Phys II- Exam 1 TQs

What is a chemical gradient?

concentration of ions differ across a membrane

What is an electrical gradient

The difference in the charges across a membrane

Typically (-) inside cell and (+) outside cell

What is an electrochemical gradient?

A gradient of electrochemical potential, for an ion that passes through a membrane. (+ and - charges moving back and forth)

What is the natural tendency to return to an even concentration-flowing from higher concentrations to lower concentrations?

Equillibrium

What does potential mean?

How is it measured?

-increased strength created by larger concentration differences across a membrane

-measured in volts of mV

What is the resting membrane potential?

How is this potential maintained?

-70mV

-Sodium Potassium Pump + leak channels

The sodium potassium pump actively pumps ______ NA out of the cell and ____ K+ into the cell

3 NA out

2 K+ in

The equilibrium potential that exactly opposes movement of ions across a cell membrane is?

Nerst Potential

What does the nerst potential help determine?

resting membrane potential (-70mV)

What is the threshold for depolarization (action potential)?

-55 mV

Neurotransmitters are considered the _____________ for communication during synapses. This leads to changes in __________________ of cell membranes to various ions.

ligands; permeability

Increase in permeability to Cl- influx or K+ efflux leads to ______________________

hyperpolarization (inhibitory of AP)

Increase membrane permeability to Na+ (cations) leads to ____________________

depolarization (stimulatory of AP)

What are some examples of stimuli/modalites that lead to stimulation/depolarization

touch

pressure

vibration

chemical (ex: salt)

sound waves

photons

etc

What is the difference between a graded potential and an action potential?

graded- signals DEGRADE. signal must be strong or summated to reach initial segment of axon. used for short distances.

action -signal does NOT degrade. signals use voltage gated Na+ channels for depolarization. used to send signal long distances

T/F: Action potentials carry signals a long distance due to their self propagating voltage fated Na+ channels spreading down the axon length.

TRUE

What causes loss of sensation by blocking voltage gated Na+ channels

lidocaine

What types of chemical synapse receptor regulates "fast" synaptic transmission due to the receptor being able to immediately change membrane permeability?

ionotropic receptors

What type of chemical synapse receptors regulate "slow" synaptic transmission and uses G-protein coupled receptors to alter membrane permeability?

metabotropic receptors

excitatory signals bring neuron _______________ depolarization.

inhibitory signals bring neuron ____________ from depolarization.

toward; away

What type of summation reaches threshold due to the number of pre-synaptic neurons sending signal and causes a cumulative convergence of signals? (TQ)

spatial summation

(everyone speaking at once)

What type of summation reaches threshold based on the frequency of firing from one presynaptic neuron?

temporal summation

Reinforcement/strengthening of neuronal pathways is called?

potentiation

Long term potentiation used __________ and ____________ receptors.

What neurotransmitter does it use?

NMDA (let in Na and Ca)

AMPA (let in Na)

glutamate

in long term potentiation, influx of Ca++ is theorized to trigger a cascade that increases the number of ____________ receptors, therefore ___________ responsiveness to stimuli

AMPA; increasing

(more receptors = stronger signal)

Increasing contrast of a signal by increasing signal strength near the center and decreasing signal strength near the periphery is called?

lateral inhibition

Long term depression is when low intensity stimulation opens ____________ receptors ONLY.

AMPA

Long term depression is theorized to initiate a cascade that removes ___________ receptors, thus ____________________ the neurons responsiveness to stimulation.

AMPA; weakening

What is the normal pH of blood?

7.4

Acidosis __________________ neuronal excitability

Alkalosis _________________ neuronal excitability

decreases; increases

Myelination increases the speed of a signal through ________________________ - _____________, which is when an impulse jumps from a node of Ranvier to the next.

saltatory conduction

What is somatic sensation and what are the exceptions to it?

the nervous mechanism that collect sensory information from all over the body

- except for special senses and deep visceral tissue

First order sensory spinal nerves are classified as?

What 2 locations hold the cell bodies?

TQ

pseudo-unipolar neurons

cell bodies in DRG and CNS ganglia (cranial nerves)

T/F: somatic sensory receptors are highly sensitive to a SINGLE stimulus/modality

TRUE

What is sensory transduction? TQ

conversion of an environmental stimulus into an electrical impulse

Where does sensory transduction occur? TQ

at RECEPTOR of the first order neuron ONLY

Classification of sensory receptors by LOCATION include: (3)

exteroreceptors

interoceptors

proprioceptors

Examples of interoceptors include ? (2)

free nerve endings

Pacinian receptors

examples of proprioceptors include? (5)

free never endings

pacinian

ruffini

muscle spindles

golgi tendon organ

classification of sensory receptors by MODALITY includes: (5)

mechanoreceptors

Nociceptors

Thermoreceptors

Photoreceptors

Chemoreceptors

Mechanoreceptors detent what modalities? (6)

touch

vibration

pressure

stretch

equilibrium

audition

Give the details for the following mechanoreceptor: Pacinian corpuscle:

Location:

Adaptation:

Sensation:

Large/Small receptive field:

-deep dermis/ intramuscular

-FASTEST adapting

-vibration

-large receptive field

Give the details for the following mechanoreceptor: Meissner corpuscle:

Location:

Adaptation:

Sensation:

Large/Small receptive field:

-Superficial dermis (fingertips/lips)

-rapidly adapting

-precise touch

-small receptive field

Give the details for the following mechanoreceptor: Ruffini corpuscle:

Location:

Adaptation:

Sensation:

Large/Small receptive field:

- deep dermis/joint capsule

-slowly adapting

-stretch

-large receptive field

Give the details for the following mechanoreceptor: Merkel Receptors (discs):

Location:

Adaptation:

Sensation:

Large/Small receptive field:

-superficial dermis/epidermis junction

-slowly adapting

-light touch/pressure

-small receptive field

What is another term for fast adapting receptor?

what about slow adapting?

fast-phasic

slow- tonic

T/F: action potentials are capable of being strong or weak.

FALSE: all or nothing approach. Action potential is determined by weak or strong stimulus.

T/F: Increased frequency of a signal creates a strong stimulus and activates an action potential.

TRUE

What are the fiber types of free nerve endings? are they myelinated or not?

reminder- free nerve endings consists of nociceptors, thermoreceptors and tickle/itch receptors.

Type A-delta and C fibers

non-myelinated

What are the extreme temperatures when nociceptors are activated?

Below 42 F, Above 120 F

Dense concentrations of nociceptors are found in what tissues? (100% TQ)

skin, joints, periosteum, arterial walls, falx

Low concentrations of nociceptors are withing what tissues (100% TQ)

Deep visceral tissue (Brain, GI tract)

Fast pain (aka pricking pain or first pain) uses what fiber type?

Is is well localized or not?

A-delta fibers

well-localized

A patient has sprained their ankle over a week ago and is still experiencing achy pain. What category of pain is the patient still experiencing?

slow pain

Slow pain (aka aching pain) uses what fiber type?

Is is well localized or not?

C-fibers

NOT well localized

(remember slow pain is particularly annoying and intolerable compared to fast pain)

Warmth thermoreceptors use what type of potential channels to transduce heat?

vanilloid transient receptor potential channels (TRP aka TRPV)

Cool thermoreceptors utilize what potential channel to transduce cool sensation?

what else do these channels transduce other than cooling?

melastatin transient receptor potential channels (TRPM)

also transduce menthol (found in topical pain relievers)

What fiber type do cool stimuli/receptors use?

What about warm stimuli/receptors?

cool- A delta fibers (fast)

warm- C fibers (slow)

Itch receptors respond to ____________ stimuli, most importantly _________________

TQ

chemical; histamine

Tickle receptors are very sensitive to light touch and have a very _____ threshold.

low

What is the order of the Erlanger's fiber type system from fastest/thickest fibers to slowest/thinnest fibers?

- A- alpha

-A -Beta

-A gamma

- A delta

-B fiber

-C fibers

What are A alpha motor neurons involved in?

What about A-gamma?

A -alpha- sensory for muscle spindles

A-gamma- motor to muscle spindles

What modality do A beta fibers carry? TQ

discriminative (fine) touch and vibration

What modality to A-delta fibers and Type III fibers carry? TQ

fast pain

crude touch

deep pressure

cold temperature

What modality to C fibers carry (TQ)

heat

tickle

postganglionic autonomic olfaction

Name the fibers of Lloyds fiber classification systems from Fastest and thickest to slowest and thinnest.

Give their function

TQ

Type Ia- muscle spindle afferents

Type Ib- golgi tendon organ afferent

Type II- touch, vibration, muscle spindle afferent

Type III- crude touch, pressure, fast pain, temp

Type IV- slow pain, olfaction

Large myelinated fibers include what fiber types?

A-alpha fibers

A-beta fibers

The dorsal-column/medial lemniscal pathways (cuneatus and gracillis) carry what modalities (100% TQ)

Fine touch

Vibration

Proprioception (conscious) from joint/muscles

The spinothalamic (anterolateral) pathway carries what modalities?

Pain

Temperature

Crude touch (poorly localized)

Sexual sensation

Tickle/itch (C fibers)

Fine touch, vibration and/or conscious proprioception carried above T6 (upper extremities) uses what pathway?

What about below T6 (lower extremities)

cuneatus (above T6)

Gracilis (below T6)

Describe the 1st, 2nd, and 3rd neurons of the dorsal column pathway

(vibration, fine touch, proprioception)

1st order- enters cord in dorsal column and ascends to synapse on nucleus gracilis or cuneatus.

2nd order- Crosses in the medial lemniscal tract and ascends to the VPL or thalamus to synapse.

3rd order- synapses in the cerebral cortex

What modalities does the anterior spinothalamic tract carry with A-delta fibers? C fibers? TQ

A-Delta: Crude touch (poorly localized), sexual sensation

C fibers: tickle and itch

What modalities does the lateral spinothalamic tract carry using A-delta and C fibers? TQ

A-delta: Fast pain and cold temperature

C-fibers: Slow pain and heat

What is the pathway of the anterior spinothalamic tract?

1st order- synapse on dorsal horn

2nd order- cross immediately and synapse on (contralateral) VPL of thalamus

3rd order- synapse on cerebral cortex

What are the two divisions of the lateral spinothalamic tract? What is the difference between them?

Neo-spinothalamic:

-Fast pain/A-delta fibers.

- Ascend to VPL of thalamus

-use glutamate

- mechanical and thermal receptors.

Paleo-spinothalamic:

-Slow pain/C fibers.

-90% terminate in reticular formation and do not make it to the thalamus.

-uses substance P.

-Chemical, mechanical and thermal receptors.

What percent of paleo spinothalamic fibers terminate in the reticular formation of the brain stem? (slow pain/ c fibers)

90%

paleo-spinothalamic nociceptors are stimulated by what type of receptors?

Chemical, mechanical and thermal. neo-spinothalamic does NOT use chemical. Know the difference!

What is an example of chemical stimuli that would travel through the paleo-spinothalamic tract?

Histamine

ischemia/inflammation

prostaglandins

bradykinin

serotonin and more

T/F: both the VPL and VPI of the thalamus can receive pain signals. TQ

TRUE

The somatosensory cortex contains how many layers of neurons?

6 layers

What are the three pain categories discussed in lecture?

nociceptive, neuropathic, nocioplastic

What type of pain is the traditional view of pain, is due to tissue injury (not nerve pain), and may be regulated bu inflammatory products? (TQ)

nociceptive pain

What type of pain is seen in peripheral neuropathy (diabetes, where numbness and burning sensation occur simultaneously).

neuropathic pain (altered firing of nociceptors due to unhealthy neurons)

What type of pain is caused by damage to sensory nerves causing altered firing of nociceptors.

neuropathic pain

Multiple sclerosis, nerve compression and shingles are all examples of what type of pain?

neuropathic

Type of pain that is an alternate explanation of pain where there is altered processing of signals withing the CNS (TQ)

nociplastic pain

What type of pain may be affected by fatigue, stress, mental status, fear and avoidance behavior? (TQ)

nociplastic pain

What type of pain has a good response to therapy? (nothing that can be healed physically)

nociplastic pain

T/F: brain tissue is almost totally insensitive to pain

TRUE

Structures that are sensitive to headaches include what?

dura

dural venous sinuses

blood vessels

tentorium

The anatomical connection between the suboccipital muscles and dura mater is referred to as?

cervical myodural bridge

Cervicogenic headache receives nociception from the greater occipital nerve and is relayed to what sensory nucleus?

tigeminal nucleus caudalic

The current theory behind migraing headaches suggests that nerve endings release the peptides ___________ and _____________________.

_____________ up regulates the production of _______, lowering the threshold for pain.

substance P; calcitonin gene related peptide (CGRP)

estrogen; CGRP

The heart referring pain to the left arm during a heart attach is due to what type of referred pain? why? TQ

visceral localization, because pain is referred to the original embryological location (heart was originally in left armpit area)

aka projection

T/F: Convergence in visceral localization causes the brain to be unable to tell the difference between two difference organs signals. TQ

true

Referred pain to the surface of the body near an organ is? TQ

parietal localization.

What is central sensitization? (TQ)

increased membrane excitability in central nociceptive pathways. (smaller stimulus is able to reach threshold for AP)

Pain with a normally non painful stimulus is referred to as (TQ)

allodynia

Describe the gate control theory and how it modulates pain?

Fast A-beta fibers give off interneurons in the spinal cord that inhibit synapses for the spinothalamic tracts through lateral inhibition.

Describe the descending analgesic system and how is modulates pain

3 regions of the brain stem nuclei send fibers to the dorsal horn that inhibit synapses for the spinothalamic tracts using endorphins and enkephalins