Complete the sentence:

Nociceptors are categorized as 1)... n. endings.  They are the distal ends of some 2)...

Nociceptors are categorized as 1)free n. endings.  They are the distal ends of some 2)1^st order neurons (unipolar).

* not encapsulated by CT like m. spindle, GTO, Pacinian corposcles*

C fibres nociceptors detect:

> thermal stimuli

> chemical stimuli

> mechanical stimuli

*not a true reflex (does not reach the CNS)*

release of substance P

*release and diffusion of substance P contributes to inflammatory response*

*Central C fibres release susbtance P to other C fibres close by as a protective mechanism*

mast cells are activated

*substance P activate mast cells → release histamine → activate other nociceptors → produce vasodilation and edema*

algogenic substances

*algogenic substances are what produce pain*

prostaglandins :intensify and prolong pain associated with inflammation

*turns on C nociceptors*

Windup: sensitization from repeatedapplication of noxious stimuli

windup contributes to

tenderness, 1^o hyperalgesia (in damaged region), prolongation of painafter termination of stimulus, alodinia, spontaneous pain

True or false?

Spontaneous pain still requires stimulus

False.

Spontaneous pain does not require stimulus.

*C fibres develop an ongoing background discharge*

What may cause secondary hyperalgesia?

Massage releases entrapped algogenic irritants/DOMS

*the skin becomes reddish, then the irritants are absorbed*

Effleurage decrease edema

> edema = high { } of algogenic products

> massage = release entrapped algogenic products

Gracilis : tract that make up fine touch in lower limbs

*only in C-spine in DC*

Fasciculus: tract that make up fine touch in upper limbs

*only in C-spine in DC*

Lamina 2 aka substantia gelatinosa

*"gelatin substance"*

* laminae are numbered sequentially from dorsal to ventral*

7 layers

*eahch layer is somatotopic*

These are somatotopic layers (contain a map of the body surface)

*each layer has a hummunculus*

*it is gray matter layered*

This tract is composed of association fibres that interconnect several ajacent laminae (side by side) in the dorsal/posterior horn.  Which tract is that?

Lissauer's tract

*made of association fibres*

*connect several laminae side by side in posterior horn*

Complete this sentence

The CNS is not a .... receiver of pain stimuli.

The CNS is not a passive receiver of pain stimuli.

axoaxonal : axon to axon synapse

*between interneuron*

*release endorphin (also enkephalins or GABBA*

Enkephalins: endorphins released in the pain

*NT from axoaxonal synapse in interneuron*

Presynaptic inhibition by interneuron

*↓ release of NT (ie: substance P) at synapse between 1^st order neuron and 2^nd order neuron*

1a or 1b beta fibres

*collateral from large afferant (ie: touch and proprioception) stimulate endorphin = release interneurons in substantia gelatinosa*

Counter-irritation: uses noxious stimuli to irritate the skin for the purpose of relieving pain in deeper structures

*A-delta fibres branch block nerve impulses along C fibres where they synapse with the 2^nd order neuron*

Which ones, below, are examples of noxious stimuli?

Bleeding

acupuncture

heat

some rough massage techs

contain capsaicin

*active ingredient in skin creams for aching muscles*

What word describes natural or synthetic substances resembling opiates in action but not derived from the juice of the opium poppy?

Opioids

*opiate-like*

in adrenal glands

*produced as a sympathetic response to stress*

*chronic pain states, one's capacity to produce endogenous opioids may become diminished = chronic pain gets worse*

Heroin

*specific mix of opiate*

*opiates differ in potency and duration but are all analgesics and contain various amounts of morphine*

Opium

*from papaver somniferum seed*

*contain morphine, codeine, other substances*

Codeine

morphine

other substances

*from papaver somniferum juice in poppy seed*