Exam #5 Ch. 14 Flashcards
what is sensation the stimulation of?
a receptor
what is perception?
the awareness of a sensation
where are general senses?
widespread on the body
what does general senses include?
touch, temperature, pain etc.
what are the three types of general senses?
1) somatic
2) propicception
3) visceral
what does somatic senses provide?
information about the body and environment
what does proprioception provide?
information on body position and movement
what does visceral senses provide?
information about internal organs
where are special senses located/
they are localized on the body
what senses does special senses include?
sight, hearing, balance, smell and taste
how are sensory receptors categorized?
1) by type of stimulus
2) by location
3) by structure
which sensory receptors are categorized by type of stimulus? (5) (MCTPN)
1) mechanoreceptors
2) chemoreceptors
3) thermoreceptors
4) photoreceptors
5) nociceptors
what do mechanoreceptors respond to?
mechanical force such as compression, bending or stretching of cells
what do chemoreceptors respond to?
chemicals
what depends on chemoreceptors?
taste and smell
what do thermoreceptors respond to?
changes in temperature at the site of the receptor
what is thermoreceptors necessary for?
the sense of temperature
what does photoreceptors respond to?
light striking the receptor cells
what are photoreceptors necessary for?
vision
what do nociceptors (pain receptors) respond to?
extreme mechanical, chemical and thermal stimuli
what is unique about nociceptors?
most sensory receptors respond to one type of stimulus but nociceptors respond to more than one
which sensory receptors are categorized by location? (3) (CVP)
1) cutaneous
2) visceroceptors
3) proprioceptors
what are cutaneous receptors associated with?
skin
what are visceroreceptors associated with?
the viscera of organs
what are proprioceptors associated with?
joints, tendons and other connective tissue.
what does cutaneous receptors provide information about?
the external environment
which sensory receptors are categorized by structure? (9) (FMHPMRMGO)
1) free nerve endings
2) merkel disks
3) hair follicle receptors
4) pacinian corpuscles
5) meissner corpuscles
6) ruffini end organs
7) muscle spindles
8) golgi tendon organs
9) others
what are free nerve endings?
relatively unspecialized neuronal branches similar to dendrites
where are free nerve endings distributed?
throughout most parts of the body and especially are abundant in epithelial and connective tissues
what are free nerve endings responsible for?
a number of sensations including pain, temperature, itch and movement
where are somatic senses (general senses) located?
in skin, muscles and joints
where are visceral (general senses) located
in internal organs
what senses does somatic senses produce?
touch, pressure, propicopetion, temperature and pain
what senses does visceral senses produce?
pain and pressure
what are the 3 types of sensations that free nerve endings are responsible for?
1) cold receptor
2) warm receptor
3) pain receptors
what does the cold receptors on free nerve endings do?
increase its rate of action potential production as skin is cooled
what is cold receptors also activated by?
menthol (gives mint its cool taste)
what does the warm receptors on free nerve endings do?
increase its rate of action potential production as skin temperature increases.
what do both cold and warm receptors respond most to?
changes in temperature
which are more abundant, cold or warm receptors in any given area of the skin?
cold receptors are 10 to 15 more numerous than warm receptors
what are pain receptors on free nerve endings stimulated by?
extreme cold or heat
at very cold temperatures (0-12 degrees C) what is the only receptor on free nerve endings stimulated?
pain receptors
when does the pain sensation end when pain receptors are stimulated by temps 0-12 degree C?
as the temp increases above 15 degrees C
what is the structure of free nerve endings?
branching, no capsule
what is the function of free nerve endings? (6) (PITTJP)
1) pain
2) itch
3) tickle
4) temperature
5) joint movement
6) proprioception
where are the receptors of merkel disks located?
throughout the basal layers of the epidermis just superficial to the basement membrane
what does a merkel disk consist of?
axonal branches that end as flattened expansions
what are merkel disks associated with?
dome-shaped mounds of thickened epidermis in hair skin
what is the structure of merkel disks?
consists of flattened expansions at the end of axons.
what is each expansion at the end of axons associated with?
a merkel cell
what is the function of merkel disks?
light touch and superficial pressure
where are hair follicle receptors (hair end organs) located?
wrapped around hair follicles or extending along the hair axis
what does each axon on hair follicle receptors supply?
several hairs
what does each hair receive on hair follicle receptors and what does it result in?
branches from several neurons resulting in continuous overlap
what is the function of hair follicle receptors?
light touch and responds to very slight bending of hair
how is a response elicited in hair follicle receptors?
they are extremely sensitive and require very little stimulation
is the sensation in hair follicle receptors localized?
not very well localized
what helps explain why light touch is not highly localized in hair follicle receptors?
the considerable overlap in the endings of sensory neurons
what makes hair follicle receptors very sensitive?
converging signals within the CNS
what is the structure of pacinian corpuscles (lamellated corpuscles)?
onion-shaped capsule composed of several cell layers with a single central nerve process
what is the function of the pacinian corpuscle (lamellated corpuscle)?
deep cutaneous pressure, vibration and proprioception
what is the structure of meissner corpuscles (tactile corpuscles)?
several branches of a single axon
what are the several branches of a single axon on meissner corpuscles associated with?
specialized schwann cells
what are the several branches of a single axon on meissner corpuscles surrounded by?
a connective tissue capsule
what is the function of meissner corpuscles?
two-point discrimination
where are meissner corpuscles distributed?
through the dermal paillae
what is two-point discrimination in meissner corpuscles?
the ability to detect simultaneous stimulation at two points on the skin.
what is the sensation of meissner corpuscles important for?
evaluating the texture of objects
where are meissner corpuscles numerously located and close together?
close together in tongue and fingertips
where are meissner corpuscles less numerous and widely separated?
in other areas such as the back
what is the structure of ruffini end organs?
branching axon with numerous, small, terminal knobs
what are the small terminal knobs of ruffini end organs surrounded by?
a connective tissue capsule
what is the function of ruffini end organs?
continous touch or pressure
what does ruffini end organs respond to?
depression or stretch of skin
where is ruffini end organs located?
in the dermis
where in the dermis are ruffini end organs primarily located?
in the fingers
what is the structure of muscle spindles?
3-10 striated muscle fibers
what are the striated muscle fibers of muscle spindles enclosed by?
a loose connective tissue capsule, striated only at the ends with sensory nerve endings in center
what is the function of muscle spindles?
procprioception
what is procprioception associated with in muscle spindles?
detection of muscle stretch
what are muscle spindles most important for?
control of muscle tone
where are muscle spindles located?
in skeletal muscles
what do muscle spindles provide information about?
the length of muscle (stretch reflex)
what do golgi tendon organs surround?
a bundle of fascili
what are golgi tendon organs enclosed by?
a delicate connective tissue capsule
what is the structure of nerve terminations in golgi tendon organs?
branched, with small swellings applied to indivisual tendon fasciculi.
what is the function of golgi tendon organs?
proprioception
what are golgi tendon organs associated with?
stretch of a tendon
what is the importance of golgi tendon organs?
for control of muscle contraction
what is the increase in tendon tension caused by?
either by contraction of the muscle or by passive stretch of the tendon
what does stimulating a receptor produce?
an action potential in the sensory neuron
what may produce an action potential?
a graded potential
what is a graded potential called?
a receptor potential
what is receptor adaptation?
reduced sensitivity to a constant stimulus
what do tonic receptors constantly generate?
action potentials
what do phasic receptors respond best to?
changes and adapt quickly
what are primary receptors?
sensory receptors that conduct action potentials in response to the receptor potential
which sensory neurons are primary receptors?
most ofthem
what are secondary receptors?
other receptor cells that have no axons or have short, axonlike projections
what do secondary receptors generally produce?
receptor potentials
what does the production of action potentials by tonic receptors depend on?
as long as a stimulus is being applied
why does a stimulus need to be applied to tonic receptors for an action potential to be generated?
so that they adapt very slowly
what is an example of tonic receptors?
information from slowly adapting receptors allow us to know where our little finger is at all times without having to look for it
how do phasic receptors adapt?
rapidly
why do phasic receptor adapt rapidly?
so they are most sensitive to changes in stimuli
what is an example of phasic receptors?
information from phasic receptors allow us to iknow where our little finger is as it movses thus we can control its movement through space and predict where it will be in the next moment
why are we usually not conscious o tonic or phasic input?
because the higher brain centers ignore it most ofthe time.
what type of pathways are sensory pathways/
ascending
what do sensory pathways carry?
certain sensory modalities
what does the anterolateral system convey?
cutaneous sensory information
what does the spinothalmic tract in the anterolateral system carry? (6) (PTLPTI)
1) perceived pain
2) temperature
3) light touch
4) pressure
5) tickle
6) itch
where do primary neurons in the spinothalmic tract synapse?
in the posterior gray horn
where are the secondary neurons located in the spinothalmic tract?
cross over and ascend in the spinothalmic tract to the thalamus
where are the tertiary neurons located in the spinothalmic tract?
they ascend to the somatic sensory cortex
what do the spinoreticular and spinomesencephalic tract of the antherolateral system carry?
pain and other touch sensations in the spinothalmic tract to other pats of the brain
what does the tactile sensory axons from cranial nerves 7, 9 and 10 in the trigeminothalmic tract in the anetherolateral system join?
the spinothalmic tract in the brainstem
what does the dorsal column/medial-lemniscal system carry? (4) (PPPV)
1) perceived 2 point discrimination
2) perceived proprioeption
3) pressure
4) vibration
where are most primary neurons in the dorsal column/medial-lemniscal system located?
they enter the spinal cord and ascend in the posterior column to the medulla
in primary neurons of the dorsal column/medial-lemniscal system, where does information from the inferior half of the body travel?
in the fasciculus gracillis to the nucleus gracillis
in primary neurons of the dorsal column/medial-lemniscal system where does information from the superior half of the body?
in the fasciculus cuneatus to the nucleus cuneatus
where are secondary neurons located in the dorsal column/medial-lemniscal system?
they crossover and travel through the medial lemniscus to the thalamus
where are tertiary neurons located in the dorsal column/medial-lemniscal system?
they ascend to the somatic sensory cortex
