"A critical component for the transmmission of sensory information to the brain as well as fro the regulation of motor and autonomic functions"
"It receives sensory information from somatic and visceral receptors through dorsal roots, transmits this information to hhigher centers of the brain through ascendign tracts, receives signals from higher enters through descending tracts, and transmits the signals to somatic and visceral target sites via the ventral roots"
Major neurotransmitter associated with motor functions
"Our ability to detect forms, images, colors, and movement of objects is derived from the functions of the visual system. The initial processing of light signals received by the photreceptors occurs in the retina. The axons emerging from teh retina terminate in a relay nucleus located in the dorsal thalamus. The neruons located in the thalamic relay nculeus, in turn, project to the visual cortex where processing occurs for visual perception" (272).
Receptor organ= eye
Visual-imply visible spectrum of light
Gamma rays-solar radiatiion light
How can we take and convert them into action potentials?
Diff. frequencies of wavelenght corresond to certain frequency of action potentials
Structure of eye has become iconic for debates (evolution vs. creationist) philosophical implications
Three layers that enclose the eye
1. Outermost layer= sclera ("tough white fibrous tissue")
anterior portion= cornea= "is transparent and permits light rays to enter the eye" continuous with cornea
2. Middle layer= choroid "highly vascularized" "It is continuous with the iris and the ciliary body"
Iris= "The colored portion of the eye that is visible through the cornea. The iris has a central opening, which is called the pupil. The size of the pupil is neurally controlled via the circular and radial muscles of the iris"
"continuous with the iris and ciliary body"
3. Innermost layer= retina "The optic nerve exits the retina at a pale circular region called the optic disc or optic nerve head"
"Because there are no photoreceptors in the otpic disc, it is called the blind spot"
"neural retina is continuous with ora serrata, and noneural retina is continuous with epithelium of the ciliary body"
"The optic nerve exits the retina at a pale circular region called the optic disc or optic nerve head"
"Because there are no photoreceptors in the otpic disc, it is called the blind spot"
Outermost layer: Pigment Epithelium Layer
Rods and Cones
yellowish pigment, "near the lateral edge of the optic disc" "For central (as opposed to periphreal) vision"
Center of macula lies fovea
Depression in the center of the macula lutea, in the retina
"Contains primarily cones"
"The layers of the cell bodies and processes that overlie the photoreceptors in other regions of the retina are displaced [here]"
Devoid of blood vessels
Foveola- small region in the center of fovea
"The fovea, including the foveola, represents the region of retina with highest visual acuity because there is minimum scattering of light rays due to the absence of layers of cells and their processes and blood vessels in this region"
Lack of blood vessels + lack of layers of cell layers + cones= "allow minimal scattering of light rays before tehy strike the photoreceptors"
"Where the optic nerve exits the retina"
"Blood vessels supplying the eye enter via the optic disc"
"Because there are no photoreceptors in the optic disc, it is called the blind spot"
"The space between the lens and the cornea...is filled with a watery fluid called aqueous humor"
"The aqueous humor flows into the anterior chamber through the pupil and provides nutrients to the lens and cornea"
"Located just behind the ciliary body and represents the limits of the neural retina (photoreceptors and other cells associated with sensing and processing of light stimulus)"
Canal of Schlemm
[Aqueous Humor] "is reabsorbed through a specicalized collection of cells (trabeculae) into [this]"
"Located at the junction of the iris and cornea"
Fluid is usually in equillibrium
If not- too much pressure reduces blood supply- glacuoma "is a major cause of blindness"
"A thick, gelatinous material...fills the space between the lens and retina. It contains phagocytes that remove blood and debris in the eye under normal circumstances. In certain situtations, such as aging, the debris particles are too large to be removed by the phagocytes in the virteous humor. These floating debris particles, called floaters, cast shadows on the retina"
Move eyeball within the bony orbit
Attatched to sclera
Travel of light rays
1. "Pass through the cornea, lens, and anterior and posterior chambers and reach the photoreceptors (rods and cones) located in the retina"
Rods and cones
"Convert light into an electrical signal"
"Include outer segment, inner segment, and a synaptic terminal"
Cons: Day vision, loss of decreased visual acuity, acuity of vision, saturate when light is very intense, mediate color vision, high concentration in fovea, less numerous that rods
Focusing of images depends on
"Refraction (bending) of light rays as they pass through the corena and the lens"
"The change in refractive power of the lens is called [this]"
"Radially arranged connective tissue bands hold the lens in place; these bands are called zonule fibers and are attatched to the ciliary muscle. The ciliary muscle forms a ring. When it contracts, the zonule fibers relax, the tension on the lens is reduced, and its shape becomes rounder and thicker, which is suited for near vision. Under normal circumstances, the ciliary muscle is relaxed, the zonule fibers are stretched to exter tension on the lens, and its shape becomes thin and flat, which is suited for distant vision"
Pigment Epithelium layer (outermost part of the retina)
Pigment epithelium layer "consisting of pigmented cubodial cells that contain melanin"
"Tight junctions prevent flow of ions and plasma, connected to choroidal layer"
Have microvilli: "provide nutrition (glucose and essential ions) to photoreceptors and other cells associated with them"
Melanin: "absorbs any light not captured by the retina and prevents it from reflecting back to the retina, which would otherwise result in the degradation of the image. Thus, the pigment epithelium layer protects the photoreceptors from damaging levels of light"
Retinal Detachment: When pigment epithelium detaches from retina "The photoreceptors may be damaged because they may not receive the nutrition that is normally provided by the pigment epithelium layer"
1. Prominent in fovea
2. Sharpness of image
3. Mediate color vision
4. Fast response
5. Conical shape "makes them mroe sensitive to direct axial rays"
1. "Highly sensitive and can detect dim light"
2. Night vision
3. Saturate in daylight
4. Slow response
5. Loss of rods= nightblindness and loss of peripheral vision
More photosensitive pigment than the cones
"Both rods and cones, unlike ganglion cells. do not respond to light with an action potential. Instead, they respond with graded changes in membrane potential."
"Our knowledge of the environment around us depends on the information that we receive from periphreal receptors that are specialized nerve endings of sensory neurons. The major sensory systems include somatic, visual, auditory, vestibular, taste, and olfactor (smell) systems" (pg. 258).
"The sensory neurons in each system project centrally, where they make synapticcontact with tehsecond-order neurons that, in turn, project to higher order neurons"
"Initial contact with our environment occurs at [these], which are specialized neural structures. The sensations experienced by the peripheral receptors include touch, postion of the body, pain, sight, sound, smell, and taste"
"Refers to type of stiumulus (e.g., mechanical, thermal, chemical, visual, or auditory) that activiates sensory receptors"
"The strength of the stimulus determiens the intesnity of sensation" (pg. 258).
"The smallest intensity at which a particular sensation is detected " (pg. 258).
"Is the period of time the sensory stimulation continues"
"Usually, intensity of the sensation diminishes when the stimulus is continuous for an extended period of time"
"Awareness of the sensory experience includes the ability of the subject to identify the site of stimulation adn teh ability to distinguish between stimuli that are applied at close distances"
"The sensory receptor converts a stimulus into neural activity; this conversion invovles a process called [this]. A stimulus induces a generator (or receptor) potential in the receptor membrane. This local potential propagates electrotonically. Usually, the stimulus depolarizes the membrane by opening channels, thus slectively permitting influx of Na+ and efflux of K+. Specific characteristics, such as intensity and duration, are converted into specific patterns of action potentials that are called neural codes" (pg. 258).
"Specific characteristics, such as intensity and duration, are converted into specific patterns of action potentials" (pg. 258).
"The space iin which the sensory receptor is located and where it produces the transduction of the stimuli" (pg. 258).
"The thalamus contains a number of [these] that serve to transmit the sensory information to different sensory receiving areas of the cerebral cortex" Ex: Olfactory system
"Sensations mediated by this system include tactile sensatiolns (touch, pressure, and vibration); perception of joing positon, joint movements, and direction and velocity of joint movements; nonconscious proprioception; pain; and temperature" (pg. 259).
1. "Rhodospin molecules are kept inactive
2. Sodium channels are kept open by cGMP
3. Sodium ions flow into the rods partially depolarizing them
4. Rods continuously release glutamate"
5. In synaptic terminals "Opens Ca2+ channel in synaptic terminal"
6. Release of inhibitory transmitter
7. Bipolar cells inhibited
8. No action potential in cell ganglion
9. No action potential propagation"
1. "Light bleaches rhodospin molecules-results in a conformational change of the retinal part-triggers the stimulation of a G protein (transducin in rods) which activates PDE that hydrolyzes or breaks down or decreases the amount of cGMP
2. As a result, cGMP is broken down and sodium channels close because they are cGMP gated
3. Sodium ions cannot enter rods, and as a result, the rods become hyperpolarized [Receptor potential] not an action potential
4. Glutamate release is blocked"
5. Receptor potential spreads to synaptic terminal via the dendrites connecting bipolar cells and horizontal cells / closure of Ca2+ channels
6. Release of inhibitory transmitter
7. Removal of inhibition (bipolar cells are uninhibited or excited)
8. Graded potential change in bipolar cells
9. May spread to ganglion cells, action potential in ganglion cells
10. Propagation of the action potential to visual cortext in occipital lobe of the brain visual perception"
Phototransduction in Light (outersegment of photoreceptors)
1. "The retinal component of rhodospin absorbs light, which results in a change in the conformation of the photoreceptor pigment, and a G protein (called transducin in rods) is stimulated
2. The G protein [transducin] activates cGMP phosphodieterase (PDE)
3. The activated PDE hydrolyzes cGMP and reduces its cocnetration
4. A reduction in the concentration of cGMP results in closing of the cGMP-gated Na + channels
5. The influx of Na+ is reduced, and the photoreceptor cell is hyperpolarized...The photoreceptors (rods and cones) do not fire action potentials" (pg. 277).
Present in rods
Protein called opsin
retinal= light-absorbing component
Absorbs light determines whether cGMP will be increased (leading to Na+ gated cGMP channels opening and depolarization of the membrane) or substantially reduced (leading to Na+ gated cGMP channels being unopened and hyperpolarization of the membrane)
Located ininner nuclear layer of the retina
The Nature of Sound
Audible vibrations in air pressure
Sound frequency: Number of cycles per second expressed in units called Hertz (Hz)
Cycle: Distance between successive compressed patches
Range:20 Hz to 20,000 Hz
Pitch: High and Low
Intensity: Difference in pressure between compressed and rarefied patches of air
High and Low (tone)
Depends on frequency (measured in Hz)
Depends on amplitude
Depends on overtones
Same loudness, same quality
External or Outer Ear
External or Outer Ear
External auditory canal
Basic Function: "Directs the sound vibrations in the air to the external auditory canal. The sound waves travel through this auditory canal and vibrate the tympanic membrane located at the end of the canal"
Three small bonescalled ossicles "articulate with each other, are suspended in the cavity"
Ossicles include: 1. Malleus (connected to the tympanic membrane)
3. Stapes (shaped like a stirrup, bound to oval window)
"Connected to the nasopharynx through the eustachian tube"
-Stapedius (The Attenuation Reflex)
Function:"To convert sound waves in the air to waves in the fluid in the inner ear"
Pressure: Force by Surface Area
Sound force amplification by ossicles
"If the airwaves bypass the middle ear and reach the oval window directly, only about 3% of the sound would enter the inner ear. The pressure transmitted to the oval window is amplified because 1) the area of the tympanic membrane is much greater than that of the oval window, and 2) greater mechanical efficienicy is provided by the ossilces (malleus and incus) because they act as levers" (pg. 294).
Connects nasopharynx to middle ear
"Helps to equalize air pressure on the inner and outer surfaces of the tympanic membrane and to drain any fluid in the middle ear to the nasopharynx"
Tensor tympani and Stapedius
Located in the middle ear
The Attenuation Reflex"Contraction of these muscles restricts the movement of the tympanic membrane and the footplate of the stapes against the oval window, respectively, and, thus reduces the deleterious effects of loud noises on the delicated middle and inner ear structures"
Function: Adapt ear to loud sounds, understand speech better
1. "Bony labryinth
2. Membranous labrynith
3. Cochela containing theorgan of Corti "
Inner Ear's Bony Labyrinth
2. 3 semicircular canals
All filled with perilymph fluid ("a clear extracelluar-like fluid containing high Na+ [sodium] and lowK+[potassium]concentration"
and semicircular canals represent peripheral components of the vestibular system, which is involved in hearing and is specialized to respond to movements"
"Is involved in hearing and is specialized to respond to airborne sounds"
"Shaped like a conical snail shell"
"Has central tubular conical axis,modiolus"- surrounded b spiral cochlear canal
Cochlear canal: upper scala vestibuli and lower scala tympani
Fluid in the scala vestibula and scala tympani
Fluid in scala media
Endolymph electric potential 80 mV
more positivethat perilymph
Lies within bonyspiral canalof the cochlea
Component of memebranous laybrinth; contains endolymph
"A spiral tube that runs along the outer wall of the bony cochlea and ends at its apex (cupula)"
Flanked by scala vestibula (follows inner contour) and scala tympani (follows outer contour)
Scala tympani ends at round window (separates space from the middle ear)
Scala vestibula "Vibrations of the stapes inresponse to sound waves are transmitted to the scala vestibuli via the oval window"
-Bound by two membranes (Basilar and vestibular)
"These two membranes separate the endolymph contained in the scala media from te perilymph contained in the scalae tympani and vestibuli"
Organ of Corti- sensory organ of [this]
Organ of Corti
Scala media's sensory organ
Contains hair cells= sensory receptors for sound stimuli
Within scala media
Runs along the length of basilar membrane
"Membrane-covered opening that is the intersection of the middle ear and inner ear; bound to the footplate of the stapes of the middle ear by an annular ligament"
Outer hair cell's sterocilia tips are embedded to
"composed of mucopolysaccharidesembedded in a collagenous matrix"
Mechanism of Sound Conduction
1. Sound waves' vibration travels in the external ear down the external auditory canal to the tympanic membrane and causes it to vibrate
2. Vibration travels and causes ossicles and stapes to vibrate (footplate of stapes vibrates against oval window)
"Converts sound waves in air to waves in fluid"
Pressure is amplified when reaching the oval window because area of tympanic membrane is greater than that of oval window and because ossicles act as levers
3. Pressure waves in the perilymph because "noncompressible fluid" enter through scala vestibula and cause the vibration of the basilar membrane
4. How Sound is Converted into an Action Potential:
Upward displacement of basilar membrane= lateral displacement of the stereocilia
influx of K+= depolarization
Triggers opening of Ca2+ voltage-sensitive channels- influx of Ca2+
Release of neurotransmitter resulting in action potential "in the afferent nerve terminal at the base of the hair cell"
5. Downward displacement of basilar membrane= medial displacement of stereocilia= hyperpolarization
Specificity of Basilar Membrane or Tonotopic distribution of responding receptors
Distribution of sensory receptors (hair cells)
Basal portion of basilar membrane responds to high frequencies of sound
Apical aspect= low frequencies of sound
Narrow stiff end near the oval window- high frequency
Wide and flexible end near the helicotrema- low frequency
Thicker- more connective tissue
Where the scalae tympani and vestibuli communicate
"Is essential for maintaining the positon of the body in space, which, in turn, is important for coordination of motor responses, eye movements, and posture"
Saccule, utricle, 3 semicircular canals
Balance, equilibrium,posture,head-eye movement
Sense of vibration or pressure changes, accomodate
Ovoid sac-like structure
Connected to cochlea and to the utricle
Sensory organ= Macula of the Saccule (containing hair cells)
Ovoid sac-like structure
Sensory organ= Macula of the Utricle
1. Supporting cells
2. Hair cell
4. Gelatinous matrix
5. Otholithic membrane
Stereocilia toward kinocilium=excited
Stereocilia displaced kinocilium= inhibited
"Displacement of thesterocilia present on the hair cells includes either depolarization or hyperpolarization of the hair cell; displacement of the cupula in the direction of the utricle results in excitation of the hair cell, whereas displacement of the cupula in the reverse direction results in inhibition of the hair cell"
"Processed by central pathways
Interpreted by neurons in the cerebellar and cerebral cortices for the sense of balance"
Regulates change in direction but also the rate of change in direction (measure when and how fast)
Sloshing: need the fluid to bend these otholic organs out of the way when the head turns
Hair cells in utricle and saccule
Any movement ofthe senor, indicates opposite movement of the head
no change in movement= no action potential
Change in movement
2 types of receptors in vestibular system
Respond to movement and rate of movement
In skeletal (flexor/extensor) muscle
Connective tissue: Intrafusal fibers
Within muscle spindles, that are within skeletal muscle
Intervated by efferent gamma motor neuron axons (on polar ends)
Types include nuclear chain and nuclear bag, nuclei clustered on both
Intervated by afferents as well,calledannulospiral endings and flower-spray endings
both types are activated with stustained stretchin muscle
Muscles and neurons that control motor movement
Spinal cord= coordinated muscle contraction
Brain= motor programs in the spinal cord
Flexors vs. Extensors
Ex: Curl arm flexing/biceps
Agonists vs. Antagonists muscles
One working, the other has to relax
Both groups of muscles always activated
Flexor- more activation (moving away)
Concentric vs. Eccentric Contractions
"Muscles shorten, while generating force" running uphill
"Muscle elongates under tension due to the opposing force being greater than the force generated by the muscle"
Axial Muscles: Trunk movement
Proximal (shoulder, elbow, pelvis, knee)
Distal ( hands, feet, digits)
The Lower Motor Neuron
Intervated by ventral horn of the spinal cord
Upper motor neuron: Supplies input to the spinal cord, implying brain, cognitive decision
Motor cortex-spinal cord- perph. nerve-muscles-contraction
Alpha motor neuron
Alpha motor neurons (α-MNs) are large lower motor neurons of the brainstem and spinal cord. They innervate extrafusal muscle fibers of skeletal muscle and are directly responsible for initiating their contraction. Alpha motor neurons are distinct from gamma motor neurons, which innervate intrafusal muscle fibers of muscle spindles.
Gamma motor neuron
Efferent nerve fibers
In the nervous system, efferent nerves, otherwise known as motor or effector neurons, carry nerve impulses away from the central nervous system to effectors such as muscles or glands (and also the ciliated cells of the inner ear).
Afferent nerve fibers
In the nervous system, afferent neurons (otherwise known as sensory or receptor neurons), carry nerve impulses from receptors or sense organs towards the central nervous system. This term can also be used to describe relative connections between structures. Afferent neurons communicate with specialized interneurons. The opposite activity of direction or flow is efferent.
Motor neuron and all the muscle fibers it intervates
Motor unit recruitment: "Recruit more to exert greater force, activate muscle fibers (all connected)"
neuron activates all
Types of Motor Units
Red muscle fibers: slow to contract, maintain contraction (Endurance)
White muscle fibers: Contract and fatigue rapidly (Explosiveness, fast)
Fast motor units: Rapidly fatiguing white fibers
Slow motor units:Slowly fatiguing red fibers
How is the muscle activated?
When activated-contract-shortening-moving bones
Muscle fibers-fibrous-Z lines- sacromeres "building block of muscle, what happens at this level happens at the larger level"
is the basic unit of a muscle. Muscles are composed of tubular muscle cells (myocytes or myofibers). Muscle cells are composed of tubular myofibrils. Myofibrils are composed of repeating sections of sarcomeres, which appear under the microscope as dark and light bands. Sarcomeres are composed of long, fibrous proteins that slide past each other when the muscles contract and relax.
Include thin and thick filaments
2 heads with respecitvely actin binding site and myosin binding ATPase site
Made up of myosin molecules
Heads will move inward and reverse
(burns energy or ATP to move the thin filament towards the middle)
Consist of actin, troponin, and tropomyosin
Actin molecules have binding site for attatchment with myosin crossbridge
Binding site of the thin filament cannot interact with the thickfilament- so not constantly contracting
Troponin tells tropomyosin out of the way
Troponin 3 subunits connect to:
c. Calcium (neurotransmitters for excocytoiss what triggers muscles to contract)
How is Calcium released in the myofibril?
-Tranverse Tubule cut through=T-tubules
arrive at every part of the myofibril
Faciliate Ca2+ to arrive
The special type of smooth endoplasmic reticulum found in smooth and striated muscle fibers whose function is to store and release calcium ions.
The sarcoplasmic reticulum releases calcium ions during muscle contraction and absorb them during relaxation.
Stores Ca2+ ions
Transport Ca2+ ions from adjacent chamber where thikc and thin filaments are, requires a channel= T-tubes (outside to inside)
(Notes) - Start near plasma membrane and works its way down into the muscle.
(Book) - Openings scattered across the surface of the sarcolemma that are filled with extracellular fluid.
- These help the speed of muscle contraction by allowing electrical impulses to quickly travel down the cell.
Will transfer the signal, depolarize muscle membrane
Changes SR shape "unlock the door"
Calcium rushes down its concentration gradient
Triggers neurotransmitter release
Communicates totroponin that trypomyosin can get out of the way
Exposes active sites
Use ATP pump to get Calcium back into the SR
Muscle Contraction Summarized
1. Motor neruon axon (cell bodyisin ventral horn) is stimulated (reaches motor end-plate and loses mylein sheath and diverges into boutons)/ Actiion potential reaches motor neuron's axon terminal and depolarizes the membrane of presynaptic bouton
Results in the opening of Ca2+ voltage-gated channels, which allows Ca2+ ions to travel down their concentration gradient into the terminal. This promotes the fusion of the presynaptic bouton's vesicle with the muscle cell's terminal.
Results in the release of Ach. Ach released by motorneuron axon-crosses cleft and binds to receptors on motor and plate junctions near the crest (or muscle cell membrane?)
2. Results in depolariztion/ EPP/ and eventually action potential (if threshold is passed) that propagates along tranverse tubules (dispersed throughout the cell) and eventually makes it to the Sacroplasmic reticulum
3. Action potential triggers the release of Ca2+ ions (electrochemically gated Ca2+ channels) and Ca2+ rushes down its concentration gradient
4. Ca 2+ ions bind to troponin on thin filament in sacromere
5. Triggers tropomyosin to be moved to the side
Thick filament's myosin active sites actively attatch (cross bridge) to thin fialment's actin (now,no longer blocked) active sites
"Located in the ventral horn of the spinal cord"
"At the neuromuscular junction, the axons of motor neurons innervate skeletal muscle fibers"
"As the motor axon reaches a specialized regionon the muscle membrane, called the motor end-plate, it loses its myelin sheath and gives off several fine brancehs. Many varicosities, called synaptic boutons, are present at the terminals of these branches"
Lie over depressions in thesurface of the muscle fiber membrane
post-synaptic junctional folds
Very significant Feature: Enclose the synaptic vesicles that contain Ach
Touch mediated by skin's cutanous and subcuntaneous mechanoreceptors (reacting to external stimuli)
Hair focciles (innervated by nerve endings),meissner's corpuscle (low threshold,rapidlyadapting,senstive to touch and vibration), merkel's receptors (belwoepidermis,low threshold, rapdily apdating, sensitive to pressure stimuli), pacinian corpuscle (low threshold, rapidly adapting, sensitive to rapid indentation caused by vibration),ruffini's corpuscle
(high threshold,slowly adapting,sensitive to stretched skin)
Proprioception (Dorsal column mediates tactile sensation and conscious proprioception)
"Sensory modalitythat provides feeback soley on the status of the body internally; indicates whether the body is moving with required effor as well as where the various parts of the body are located in relation to each other. In conscious proprioception, te receptors located in the joints and join capsuels (proprioceptors) provide sensory information to the cerebral cortex, which, in turn, uses this information to generate conscious awareness of kinesthesia (i.e., thejoin postion, direction, and velocity of joint movements). In onconscious proprioception, the impulses arising from the proprioceptors mediating this type of sensation (muscle spindles and Gogli tendon organs) are relayed to the cerebellum rather than to the cerebral cortex"
Proprioceptors= Muscle Spindles and Gogli tendon organs
Unlike conscious proprioception in which info. is sent to the cerebral cortex, info. sent to cerebellum
Connective tissue case
Present in skeletal muscles
more of in muscles that control fine movements
Intrafusal fibers that are innervated by spinal gamma neruon axons and oriented parallel to surrounding muscle fibers called extrafusal fibers
Extrafusal fibers- innervated by alpha motor neruon axons (cell bodies are located in the spinal cord's ventral horn)
1. Muscle stretched
2. Afferent receptors of intrafusal fibers of the muscle spindle (annuiospiral and flower-spray endings) are stimualted and project to the alpha motor neuron to ventral horn in the spinal cord
3. Respond with efferents sent to the extrafusal fibers and a reflex-induced contraction occurs
"Muscle tension opposes the stretch"
Gamma Motor Neurons
Between alpha motor neurons in spinal cord's ventral horn
Do not receive afferents from muscle spindles
Regulate how sensitive the stretch reflex is by tightening or relaxing the fibers within the spindle
Golgi Tendon Reflex
Inverse Myotatic Reflex
Activated or sensitive to an active or a change in the contraction or stretch of muscle fibers
Activated when muscle fibers contract
Send signal to its afferent fibers that innervate an interneuron that innervate an alpha motor neuron which receives an inhibitory signal
Contraction is relaxed