Chapter 15 Part 1 Flashcards
what are sensory receptors?
specialized cells that monitor specific conditions in the body or external environment
when stimulated, what does a sensory receptor do?
when stimulated, a sensory receptor passes information to the CNS in the form of action potentials along the axon of a sensory neuron
what does the term “sensory pathway” refer to?
the nerves, axons, nuclei, and tracts that deliver somatic and visceral sensory information to their final destinations inside the CNS
Taken together, the receptors, sensory neurons, and sensory pathways make up the ______ division of the CNS
afferent
somatic sensory information is delivered to….
sensory processing centers in the brain
–either the primary sensory cortex of the cerebral hemispheres OR appropriate areas of the cerebellar hemispheres
visceral sensory information is distributed to…
reflex centers in the brain stem and diencephalon
somatic motor commands, regardless of whether they arrive at the conscious or unconscious levels, travel from motor centers in the brain along……..
SOMATIC MOTOR PATHWAYS which consist of motor nuclei, tracts, and nerves
what forms the somatic nervous system?
the motor neurons and pathways that control skeletal muscles
the term “general senses” is used to describe…
our sensitivity to temperature, pain, touch, pressure, vibration, and proprioception
where are general sensory receptors located on the body?
distributed throughout the body
the harder the pressure, the _______ the frequency of action potentials
higher
sensory information is interpreted on the basis of…..
the frequency of action potentials
the arriving information is called a _____
the conscious awareness of a sensation is called ________
the arriving information is called a SENSATION
the conscious awareness of a sensation is called PERCEPTION
what are the “special senses”?
olfaction (smell)
vision (sight)
gustation (taste)
equilibrium (balance)
hearing
what can you say about the receptors of the 5 special senses?
they are structurally more complex than the receptors for general senses
sense receptors are protected by surrounding tissue
WHERE are special sensory receptors located?
in SENSE ORGANS such as the eye or ear
sensory receptors represent the interface between the ____ and the _____
nervous system and the internal and external environments
What is transduction?
the translation process of a sensory receptor detecting an arriving stimulus and translating the stimulus into an action potential and conducting it to the CNS
What happens if transduction does NOT occur?
as far as you’re concerned, the stimulus didnt even exist
explain what “receptor specificity” is
each receptor has a characteristic sensitivity
a touch receptor is very sensitive to pressure but relatively insensitive to chemical stimuli.
whereas a taste receptor is sensitive to dissolved chemicals but insensitive to pressure
what are the SIMPLEST of all receptors
the dendrites of sensory neurons
receptor specificity may result from ______ or _______
- the actual structure of the receptor cell or..
- accessory cells or structures that shield the receptor cell from other stimuli
“the simplest receptors are the dendrites of sensory neurons.”
the branching tips of these dendrites are called ___________. explain
free nerve endings.
they are not protected by accessory structures
true or false:
free nerve endings show high receptor specificity
explain
FALSE - they show little receptor specificity
for example, free nerve endings that respons to tissue damage by providing pain sensations may be stimulated by chemical stimulation, pressure, temp changes, or trauma
true or false:
complex receptors such as the eye’s visual receptors provide very specific information.
explain
true
complex receptors are protected by accessory cells and connective tissue layers. These receptors are seldom exposed to any other stimulus than light, so they provide very specific information
the area monitored by a single receptor is called its….
receptor field
the larger the receptive field, the _______ your ability to localize a stimulus
poorer
whenever a sufficiently strong stimulus arrives in the receptive field, explain what happens
the CNS receives the information: “stimulus arriving at receptor X”
what areas of our body have large receptive fields? what areas have very small receptive fields?
what does this indicate
large receptive fields = a touch receptor on the general body surface
small receptive fields = tongue or fingertips
this means that the brain can precisely locate the stimulus when it arrives at the tongue or fingertips, but it only defines a broad area when a stimulus arrives from a general touch receptor on the body surface
sensory information is sent to the CNS EXCLUSIVELY in the form of………
action potentials, which are electrical events
true or false:
an arriving stimulus can take only 1 form
false
an arriving stimulus can take many forms such as a physical force (pressure), a dissolved chemical, sound, or light
recap: what is transduction?
the translation of an arriving stimulus into an action potential by a sensory receptor
when does the transduction process begin?
transduction begins when a stimulus changes the transmembrane potential of a receptor cell (called a receptor potential)
what is a “receptor potential”
when a stimulus changes the transmembrane potential of a receptor cell (signals the beginning of transduction)
a receptor potential is either a graded ______ or a graded ______
depolarization or hyperpolarization
the stronger the stimulus, the ______ the receptor potential
larger
for the general senses, what are the typical receptors and what is the sensory neuron?
for the general senses, the typical receptors are the DENDRITES OF SENSORY NEURONS and the sensory neuron is the RECEPTOR CELL
Any receptor potential that depolarizes the plasma membrane will bring the membrane closer to….
threshold