NURS 232 Stress and Adaptation (2)

Page 1: Stress and Adaptation

  • Stress: The body’s response to any demand or challenge, whether physical, emotional, or psychological.

  • Adaptation: The process by which the body adjusts to stressors to maintain balance (homeostasis).

Page 2: Homeostasis

  • Definition: The body’s ability to keep a stable internal environment despite external changes.

  • Importance: Essential for survival, regulating temperature, pH, blood pressure, glucose levels, and more.

Page 3: What Maintains Homeostasis?

  • Trick Question Answer: Diffusion

  • Why? Diffusion allows substances (like oxygen, nutrients, and waste) to move across membranes and maintain balance in the body.

Page 4: Physiological Processes Maintaining Homeostasis

  • Airway: Ensures oxygen can enter the lungs.

  • Breathing: Exchanges oxygen and carbon dioxide in the lungs.

  • Circulation: Transports oxygen and nutrients through the blood.

  • Perfusion: Ensures blood reaches tissues for oxygen delivery and waste removal.

Page 5: Gas Exchange in the Lungs

  • Oxygen (O₂): Moves from the alveoli into red blood cells (via diffusion).

  • Carbon Dioxide (CO₂): Moves from blood into alveoli to be exhaled.

Page 6: Oxygen Transport in the Blood

  • Red blood cells (RBCs) carry oxygen from the lungs to tissues.

  • RBCs return carbon dioxide from tissues to the lungs for exhalation.

Page 7: Why Homeostasis is Crucial

  • The body continuously adjusts to maintain balance, despite external challenges (e.g., temperature, hydration, stress).

Page 8: Negative Feedback in Homeostasis

  • Example: Blood Sugar Regulation

    • Low blood sugar → Pancreas releases glucagon → Liver releases glucose into the blood.

    • High blood sugar → Pancreas releases insulin → Cells take in glucose, lowering blood sugar.

Page 9: Hypothalamic Regulation of Homeostasis

  • Thirst Mechanism: Triggered by dehydration (high solute concentration).

  • Antidiuretic Hormone (ADH): Released to retain water in the kidneys.

Page 10: Stress Response & General Adaptation Syndrome (GAS)

  • Key Systems Activated in Stress:

    • Corticotropin-Releasing Hormone (CRH)

    • Antidiuretic Hormone (ADH)

    • Sympathetic Nervous System (SNS)

    • Renin-Angiotensin-Aldosterone System (RAAS)

Page 11: Sympathetic Nervous System (SNS) – Fight or Flight

  • Triggered by stress → Body shifts into survival mode:

    • Release of epinephrine & norepinephrine

    • ↑ Heart rate & BP

    • ↓ Blood flow to non-essential areas (e.g., digestion slows down)

Page 12: Nervous System Overview

  • Central Nervous System (CNS): Brain & spinal cord.

  • Peripheral Nervous System (PNS):

    • Sensory Division: Sends signals to the brain.

    • Motor Division: Controls muscle movements.

  • Autonomic Nervous System:

    • Sympathetic (fight or flight)

    • Parasympathetic (rest & digest)

Page 13: Autonomic Nervous System – Sympathetic vs. Parasympathetic

  • Sympathetic (Stress Response):

    • ↑ Heart rate & BP

    • Dilates pupils

    • Inhibits digestion

  • Parasympathetic (Recovery Response):

    • ↓ Heart rate & BP

    • Constricts pupils

    • Stimulates digestion

Page 14: Cortisol – The Body’s Primary Stress Hormone

  • Secreted by the adrenal cortex in response to stress.

  • Effects:

    • Increases blood glucose for energy.

    • Suppresses the immune system.

    • Alters metabolism to manage prolonged stress.

Page 15: Effects of Chronic Cortisol Release

  • ↑ Blood sugar (risk of diabetes).

  • ↓ Immune function (increased risk of illness).

  • Delayed wound healing (due to suppressed inflammation).

Page 16: Renin-Angiotensin-Aldosterone System (RAAS)

  • Activated by low blood flow to kidneys or SNS activation.

  • Produces angiotensin II → Vasoconstriction → ↑ BP.

  • Stimulates aldosterone → Retains sodium & water → ↑ blood volume & BP.

Page 17: RAAS Pathway Summary

  • Goal: Maintain blood pressure & fluid balance.

Page 18: Antidiuretic Hormone (ADH) – Water Retention

  • Also known as vasopressin.

  • Prevents water loss by increasing kidney reabsorption of water.

Page 19: Stressors – What Disrupts Homeostasis?

  • Physical stressors (injury, illness, dehydration).

  • Emotional stressors (anxiety, trauma).

  • Environmental stressors (heat, cold, noise).

Page 20: Allostasis – The Body’s Adaptation to Stress

  • The body's process of maintaining stability (homeostasis) through change.

  • Influenced by environment, experiences, and perception of stress.

Page 21: Allostatic Load – The Wear and Tear of Stress

  • High allostatic load = Increased strain on the body.

  • Chronic stress leads to:

    • Hypertension

    • Weakened immune system

    • Increased metabolic disorders (diabetes, obesity)

Page 22: Long-Term Effects of Stress

  • Chronic stress keeps the body in "fight or flight" mode, leading to:

    • Persistent high BP (hypertension).

    • High cortisol levels → Increased fat storage.

    • Suppressed immune function → Increased illness.

Page 23: Consequences of Prolonged Sympathetic Activation

  • RAAS activation → Hypertension & cardiovascular disease.

  • Increased heart workload → Heart failure risk.

Page 24: Effects of Prolonged Cortisol Elevation

  • Insulin resistance → Type 2 diabetes.

  • Muscle wasting & weight gain.

Page 25: Key Takeaways

  • Homeostasis = Balance; Stress = Disruption.

  • Negative feedback mechanisms help restore balance.

  • Chronic stress = Increased health risks (cardiovascular, immune, metabolic).

  • Coping strategies are essential for managing stress effectively and promoting resilience.

  • Positive adaptation can lead to improved mental health and overall well-being.