Block 4, Week 2

Front 1

Name two type of pain.

Back 1

Nociceptive and neuropathic

Front 2

What receptors does nociceptive pain involve and what drugs relieves the pain?

Back 2

- involves nociceptive receptors
- responds to opioids and NSAIDs

Front 3

Examples of injuries involving nociceptive pain.

Back 3

sprains, bone fractures, and bruises

Front 4

How is neuropathic pain different from nociceptive pain?

Back 4

- involves neural tissue damage
- spontaneous discharge and abnormal activity of pain transmission pathways leading to maladaptive changes in nociceptive pathways
- resistant to opioids and NSAIDs

Front 5

Examples of neuropathic pain.

Back 5

peripheral neuopathies, complex regional pain syndrome (CRPA), postherpetic neuralgia

Front 6

Procaine

Back 6

- local anesthetics
- block voltage-dependent Na+ channels in open conformation
- potency: 1
- SHORT duration (~20 sec to a few minutes)
- metabolized by BuChE into PABA, which antagonizes antibacterial action of Sulfonamides.

Front 7

Lidocaine

Back 7

- local anesthetics blocking vg-Na+ channels in open conformation
- potency= 4
- duration is long (0.5-4 hr)

Front 8

Benzocaine

Back 8

- local anesthetics blocking vg-Na+ channels in open conformation
- potency = topical

Front 9

Bupivacaine

Back 9

- local anesthetics blocking vg-Na+ channels in open conformation
- potency= 16
- long duration = ~2.7 hours

Front 10

Cocaine

Back 10

- local anesthetics blocking vg-Na+ channels in open conformation
- potency = topical

Front 11

Ropivacaine

Back 11

- local anesthetics blocking vg-Na+ channels in open conformation
- potency = 11
- long duration = 1.6-6 hours

Front 12

Mepivacaine

Back 12

Very similar to procaine but works faster with a shorter duration.

Front 13

Tetracaine

Back 13

Local anesthetic that blocks intracellular storage calcium channels.

Front 14

What is significant about the previously listed drugs with two "i's" in their names?

Back 14

They are all amides.

Front 15

LA (local anesthetics) target and characteristics of action.

Back 15

Bind to one or more conformational states of vg-Na+ gated channels and affects the rates of going into another conformational state.

Front 16

If LAs bind more to open conformation of Na channels, what kind of fibers are they more likely to affect?

Back 16

LAs that bind to open conformations are more likely to block smaller diameter cells, like pain fibers.

Pain>cold>warmth>touch> deep pressure

Front 17

LAs work better in a basic (pH) environment. What are the consequences in tissue infected with bacteria?

Back 17

LAs will be less effective because bacterial infection is usually associated with acidification.
Also, because there is inflammation and more blood flow in the area, LAs will be flushed out quicker and diluted in the body. This will further decrease its effectiveness.

Front 18

You need to administer a LA to a patient, but she has atypical plasma cholinesterase. What may occur if you continue, and how should you respond instead?

Back 18

LAs may be lethal for patients with atypical plasma cholinesterase. Drug doses should be appropriately adjusted.

Front 19

allodynia

Back 19

normall innocuous stimuli (such as light touch) becomes painful

Front 20

hyperalegesia

Back 20

increased sensitivity to stimuli that are usually moderately painful.
For example, hyperalgesia of sunburned skin.

Front 21

What are gamma fibers?

Back 21

Small and few nerve fibers. Role of Gamma fibers is maintaining the sensitivity and tension of the muscle spindle during muscle contraction.

Front 22

Nociceptors that respond to fast, stabbing pain are...?

Back 22

alpha-delta fibers. they are thin and myelinated fibers

Front 23

What nociceptor detects slow, burning, or itching and dull pain?

Back 23

C fibers. they are unmyelinated, which is why they are slow. They also have autonomic functions.

Front 24

Effects of tissue damage

Back 24

1. Following injury to a tissue there is release of bradykinin, histamine and prostaglandin in area of lesion and surrounding area.
2. These three substances excite nociceceptor fibers and Neurotransmitter release (Glutamate) to stimulate second order neurons in spinal cord.
3. Neurotransmitters (Substance P) are also released from sensory endings, causing release of more histamine and Bradykinin.
4. This results in sensation of more nociceptors, causing allodynia and hyperalgesia.

Front 25

What do muscle spindles do?

Back 25

Receive somatosensory nerve endings and provide info about muscle length. Activated by stretch.

Front 26

What are the different types of muscle fibers within the muscle spindle?

Back 26

Intrafusal muscle fibers are fibers within muscle spindle.
Extrafusal muscle fibers (large muscle fibers) are supplied by alpha motor neurons.
The ends of intrafusal muscle fibers are attached to extrafusal muscle fibers.

Front 27

What are the 3 types of nerve fibers in a muscle spindle?

Back 27

1. Primary Ia nerve fibers (in the center) – sensory afferents (large nerve fibers, more sensitive, discharge slower)
2. Secondary II nerve fibers (surrounds primary fibers) – sensory afferents (smaller nerve fibers, less sensitive)
3. Gamma nerve fibers (innervate small muscle fibers) – motor neuron efferents

Front 28

What are golgi tendon organs?

Back 28

Golgi tendon organ consists of collagen bundles surrounded by a thin capsule.
Large sensory fibers enter the capsule and branch into fine processes, between the collagen bundles.
Tension squeezes the fine processes. It is slowly adapting receptors.

Front 29

Name situations in which a case control study would be required.

Back 29

- studies of exposure that can't be randomly assign for ethical or other reasons
- studies of rare diseases
- study disease with >1 risk factor
- studies in which you want to evaluate several competing hypotheses
- disease with long latency periods
- situations that require a "quick answer"

Front 30

Advantages of case control study design.

Back 30

- it is an analytic design and test medical hypothesis
- only practical design for study rare disease or diseases with long latency periods
- ivolves little added risk to patients
- can study multiple and inter-related etiologies of disease
- useful for generating hypotheses
- requires smaller sample size
- relatively quick, easy to conduct and inexpensive
- can use existing records to determine exposures

Front 31

Weaknesses of case control design

Back 31

- relies on subject recall or past records for exposure history
- validation of true exposure may be impossible
- control of extraneous factors (confounders) may be incomplete
- choosing appropriate controls will be difficult
- highly susceptible to biases
- can't directly calculate incidence
- can't study disease natural history
- can't know if exposure precede onset of disease
- inefficient for studying rare exposures

Front 32

What is absolute risk?

Back 32

incidence/prevalence of disease in a population group

Front 33

What is risk ratio/relative risk?

Back 33

ratio of incidence/risk in an exposed and unexposed group

Front 34

Where are cell bodies of somatosensory receptors localized?

Back 34

Dorsal root ganglion

Front 35

What are Aδ fibers?

Back 35

- nociceptors that are thin, myelinated fibers
- fast/stabbing pain

Front 36

What are C fibers?

Back 36

- nociceptors that are not myelinated fibers
- slow, burning or itching pain