Chapter 07 Sensory Physiology L2

widespread inhibition/interneurons/motor neurons of the antagonistic muscles/opposite/

-Golgi Tendon Organs (GTO)- • Branches of the afferent neuron from the GTO cause __________________ of the contracting muscle via _______________ (Path A) • They also stimulate __________________ (Path B) • Note: this reciprocal innervation is the ______________ of that produced by the muscle spindle afferents which were excitatory to extensors/inhibitory to flexors

local homeostatic control of muscle length/local homeostatic control of muscle tension/higher-level motor control/modify ongoing motor programs/

-Golgi Tendon Organs- This difference reflects the different functions of the two systems: Muscle spindles provides _____________________. Golgi tendon organs provides ____________________. Plus, the activity of afferent fibers from these two receptors supplies the ______________ systems with information about muscle length and tension→ used to _____________________.*

slightly bowed in the resting state/exerted on the tendon/straightens/distorts/active contraction/

-Golgi Tendon Organs- • These collagen bundles are ________________. • When muscles contract, tension is ____________________. • This tension ______________ the collagen bundles and _____________ the receptor endings, activating them. • The tendon is typically stretched much more by an _______________ of the muscle than when the whole muscle is passively stretched. • So, the Golgi tendon organs discharge in response to the tension generated by the contracting muscle and initiate action potentials that are transmitted to the CNS

pulls/greater the rate of receptor firing/

-Length-Monitoring Systems- An external force that stretches the muscle also __________ on the intrafusal fibers, stretching them and activating their receptor endings. The more or the faster the muscle is stretch, the _______________________.

reduce the available sensory information/alpha-gamma co-activation/large-diameter alpha motor neurons/gamma motor neurons/

-Length-Monitoring Systems- If muscles were always activated as in (b), slackening of muscle spindles would _____________________ about muscle length during rapid shortening contractions. A mechanism called ___________________ prevents this loss of information. Extrafusal fibers of a muscle are activated by ____________________, and the two ends of the intrafusal muscle fibers are innervated by smaller diameter neurons called ______________________.

slows the rate of firing in the stretch receptor/

-Length-Monitoring Systems- In contrast, if action potentials along motor neurons cause contraction of the extrafusal fibers, the resultant shortening of the muscle removes tension on the spindle and _____________________________.

increases the sensitivity of a muscle to stretch/Co-activating gamma motor neurons/alpha motor neurons/continuously available/plan & program future/

-Length-Monitoring Systems- So, activating gamma motor neurons alone __________________________. _____________________ along with __________________ prevents the central region of the muscle spindle from going slack during a shortening contraction → ensures info about muscle length is _____________________ → provides info for adjustments during ongoing actions & to ___________________ movements.

close together/interneurons/directly by neurons/not large or strong enough/tension and stretch/

-Length-Monitoring Systems- The cell bodies of alpha and gamma motor neurons to a given muscle lie ______________ in the spinal cord or brainstem. Both types are activated by _____________ in their immediate vicinity and sometimes _________________ of the descending motor pathways. The contractile ends of the intrafusal fibers are ________________ to contribute to the force or shortening of the whole muscle But they can maintain the ________________ in the central receptor region of the intrafusal fibers

sensory/Skeletal muscles/antagonistic actions/Tendons, joints and skin/length & tension/movement/movement/afferent input/

-Local Afferent Input- Afferent fibers that signal interneurons & motor neurons carry info from ___________ receptors located in three places: -________________ controlled by motor neurons -Other nearby muscles, such as those with _________________. -_________________ of the body parts affected by the action of the muscle These receptors monitor the ______________ of muscles, _____________ of joints, and the effect of ______________ on the overlying skin. So, the movements give rise to _______________ that influences how the movement proceeds→fine adjustments.

length and the rate of change/Muscle spindles/connective tissue capsule/Intrafusal fibers/extrafusal fibers/extrafusal fibers/

-Local Afferent Input: Length-Monitoring Systems- Stretch receptors (muscle spindles) embedded within muscles monitor muscle _________________ in the muscle length _______________: consist of peripheral endings of afferent nerve fibers (stretch receptors) wrapped around modified muscle fiber (called intrafusal muscle fibers), several of which are enclosed a __________________. -______________ do not contribute much to the force of muscle contractions -Muscle spindles are attached to ______________ by connective tissue -The bulk of the muscle fibers that generates its force and movements are called ________________.

ascending anterolateral pathway/spinothalamic/dorsal/anterolateral/thalamus/cortically projecting/pain and temperatures/

-Neural Pathways of the Somatosensory System- • The ___________________, also called the _____________ pathway, makes its first synapse between the sensory receptor neuron and a second neuron located in the gray matter of the _________ horn of the spinal cord. • This second neuron crosses to the opposite side and projects through the _______________ column of the spinal cord to the ____________, where it synapses on __________________ neurons. • The anterolateral pathway carries ________________ information.

the CNS/neurons/ the specific ascending pathways/somatosensory/interneurons/nonspecific ascending pathways/ascending anterolateral pathway, (AKA spinothalamic pathway) /Dorsal column pathway/

-Neuronal Pathways of the Somatosensory System- Organization of somatosensory systems -Afferent axons (from neuron #1) from the somatic neurons enter ___________ and synapse on __________. -These neurons (neuron #2) form _________________ projecting primarily to the _______________ cortex via the brainstem and thalamus (neuron #3). Afferent axons also synapse on ______________ that give rise to the ___________________. There are two major somatosensory pathways from the body; these pathways are organized differently from each other in the spinal cord and brain -_________________________ -_________________________

Pharmacological agents (NSAIDs like Tylenol®)/Morphine (opioids)/Acupuncture/Transcutaneous Electrical Stimulation (TENS)/Massage/

-Pain Management- We use many mechanisms to achieve pain relief: -___________________ and _______________ (Non-steroidal anti-inflammatory drugs) -________________ (seems to be linked to activation of the endogenous opioid pathways) -_________________________ works because the stimulation of non-pain, low-threshold afferent fibers (e.g., the fibers from touch receptors) leads to the inhibition of neurons in the pain pathways. ________________: You perform a low-tech version of TENS when you vigorously rub your scalp at the site of a painful bump on the head.

Analgesia/stimulation/analgesia/inhibiting/descending/

-Pain Management- _______________ is the selective suppression of pain without effects on consciousness or other sensations. The body has natural mechanisms to achieve pain relief: -Electrical stimulation of specific areas of the CNS can produce profound reduction in pain, called _______________-produced ___________; occurs by ______________ pain pathways by _____________ pathways from these specific brain areas

serotonin or norepinephrine/opiate/Presynaptic opiate receptors/

-Pain Transmission- Descending inputs from the brainstem release ____________________ (1.), stimulate dorsal horn interneurons to release ___________ neurotransmitters (NT) (2). ___________________ inhibit neurotransmitter release from afferent pain fibers (3.), & postsynaptic receptors inhibit ascending neuron (4.). Morphine inhibits pain in a similar manner.*

ascending/substance P (neuropeptide)/glutamate/thalamus/somatosensory cortex (note: three neurons)/

-Pain Transmission- • The primary afferents having nociceptor endings synapse on _______________ neurons after entering the CNS. • Painful stimulation releases _____________ or ______________ from afferent fibers in the dorsal horn of the spinal cord. • Neurons in the spinal cord/brainstem send their axons to the _________________. The thalamus relays the information to the ___________________.

Hyperalgesia/for hours/severe burn injuries/past experiences, suggestion, emotions (particularly anxiety), and the simultaneous activation of other sensory modalities/not solely a physical property of the stimulus/

-Pain- ______________ is an increased sensitivity to painful stimuli. The pain can last ____________ after the original stimulus is over. (This type of pain response is common with ______________.) Pain can be altered by _____________________. Thus, the level of pain experienced is ____________________.

sensation of pain/nociceptors/free nerve endings (called nocicetors)/small-diameter/Intense mechanical deformation/ Extremes of temperature/chemicals/H+/cells of the immune system/specific ligand-gated ion/

-Pain- • A stimulus that causes - or could potentially cause - tissue damage usually elicits a _________________. • Pain receptors are known as _____________, which are ________________ of ________________ afferent neurons with little or no myelination. They respond to: • ______________________, •________________________ • Many _____________ - including ______, neuropeptide transmitters, bradykinin, histamine, cytokines, and prostaglandins, several of which are released by damaged cells • Some of these chemicals are secreted by ___________________ that move into the injured area • These substances act by binding to ____________________.

inhibited/removing the inhibition (allowing a greater degree of signal transmission)/increasing the inhibition (blocking the signal more completely)/

-Pain- • In the pain pathways, the afferent input is continuously _______________ to some degree. • This allows either __________________ or _____________________.

visceral and somatic/converge/Excitation of the somatic afferent/

-Referred Pain- Referred pain occurs because both _______________ afferents often ___________ on the same neurons in the spinal cord. _____________________ fibers is the more usual source of afferent discharge, so we "perceive" the location of receptor activation as the somatic source even though, in the case of visceral pain, the perception is incorrect

may lead to the phenomenon of referred pain/a site other than the injured or diseased tissue/pain in the left arm/

-Referred Pain- • When incoming nociceptive afferents activate interneurons, it ______________________ - The sensation of pain experienced at _____________________. • For example, during a heart attack, a person often experiences _______________.

posture & movement/muscle-spindle stretch receptors/golgi tendon organs/skeletal muscle/tendons/

-Sense of Posture and Movement- Senses of _________________ are complex Receptors responsible for these senses are the ___________________ and __________________. -Muscle spindles - embedded in ______________. -Golgi tendon organs- in _____________.

Golgi tendon organ/muscle to bone/muscle tension/Vision and vestibular organs (sense organs for balance)/Mechanoreceptors/Kinesthesia/

-Sense of Posture and Movement- _______________ - modified nerve endings located in fibrous tendons (connect ____________) Monitor ______________. _____________________ support the senses of posture and movement ________________ in the joints, tendons, ligaments, and skin also play a role. _________________ - the sense of movement at a joint

spinal cord/brainstem/somatosensory cortex/right/not travel to the brain/directly via cranial nerves (review Table 6-8)/

-Somatosensory Pathways- • Note that both pathways cross from the side where the afferent neurons enter the CNS to the opposite side -Anterolateral system in the _____________. -Dorsal column system in the ______________. • Consequently, sensory pathways from somatic receptors on the left side of the body terminate in the ________________ of the _________ cerebral hemisphere. • Somatosensory information from the head and face does _______________ within these two spinal cord pathways; it enters the brainstem ____________________.

Labeled Lines/View Figure

-Specific Pathways & Somatotopic Arrangement- ____________: Each pathway is a modality, within each pathway location of body is coded by its location within the pathway

inhibit/morphine/opioid receptors/Cymbalta/NT (serotonin/norepinephrine)/opiate release/

-Stimulation-Produced Analgesia- • Thus, these opioids __________ the propagation of pain signals from afferent nerves to the higher levels of the CNS. • So, treating a patient with ____________ can provide relief in many cases of intractable pain by binding to and activation _____________ at the level of entry of the active nociceptor neurons. • _____________ is thought to act on the descending neurons by inhibiting ______________ reuptake→ NT stays in synapse longer→ promotes _____________.

inhibitory interneurons/antagonistic muscle/polysynaptic/reciprocal innervation/

-Stretch Reflex- In path B, the branches of the afferent nerve fibers from stretch receptors end on __________________. When activated, these inhibit the motor neurons that control _______________ whose contraction would interfere with the reflex response. In the knee jerk, neurons to muscle that flex the knee are inhibited. This component of the reflex is _______________. The activation of neurons to one muscle with the simultaneous inhibition of neurons to its antagonistic muscle is called ______________________. This is characteristic of many movements, not just the stretch reflex.

motor neurons of synergistic muscles/assists the intended motion/

-Stretch Reflex- In path C, the branches of the afferent nerve fibers from stretch receptors end on ___________________. Synergistic muscles- muscles whose contraction __________________. Eg in knee jerk reflex: other muscles that extend the leg.

monosynaptic reflex/Stretch receptors/polysynaptic/

-Stretch Reflex- Note: afferent nerve fibers synapse directly on motor neurons that control that muscle without any interneurons→_________________. ________________ have the only known monosynaptic reflex arcs All other reflex arcs are _______________, they have at least one interneuron- and usually many- between the afferent and efferent neurons.

changes in muscle length/continues to the brainstem/form the next link/motor control/slow, controlled movements/conscious perception of the position of a limb/

-Stretch Reflex- Path D is not explicitly part of the stretch reflex this path sends info about ___________________ to higher centers This axon of the afferent neuron ___________________ and synapses there with interneurons that ___________________ in the pathway that conveys information about the muscle length to areas of the brain dealing with _______________. This info especially important during __________________ such as performing an unfamiliar action. Also provide information that contributes to the ________________________.

thigh muscles/all the stretch receptors/burst of action potentials/excitatory/these same muscles/stimulated/contract/afferent fibers, the balance of synaptic input to the motor neurons, the motor neurons, the neuronmuscular junction and the muscles/

-Stretch Reflex- This stretches the ____________ and ______________ within these muscles are activated This stimulates a _________________ in the afferent nerve fibers from the stretch receptors. These action potentials activate ___________ synapse on the motor neurons that control ______________. The motor units are ____________ and the thigh muscles _____________ causing the patient's lower leg to extend knee jerk. Tells the physician that the _____________________________ are functioning normally.

divide into branches that take different paths/excitatory/stretch reflex (AKA the knee jerk)/routine medical exam/patellar tendon/extensor muscles/tibia/

-Stretch Reflex- • When afferent fibers from muscle spindles enter the CNS, they ___________________________. • One path (A), makes _____________ synapses directly onto motor neurons that return to the muscle that was stretched completes a reflex arc, called the ______________________. • Part of a _________________. • Examiner taps the ______________, which connects the ______________ in the thigh to the ___________ in the lower leg.

Different isoforms of TRP/ flux of a nonspecific cation current/depolarizing/labeled lines/

-Temperature- __________________ channels have gates that open in different temperature ranges These channels allow _________________, but is dominated by the _______________ inward flux of Na+ → APs. APs travel along ______________ to the brain where the temperature stimulus is perceived

overlap/chemical ligands/capsaicin and ethanol (TRPV1) or menthol (TRPM8)/

-Temperature- • Temperature ranges __________ among the different channels • Some TRP proteins can be opened by ____________. • Example: __________________ can be perceived as hot and cold, respectively

small-diameter afferent/little or no myelination/ion channels (temperature-gated)/transient receptor potential (TRP)/

-Temperature- •Information about temperature is transmitted along _________________ neurons with __________________. •Free nerve ending (no specialization: C) -The temperature sensors are _________________ in the plasma membrane of the axon terminals -These receptors belong to a family of proteins called ________________ proteins (ion channels)

tension/endings of afferent nerve fibers (receptor)/collagen bundles/muscle/

-Tension-Monitoring Systems- • Receptors employed in ____________ monitoring are the Golgi tendon organs • Golgi tendon organs are _________________ that wrap around _______________ in the tendons near their junction with the _____________.

crosses in the brainstem/thalamus/somatosensory cortex/body movements, limb positions, fine touch discrimination and pressure/

-The Dorsal Column Pathway- The secondary neuron then __________________ as it ascends. Like the anterolateral pathway, the second synapse is in the ____________, from which projections are sent to the _________________. Carries information for ___________________.

dorsal column pathway/section of white matter (the dorsal columns of the spinal cord)/ascend to the brainstem/

-The Dorsal Column Pathway- • The second major pathway for somatic sensation is the _________________. • Also named for the _________________ through which the primary sensory neurons project. • In the dorsal column, the sensory receptor neurons __________________, where the first synapse occurs.

the peripheral location of the receptors that give input to the pathways (somatotopic organization)/

-The Somatosensory Cortex- In the somatosensory cortex, the endings of the axons of the specific somatic pathways are grouped according to ____________________. Labeled lines end a specific sites in cortex.

finger, thumb, and lips/largest/overlap/

-The Somatosensory Cortex- The parts of the body that are most densely innervated - ________________ - are represented by the __________ areas of the somatosensory cortex. There are qualifications, however, to this seemingly precise picture. There is considerable ___________ of the body part representations, and the sizes of the areas can change with sensory experience.

dynamic nature/cortical areas/ "rewired"/face/

-The Somatosensory Cortex- The phantom limb phenomenon described earlier is a good example of the ____________ of the somatosensory cortex. Studies of upper-limb amputees show that _____________ formerly responsible for a missing arm and hand are commonly __________ to respond to sensory inputs originating in the ___________ (note the proximity of the cortical regions representing these areas. As the somatosensory cortex undergoes this reorganization, a touch on a person's cheek is often perceived as a touch on his or her missing arm.

flexor muscles/extensor muscles/ipsilateral (on the same side of the body)/away from the harmful stimulus/withdrawal reflex/

-The Withdrawal Reflex- Painful stimulation of the skin, as occurs from stepping on a tack, activates the ____________ and inhibits the ______________ of the ______________ leg. The resulting action moves the affected limb __________________, and is thus known as a ___________________.

contralateral leg (opposite side of the body)/activated/inhibited/the contralateral leg to support the body's weight/

-The Withdrawal Reflex- Painful stimulation of the skin, as occurs from stepping on a tack, activates the flexor muscles & inhibits the extensor muscles of the ipsilateral (same side of the body) leg. ? This moves the affected limb away from the harmful stimulus, called a withdrawal reflex. ? The same stimulus causes an opposite response in the ________________________ from the stimulus). Motor neurons to extensors are ____________ while the flexor muscle motor neurons are _____________. This crossed-extensor reflex enables ________________________ as the injured foot is lifted by flexion.