Neuromuscular Physiology - Exam #2 study guide

The nervous system has TWO different kinds of systems, what are they?

CNS and PNS

What makes up the Central Nervous System (CNS)?

Brain and spinal cord

What makes up the Peripheral Nervous System (PNS)

• Ganglia

• Cranial and Spinal nerves

What are the TWO (three ig) FUNCTIONAL DIVISONS for the PNS?

1. Somatic Division

2. Autonomic Division

3. Enteric

The Somatic Division has TWO NEURONS, sensory neurons and motor neurons. Explain what the sensory neurons are responsible for.

Somatic Division - Sensory neurons

Sensory information from skin, skeletal muscles, and joints to CNS

The Somatic Division has TWO NEURONS, sensory neurons and motor neurons. Explain what the motor neurons are responsible for.

Somatic Division - Motor neurons

Motor impulses from CNS to skeletal muscles

The Autonomic Division has TWO NEURONS, sensory neurons and motor neurons. Explain what the sensory neurons are responsible for.

Autonomic Division - Sensory neurons

Sensory information from visceral organs to CNS

The Autonomic Division has TWO NEURONS, sensory neurons and motor neurons. Explain what the motor neurons are responsible for.

Autonomic Division - Motor neurons

Motor impulses from CNS to smooth muscle, cardiac muscle, and glands

The CNS is divided into FIVE PARTS what are they?

1. Spinal cord

2. Brainstem

3. Cerebellum

4. Diencephalon (die-in-seph-uh-lawn)

5. Cerebral hemispheres

What are afferent and efferent tracts?

NS pathways for many physical actions

What does the Afferent do (name 4 functions)?

1. Sensory Receptor

2. Sensory neuron to spinal cord

3. Ascending pathway to thalamus 

4. Distributed to various cortex areas 

Where does afferent enter and exit the spinal cord (Dorsal & Ventral Roots)

carries sensory information into the spinal cord through the dorsal root

What does the Efferent do (name 3 functions)?

1. Signal from cortex to spinal cord 

2. Activates motor neurons 

3. Muscle contraction

Where do efferent enter and exit the spinal cord (Dorsal & Ventral Roots)

Carries motor commands out of the spinal cord to muscles; exits out of ventral root

*Define Lesion

area of abnormal or damaged tissue caused by injury or disease

How are circuity diagrams used in neuroscience?

Used to illustrate neural pathways

(method used to visualize the mapping of connections between neurons)

True or False:

Sensory receptors transduce stimuli into an electrical
signal (change in membrane potential)

TRUE

What are the FIVE common types of Receptors?

1. Mechanoreceptors 

2. Chemoreceptors 

3. Thermoreceptors

4. Photoreceptors 

5. Nociceptors

Mechanoreceptors are receptors activated by what?

activated by touch, pressure, stretching, sound waves and motion.

How are Mechanoreceptors Activated?

activated by touch, pressure, stretching, sound waves and motion.

How are Chemoreceptors Activated?

Activated by chemicals (e.g. olfaction and taste).

How are Thermoreceptors Activated?

located in the skin and include cold and warm receptors.

How are Photoreceptors Activated?

Activated by light on the retina (Rods and Cones).

How are Nociceptors Activated?

extreme pressure, temperature, noxious chemicals.

Explain what a Local Potential (graded) is.

Hint: LOCAL = SMALL

Small local changes in membrane potential; serve as triggers for action potentials

Local potentials (graded) may cause one of two effects which are what?

• Depolarization

• Hyperpolarization

Local potentials (graded):

Define Depolarization

Positive charges enter cytosol and make membrane potential less negative (e.g., a change from -70mv to -60mv)

De-polarization

De = remove

Sentence example: de frost (to melt, become less)

Local potentials (graded):

Define Hyperpolarization

Either positive charges exit or negative charges enter cytosol; makes membrane potential more negative (e.g., change from -70mv to -80mv)

True or False:

Ligand-gated & mechanically-gated channels cause local potentials

TRUE

What is an Axonal action potential?

A type of action potential that is mediated by voltage-gated receptors (for Na+ and K+) and is transmitted down the axon and to the axon terminals

What are Generator/Receptor potentials?

are similar to local potentials except they’re formed in the dendrites or of the 1st order afferent sensory neuron or in “separate” receptors (i.e. chemo, photo)

What types of information does the somatosensory system obtain and process (4)

1. Modality

2. Location

3. Intensity

4. Timing

Define Modality 

Defines the class of stimulus, determined by the type of energy transmitted by the stimulus and the receptors specialized to sense the energy 

Define Receptor Specificity

Different forms of energy are converted by the NS into different sensations or sensory modalities (e.g. touch, proprioception, pain, thermoreception)

Different forms of energy are converted by the NS into different
sensations or sensory modalities (e.g. touch, proprioception, pain,
thermoreception).- “receptor specificity”:

These are further divided two into sub modalities 

• Touch

• Proprioception

What are the characteristics of these TWO sub modalities?

Touch:
-  Itch/tickle & crude touch
– Discriminative touch (light touch, pressure, flutter, vibration)
• Proprioception:
– static and dynamic

Different forms of energy are converted by the NS into different
sensations or sensory modalities (e.g. touch, proprioception, pain,
thermoreception).- “receptor specificity”:

These are also compound modalities, name one and examples of two

Wetness: (touch, temp)

Modality is encoded by a “Labeled Line Code,” WHAT IS THE DEFINTION OF THIS

axons of the receptors are modality-specific lines of communication between the periphery and CNS.

True or False:

“Labeled Line Code” is a separate dedicated pathway?

TRUE

Define Location

represented by the set of sensory receptors within the sensory system that are active.

Fill in the blank:

Sensory receptors have a _______ _____ allowing them to encode the location of a stimulus.

Receptive Field

What does this statement say about the somatosensory cortex?:

“The somatosensory cortex is topographically organized”

meaning it contains a spatial map of the body where areas of the brain correspond to areas of the body

Define Dermatome

area of skin that is supplied by afferent nerve fibers from the dorsal root of a given spinal nerve.

How many cervicals, thoracics, lumbars, and sacral does the DERMATOME have?

• 8 cervical

• 12 thoracic

• 5 lumbar

• 5 sacral

what triggers symptoms in in the corresponding dermatome?

Damage to a spinal nerve from infection, compression, or traumatic injury

Define myotome

A group of muscles controlled by motor fibers from a single spinal nerve root

Define Intensity

signaled by the response amplitude of each receptor, which reflects the total amount of stimulus energy delivered to the receptor.

Intensity is coded by the total number of what?

The total number of action potentials received in a given time period

What TWO codes are established under intensity?

1. Frequency code 

2. Population code

Define Frequency Code

Discharge frequency of an afferent fiber increases with increasing stimulus intensity

Define Population Code

Stronger stimuli also activate a greater number of receptors

What is the RED circle called on the graph*

What the graph is representing (not the answer):

Discharge Frequency vs Stimulus Intensity

Absolute Physiological Threshold

Define Timing/Duration

defined when the response in the receptor starts and stops, and is determined by how quickly the energy is received or lost by the receptor

True or false:

All sensory receptors adapt to constant stimulation

TRUE

What are the Two main Somatosensory System Receptors?

1. Touch (and to a limited extent proprioception/kinesthesis)

2. Limb proprioception/kinesthesis

1. Touch (and to a limited extent proprioception/kinesthesis)

Finish this sentence:

is mediated by…….

Mechanoreceptors in the skin

1. Limb proprioception/kinesthesis

Finish this sentence:

is mediated by……

Mechanoreceptors in the joints and muscles

Define Exteroception

Information about the body’s external environment

Name of THREE EXAMPLES OF EXTEROCEPTION

1. Audio Perception

2. Visual perception

3. Touch

Define Interoception

Information about the internal state of the body

Name of THREE EXAMPLES OF INTEROCEPTION

1. perception of one’s own heartbeat 

2. Sensing stomachache 

3. Feeling pain

Define Proprioception

(static, limb position);proprio meaning “from within the body”

extra info:

The body’s ability to sense the position, movement, and orientation of the body without looking (know where your limbs are without looking)

Define Kinesthesis

(dynamic, limb motion) kines meaning “movement”, thesis meaning “sense of”

What does proprioception and kinesthesis refer to?

Generally, both of these terms refer to the internal sensory information

Generally, kinesthesis and proprioception refer to the internal sensory information that informs us about what THREE things?

1. Orientation of our bodies in space

2. The relative position of our joints

3. The tension in our muscles

   
   

What are SIX HUMAN SENSES?

• Auditory 

• Gustation 

• Olfactory 

• Visual

• Vestibular 

• Somatosensory

what does these terms mean:

• Auditory 

• Gustation 

• Olfactory 

• Visual (except this one)

• Vestibular 

• Somatosensory

• Auditory (hearing)

• Gustation (taste)

• Olfactory (smell)

• Visual

• Vestibular (balance)

• Somatosensory (proprioception, touch, pain, temp)

Somatosensory inputs participate in what THREE THINGS?

1. Reflexes

2. Pathways to cerebellum (unconscious pathway, coordinate movements)

3. Pathways to cortex (conscious pathway)
   
   

What does SOMA mean

BODY

Dorsal root ganglion cells transmit sensory information from ____ to ____

Hint: ganglion belongs to what nervous system

PNS to CNS

What is a Neural Pathway?

Bundle of axons that connects two or more different neurons

Define Tracts

neural pathways that are located in the brain and spinal cord (CNS)

Name 3 FACTS about TRACTS

1. Have different names depending upon where they are and where they go to (e.g. lemnisci, peduncles, fasciculi)

2.  Can be ascending or descending

3. Usually named by their origin (1st part) and termination point (2nd part) (e.g. corticospinal)

Where do we find tracts in the spinal cord & brain?

White matter

What are the two major tracts for ascending somatosensory input?

1. Dorsal Column-Medial Lemniscus Tract (limb-niss-kiss) 

2. Anterolateral System

There are two major tracts for ascending somatosensory input:

What TWO abilities (thing it can do) does Dorsal Column-Medial Lemniscus Tract have?

• Proprioception- sense of static and dynamic positioning of limbs and body

• Touch- required to recognize size, shape, and texture of objects; movement across skin

There are two major tracts for ascending somatosensory input:

What TWO abilities (thing it can do) does the Anterolateral System have?

• Nociception: Signaling of tissue damage; pain

• Temperature: Warmth and cold

The Dorsal Column-Medial Lemniscal pathway signals _____ and ______

touch and proprioception

Where does the Dorsal Column-Medial Lemniscus pathway start/enter and where does it go?

1st-order neurons-

starts on the dorsal root ganglia and ascends on the same side of the spinal cord

2nd-order neurons-

crosses the medulla, and goes to the thalamus,

3rd- order neurons-

Begins in the thalamus then goes to the somatosensory

Where does the Anterolateral pathway start/enter and where does it go?

1st-order neuron:

starts in the dorsal ganglion, crosses in the spinal cord

2nd-order neuron:

ascends on the opposite side of the spinal cord

3rd-order neuron:

goes to the thalamus, then the somatosensory cortex

Anterolateral System tracts signal pain and temperature (and crude touch):

What are the THREE main tracts within the Anterolateral system/pathway?

1. Spinothalamic

2. Spinotecal (spuh-no-ticul)

3. Spinoreticular

What is the function of Spinothalamic

we are aware of pain and temp

Hint:

Spinothalamic

Thermal - Temperature

hot temp = Pain

What is the function of Spinotecal?

We turn our heads to look where we’ve been hurt

Hint:

Spinotecal = Spin or turn to detect

what is the function of Spinoreticular 

We are awakened by pain or temperature 

TRUE or FALSE

Anterior spinothalamic tract carries crude touch and pressure

TRUE

TRUE or FALSE:

Lesions of the anterolateral system and DCML pathways result in different impairments

TRUE

Lesions of the anterolateral system and DCML pathways result in different impairments:

What kind of loss of pain and temp. sensation does Anterolateral system experience?

Contralateral loss of pain and temperature sensation

Lesions of the anterolateral system and DCML pathways result in different impairments:

What kind of loss of tactile sensation and proprioception does (DCML) Dorsal Column-Medial Lemniscus pathway have?

Ipsilateral loss of tactile sensation and proprioception

Cortical processing of Somatosensory Signals:

The postcentral gyrus corresponds to what kind of Cortex?

Primary Somatosensory Cortex

Cortical homunculus 

size of features represent the relative proportions of the parts of the
human brain responsible for motor and somatosensory function.

Where is the Cortical Homunculus found?

The overall body map found on the cerebral cortex

and has two types:

Motor homunculus and sensory homunculus

Motor Homunculus

map of brain areas (precentral gyrus) dedicated to motor processing for different areas of the body.

Where is the Motor Homunculus found?

the primary motor cortex

Sensory Homunculus

map of brain areas (postcentral gyrus) dedicated to sensory
processing for different areas of the body.

Where is the Sensory Homunculus found?

The primary somatosensory cortex

What are the different receptors involved in proprioception and kinesthesia? (ken-es-Dee-Juh) (4)

1. Cutaneous Receptors

2. Joint Receptors

3. Muscle Spindles

4. Golgi Tendon Organs

Cutaneous receptors:

Meissner Corpuscle responds to what three things?

*Light touch

• Flutter and movement detection

• Rapidly adapting

Hint: Meissner = Mild = light

(extra info: found in the dermis; specifically, the papillary)

Cutaneous receptors:

Merkel Disks responds to what TWO things?

*Pressure 

• Slowly adapting 

(extra info: found in the epidermis; specifically the stratum Basale) 

Cutaneous receptors:

Ruffini Endings responds to what THREE things?

*Constant Pressure

• Skin stretch

• Slowly adapting

Hint: Ruffini Endings = hold the ends to STRETCH

(extra info: found in the dermis; specifically, the reticular layer)

Cutaneous receptors:

Pacinian Corpuscle responds to what TWO things?

*Vibration

• Rapidly adapting

(extra info: found in the subcutaneous)