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pres.layout = "LAYOUT_16x9";
pres.title = "Physiology of Yoga and Meditation";

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// ═══════════════════════════════════════════════════════════════════════════════
//  SLIDE 1 — TITLE SLIDE
// ═══════════════════════════════════════════════════════════════════════════════
{
  const s = pres.addSlide();
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}

// ═══════════════════════════════════════════════════════════════════════════════
//  SLIDE 2 — OVERVIEW / CONTENTS
// ═══════════════════════════════════════════════════════════════════════════════
{
  const s = contentSlide("Overview & Contents", "INTRODUCTION");
  const topics = [
    "Definition & Historical Background",
    "Types of Yoga & Meditation",
    "Autonomic Nervous System Effects",
    "Cardiovascular System Effects",
    "Respiratory System Effects",
    "Neuroendocrine & Hormonal Effects",
    "Musculoskeletal & Metabolic Effects",
    "Brain & Psychological Effects",
    "Clinical Applications & Evidence",
    "Summary & Conclusion",
  ];
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}

// ═══════════════════════════════════════════════════════════════════════════════
//  SLIDE 3 — DEFINITION & HISTORY
// ═══════════════════════════════════════════════════════════════════════════════
{
  const s = contentSlide("Definition & Historical Background", "INTRODUCTION");
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    x: 0.18, y: 1.32, w: 9.65, h: 0.9,
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    { text: " (Sanskrit: युज, 'to unite'): a mind-body discipline combining physical postures (asanas), breath control (pranayama), and meditation to achieve union of body, mind, and spirit.", options: { color: C.white } },
  ], { x: 0.28, y: 1.32, w: 9.4, h: 0.9, fontSize: 14, valign: "middle" });

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    { text: ": a practice of focused attention, awareness, and mental stillness — producing a reproducible psychophysiological state termed the 'Relaxation Response' (Benson, 1975).", options: { color: C.white } },
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    "Originated in ancient India — Vedic texts (~1500 BCE), Patanjali's Yoga Sutras (~400 CE)",
    "Patanjali's Ashtanga (8-limbed) Yoga: Yama, Niyama, Asana, Pranayama, Pratyahara, Dharana, Dhyana, Samadhi",
    "Modern scientific study began in the 1950s–70s (Wenger, Anand, Benson)",
    "WHO recognizes yoga & meditation as complementary integrative health practices",
  ], { y: 3.22, fontSize: 15 });
}

// ═══════════════════════════════════════════════════════════════════════════════
//  SLIDE 4 — TYPES OF YOGA
// ═══════════════════════════════════════════════════════════════════════════════
{
  const s = contentSlide("Types of Yoga & Meditation", "CLASSIFICATION");
  const yogaTypes = [
    ["Hatha Yoga", "Physical postures + breath; prepares body for meditation"],
    ["Raja Yoga", "Mind control & meditation (Patanjali system)"],
    ["Karma Yoga", "Selfless action & service"],
    ["Jnana Yoga", "Path of knowledge & wisdom"],
    ["Bhakti Yoga", "Devotion and surrender"],
    ["Kundalini Yoga", "Energy activation, chanting, movement"],
  ];
  const medTypes = [
    ["Mindfulness", "Non-judgmental present-moment awareness (MBSR)"],
    ["Transcendental", "Use of mantras, eyes closed (TM — Maharishi)"],
    ["Breath-focused", "Pranayama: deep breathing, alternate nostril"],
    ["Loving-kindness", "Cultivation of compassion & positive emotion"],
    ["Guided Imagery", "Visualization for relaxation response"],
    ["Body Scan", "Progressive relaxation, proprioception awareness"],
  ];

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// ═══════════════════════════════════════════════════════════════════════════════
//  SLIDE 5 — AUTONOMIC NERVOUS SYSTEM
// ═══════════════════════════════════════════════════════════════════════════════
{
  const s = contentSlide("Autonomic Nervous System (ANS) Effects", "ANS PHYSIOLOGY");
  // Central concept box
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    x: 3.5, y: 1.35, w: 3.0, h: 0.72,
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    fontSize: 13, bold: true, color: C.dark, align: "center", valign: "middle", margin: 0,
  });
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  const sympItems = [
    "↓ Norepinephrine & Epinephrine",
    "↓ Heart rate (resting bradycardia with training)",
    "↓ Blood pressure (SBP & DBP)",
    "↓ Cortisol & ACTH secretion",
    "↓ Fight-or-flight arousal",
    "↓ Muscle tension & oxygen consumption",
  ];
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    "↑ Vagal tone (↑ HRV — heart rate variability)",
    "↑ Acetylcholine release",
    "↑ Rest-digest-repair state",
    "↑ Baroreceptor sensitivity",
    "↑ Slow oscillations in BP (Mayer waves)",
    "↓ Sympathovagal ratio",
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}

// ═══════════════════════════════════════════════════════════════════════════════
//  SLIDE 6 — CARDIOVASCULAR EFFECTS
// ═══════════════════════════════════════════════════════════════════════════════
{
  const s = contentSlide("Cardiovascular System Effects", "CVS PHYSIOLOGY");
  addTwoCol(
    s,
    "ACUTE EFFECTS (Single Session)",
    [
      "↓ HR by 5-10 bpm during practice",
      "↓ SBP by 5-15 mmHg during deep relaxation",
      "↑ Peripheral vasodilation",
      "↑ Cardiac output transiently in vigorous asanas",
      "Inversions (Sirsasana): ↑ venous return → baroreceptor activation",
    ],
    "CHRONIC EFFECTS (Regular Practice)",
    [
      "↓ Resting HR (training bradycardia)",
      "↓ SBP 5-17 mmHg; DBP 3-10 mmHg (meta-analyses)",
      "↑ Heart Rate Variability (HRV) — index of vagal tone",
      "↓ LDL cholesterol; ↑ HDL",
      "↓ Atherosclerotic risk markers (hs-CRP, fibrinogen)",
      "Beneficial in hypertension, CAD, heart failure",
    ]
  );
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    x: 0.18, y: 5.1, w: 9.65, h: 0.42,
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    { text: "KEY EVIDENCE: ", options: { bold: true, color: C.gold } },
    { text: "Cramer et al. (2014) — systematic review of 44 RCTs; yoga significantly reduces BP in hypertensive patients comparable to aerobic exercise.", options: { color: C.offWhite } },
  ], { x: 0.28, y: 5.1, w: 9.4, h: 0.42, fontSize: 10, valign: "middle" });
}

// ═══════════════════════════════════════════════════════════════════════════════
//  SLIDE 7 — RESPIRATORY EFFECTS
// ═══════════════════════════════════════════════════════════════════════════════
{
  const s = contentSlide("Respiratory System Effects", "RESPIRATORY PHYSIOLOGY");

  // Pranayama types row
  const pranayamas = [
    { name: "Nadi Shodhana", desc: "Alternate nostril breathing — equalizes tidal airflow, balances ANS" },
    { name: "Kapalabhati", desc: "Rapid forced exhalations — exercises diaphragm, expels CO₂" },
    { name: "Bhramari", desc: "Humming breath — stimulates vagus via vibration, ↑ NO production" },
    { name: "Ujjayi", desc: "'Victorious' breath — partial glottic closure, ↑ airway resistance → diaphragmatic training" },
  ];
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    const xPos = 0.18 + i * 2.42;
    s.addShape(pres.ShapeType.rect, { x: xPos, y: 1.32, w: 2.3, h: 0.48, fill: { color: i % 2 === 0 ? C.softTeal : C.accent } });
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    s.addText(p.desc, { x: xPos + 0.08, y: 1.80, w: 2.14, h: 1.1, fontSize: 11, color: C.bodyText, valign: "middle" });
  });

  // Measurable changes
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  s.addText("MEASURABLE PHYSIOLOGICAL CHANGES WITH TRAINING", {
    x: 0.18, y: 3.0, w: 9.65, h: 0.38, fontSize: 12, bold: true, color: C.white, align: "center", valign: "middle", margin: 0,
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  const changes = [
    ["↑ Vital Capacity (VC)", "Diaphragmatic strengthening improves maximum air volume"],
    ["↑ FEV₁ & PEFR", "Improved airway patency; benefit in asthma & COPD"],
    ["↓ Respiratory Rate", "Slower, deeper breaths (4-8 breaths/min vs 12-20 normal)"],
    ["↑ Tidal Volume", "Greater diaphragmatic excursion per breath"],
    ["↑ Breath-Hold Time", "Improved CO₂ tolerance & chemoreceptor adaptation"],
    ["↑ SaO₂ efficiency", "Better ventilation-perfusion matching at rest"],
  ];
  changes.forEach(([param, mech], i) => {
    const xPos = i < 3 ? 0.18 : 5.18;
    const yy = 3.42 + (i % 3) * 0.65;
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    s.addText(param, { x: xPos, y: yy, w: 2.0, h: 0.58, fontSize: 11.5, bold: true, color: C.accent, align: "center", valign: "middle", margin: 0 });
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    s.addText(mech, { x: xPos + 2.08, y: yy, w: 2.6, h: 0.58, fontSize: 11, color: C.bodyText, valign: "middle", margin: 0 });
  });
}

// ═══════════════════════════════════════════════════════════════════════════════
//  SLIDE 8 — NEUROENDOCRINE EFFECTS
// ═══════════════════════════════════════════════════════════════════════════════
{
  const s = contentSlide("Neuroendocrine & Hormonal Effects", "NEUROENDOCRINE");

  // HPA axis section
  s.addShape(pres.ShapeType.rect, { x: 0.18, y: 1.32, w: 4.6, h: 0.42, fill: { color: "8E44AD" } });
  s.addText("HPA AXIS MODULATION", { x: 0.18, y: 1.32, w: 4.6, h: 0.42, fontSize: 12, bold: true, color: C.white, align: "center", valign: "middle", margin: 0 });

  const hpaItems = [
    "↓ Cortisol (salivary & plasma) — key stress hormone",
    "↓ ACTH & CRH output from hypothalamus",
    "↓ Inflammatory cytokines (IL-6, TNF-α, NF-κB)",
    "↑ DHEA-S (protective adrenal androgen)",
    "Normalization of HPA feedback in stress disorders",
  ];
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    "↑ GABA (gamma-aminobutyric acid) — yoga > walking (Streeter 2010)",
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    "↑ β-Endorphin & Enkephalins — pain modulation",
    "↑ Dopamine — reward, attention, motivation",
    "↑ Brain-derived neurotrophic factor (BDNF)",
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// ═══════════════════════════════════════════════════════════════════════════════
//  SLIDE 9 — BRAIN & CNS EFFECTS
// ═══════════════════════════════════════════════════════════════════════════════
{
  const s = contentSlide("Brain & Psychological Effects", "CNS PHYSIOLOGY");

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    "EEG / BRAIN WAVE CHANGES",
    [
      "↑ Alpha waves (8-13 Hz) — relaxed alertness, begin soon after practice starts",
      "↑ Theta waves (4-8 Hz) — deep meditative states, creativity",
      "↑ Gamma waves (>30 Hz) — long-term meditators; focused attention",
      "↓ Beta dominance (stress/anxiety state)",
      "Coherence between frontal & parietal lobes during meditation",
    ],
    "STRUCTURAL BRAIN CHANGES (Neuroplasticity)",
    [
      "↑ Cortical thickness — insula, prefrontal cortex (PFC), somatosensory cortex",
      "↑ Hippocampal grey matter volume — memory & emotional regulation",
      "↓ Amygdala volume & reactivity — reduced fear/stress responses",
      "↑ Default Mode Network (DMN) deactivation — reduced mind-wandering",
      "↑ Corpus callosum integrity — bilateral integration",
    ]
  );

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}

// ═══════════════════════════════════════════════════════════════════════════════
//  SLIDE 10 — MUSCULOSKELETAL & METABOLIC
// ═══════════════════════════════════════════════════════════════════════════════
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      "↑ Flexibility & joint range of motion (ROM)",
      "↑ Muscle strength & endurance (especially core)",
      "↑ Proprioception & balance (cerebellum, vestibular)",
      "↓ Chronic low back pain, neck pain",
      "↑ Bone mineral density (weightbearing asanas)",
    ]},
    { cat: "Metabolism", color: "E67E22", items: [
      "↓ Fasting blood glucose & HbA1c (Type 2 DM benefit)",
      "↓ BMI & waist-hip ratio with regular practice",
      "↑ Insulin sensitivity",
      "↓ Triglycerides; favorable lipid profile",
      "↑ Basal metabolic rate (vigorous Vinyasa)",
    ]},
    { cat: "Immune System", color: "8E44AD", items: [
      "↑ NK cell activity & lymphocyte counts",
      "↓ Inflammatory markers (CRP, IL-6, TNF-α)",
      "↑ Secretory IgA (mucosal immunity)",
      "↑ Telomerase activity — may slow cellular aging",
      "Benefit in autoimmune conditions",
    ]},
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// ═══════════════════════════════════════════════════════════════════════════════
//  SLIDE 11 — CLINICAL APPLICATIONS
// ═══════════════════════════════════════════════════════════════════════════════
{
  const s = contentSlide("Clinical Applications & Evidence", "CLINICAL RELEVANCE");

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    { cond: "Hypertension", evidence: "↓ SBP 5-17 mmHg; DBP 3-10 mmHg — JNC 8 lists lifestyle measures", color: C.softTeal },
    { cond: "Type 2 Diabetes", evidence: "↓ HbA1c, ↓ FBG, ↑ insulin sensitivity; ADA endorses yoga", color: "E67E22" },
    { cond: "Depression & Anxiety", evidence: "↑ GABA, serotonin; comparable to antidepressants in mild-moderate cases", color: "8E44AD" },
    { cond: "Asthma & COPD", evidence: "↑ FEV₁, ↑ VC, ↓ frequency of attacks with pranayama", color: "1A6B6B" },
    { cond: "Chronic Pain (LBP)", evidence: "↓ Pain scores; ↑ function — evidence level: Moderate-Strong RCTs", color: "D9534F" },
    { cond: "Insomnia", evidence: "↑ Melatonin, ↑ GABA; yoga nidra improves sleep architecture", color: C.midTeal },
    { cond: "PTSD / Stress", evidence: "↓ Cortisol, ↓ amygdala reactivity; Trauma-sensitive yoga (van der Kolk)", color: C.deepTeal },
    { cond: "CAD Rehabilitation", evidence: "Ornish Program: regression of atherosclerosis with yoga + diet", color: "C0392B" },
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// ═══════════════════════════════════════════════════════════════════════════════
//  SLIDE 12 — RELAXATION RESPONSE
// ═══════════════════════════════════════════════════════════════════════════════
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  const s = contentSlide("The Relaxation Response — Benson (1975)", "INTEGRATIVE MECHANISM");

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    "↓ Respiratory rate",
    "↓ Heart rate",
    "↓ Blood pressure",
    "Slow alpha-wave EEG predominance",
    "↓ Serum lactate (→ ↓ anxiety)",
    "↑ Skin resistance (↓ galvanic response)",
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// ═══════════════════════════════════════════════════════════════════════════════
//  SLIDE 13 — SUMMARY TABLE
// ═══════════════════════════════════════════════════════════════════════════════
{
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    ["Autonomic NS", "↓ Sympathetic tone; ↑ Parasympathetic / vagal tone; ↑ HRV", "Stress reduction, cardiovascular protection"],
    ["Cardiovascular", "↓ HR, BP; ↑ HRV; favorable lipids", "Hypertension, CAD prevention"],
    ["Respiratory", "↑ VC, FEV₁, PEFR; ↓ RR; diaphragm strengthening", "Asthma, COPD, dyspnea"],
    ["Neuroendocrine", "↓ Cortisol; ↑ GABA, serotonin, β-endorphin, BDNF", "Anxiety, depression, pain"],
    ["Brain (CNS)", "↑ Alpha/theta EEG; ↑ grey matter; ↓ amygdala", "PTSD, stress, cognition"],
    ["Metabolic", "↓ FBG, HbA1c; ↑ insulin sensitivity; ↓ BMI", "Type 2 Diabetes, obesity"],
    ["Immune", "↓ CRP, IL-6; ↑ NK cells; ↑ IgA", "Inflammatory & autoimmune disease"],
    ["MSK", "↑ Flexibility, strength, proprioception; ↓ pain", "LBP, arthritis, rehabilitation"],
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// ═══════════════════════════════════════════════════════════════════════════════
//  SLIDE 14 — CONCLUSION
// ═══════════════════════════════════════════════════════════════════════════════
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    "Yoga and meditation are not merely cultural practices — they induce measurable, reproducible physiological changes across multiple organ systems.",
    "The core mechanism is modulation of the Autonomic Nervous System: shifting the sympathovagal balance toward parasympathetic dominance (Relaxation Response).",
    "Key downstream effects: ↓ Cortisol, ↑ GABA/Serotonin, ↓ HR & BP, ↑ HRV, ↑ grey matter, ↑ lung function.",
    "Evidence-based clinical applications include hypertension, Type 2 DM, anxiety, depression, COPD, chronic pain, and CAD rehabilitation.",
    "Regular practice induces neuroplasticity — structural brain changes visible on MRI — making these effects durable.",
    "As future physicians, integrating knowledge of yoga physiology equips us to recommend evidence-based mind-body medicine to our patients.",
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// ═══════════════════════════════════════════════════════════════════════════════
//  SLIDE 15 — REFERENCES
// ═══════════════════════════════════════════════════════════════════════════════
{
  const s = contentSlide("References", "REFERENCES");
  const refs = [
    "1. Benson H, Beary JF, Carol MP. The relaxation response. Psychiatry. 1974;37(1):37-46.",
    "2. Patanjali. Yoga Sutras (~400 CE). Classical Sanskrit text.",
    "3. Streeter CC et al. Effects of yoga versus walking on mood, anxiety, and brain GABA levels. J Altern Complement Med. 2010;16(11):1145-52.",
    "4. Cramer H et al. A systematic review and meta-analysis of yoga for hypertension. Am J Hypertens. 2014;27(9):1146-51.",
    "5. Lazar SW et al. Meditation experience is associated with increased cortical thickness. Neuroreport. 2005;16(17):1893-7.",
    "6. Harinath K et al. Effects of Hatha yoga and Omkar meditation on cardiorespiratory performance, psychologic profile, and melatonin secretion. J Altern Complement Med. 2004;10(2):261-8.",
    "7. Ross A, Thomas S. The health benefits of yoga and exercise: a review of comparison studies. J Altern Complement Med. 2010;16(1):3-12.",
    "8. Innes KE, Bourguignon C, Taylor AG. Risk indices associated with the insulin resistance syndrome, cardiovascular disease, and possible protection with yoga: A systematic review. J Am Board Fam Pract. 2005;18:491-519.",
    "9. Guyton & Hall Textbook of Medical Physiology, 14th Ed. — Autonomic Nervous System chapter.",
    "10. Harrison's Principles of Internal Medicine, 22nd Ed. (2025) — Complementary and Integrative Medicine.",
  ];
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