FINAL ANATOMY EXAM, ANATOMY LECTURE 5
physiology of ANS
-ACh neurotransmitter synapses with Cholinergic receptors. - Types of Cholinergic receptors : 1) Nicotinic ACh- are iontropic meaning they change and open/close ion channels 2) Muscarinic ACh- are Metabotropic meaning it changes or increases/ decreases enzyme activity
Which of the following is/are themes common among the visual, auditory, olfactory and gustatory systems?
-Adaptation -Change in receptor cell membrane potential -Release of neurotransmitter -Message carried to CNS in the form of action potential frequency
Select all that apply. Which receptors are metabotropic?
-Adrenergic -Muscarinic
The convex shape of the lens of the eye is essential for:
-Allowing light to be refracted and converge at a focal point on the retina -Changing the refractive power of the eye
Sensory receptors use which of the following as they respond to a stimulus?
-Modality -Location -Intensity -Duration
Which of the following statements is(are) true regarding neurotransmitters and receptors in the ANS?
-Nicotinic receptors are ionotropic receptors that are activated by acetylcholine. -Muscarinic receptors are matabotropic receptors that are activated by acetylcholine. -Adrenergic receptors are matabotropic receptors that are activated by epinephrine & norepinephrine.
Which of the following statements is(are) TRUE regarding olfaction?
-Olfaction sensory receptors are rapidly-adapting -Chemoreceptors are used in olfaction -The mucous layer in the nasal cavity protects exposed olfactory sensory receptors -Cilia receive molecular components of odorants that are responsible for olfactory transduction
Select all that apply: Which of the following statements are true about frequency tuning in the cochlea?
-Organs of corti near the base of the cochlea detect high frequency sound waves -Organs of corti near the apex of the cochlea detect low frequency sound waves
Para. system is cholinergic
-Recieve an impulse from CNS. -Then pre-ganglionic fires send an impulse towards ganglion and ACh is released. -It can bind to either nicotinic or muscarinic receptors -ACh is released from post ganglionic fiber in the parasympathetic nervous system. -ACh then binds to another cholinergic receptor on the specific effector organ. Reaction will be based on whatever organ it is .
Which of the following is true about the autonomic nervous system?
-Responsible for involuntary responses -Contains myelinated pre-ganglionic cells -Responds to neurotransmitters including ACh Norepinephrine & Epinephrine
Taste receptor cells have microvilli that detect the actual taste molecule. Each taste receptor cell expresses ________ (of) type(s) of taste receptor.
-Shutting off the signal in the taste receptor cells -Negative feedback in the CNS
Third order neurons
-Situated in Thalamus -Carry sensory information to the cerebral cortex. -Results in a conscious perception of the stimulus.
Predict what would happen if the stereocilia of the hair cells within the organ of Corti were unable to sway in response to the vibration of the basilar membrane.
-The hair cells within the inner ear would not be able to mount a physiological response to sound waves. -A person with this condition would likely be deaf or hard of hearing. -A cochlear implant could be implanted to help regain hearing. -Glutamate would never be released onto the sensory afferent neurons.
Which of the following statements regarding the determination of the intensity of the stimulus is true?
-The magnitude of receptor potentials increases with increasing stimulus intensity. -The frequency of action potentials increases with increasing stimulus intensity.
Mechanoreceptors have different receptive field sizes
-The sensation generated by a sensory neuron and all of its receptors is referred to as a sensory unit. -The area of the skin, or any other surface that is covered by a single sensory unit, is referred to as its receptive field
Which of the following statements correctly describe chain ganglia?
-They are found along the entire length of the spinal cord. -They carry sympathetic post-ganglionic fibers out to target tissues.
Olfactory system
-allow you to smell -contains specialized epithelial cells that possess receptors for smell.
Second-order neurons (interneurons)
-are located either in the spinal cord or the brainstem. -They receive information from one or more primary sensory neurons and conduct it further to the thalamus. -may cross over to the opposite side of the body in the spinal cord or the brainstem.
sympathetic nervous system pre ganglionic fibers
-are located in thoracic and lumbar segments of spinal cord. -Synapses: In sympathetic chain ganglia (closer to spinal cord) -Post ganglionic innervated more organs than parasympathetic branch.
PARASYMPATHETIC pre-ganglionic fibers
-are myelinated, post -ganglionic fibers are NOT. -are craniosacral, meaning they arise from the cell bodies of the nuclei of the cranial nerves and sacral spinal cord segments. -Synapse: The ganglia close to target organ
Mechanoreceptors ________________.
-are part of general sensation -are widely distributed throughout the body
First-order neurons
-are the primary sensory neurons that receive the transduced signal and conduct the information to the CNS. -Cell bodies of the primary afferent neurons are in the dorsal root ganglia of the spinal cord or in cranial nerve nuclei.
The parasympathetic branch of the ANS
-arises from the brainstem and lower regions of the spinal cord. -has long pre-ganglionic fibers.
sympatheic division exerts more systemic effects
-because the response is enhanced by the release of epinephrine and norephinephrine from the adrenal medulla. - last longer in the bloodstream -a single sympathetic pre-ganglionic cell will synapse on many post-ganglionic cells (up to 20)
Mechanoreceptors detect ________.
-changes in the cell membrane -movement of cilia -temperature changes -cell damage
automatic nervous system (motor neurons)
-originate in SPINAL CORD or BRAIN STEM. -Synapse with other neurons within ganglia -controls involuntary movements and innervate smooth muscle, cardiac muscle, and glands. Pre ganglionic fibers are myelinated, post are not. -Uses several neurotransmitters: ACh, norepinephrine, and epinephrine (adrenal grands) -Receptors are nicotinc, muscant etc - Has Ganglion which can inhibit and and excite an organ.
somatic nervous system (motor neurons) *EXCITATION
-originate in ventral horn of the spinal cord in the peripheral nervous system control SKELETAL muscle contraction. voluntary movements -fibers are myelinated -Achelytcholine (ACh) -Receptor is Nicotinic
Thermoreceptors
-there are approximately six times more cold receptors than warm receptors. - detect heat via channels known as transient receptor potential cation (TRP) channels.
Place the steps of sympathetic nervous system activation in chronological order.
1) An action potential from a visceral sensory organ stimulates a sympathetic NS chain. 2) The preganglionic neuron releases acetylcholine at synapse 1. 3) Acetylcholine stimulates the postganglionic neuron. 4) The postganglionic neuron releases norepinephrine. 5) Norepinephrine causes an excitatory response stimulating heart rate to increase.
Match characteristics
1) Long preganglionic neurons - Parasympathetic NS 2) Acetylcholine will always have an excitatory effect Parasympathetic nervous system - Somatic NS 3) May release norepinephrine or acetylcholine at its terminating neuron Autonomic nervous system - Autonomic NS 4) Involved in fight and flight - Sympathetic NS 5) Cholinergic receptors respond to this neurotransmitter - ACh 6) Adrenergic receptors respond to this neurotransmitter - Norepinephrine
Steps of a somatic reflex
1) Proprioceptive receptor signal to dorsal root neuronal cell bodies 2) Afferent dorsal root sensory cells send information via the posterior gray matter of spinal cord/brainstem, where they synapse onto interneurons 3) Cells in motor cortex project to interneurons that synapse on an ɑ-motor neuron in the dorsal horn 4) Interneurons send signals through the thalamus to the motor cortex in the cerebral cortex 5) The ɑ-motor neuron synapses with skeletal muscle
Steps of an autonomic reflex
1) Visceral sensory receptors signal to dorsal root neurons 2) Dorsal root neurons send sensory information directly to CNS (no interneuron) 3) Efferent information is sent to hypothalamus or cranial nerve nuclei in the brainstem, or into the lower cord to pre-ganglionic neurons 4) Pre-ganglionic neurons project out to ganglia and synapse onto post-ganglionic cells 5) Post-ganglionic cells project out and synapse onto target cells
dorsal column are separated into two component tracts
1) fasciculus gracilis contains axons from the legs and lower body 2) fasciculus cuneatus contains axons from the upper body and arms.
major parasympathetic pathways
1) oculomotor (nerve III) project to the ciliary ganglia and innervate the ciliary muscles and lens of the eye. 2) facial (VII) project to the pterygopalatine and submandibular ganglia and innervate the lacrimal and mucosal glands of the nasal cavity and salivary glands. 3) glossopharyngeal project to the otic ganglia and innervate the parotid salivary gland. 4) Vagus are responsible for the vast majority of the body's parasympathetic output (80% to 95%) -
Recruitment
A strong stimulus may allow the activation of more and more sensory neurons in a given sensory region. -Activates more sensory units -a weak stimulus will activate sensory receptors with a lower threshold, -a stronger stimulus can activate sensory receptors with a higher threshold.
Which of the following does not describe the ANS?
A system of sensory neurons that innervates all muscle cells
ALL pre ganglionic neurons release
ACh
Which neurotransmitter will result in better learning of new material (like the autonomic nervous system), increase in digestive and salivary activity?
ACh
Which of the following is an incorrect pairing?
ACh dilates the pupil.
Mr. Harris asks you a question, to which you nod your head "yes". Which semicircular canal is responsible for sensing this movement?
Anterior
Receptor cells:
Are found in all of the sensory systems Are specialized in both structure and function to capture stimuli
sensory modality
Baroreceptors- Pressure Proprioceptors- Body position Nociceptors- Pain Tactile receptors- Touch
The vibrations of sound waves are transmitted into the cochlea, and the movement of the ______________ causes the hair cells within the organ of Corti to sway.
Basilar membrane
Which is true of both the somatic and autonomic nervous system?
Both respond to stimuli
The role of the rod and cone photoreceptor cells are to:
Capture a photon and convert that signal into an electrical signal that can be relayed to the next cells in the retina
Which auditory structure contains hair cells and responds to sound vibrations?
Cochlea
Photopic vision
Cone cells contain opsin Function optimally under intense, bright light conditions -can also discriminate color and contain one of three types of photopigment proteins
You walk outside on a crisp fall day in Philadelphia. What cells in the eye allow you to take in all the colors of the trees?
Cones
Parasympathetic "Rest and digest"
Constricts pupils Stimulates salivation Slows heartbeat Constricts bronchi Stimulates digestion Stimulates bile release Contracts bladder
parasympathetic nervous system (rest and digest or feed and breed)
Constricts pupils Stimulates salivation Slows heartbeat Constricts bronchi Stimulates digestion Stimulates bile release Contracts bladder
tactile sensation
Cutaneous mechanoreceptors sense touch, pressure, vibration, and temperature.
Sympathetic "Fight or flight"
Dilates pupils Inhibits salivation Accelerates heartbeat Dilates bronchi Inhibits digestion Conversion of glycogen to glucose Inhibits bladder constriction
sympathetic nervous system (flight or flight)
Dilates pupils Inhibits salivation Accelerates heartbeat Dilates bronchi Inhibits digestion Conversion of glycogen to glucose Inhibits bladder constriction
Which of the following is not a result of parasympathetic stimulation?
Dilation of the pupils
Which of the following is the ampulla associated with?
Dynamic equilibrium
Which neurotransmitter will result in increased heart rate, efficient breathing, and blood pressure ?
Epinephrine
physiology of ANS pt.2
Epinephrine and Norepinephrine both bind to Adrenergic (adrenal gland) receptors. -Are metabotropic meaning they change enzyme activity
True or False: In the sympathetic nervous system, the synapse between the pre-ganglionic neuron and the post-ganglionic neuron occurs near the effector organ in most cases.
F
All receptor potentials are strong enough to elicit an action potential in the afferent nerve cell.
FALSE
True or False: A single rod or cone cell will capture the entire image in front of the eye?
FALSE
The tongue has specialized areas for each of the five tastes.
False
types of pain
Fast pain is felt in 0.1 second and refers to sharp or short pain that can be localized. Slow pain, also referred to as burning or aching pain, begins after one second. It increases slowly over many seconds and even minutes. It is referred to as dull or unpleasant pain that is diffused and cannot be easily localized. Acute pain has a sudden onset but declines when the stimulus is removed. Chronic pain persists, and relief depends on the source as well as the cause of the pain. Visceral pain is pain originating in the abdominal organs where there are, in general, fewer nociceptors. The sensation of pain is therefore poorly localized. The pain may radiate to adjacent areas, making diagnosis difficult. It is often associated with nausea and unpleasant experiences.
Slow adapting
Free nerve Merkel cells Ruffini corpuscles
Classification of sensory receptors by structure
Free nerve ending: Unipolar neuron with dendrites as sensory receptors Encapsulated nerve ending: Unipolar neuron with encapsulated dendrites Sensory cell: Sensory cell synapsing directly onto a neuron. Peripheral processes: Neuron with peripheral processes
Which of the following receptors would a papercut activate
Free nerve endings
The pitch of a sound is directly related to the ________ of sound waves
Frequency
Loss of proprioceptive sensation in a patient with damage to the dorsal column is ______________ the loss of pain sensation in the same patient.
GREATER THAN
Most of your senses rely on the use of cilia to receive sense information and depolarize neurons leading to actual sensation. Which of the following senses does not?
Gustation
Olfactory transduction
Gustatory transduction is dependent on the type of taste receptor involved.
The specialized receptor cells within the organ of Corti are called:
Hair cells
peripheral adaptation.
If the sensitivity declines at the sensory receptor level, it is referred to as. Typically, the initial response is strong with a decline in response to the same stimulus over time.
When the head moves, which way does the stereocilia move?
In the opposite direction head rotation
A stiffening of the tympanic membrane would most directly impact which step in hearing?
Inability to vibrate and move the malleus
Stereotypic responses of the sympathetic division of the ANS
Increased heart rate, heart contraction force, blood pressure Vasoconstriction of most blood vessels but vasodilation in skeletal muscle, heart and lung Mobilization of energy sources from liver, skeletal muscles and adipocytes Increased sweat production Decreased food digestion
Stereotypic responses of the parasympathetic division of the ANS
Increased mouth salivaSwallowing reflex Secretion of acid and enzymes in stomach for digestion of food; increased stomach wall tone and contraction strength Secretion of enzymes and bicarbonate-rich buffers in the small intestine; increased contractions in the GI tract Control of nausea, vomiting, abdominal cramps and diarrhea
What type of mechanoreceptor would ice on the skin activate?
Krause corpuscles
Indicates parasympathetic branch
Long pre-ganglionic neurons and short unmyelinated fibers that have ACh muscarinic receptors
These three small bones sit within the middle ear.
Malleus, incus, stapes
Rapid adapting
Meissner's corpuscles Krause corpuscles Pacinian corpuscles
Which of the following two types of sensory receptors are free nerve endings?
Nociceptors and thermoreceptors
Overview of the olfactory system
Olfactory tract: Axons of mitral cells that carry olfactory information to the cortex Glomerulus: Bundles of synapses between sensory neurons and mitral cells Olfactory stem cell: Replace old sensory neurons every few months Olfactory sensory neurons: Cilia protrude downward into nasal cavity; axons project upwards and synapse with mitral cells
Visual Pathway to the Brain
Optic nerve: Bundled axons of ganglion cells Optic chiasma: Where medial fibers from each eye criss-cross Lateral geniculate: Relay station for visual information within the thalamus Primary visual cortex: Ultimate destination/processing center for visual information
Within the inner ear, the location of the hair cells responsible for auditory transduction is the ________.
Organ of Corti
Somatic Nervous system vs Autonomic Nervous system
Originates in the spinal cord (BOTH) Originates in the brainstem (SNS) Under conscious control (SNS)
Overview of the gustatory system
PAPILLAE: bumps on tongue that contain taste buds TASTE RECEPTOR CELLS: contain molecular components required for taste sensation TRANSITIONAL CELLS: supporting cells between taste receptor cells BASAL CELLS: replace old taste receptor cells TASTE PORE: trap dissolved food molecules and activate taste hair receptors
Taste receptor cells are contained within:
Papillae
-Which nervous system has short, un-myelinated post-ganglionic neurons? -Which nervous system has its ganglion located near the effector organ?
Parasympathetic
Which branch has short, unmyelinated post-ganglionic fibers?
Parasympathetic
The process by which sensory information is interpreted in a meaningful form is known as
Perception
Which branch of the nervous system is the autonomic nervous system a part of?
Peripheral
Where is the autonomic nervous system is acetylcholine always released?
Pre-ganglionic neuron
Following a concussion, a soccer player can no longer properly touch their finger tip to their nose with their eyes closed. What receptors were impacted?
Proprioceptors
ANS
Responsible for maintaining homeostasis. -heartbeat, respiratory rate, moves food through digestive tract, coordinates nutrient absorption, and adjusts sunlight.
Touch and pressure are sensed by the following receptors except one. Identify the receptor that is not associated with touch and pressure sensation.
Ruffini corpuscles
When traveling in an elevator which of the following is stimulated?
Saccule
What type of somatosensory neurons carry information from the spinal cord or brainstem to the thalamus?
Second order
Which of the following neurons connect the spinal cord to the thalamus in the anterolateral pathway?
Second-order neuron
Arrange the following structures in the sensory pathway in the correct order.
Sensory receptor Dorsal root ganglion Dorsal root Thalamus Cerebral cortex
-Which branch of the peripheral nervous system targets skeletal muscles? -What nervous system branch uses 1 motor neuron to send signals?
Somatic
Select all the apply: At which of the following locations in the neuron chain might you find acetylcholine being released?
Somatic efferent innvervation. (At somatic effectors in skeletal muscle).
Transmission of Sound to the Inner Ear
Sound waves are captured by outer ear and sent to inner ear via tympanic membrane Tympanic vibrations push on malleus--> incus ---> stapes; moves oval window Oval window transmits vibrations to scala vestibuli •Basilar membrane moves, as well as the hair cells in the Organ of Corti
ascending pathway
Spinal cord pathways that carry sensory information into the brain -A sensory pathway that conducts peripheral sensations to the brain
Which nerve has sympathetic control of arrector pili smooth muscle?
Spinal nerve
Horizontal movement of the head in a straight line causes:
Stimulation of the stereocilia of the utricle
Poisoning of a person with mushrooms containing muscarine would be expected to have which of the following effects?
Stimulus of target cells innervated by post-ganglionic parasympathetic fibers
innervated exclusively by sympathetic system
Sweat glands, cutaneous arterioles and veins, and the adrenal medulla
Which of the following choices about norepinephrine (NE) is incorrect?
Sympathetic pre-ganglionic neurons secrete NE.
The secretions of the adrenal medulla act to supplement the effects of ______________.
Sympathetic stimulation
Which of the following channels open at temperatures above 34°C?
TRPV1 TRPV2 TRPV3 TRPV4
Each specialized receptor cell has a "switch" that must be turned on in order for the cell to turn on.
TRUE
The vestibular system relies on hair cells that are similar in structure and function to those found in the auditory system.
TRUE
How do somatic nervous system reflexes differ from autonomic nervous system reflexes?
The hypothalamus plays a critical role in autonomic nervous system reflexes.
When comparing the ANS and the SNS, which of the following statements is incorrect?
The neurotransmitter utilized at the effector in both systems is ACh.
The somatic nervous system (SNS) and ANS differ in all of the following ways except ______________.
The origin of the nerve cell bodies
Linear acceleration of the head is determined by hair cells located within:
The utricle and saccule
Classification of sensory receptors by modality
Thermoreceptors: Sense changes in temperature CHEMORECEPTORS: Sense changes in chemicals (e.g. blood gases and pH) MECHANORECEPTORS: Sense mechanical stress and changes in pressure, gravity, cell volume/shape, position, touch, itch and movementE.g. touch receptors, baroreceptors, osmoreceptors, proprioreceptors NOCICEPTORS: Sense tissue damage, physical trauma or thermal injury
Which of the following correctly describes an ANS reflex?
Tissues can be innervated by both branches and they usually have opposite effects.
The amplitude of a sound wave is the total height of a wave, from the peak to the valley.
True
I-76 is backed up and you slam on breaks to keep from hitting the car in front of you. Which vestibular sense organ would register your head slowing down?
Utricle
Interoceptors
VISCERAL INTROCEPTORS: detect changes within the visceral organs are referred to as visceral sensory receptors. (e.g. baroreceptors that detect pressure, stretch receptors that detect distension, and pain receptors that detect pain SOMATIC INTROCEPTORS: found within musculoskeletal structures; detect body interactions with environment
Match the special sense with the type of receptor.
Vision: Photoreceptor Audition/Balance: Mechanoreceptor Olfaction/Gustation: Chemoreceptor
What type of vision allows the eyes to detect color?
What type of vision allows the eyes to detect color?
strong stimuli produce
action potentials at a higher frequency.
Post ganglionic fibers in sympathetic branches
are ADRENERGIC. So you will see epin/noep. being released and will bind to adrenergic receptors on the effector organ.
Nonmyelinated C fibers
are activated by a variety of high-intensity mechanical, chemical, hot, and cold stimuli.
The simplest sensory receptors
are free nerve endings of unipolar neurons that vary in density around the body.
cell bodies of sympathetic pre-ganglionic neurons
are located in the thoracic and lumbar segments of the spinal cord
automatic neurons that originate within the cns
are pre-ganglionic neurons. neurons that receive messages from pre-ganglionic fibers and innervate target tissues are known as post-ganglionic neurons.
stereocilia
are responsible for receiving messages from the environment about sound (in the form of a sound wave) or a change in head position.
Mechanoreceptor receptive fields
are smaller where the skin has a greater density of sensory neurons. Mechanoreceptor receptive fields in the fingertip, for example, are much smaller than those in the forearm because of differences in mechanoreceptor densities. The larger the receptive field, the harder it is to localize the stimulus.
sensory adaptation
become less responsive in the presence of a constant stimulus
The logarithmic relationship between stimulus intensity and sensory cell action potential frequency allows the body to detect large changes in stimulus intensity
but also makes it more difficult to detect small changes in stimulus intensity.
large-diameter myelinated Aa fibers
carry information about sharp, well-localized pain -rapidly conducting
Anterolateral pathway (spinothalamic)
deals with pain and temperature sensation. -myelinated Aδ and unmyelinated C fibers. •Sensory neurons: -Begin in dorsal root ganglion -Synapse with interneurons in dorsal horn •Interneurons: Have cell body within spinal cord gray matter -Decussate from spinal cord and end at thalamus •Third-order neurons: -Axons project to somatosensory cortex
pain pathways
first order fibers: axonal projections associated with nociceptors convey painful stimuli to the CNS The slowly conducting, thinly myelinated Aδ fibers mediate diffused burning or aching pain, whereas rapidly conducting, large-diameter myelinated Aa fibers carry information about sharp, well-localized pain. Nonmyelinated C fibers are activated by a variety of high-intensity mechanical, chemical, hot, and cold stimuli.
At which of the following locations in the neuron chain might you find norepinephrine being released?
in Autonomic efferent innervation. (at visceral effectors such as cardiac and smooth muscle glands).
sensory neurons
in the peripheral nervous system collect information about the external and internal environments
An antagonist
is a molecule that can bind to a receptor (e.g., the same receptor as the neurotransmitter)—either at the same site or on a nearby site on the receptor protein—but instead of activating the receptor, it blocks there receptor (e.g., it blocks the effect of the neurotransmitter).
An agonist
is a molecule that can bind to a receptor (e.g., the same receptor to which a neurotransmitter binds) and activate that receptor to produce a response (e.g., the same response produced by the neurotransmitter).
The major difference between the the sympathetic and parasymathetic divisions
is that sympathetic post-ganglionic neurons are adrenergic and release norepinephrine or epinephrine onto target tissues. -Length also differs. (para. has longer pre-ganglionic neurons and shorter post gang.)
Dorsal column pathway
is the major pathway for detecting mainly fine touch and proprioception. -Cell body in dorsal root ganglion, axons project into dorsal column. -Synapse with interneurons in the medulla. -are myelinated Aβ fibers. -lower levels of the body position themselves medially, whereas axons from upper levels of the body position themselves laterally.
visible spectrum
is the wavelengths of light that can be detected by the human eye
Which of the following tissues are only innervated by the sympathetic NS?
kidney and liver
Ciliary muscles contract Ciliary muscles relax
lens relaxes into thicker shape --> increased refractive power lens pulled into flatter position --> decreased refractive power Controlled by parasympathetic Lens elasticity decreases with age
thinly myelinated Aδ fibers
mediate diffused burning or aching pain
The olfactory membrane sits at the top of the ________.
nasal conchae
pathway to the brain olfactory
olfactory tract (cranial nerve I) carries information from the olfactory bulb to the olfactory cortex and the limbic system. I
TRANSIENT RECEPTOR POTENTIAL CATION (TRP) channels:
open at different temperatures and release Ca2+ to detect temperature changes in humans
The portion of a photoreceptor cell that can capture a photon is the ________.
outer segment
Somatosensory stimuli from below the neck
pass along the sensory pathways of the spinal cord
rods and cones are
photoreceptors
Rapidly adapting / phasic receptors
primarily detect the onset and offset of a stimulus (e.g. include receptors that sense temperature, pressure, and light touch.) The decrease in sensitivity at the sensory receptor level helps to reduce the processing of sensory signals when the situation remains the same with a constant stimulus.
high frequency sounds
produce standing waves close to the oval window
low frequency sounds
produce standing waves near the apex of the cochlea
Muscle spindles are:
proprioceptors
visceral organs completely lack
proprioceptors
Visceral senses (General sensory receptor)
provide information about internal organs and are composed mainly of pressure and pain receptors.
Somatic senses (General sensory receptor)
provide information about touch, pressure, temperature, proprioception, and nociception
dominated by parasympathetic system
regulation of the heart, lungs, stomach, and salivary glands
dominated by sympathetic system
regulation of the kidneys, reproductive tissues, ureter, uterus, pancreas, liver, and skin i
Scotopic (low light)
rod cells function optimally here under low light conditions with shades of gray and black
Coding
signal received by the individual receptor cells must be transduced to a signal that can be relayed and understood by the brain. -determined by AP frequency -allows the central nervous system to determine the duration of the original stimulus, the intensity of that stimulus, and the precise location of that stimulus
vestibular system
sits within the inner ear and is composed of the semicircular canals, utricle, and saccule, and is connected to the cochlear duct. -also relies on the movement of inner hair cells to determine direction of movement, angular acceleration, and balance.
Which type of reflex involves interneurons?
somatic
autonomic nervous system
somatic- skeletal autonomic - visceral motor
regions of the CNS that play a role in somatic processes
spinal cord, the brainstem, the thalamus, and the cerebral cortex.
wavelength
the distance between the peaks of two successive waves
faster the sound vibrations
the higher the frequency and pitch.
somatosensory stimuli from the head and neck
travel through the cranial nerves (specifically, the trigeminal system).
Amplitude
vertical distance between peak and valley of a sound wave
pitch
vertical distance between peak and valley of a sound wave
parasympathetic division originates at the top and bottom of the CNS
whereas the sympathetic division originates in the middle regions. originates between T1 and L2 of the spinal cord, and target tissues including the lens of the eye, salivary glands, heart, lungs, stomach, reproductive organs, and many others.
sensory modality
Each sensory receptor is optimized to respond to one specific type of stimulus at a much lower threshold than for other types of stimuli
Meissner's corpuscles
•Encapsulated nerve endings found beneath epidermis and dermal papillae •Surrounded by horizontal lamellae of cells and connective tissue capsule •Sensitive to light touch and vibrations •Concentrated in fingertips and lips •Found within dermal papillae in areas of skin with no hair *Rapid *Detect VIBRATIONS
Ruffini corpuscles
•Free nerve endings intertwined with collagen fibers encased within a capsule •Sensitive to skin stretch and important for grasping and holding objects •Highest density around fingernails; also found deep in dermis where they signal the degree of joint rotation •Respond to sustained pressure (little adaptation) *Slow adapting
Balance (2): movement of hair cells within the utricle and saccule
•Hair cells of utricle and saccule are covered by gelatinous substance •Contains embedded calcium carbonate crystals called otoliths •When head moves, otoliths pull gelatinous substance and stereocilia in direction of gravity are responsible for determining linear acceleration of the head
Balance (1): movement of hair cells within the cupula
•Hair cells stick up into ampulla and are submerged in jelly-like substance (cupula) •As head rotates, fluid surrounding cells lags behind •Causes hair cell movement in opposite direction to head movement
Pacinian corpuscles (Mechanoreceptors)
•Nerve ending situated within a series of concentric layers of collagen fibers and surrounding cells; enclosed by capsule •Found in hairless skin (deep part of dermis and fascia) •Respond to deep pressure and vibration •Very rapidly adapting
Nociceptors
•Nociceptors are concentrated in areas more prone to injury •Absent from brain and sparse on most internal organs •Very slowly or non-adapting •Respond to cellular damage, noxious chemicals and signals released by the body itself
merkel cells
•Oval-shaped mechanoreceptors •Located in tips of fingers and lips (extend into stratum basale) •Most sensitive of the tactile receptors for detecting fine touch and texture •Provide steady-state signals, detecting continuous touch of objects against skin •Slowly-adapting
Krause Corpuscles
•Small round or oval-shaped encapsulated mechanoreceptors •Found in dermis of dry skin as well as mucous membranes (e.g. lips, external genitalia) •Detect pressure and cold temperatures *Rapid adapting
free nerve ending
•Unencapsulated; no complex structures •Penetrate dermis, end in stratum granulosum (also surround hair follicles) •Range from slowly to rapidly adapting •Detect temperature, touch, pressure, stretch and cell damage (Polymodal)
