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Pain, Temperature Regulation, Sleep, and Sensory Function

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Presentation on theme: "Pain, Temperature Regulation, Sleep, and Sensory Function"— Presentation transcript:

1 Pain, Temperature Regulation, Sleep, and Sensory Function
Chapter 15

2 Pain “Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage” —International Association for the Study of Pain “Pain is whatever the experiencing person says it is, existing whenever he says it does” —McCaffrey

3 Pain Theories Specificity theory Gate control theory
Amount of pain is related to the amount of tissue injury Accounts for many types of injuries but does not explain psychological contributions Gate control theory Developed to explain the complexities of the pain phenomenon

4 Neuroanatomy of Pain Nociception Nociceptors Perception of pain
Bare nerve endings in skin, muscle, joints, arteries, and the viscera that respond to chemical, mechanical, and thermal stimuli Can detect a wide range of stimuli Aδ fibers Unmyelinated C polymodal fibers

5 Pathways of Nociception

6 Pathways of Nociception

7 Pathways of Nociception

8 Neuromodulation of Pain
Segmental inhibition Diffuse noxious inhibitory controls Integration of: Peripheral sensory axon terminals Spinal interneurons Top-down control pathways All converge on the spinal dorsal horns

9 Neuromodulation of Pain

10 Neuromodulation of Pain
Chemicals and neurotransmitters Pain excitatory Pain inhibitory Modulators of pain Direct excitation Threshold depolarization from direct stimuli Indirect excitation Threshold depolarization from inflammatory mediators after tissue injury

11 Endorphin Response

12 Clinical Description of Pain
Pain threshold Point at which a stimulus is perceived as pain Perceptual dominance Pain at one location may cause an increase in the threshold in another location Pain tolerance Duration of time or the intensity of pain that a person will endure before initiation of pain responses

13 Pain Classifications Nociceptive pain Non-nociceptive pain
Pain with a cause of normal tissue injury Somatic Visceral Non-nociceptive pain Neuropathic pain Peripheral and central

14 Acute Pain Protective mechanism Manifestations
Alerts an individual to a condition or experience that is immediately harmful to the body Manifestations Fear and anxiety Tachycardia, hypertension, fever, diaphoresis, dilated pupils, outward pain behaviors, elevated blood sugar levels, decreased gastric acid secretion and intestinal motility, and a general decrease in blood flow

15 Acute Pain Acute somatic Acute visceral
Arises from connective tissue, muscle, bone and skin Aδ fibers—pain is sharp and well localized C fibers—dull, aching, and poorly localized Acute visceral Pain in the internal organs and abdomen Poorly localized due to the lesser number of nociceptors

16 Acute Pain Referred pain
Pain that is present 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 Myocardial infarction pain

17 Referred Pain

18 Chronic Pain A situation; state of existence
May be sudden or develop insidiously Usually defined as lasting at least 3 months Response patterns vary Produces significant behavior and psychological changes

19 Common Types of Chronic Pain
Myofascial pain syndromes Injury to the muscle and fascia Spasm, tenderness, and stiffness Chronic postoperative pain Cancer pain

20 Neuropathic Pain Result of trauma or disease of nerves
Most often chronic Painful diabetic neuropathy Postherpetic neuralgia

21 Neuropathic Pain Deafferentation pain Sympathetically maintained pain
Complex regional pain syndromes (CRPS) Central pain Phantom limb pain

22 Pediatrics and Pain Pathways and chemicals associated with pain are functional in preterm and newborn infants Nociceptor system is functional by 24 weeks’ gestation Expressions of pain Facial expression Crying Body language

23 Pediatrics and Pain

24 Aging and Pain Increase in pain threshold Decrease in pain tolerance
Peripheral neuropathies Skin thickness changes Decrease in pain tolerance Alteration in metabolism of drugs and metabolites

25 Temperature Regulation
Variable Location Activity Environment Circadian rhythm Gender

26 Temperature Regulation
Peripheral thermoreceptors Hypothalamic control Heat production and conservation Chemical reactions of metabolism Skeletal muscle contraction Chemical thermogenesis Vasoconstriction Voluntary mechanisms

27 Heat Loss Radiation Conduction Convection Vasodilation
Decreased muscle tone Evaporation Increased respirations Voluntary measures Adaptation to warmer climates

28 Temperature Regulation
Pediatrics Produce sufficient body heat but are unable to conserve heat produced Small body size and high body surface to weight ratio Thin subcutaneous layer Aging Slow blood circulation, vasoconstrictive response, and metabolic rate Decreased sweating and perception of heat and cold

29 Fever Resetting of the hypothalamic thermostat
Activate heat production and conservation measures to a new “set point” Exogenous pyrogens Endogenous pyrogens Endogenous cryogens

30 Fever

31 Benefits of Fever Kills many organisms
Decreases serum levels of iron, zinc, and copper Deprives bacteria of food Promotes lysosomal breakdown and autodestruction of cells Increases lymphocytic transformation and phagocyte motility

32 Hyperthermia Not mediated by pyrogens
No resetting of the hypothalamic set point 41o C (105.8o F): nerve damage produces convulsions 43o C (109.4o F): death results Forms Heat cramps, heat exhaustion, heat stroke

33 Heat Cramps Severe spasmodic cramps in the abdomen and extremities
Following prolonged sweating and associated sodium loss Common in individuals not accustomed to heat or those performing strenuous work in warm climates Fever, rapid pulse, and increased blood pressure often accompany the cramps

34 Heat Exhaustion Collapse due to prolonged high core or environmental temperatures Prolonged vasodilation and profuse sweating Dehydration, depressed plasma volumes, hypotension, decreased cardiac output, tachycardia Manifestations Dizziness, weakness, nausea, and syncope

35 Heatstroke Potentially lethal result of a breakdown in an overstressed thermoregulatory center Brain cannot tolerate temperatures >40.5o C (104.9o F) Temperature maintained by blood flow through the veins in the head and face Cardiovascular and thermoregulatory centers may cease functioning with higher temperatures

36 Heatstroke Manifestations
Cerebral edema, degeneration of the CNS, swollen dendrites, and renal tubular necrosis Rapid peripheral cooling will cause peripheral vasoconstriction and limit core cooling Children are more susceptible Produce more metabolic heat when exercising Greater surface area to mass ratio Sweating capacity is less than adults

37 Malignant Hyperthermia
Complication of inherited muscular disorder Precipitated by the administration of volatile anesthetics and neuromuscular blocking agents Increased calcium release or decreased calcium uptake with muscle contraction Causes sustained muscle contractions Increased oxygen consumption and lactic acid production

38 Hypothermia Body temperature less than 35° C Produces:
Vasoconstriction, alterations in the microcirculation, coagulation, and ischemic tissue damage Ice crystals, which form inside the cells, causing them to rupture and die Tissue hypothermia slows the rate of chemical reactions; increases blood viscosity and slows blood through the microcirculation; facilitates blood coagulation and stimulates vasoconstriction

39 Hypothermia Accidental hypothermia Therapeutic hypothermia
Commonly the result of sudden immersion in cold water or prolonged exposure to cold Therapeutic hypothermia Used to slow metabolism and preserve ischemic tissue during surgery or limb reimplantation May lead to ventricular fibrillation and cardiac arrest

40 Trauma-Induced Temperature Change
CNS trauma Accidental injuries Hemorrhagic shock Major surgery Thermal burns

41 Sleep Active, multiphase process
Hypothalamus is the major sleep center Hypocreatins (ovexins) Promote wakefulness and rapid eye movement (REM) sleep Two phases Rapid eye movement (REM) sleep Non–rapid eye movement (NREM) sleep

42 EEG Stages of Wakefulness and Sleep

43 NREM Sleep 75% to 80% of sleep time Four stages evaluated by EEG
Stage I Stage II Stage III Stage IV

44 REM Sleep 20% to 25% of sleep time Also known as paradoxic sleep
Occurs every 90 minutes beginning after 1 to 2 hours of sleep

45 Normal Sleep Cycles

46 Pediatrics and Sleep Newborns sleep 16 to 17 hours per day
53% of that time is spent in active (REM) sleep The infant sleep cycle is about 50 to 60 minutes Infants enter REM sleep immediately upon falling asleep

47 Aging and Sleep Total sleep time is decreased
Elderly take longer to fall asleep, and awaken more frequently during the night Amount of time in stage IV sleep decreases Potential causes Physical ailments, lack of daily routine, circadian rhythm changes, and medications

48 Sleep Disorders Four classifications Disorders initiating sleep
Insomnia Sleep-disordered breathing Upper airway resistance syndrome Obstructive sleep apnea Obesity hypoventilation syndrome

49 Sleep Disorders Four classifications (cont’d)
Disorders of sleep/wake cycle Parasomnias Somnambulism Night terrors Enuresis Dysfunctions of sleep, sleep stages, or partial arousals

50 Sleep and Disease Secondary sleep disorders Sleep-provoked disorders
Alterations in the quality and/or quantity of sleep due to primary diseases Depression, pain, sleep apnea syndromes, and alterations in thyroid hormone secretion Sleep-provoked disorders Sleep stage alterations produced in certain disease states

51 Vision Blepharitis Hordeolum (stye) Chalazion Keratitis
Inflammation of the eyelids Hordeolum (stye) Infection of the sebaceous glands of the eyelids Chalazion Infection of the meibomian (oil-secreting) gland Keratitis Infection of the cornea

52 Vision Conjunctivitis Inflammation of the conjunctiva
Acute bacterial conjunctivitis (pinkeye) Highly contagious Mucopurulent drainage from one or both eyes Viral conjunctivitis Allergic conjunctivitis Trachoma (chlamydial conjunctivitis)

53 The Eye

54 Visual Field and Neuronal Pathways

55 Vision Changes and Aging
Cornea Anterior chamber Lens Ciliary muscles Retina

56 Visual Dysfunctions Alterations in ocular movements Strabismus
Diplopia Nystagmus Pendular nystagmus Jerk nystagmus

57 Visual Dysfunctions Alterations in visual acuity Amblyopia Scotoma
Retrobulbar neuritis Cataracts

58 Visual Dysfunctions Alterations in visual acuity Papilledema
Dark adaptation Glaucoma Age-related macular degeneration (AMD)

59 Visual Dysfunctions Alterations in accommodation
Accommodation is the process whereby the thickness of the lens changes Oculomotor nerve changes Decreased flexibility of the lens Manifestations: Diplopia, blurred vision, and headache

60 Visual Dysfunctions Alterations in refraction Myopia (nearsighted)
Hyperopia (farsighted) Astigmatism May coexist with myopia or hyperopia

61 Alterations in Refraction

62 Visual Dysfunctions Alterations in color vision
Age-related yellowing of the lens Colorblindness Generally an X-linked recessive trait Commonly red-green colorblindness

63 Visual Dysfunctions Neurologic disorders Hemianopia
Injury to the optic chiasm Homonymous hemianopsia

64 Neurologic Disorders Causing Visual Dysfunction

65 The Ear

66 The Ear

67 Aging and Hearing Cochlear hair cell degeneration
Loss of auditory neurons in spiral ganglia of organ of Corti Degeneration of basilar conductive membrane of the cochlea Decreased vascularity of cochlea Loss of cortical auditory neurons

68 Ear Infections Otitis externa Otitis media Infection of the outer ear
Commonly caused by prolonged moisture exposure (swimmer’s ear) Otitis media Acute otitis media Otitis media with effusion

69 Auditory Dysfunction Conductive hearing loss
Impaired sound conduction Sensorineural hearing loss Impairment of the organ of Corti or its central connections Presbycusis (age-related hearing loss) Mixed hearing loss Functional hearing loss

70 Olfaction Cranial nerve I and part of V
Strong relationship between taste and smell Olfactory stimulants Camphoraceous Musky Floral Peppermint Ethereal Pungent Putrid

71 Taste Cranial nerve VII and part of IX
Nerves in the tongue, soft palate, uvula, pharynx, and upper esophagus Gustatory stimulants Sour Sweet Salty Bitter

72 Age-Related Olfaction and Taste Changes
Decline in odor sensitivity Loss of olfactory sensory neurons and cells in the olfactory bulbs Causes diminished appetite and food selection Taste Higher concentration of flavors is required Decline in the number of fungiform papillae

73 Olfactory Dysfunction
Hyposmia Anosmia Olfactory hallucinations Parosmia

74 Taste Dysfunction Hypogeusia Ageusia Parageusia

75 Somatosensory Function
Touch Sensation involves modality, intensity, location, and duration Receptors are present in the skin Proprioception Depends on inner ear, vision, and receptors in joints and ligaments

76 Proprioceptive Dysfunction
Vestibular nystagmus Vertigo Ménière disease

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