Pain

Pain is defined as an unpleasand sensory and emotional experience that is associated with actual or potential tissue damage

pain receptors

• When afferent impulses reach the spinal cord, a reflex loop is formed within one to to levels of the spinal input
• Some info is sent back for reaction to the stimulus
• Remaining impulses to go the brain to be processed as pain

• Chemosensitive nociceptors
• Mechanosensitive nociceptors

• Mechanical nociceptors are depolarized first
• Mechanical stress or damage to the tissues excite mechanosensitive nociceptors

• Painful impulse is continued by chemical irritation resulting from the inflammatory process
• bradykinin, serotonin, hisamine, and prostaglandins

• nociceptors desplay sensitization to repeated or prolonged stimulation
• during the inflammatory process the threshould required to initiate an action potential is lowered

Primary hyperalgesia occurs lowering the pain threshold no noxious stimuli and increasing the pain response

• C fiber - slow deeper small unmyelinated fibers
• A-delta - larger, thinly myelinated faster fibers
• cell bodies are located in the dorsal root ganglia

• triggered by strong mechanical pressure or intense heat
• 10-25%
• 30 meters/second
• sensation is sparp and to the point

• slow 1-2.50meters per/second
• 50-80%
• Mild Pain
• mechanical and chemical

• first pain
• a-delta

• Second pain
• c fibers

• a third type of peripheral afferent nerve fiber
• large myelinated
• low thershold
• mechanoreceptors that respond to light touch
• stimulation may interrupt nocieption in the dorsal horn of spinal cord
• Break pain cycle
• best friend in physical therapy

• ascending from peripheray to spinal cord
• A-beta, A-delta, C-fibers

• ascend from dorasl horn level of the spinal cord to the brain
• nows as T-cells

The neopinothalamic tract sends immediate warning to the thalumus via a-delta and the paleospinothalamic tract sends slow reminder via c-fibers

• receives input form a-delta
• sympathetic and parasympatheitc to thalamus
• automatic respones
• ventral

• lateral
• Recieves c-fibers
• gives info to medulla, midbrain, hypothalamus, thalamus, limbis systme and periaqueductal gray

Controls autonomic funtions sucha s HR, respirations, and vomiting

Serves as center for many reflexes and assists in coordination movement and visual tracting

cortols the endocrine systems release of hormones through this mechanism the hypothalmus regulates metabolis and stress response

influences mood and body movement that are associated with fear, anxiety, and rage

• link to emotionsand thourgh the cingulate gyus control sthe visceral response to emations dn the senstaion of pain and pleasure
• This is why ppl cry

Hormonally control the release of endorphine and other pain reducing chemicals

• Central Control (descending control)
• A-delta and C fibers
• Ascending A-beta Fibers

• One the nozious stimuli have reached the higher centers of the brain the descenting control mechanisms are activated
• Central Biasing
• PAG
• Upper meddula

Pain inhibiting substances produced in the brian

• CLOSES GATE SO PAIN CANT GET TO THE BRAIN
• Chemicals released by the body to block the pain
• impulses from the thalamus and brianstem (central biasing) via efferent fibers to the dorsal horn
• impulses from the higher center act to close the gate and blcok transmission of the pain message at the dorsal horn synapse

• periaqueductal gray region
• sends endorphins

• sends serotonin - analgesia
• enkephalins - blck transmission

stimulation of fibers causes of release of endogenous opiods

• a-beta blocks a-delta and c-fibers
• act as counterirritant
• gate control theory

• Level of noxious stimulus required to alert the individual to an potentioal threat to tissue
• can't be changed

how much pain a person can take

• acute
• subacute
• chronic
• referred
• otehr aspects of pain (trigger points)