Chp 13 Flashcards
Every time you hear receptor what system are we talking about? Afferent or efferent
afferent
Mechanoreceptors
are found in areas where there are any physical changes to the area. Are always keeping track of any physical changes
Thermoreceptors
any changes in heat
Modality
each input is a specific type of sensation: temperature, pain, pressure, touch, body position, equilibrium, hearing, vision, smell, taste
individual sensory neurons generally carry only one modality
individual sensory neurons generally carry only one
modality
Selectivity of Receptors
sensory neurons respond strongly to one type of stimulus and weakly or not at all to other types
some respond accidentally to other types of stimuli – rubbing one’s eyes mechanically stimulates the eyes’ light receptors in the retina is an example of
Selectivity of Receptors
transduction
requires a sensory receptor cell or organ which responds to specific stimuli and converts them into receptor/generator potentials
integration generally occurs?
in the cerebral cortex
types of sensory receptors classified by stimulus
mechanorecpetors
thermoreceptors
photoreceptors
chemoreceptors
types of sensory receptors classified by location
exteroreceptors
interoreceptors
proprioreceptors
Mechanoreceptors
mechanical pressure or stretching
generate action potentials when deformed
Thermoreceptors
changes in temperature
Nociceptors
pain due to physical or chemical damage to nearby tissue
Photoreceptors
light strikes retinal receptor cells
generates action potentials in response to light energy
Chemoreceptors
certain specific chemical molecules are detected in the mucous fluids of the GI & respiratory tracts, or in the blood or other body fluids
Exteroceptors
located at or near the body’s surface
provide information about the external environment
Thermoreceptor sends temp to where in the brain
hypothalamus cause it deals with temperature
Interoceptors (visceroceptors)
found in blood vessels, connective tissues, and organs
provide information about the internal environment
If there was physical damage or chemical damage to the tissue like stomach acid eroding up will alert what receptor
nociceptor
Photoreceptors are found
in our eyes
Proprioceptors
located in muscles, tendons, joints and the internal ear
provide information about gravity, body and limb positions and skeletal muscle movements
Changes in any kind of chemical composition of things internally. PH of blood stream triggers what receptor
Chemoreceptors
Baroreceptors are found where
In the cardiovascular system
Baroreceptors keep track of
all of the pressure in blood vessels
Receptors found on joint endings, tendons and internal ear. That tell us our balance and send signals to the cerebellum
proprioceptors
Anesthesia means
lack of sensation. Blocking the afferent pathway from being read or intergrated
gas agents that affect the brain or spinal cord from receiving any messages
general anesthesia
Anesthesia that only effects that peripheral nerve
local anesthesia
Can be ingested or applied topically.
Nonsteriodal antiinflamittory. Ibprofen… advil.
Analgesia
Can start to mimic our own bodies natural endorphants
analgesic
anagesic reduce
the perception of pain by blocking the nociceptors from sending the messages to the brain
the bodies natural ability to block nociceptors
endorphins
endorphins suppress
pain
Local anesthesia
– drugs injected near peripheral nerves inhibit the opening of gated sodium channels, preventing local transmission of action potentials
Analgesia vs anethesia
analgesia reduce the perception of pain by blocking nociceptors. anesthesia nerves inhibit the opening of gated sodium channels, preventing local transmission of action potentials
Paresthesias
abnormal sensations (burning, tingling, numbness) not related to normal stimulation, e.g., mechanical pressure on nerves in your leg puts your foot “to sleep”
alerts you to thinking nerve pain on the efferent or afferent pathway
parasthesias
dermatome
is if you were to follow the spinal cord and nerve roots that come off of it. Each area has a pattern where the nerve innervates the skin. Only for cutaneous branches of the spinal nerve.
why are dermatomes important for a clinical setting
to determine which level is effected if you have nerve damage
Reflex Activity 5 Steps
1) Receptor
2) Sensory neuron
3) Integrating center
4) Motor Neuron
5) Effector
Is the reflex arch ipsilateral or contralateral
ipsilateral, because it never crosses over to the other side of the spinal cord. The afferent and efferent pathways are on the same side.
Stretch receptors are know as and found
golgi tendon organ
inborn in all of our muscles. Rectus femoris.
Along the muscle are these stretch receptors cause an automatic contraction to protect the muscle.
dendrites or other sensory structures respond to changes in the environment
receptor (step 1)
conducts an impulse from a receptor to its axon terminals
sensory neuron (step 2)
some region within the CNS
simple - monosynaptic (2 cells only: sensory and motor neurons)
complex – polysynaptic (> 2 cells: interneurons involved)
integrating center (step 3)
impulses from integrating center to an effector
motor neuron (step 4)
body part (muscle or gland) which responds to the motor nerve impulse
effector (step 5)
Areas of skin innervated by the cutaneous branches of each pair of spinal nerves
Each pair also provides some service to the region of the spinal nerve above and the spinal nerve below (redundancy)
dermatomes
contain both sensory and motor fibers
mixed nerves
endoneurium
around individual processes
perineurium
around fascicles
individual nerve fibers with their endoneurium
epineurium
outermost covering around entire peripheral nerve
First 2 pairs of nerves originate from the
(olfactory, optic)
forebrain
Remaining 10 pairs of nerves originate from the
brain stem
are spinal nerves motor or sensory
both
each pair of spinal nerves serve
a particular region of the body
dorsal ramus - supplies
supplies posterior body trunk
ventral ramus - supplies the
rest of body trunk and the limbs
meningeal branch - supplies the
meninges and blood vessels within meninges
a rapid, predictable, automatic response to a stimulus
reflex
is unlearned, unpremeditated, and involuntary
reflex
reflexes are involved in
homeostasis
two fundamental types of reflexes
somatic and autonomic
somatic reflexes
produce contraction of skeletal muscle
autonomic (visceral) reflexes
generally, they are not perceived consciously
produce responses by smooth muscle, cardiac muscle, glands to adjust conditions of the internal environment
muscle spindles and Golgi tendon organs
receptors
contraction of the skeletal muscle reduces tension
on the muscle spindle
Remember that if a muscle is being stretched, the stretch is caused by the contraction of its
antagonist
This sensory proprioception information contributes to maintaining
proper muscle tone
flexor reflex causes an
automatic withdrawal from the dangerous stimulus
Flexor reflexes are
polysynaptic, ipsilateral, and segmental
crossed extensor reflexes.m flexion of a body part is often balanced by
extension of the same body part on the opposite side of the body
Cranial Nerve I
name and function
olfactory- carries afferent impulses for the sense of smell
olfactory fibers run through
the olfactory bulb and terminate in the primary olfactory cortex
Cranial Nerve II
name and function
Optic- by carrying afferent impulses for vision
Otic nerve pathway
pass through the optic canals. converge at the optic chiasma. Continue to the thalamus where they synapse
Cranial Nerve III
name and function
Oculomotor- Functions in raising the eyelid, directing the eyeball, constricting the iris, and controlling lens shape
Cranial Nerve IV
name and function
trochlear- Primarily a motor nerve that directs the eyeball
Trochlear nerve pathway
Fibers emerge from the dorsal midbrain and enter the orbits via the superior orbital fissures; innervate the superior oblique muscle
Cranial Nerve V
name and function
Trigeminal-Conveys sensory impulses from various areas of the face ophthalmic, (V1) and maxillary (V2), and supplies motor fibers mandibular (V3) for mastication
Cranial Nerve VI name and function
Abdcuens- Primarily a motor nerve innervating the lateral rectus muscle
Cranial Nerve VII
name and function
Facial nerve-
Motor functions include facial expression, and the transmittal of autonomic impulses to lacrimal and salivary glands
Sensory function is taste from the anterior two-thirds of the tongue
Mixed nerve with five major branches
facial
Cranial Nerve VIII. Name and function
Vestibulocochlear- Two divisions – cochlear (hearing) and vestibular (balance)
Functions are solely sensory – equilibrium and hearing
Cranial Nerve IX
name and function
Glossopharyngeal
Nerve IX is a mixed nerve with motor and sensory functions
Motor – innervates part of the tongue and pharynx, and provides motor fibers to the parotid salivary gland
Sensory – fibers conduct taste and general sensory impulses from the tongue and pharynx
Cranial Nerve X Name and function
Vagus-The Vagus is a mixed nerve
Most motor fibers are parasympathetic fibers to the heart, lungs, and visceral organs
Its sensory function is in taste
The only cranial nerve that extends beyond the head and neck
vagus
Cranial Nerve XI name and function
Accessory
Primarily a motor nerve
Supplies fibers to the larynx, pharynx, and soft palate
Innervates the trapezius and sternocleidomastoid, which move the head and neck
Cranial Nerve XII
Hypoglossal
Innervates both extrinsic and intrinsic muscles of the tongue, which contribute to swallowing and speech
Adaptation by Sensory Receptors is due to
a change in sensitivity to a long-lasting stimulus
primarily by rapidly-adapting phasic receptors
little adaptation by slowly-adapting tonic receptors
primarily by rapidly-adapting phasic receptors
pressure, touch, hearing, smell
adapt very quickly, i.e., respond less if the stimulus remains constant
allows us to shut out background “noise”
little adaptation by slowly-adapting tonic receptors
pain, body position, chemicals in the blood or CSF
adapt slowly, continue to respond even when the stimulus remains constant
continuous input is useful for some modalities because the body needs to make continuous responses to that kind of information
how many pairs of spinal nerves originate from the spinal cord
31
All are mixed (m/s) nerves
Spinal Nerves
Thousands of fibers per spinal nerve
Each pair serves a particular region of the body
Each pair also provides some service to the region supplied by the spinal nerve above it and the spinal nerve below it (redundancy)
spinal nerves
dorsal ramus supplies
posterior body trunk
ventral ramus supplies
the rest of body trunk and the limbs
what nerves are very short, they divide almost immediately
spinal nerves
meningeal branch - supplies
the meninges and blood vessels within meninges
Patellar Reflex
monosynaptic
ipsilateral (same side)
segmental (at one level of the spinal cord)
polysynaptic component – for reciprocal inhibition of the antagonist
input from the Golgi tendon organs are sent to the
cerebellum and the cortex
Golgi deep tendon reflex inhibits the
agonist
Golgi deep tendon reflex excites the
antagonist
a pull on the limb, extending it, will trigger the reflex
flexor
an increase in muscle tension in the tendon activates receptors in what organ
(Golgi tendon organ)
