Pathophysiology Exam 3

Explain the 3 systems that are involved in the experience of pain

Sensory Discriminative, affective-motivational system, cognitive-evaluative system

sensory-discriminative system

mediated by the somatosensory cortex and is responsible for identifying the presence, character, location, and intensity of pain. mediated through the somatosensory cortex.

affective-motivational system

determines an individual's conditioned avoidance behaviors and emotional response to pain. mediated through the limbic system and the brain stem

cognitive-evaluative system

overlies the individuals learned behavior concerning the experience of pain and therefore can modulate perception of pain. it is mediated through the cerebral cortex

Differentiate among the 3 areas of the nervous system responsible for the sensation of pain

Afferent pathways: begin in the peripheral nervous system (PNS), travel to the spinal gate in the dorsal horn and then ascend to higher centers in the central nervous system (CNS).
Interpretive centers: located in the brainstem, midbrain, diencephalon, and cerebral cortex.
Efferent pathways that descend from the CNS back to the dorsal horn of the spinal cord.

nociception

Process whereby noxious stimuli are perceived as pain. Involves four processes: (1) transduction, (2) transmission, (3) perception, (4) modulation

nociceptors

which are free nerve endings in the afferent peripheral nervous system that selectively respond to different types of stimuli. Nociceptors are located throughout the body (Table 13-1) but are not evenly distributed so the relative sensitivity to pain differs according to their location., receptors in the skin that give rise to the sense of pain; they respond to various forms of tissue damage and to temperature extremes

C Fibers

nerve fibers that carry messages for dull, aching, and other types of pain, small and slow unmyelinated pain fibers that carry pain impulses to the spinal cord. these action potentials are slow, chronic, dull, and throbbing pain

A Fibers

large and rapid myelinated pain fibers that carry pain impulses to the spinal cord. these action potenitals are acute, sharp, fast pain signals to the brain. Responsible for pain reflex

Describe the pathway of pain sensation transmission

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excitatory neuromodulators

Substances such as substance P and histamine that sensitize nociceptors leading to increased responsiveness and reduced threshold of nociceptors that cause them to fire with increased frequency

inhibitory neuromodulators

Inhibitory neuromodulators include gamma-aminobutyric acid (GABA), glycine, 5-hydroxtryptamine (serotonin), norepinephrine, and endorphins. thus raising the pain threshold

endogenous opioids

naturally occurring opioids that bind to opiate receptor sites in the central and peripheal nervouse systems, decreaseing or blocking any pain impulse (enkephalins, dynorphins, and beta endorphins

somatogenic pain

Pain that has a physical cause., pain with a cause
Ex. crushed finger

psychogenic pain

pain with no known physical cause; likely has a psychiatric or emotional cause

Peripheral pain

phantom pain, postherpetic neuralgia, or carpal tunnel syndrome that follows damage and/or sensitization of peripheral nerves

Somatic Pain

is superficial, arising from the skin. It is typically well localized and described as sharp, dull, aching, or throbbing

Visceral pain

refers to pain in internal organs and lining of body cavities and tends to be poorly localized with an aching, gnawing, throbbing, or intermittent cramping quality. It is carried by sympathetic fibers and is associated with nausea and vomiting, hypotension, and, in some cases, shock. Visceral pain often radiates (spreads away from the actual site of the pain) or is referred

Referred pain

is felt in an area removed or distant from its point of origin�the area of referred pain is supplied by the same spinal segment as the actual site of pain. Referred pain can be acute or chronic. Impulses from many cutaneous and visceral neurons converge on the same ascending neuron, and the brain cannot distinguish between the different sources of pain

acute pain

is a protective mechanism that alerts the individual to a condition or experience that is immediately harmful to the body and mobilizes the individual to take prompt action to relieve it.11 Acute pain is transient, usually lasting seconds to days, sometimes up to 3 months.22 It begins suddenly and is relieved after the chemical mediators that stimulate pain receptors are removed.23 Stimulation of the autonomic nervous system results in physical manifestations including increased heart rate, hypertension, diaphoresis, and dilated pupils. Anxiety related to the pain experience, including its cause, treatment, and prognosis, is common as is the hope of recovery.11
Acute pain arises from cutaneous, deep somatic, or visceral structures and can be classified as (1) somatic, (2) visceral, or (3) referred

Chronic Pain

has been defined as lasting for more than 3 to 6 months; however, a more accurate definition is pain lasting well beyond the expected normal healing time following the initial onset of tissue damage or injury. "Normal healing time" varies depending on the type of injuryChanges in the peripheral and central nervous systems that cause dysregulation of nociception and pain modulation processes are thought to lead to chronic pain

How do infants and children respond to pain in terms of their physiologic
and behavioral responses?

Physiologic:Increased heart rate, blood pressure, and respiratory rate; flushing or pallor, sweating, and decreased oxygen saturation
Behavioral:Changes in facial expression, crying, and body movements, with lowered brows drawn together; vertical bulge and furrows in forehead between brows; broadened nasal root; tightly closed eyes; angular, square-shaped mouth, chin quiver; withdrawal of affected limbs, rigidity, flailing

Glaucoma

Open angle. This type of glaucoma is characterized by outflow obstruction of aqueous humor at the trabecular meshwork or canal of Schlemm even though there is adequate space for drainage; often this is an inherited disease and is a leading cause of blindness with few preliminary symptoms.
Angle closure. In this type of glaucoma there is displacement of the iris toward the cornea with obstruction of the trabecular meshwork and obstruction of outflow of aqueous humor from the anterior chamber; it may occur acutely with a sudden rise in intraocular pressure, causing pain and visual disturbances.

cataracts

Clouding of lens occur as a consequence of: aging, diabetes mellitus, heavy smoking, and frequent exposure to intense sunlight., eye disease in which the lens becomes covered in an opaque film that affects sight, eventually causing total blindness.

Age-related macular degeneration

is a severe and irreversible loss of vision and a major cause of blindness in older individuals. Hypertension, cigarette smoking, diabetes mellitus and family history of AMD are risk factors. The degeneration usually occurs after the age of 60 years. There are two forms: atrophic (dry, nonexudative) and neovascular (wet, exudative). The atrophic form is slowly progressive with accumulation of drusen (waste products from photoreceptors) in the retina and may include limited night vision and difficulty reading. The neovascular form includes accumulation of drusen, abnormal choroidal blood vessel growth, leakage of blood or serum, retinal detachment, fibrovascular scarring, loss of photoreceptors, and more severe loss of central vision. Both medical and surgical therapies are available.

retinal detachment

Tear or break in retina with accumulation of fluid and separation from underlying tissue; seen as floaters, flashes of light, or a curtain over visual field; risks include extreme myopia, diabetic retinopathy, sickle cell disease

presbyopia

Loss of accommodation with advancing age is termed presbyopia, a condition in which the ocular lens becomes larger, firmer, and less elastic. The major symptom is reduced near vision, causing the individual to hold reading material at arm's length. Treatment includes corrective forward, contact, and intraocular lenses or laser refractive surgery for monovision. (McCance 337)
McCance, Huether and. Understanding Pathophysiology, 5th Edition. Mosby, 122011. <vbk:978-0-323-07891-7#outline(18.4.1.2.3.1)>.

myopia

nearsightedness; the condition in which parallel rays of light are brought into focus in front of the retina, rather than on it

hyperopia

abnormal condition in which vision for distant objects is better than for near objects

astigmatism

distorted vision caused by an oblong or cylindrical curvature of the lens or cornea that prevents light rays from coming to a single focus on the retina (stigma = point)

sensorineural hearing loss

is caused by impairment of the organ of Corti or its central connections.

Presbycusis

is the most common form of sensorineural hearing loss in elderly people. Its cause may be atrophy of the basal end of the organ of Corti, loss of auditory receptors, changes in vascularity, or stiffening of the basilar membranes.

conductive hearing loss

occurs when a change in the outer or middle ear impairs conduction of the sound from the outer to the inner ear. Conditions that commonly cause a conductive hearing loss include impacted cerumen, foreign bodies lodged in the ear canal, benign tumors of the middle ear, carcinoma of the external auditory canal or middle ear, eustachian tube dysfunction, otitis media, acute viral otitis media, chronic suppurative otitis media, cholesteatoma, and otosclerosis

otitis media

is a common infection of infants and children. Most children have one episode by 3 years of age. The most common pathogens are Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. Predisposing factors include allergy, sinusitis, submucosal cleft palate, adenoidal hypertrophy, eustachian tube dysfunction, and immune deficiency. Breast-feeding is a protective factor. Recurrent acute otitis media may be genetically determined.