Chapter 15 Part 2 Flashcards
temperature receptors
thermoreceptors
what type of receptors are thermoreceptors and where are they located?
free nerve endings located in the dermis, skeletal muscles, the liver, and the hypothalamus
which are more numerous – cold receptors or warm receptors?
is there a structural difference between them?
cold receptors are3-4 times more numerous
NO structural differences
Are thermoreceptors phasic or tonic receptors?
phasic.
they are very active when the temperature is changing but quickly adapt to a stable temp
are temp sensations carried along the same pathway as pain sensations?
yes
-reticular formation, thalamus, and primary sensory cortex
mechanoreceptors are sensitive to stimuli that….
distort their plasma membranes
their plasma membranes contain mechanically gated ion channels that open/close in response to stretching, compression, twisting, or other distortions of the membrane
what are the 3 classes of mechanoreceptors?
-tactile receptors – touch, pressure, vibration
-baroreceptors – pressure changes in the walls of blood vessels, portions of the digestive, respiratory, and urinary tracts
-proprioceptors – monitor positions of joints and skeletal muscles
_____ touch and pressure receptors vs _____ touch and pressure receptors:
fine touch and pressure receptors –provide detailed info about a source of stimulation, including its exact location, shape, size, texture, and movement. EXTREMELY SENSITIVE AND HAVE NARROW RECEPTIVE FIELDS
crude touch and pressure receptors – provide poor localization and have large receptive fields that give little information about the stimulus
types of TACTILE RECEPTORS
Name 6 types of tactile receptors in the skin
-free nerve endings
-root hair plexus
-tactile discs (merkel discs)
-tactile corpuscles
-lamellated corpuscles
-ruffini corpuscles
FREE NERVE ENDINGS that provide touch sensations are _____ receptors with ____ receptive fields
tonic receptors with small receptive fields
where are free nerve endings sensitive to touch located?
between epidermal cells
where are root hair plexuses located?
explain how they work
wherever hairs are located
when a hair is displaced, the movement of its follicle distorts the sensory dendrites and produces action potentials
do root hair plexuses adapt rapidly? explain
yes!
we only feel our clothing when we move or consciously think on tactile sensations from the skin
are tactile discs (merkel discs) sensitive? are they tonic or phasic?
HIGHLY SENSITIVE. tonic receptors with small receptive fields. located in stratum basale of the ksin
where are tactile corpuscles most abundant?
in the eyelids, lips, fingertips, nipples, and external gentilia
which tactile receptors are sensitive to DEEP pressure and are located in the fingers, mammary glands, and external gentilia?
lamellated corpuscles
Which corpuscles are located in the DEEP dermis, are Tonic, and show little to no adaptation?
Ruffini corpuscles
Our sensitivity to tactile sensations may be altered by…
infection, disease, or damage to sensory neurons or pathways
explain how sensory losses can have clinical significance
sensory losses with clear regional boundaries can indicate trauma to spinal nerves.
for example, sensory loss within the boundaries of a dermatome can help identify the spinal nerve
explain tickle and itch sensations
-closely related to the sensations of touch and pain
-receptors are free nerve endings
-unmyelinated Type C axons
baroceptors monitor changes in…
pressure in an organ
a baroceptor consists of….
free nerve endings that branch into the walls of distensible organs. when the pressure changes, the elastic walls of the tract recoil or expand, which distorts the dendritic branches and alters the rate of action potential generation
do baroceptors adapt rapidly?
yes
they respond immediately to a change in pressure, but adapt rapidly
baroceptors in the lungs monitor what?
the degree of lung expansion
name the 3 major groups of proprioceptors
-muscle spindles
-golgi tendon organs
-receptors in joint capsules
proprioceptors monitor…
the position of joints, the tension in tendons and ligaments, and the state of muscular contraction
muscle spindles monitor what? what type of receptors are they?
muscle spindles are a type of proprioceptor.
they monitor skeletal muscle length and trigger stretch reflex (ch 13)
explain golgi tendon organs
type of proprioceptor, similar in function to ruffini corpuscles but are located at the joint between a skeletal muscle and its tendon.
in a golgi tendon organ, dendrites branch repeatedly and wind around the collagen fibers of the tendon. these receptors are stimulated by tension in the tendon
THEY MONITOR THE EXTERNAL TENSION DEVELOPED DURING MUSCLE CONTRACTION
Your sense of body position results from the integration of….
information from receptors in joint capsules, information provided by muscle spindles, golgi tendon organs, and the receptors of the internal ear
do proprioceptors adapt to constant stimulation?
NO
each receptor continually sends information to the CNS. Only a small portion of arriving proprioception information reaches our awareness. – most is subconscious
chemoreceptors respond only to….
water-soluble and lipid-soluble substances that are dissolved in bodily fluids
Do chemoreceptors exhibit peripheral adaption?
yes and sometimes central adaptation
name 2 specific regions where chemoreceptors are located
carotid bodies and aortic bodies – monitor the pH and carbon dioxide in arterial blood
the afferent fibers leaving the carotid or aortic bodies reach the respiratory centers by travelling within which cranial nerves?
IX and X
glossopharyngeal and vagus
what is a first order neuron?
a sensory neuron that delivers information to the CNS
The cell body of a first order neuron is located where?
in a dorsal root ganglion or cranial nerve ganglion
in the CNS, the axon of a first order neuron synapses on an interneuron known as….
a second order neuron which may be located in the brainstem or spinal cord
when will a 3rd order neuron come into play?
if the sensation is to reach our awareness, the second order neuron synapses on a third order neuron
WHERE is the 3rd order neuron located?
in the thalamus
the right side of the thalamus receives information from the ____ side of the body.
explain
LEFT
Somewhere along its length, the axon of the second order neuron crosses over to the opposite side of the CNS
The axons of third order neurons synapse where?
on neurons of the primary sensory cortex of the cerebral hemisphere (reaches our consciousness!)
name 3 MAJOR SOMATIC SENSORY PATHWAYS
- the spinothalamic pathway
- the posterior column pathway
- the spinocerebellar pathway
spinothalamic tract
where does it begin and end?
is it a sensory or motor pathway?
begins with spino, so it starts in the spinal cord.
ends in thalamic, so it ends in the thalamus
must be an ascending sensory tract
where does the corticospinal tract begin and end?
begins with cortico, so it begins in the cerebral cortex and ends in the spinal cord
the spinothalamic pathway carries sensations of….
poorly localized touch, pain, temperature, and pressure
the perception that an arriving stimulus is painful rather than cold, hot, or vibrating depends on what?
which second order and third order neurons are stimulated
what is phantom limb pain and what causes is
when an individual experiences painful sensations that are not real.
caused by activity in the sensory neurons or interneurons in the spinothalamic pathway
what is referred pain?
give examples
when an individual feels pain in an uninjured part of the body when the pain actually originates at another location.
the strong visceral pain sensations arriving at the spinal cord (the pain that SHOULD be felt) can stimulate interneurons that are part of the spinothalamic pathway. activity in these interneurons leads to the stimulation of the primary sensory cortex, so an individual feels pain in a specific part of the body surface
ex: pain of heart attack is felt in the left arm
appendicitis is first felt in the naval, and then in the right lower quadrant
the posterior column pathway carries sensations of…
precise touch and vibrations, and proprioception
name the spinal tracts involved in the posterior column pathway
fasciculus gracilis and fasciculus cuneatus
crude touch and pressure sensations use which spinothalamic tract?
pain and temperature sensations use which spinothalamic tract?
crude touch and pressure = anterior spinothalamic tract
pain and temp = lateral spinothalamic tract
(posterior column pathways)
axons carrying sensations from the INFERIOR half of the body ascend within the ____ and synapse in the ______
ascend within the fasciculus gracilis and synapse in the nucleus gracilis of the medulla oblongata
(posterior column pathway)
axons carrying sensations from the SUPERIOR part of the upper trunk, limbs, and neck ascend in the ________ and synapse in the _______
ascend in the fasciculus cuneatus and synapse in the nucelus cutaneatus
the crossing of an axon from the left to the right side or vice versa is called…
decussation
processing in the _____ determines whether you perceive a given sensation as fine touch, pressure, or vibration
thalamus
our ability to localize the sensation – to determine precisely where on the body a specific stimulus originated – depends on…
the projection of information from the thalamus to the primary sensory cortex
the area of sensory cortex devoted to a particular body region is proportional to….
NOT THE REGION’S SIZE – but the number of sensory receptors there
are more cortical neurons required to process sensory information from the tongue or the bakc?
the tongue because the size of the region does not matter.
only the number of receptors and the tingue has thousands
does information from the spinocerebellar pathway reach our consciousness?
no
what kind of information does the spinocerebellar pathway relay?
information about muscle, tendon, and joint positions
what are the tracts of the spinocerebellar pathway
the posterior cerebellar tracts and the anterior spinocerebellar tracts
the sensations carried by anterior spinocerebellar trunks……
reach the cerebellar cortex via the superior cerebellar punduncle.
the axons crossover and extend to the cerebellum and then crossover again within the cerebellum, synapsing on the SAME SIDE of the stimulus
called double cross
the information carried by the spinocerebellar pathway ultimately ends up…
at the Purkinje cells of the cerebellar cortex
cranial nerves ________________, carry visceral sensory information from the mouth, palate, larynx, pharynx, trachea, esophagus, and associated vessels and glands
V,VII,IX,X
Visceral sensory information is collected by…
interoceptors monitoring visceral tissues and organs
(nociceptors, thermoreceptors, chemoreceptors, baroreceptors, tactile receptors)
cranial nerves V,VII,IX,X carry visceral sensory information from the mouth, palate, pharynx, larynx, esophagus, etc
this information is delivered to the ____
solitary nucleus – a large nucleus on each side of the medulla oblongata
solitary nucleus is a mojor processing and sorting center for visceral sensory information
