative)
In the visual projection pathway there is a lot of what?
decussation
