Ch 16 flashcards

Chapter 16: Pain, Temperature Regulation, Sleep, and Sensory Function

Pain

• Definition: Pain is described as an unpleasant sensory and emotional experience associated with actual or potential tissue damage (International Association for the Study of Pain).

• Complex Phenomenon: Pain involves dynamic interactions among various factors: physical, cognitive, spiritual, emotional, and environmental.

Theories of Pain

• Specificity Theory: Suggests that specific pathways and neurons are solely responsible for the sensation of pain.

• Pattern Theory: Proposes that pain is a result of patterns of stimulation rather than specific pain pathways.

• Gate Control Theory: Introduces a mechanism wherein the spinal cord contains a gate that either allows or inhibits pain signals to the brain depending on the activation of non-pain pathways.

• Neuromatrix Theory: Emphasizes that pain is produced by a neural network and is influenced by various factors including emotional and cognitive states.

Neuroanatomy of Pain

• Nociception Phases:

  • Transduction: Conversion of painful stimuli into neural signals.

  • Transmission: The relay of these neural signals to the spinal cord and brain.

  • Perception: The conscious experience of pain once signals reach the brain.

  • Modulation: Altering pain transmission through various mechanisms.

• Pathways:

  • Afferent pathways: Carry sensory information to the brain.

  • Interpretive centers: Brain regions that process pain information.

  • Efferent pathways: Carry signals from the brain to reduce pain perception.

Pain Perception Systems( S. A. C. )

• Sensory-discriminating system: Identifies the location, intensity, and quality of pain.

• Affective-motivational system: Involves emotional responses to pain.

• Cognitive-evaluative system: Influences how pain is perceived based on past experiences or situational context.

Pain Threshold and Tolerance

• Pain Threshold: Minimum intensity of a stimulus that is perceived as painful.

• Pain Tolerance: Maximum intensity of pain that an individual can endure, which varies widely among individuals and can change with time.

Pain Modulation

• Mechanisms:

  • Segmental inhibition: Involves inhibition of pain at the spinal cord level.

  • Conditioned pain modulation: Mechanism where one painful stimulus can inhibit pain from another stimulus.

  • Expectancy-related cortical activation: Brain anticipates pain relief or intensity based on prior experiences.

Modulating Factors

• Pain Inhibitors: Opioids, GABA, cannabinoids, serotonin, and norepinephrine help reduce pain.

• Pain Facilitators: Glutamate, substance P, histamine, prostaglandins, and bradykinin increase pain perception.

Acute Pain

• Types:

  • Acute somatic pain: Originates from skin, muscles, and joints (sharp A-delta fibers vs. dull C fibers).

  • Acute visceral pain: Arises from internal organ damage, generally poorly localized due to less nociceptors.

Chronic Pain

• Definition: Lasts more than three months; poorly understood mechanisms of pain.

• Characteristics: Does not serve any protective function and often leads to depression or anxiety.

Temperature Regulation

• Importance: Critical for maintaining homeostasis; involves heat production, conservation, and loss.

• Normal Body Temperature: Ranges from 36.2–37.7°C (97.2–99.9°F).

• Control: Regulated by the hypothalamus through thermoreceptors and hormonal responses.

Pathogenesis of Fever

• Causes: Inflammation, infection, and microbial products that activate the hypothalamus lead to increased temperature set point.

• Responses: Includes elevated temperature and immunologic responses such as increased circulating neutrophils.

Disorders of Temperature Regulation

• Hyperthermia: Includes heat cramps, exhaustion, and stroke.

• Hypothermia: Results from exposure to extreme cold or can be therapeutic in certain medical procedures.

Sleep

• Nature of Sleep: An active, multiphase process essential for restoration and memory consolidation.

• Phases: Divided into REM and non-REM sleep with distinct processes and structures involved.

Sleep Disorders

• Classifications:

  • Dyssomnias: Including intrinsic and extrinsic sleep issues.

  • Parasomnias: Disorders involving abnormal behavior during sleep.

Sensory Functions

• Vision: Involves complex processes of light detection and visual signal processing.

• Auditory Dysfunction: Types include conductive and sensorineural hearing loss with infections being a significant cause.

• Olfactory and Gustatory Dysfunction: Conditions such as hyposmia or anosmia highlight alterations in the sense of smell and taste.

• Neurological Disorders: Can directly affect sensory perception across modalities.