<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <title>Double Circulation Pressure</title>
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }
    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      background: #f8fafc;
      color: #1e2945;
      padding: 12px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      min-height: 100%;
    }

    .toolbar {
      display: flex;
      gap: 6px;
      width: 100%;
      max-width: 560px;
      justify-content: center;
      margin-bottom: 6px;
    }

    .tab-btn {
      flex: 1;
      padding: 6px 10px;
      font-size: 13px;
      font-weight: 600;
      border: 1px solid #cbd5e1;
      background: #ffffff;
      color: #475569;
      border-radius: 6px;
      cursor: pointer;
      text-align: center;
      transition: all 0.2s ease;
    }

    .tab-btn.active {
      background: #2563eb;
      color: #ffffff;
      border-color: #2563eb;
      box-shadow: 0 2px 4px rgba(37, 99, 235, 0.2);
    }

    .graph-container {
      position: relative;
      width: 100%;
      max-width: 560px;
      background: #ffffff;
      border-radius: 8px;
      border: 1px solid #e2e8f0;
      padding: 8px;
    }

    svg {
      width: 100%;
      height: auto;
      display: block;
    }

    .axis-line {
      stroke: #cbd5e1;
      stroke-width: 1.5;
    }

    .grid-line {
      stroke: #f1f5f9;
      stroke-width: 1;
      stroke-dasharray: 4,4;
    }

    .axis-label {
      font-size: 11px;
      fill: #64748b;
      font-weight: 500;
    }

    .section-label {
      font-size: 12px;
      font-weight: 700;
      fill: #334155;
    }

    .trace-path {
      fill: none;
      stroke: #dc2626;
      stroke-width: 3.5;
      stroke-linecap: round;
      stroke-linejoin: round;
    }

    .trace-bg {
      fill: none;
      stroke: #fecaca;
      stroke-width: 8;
      stroke-linecap: round;
      opacity: 0.6;
    }

    .pulse-dot {
      fill: #dc2626;
      stroke: #ffffff;
      stroke-width: 2.5;
      filter: drop-shadow(0 2px 4px rgba(0,0,0,0.25));
      transition: cx 0.4s ease, cy 0.4s ease;
    }

    .zone-rect {
      fill: transparent;
      transition: fill 0.3s ease;
      cursor: pointer;
    }

    .zone-rect.active {
      fill: rgba(37, 99, 235, 0.08);
    }

    .callout {
      width: 100%;
      max-width: 560px;
      margin-top: 8px;
      padding: 8px 12px;
      background: #eff6ff;
      border-left: 4px solid #2563eb;
      border-radius: 0 6px 6px 0;
      font-size: 13px;
      font-weight: 600;
      color: #1e3a8a;
      line-height: 1.35;
      text-align: center;
    }
  </style>
</head>
<body>

  <div class="toolbar">
    <button class="tab-btn active" id="btn-0">1. Lungs</button>
    <button class="tab-btn" id="btn-1">2. Heart Boost</button>
    <button class="tab-btn" id="btn-2">3. Body</button>
  </div>

  <div class="graph-container">
    <svg viewBox="0 0 540 230">
      
      <line x1="50" y1="30" x2="510" y2="30" class="grid-line" />
      <line x1="50" y1="90" x2="510" y2="90" class="grid-line" />
      <line x1="50" y1="150" x2="510" y2="150" class="grid-line" />
      <line x1="50" y1="190" x2="510" y2="190" class="axis-line" />
      <line x1="50" y1="20" x2="50" y2="190" class="axis-line" />

      
      <text x="42" y="34" class="axis-label" text-anchor="end">120</text>
      <text x="42" y="94" class="axis-label" text-anchor="end">80</text>
      <text x="42" y="154" class="axis-label" text-anchor="end">30</text>
      <text x="42" y="194" class="axis-label" text-anchor="end">0</text>

      <text x="18" y="110" class="axis-label" text-anchor="middle" transform="rotate(-90 18 110)">mmHg</text>

      
      <rect id="zone-0" x="50" y="20" width="145" height="170" class="zone-rect active" rx="4" />
      <rect id="zone-1" x="195" y="20" width="130" height="170" class="zone-rect" rx="4" />
      <rect id="zone-2" x="325" y="20" width="185" height="170" class="zone-rect" rx="4" />

      
      <text x="122" y="15" class="section-label" text-anchor="middle">Pulmonary Bed</text>
      <text x="260" y="15" class="section-label" text-anchor="middle" fill="#dc2626">❤️ Re-Pump</text>
      <text x="417" y="15" class="section-label" text-anchor="middle">Systemic Bed</text>

      
      <line x1="195" y1="20" x2="195" y2="190" stroke="#e2e8f0" stroke-dasharray="3,3" />
      <line x1="325" y1="20" x2="325" y2="190" stroke="#e2e8f0" stroke-dasharray="3,3" />

      
      
      
      
      <path d="M 60 150 
               C 90 150, 120 174, 185 174
               C 210 174, 230 30, 270 30
               C 310 30, 340 50, 365 90
               C 400 150, 460 183, 500 183" 
            class="trace-bg" />

      <path id="graph-line" d="M 60 150 
               C 90 150, 120 174, 185 174
               C 210 174, 230 30, 270 30
               C 310 30, 340 50, 365 90
               C 400 150, 460 183, 500 183" 
            class="trace-path" />

      
      <circle cx="60" cy="150" r="4" fill="#64748b" />
      <text x="65" y="142" font-size="11" fill="#64748b" font-weight="600">~25</text>

      <circle cx="185" cy="174" r="4" fill="#0284c7" />
      <text x="185" y="165" font-size="11" fill="#0284c7" font-weight="600" text-anchor="middle">~12</text>

      <circle cx="270" cy="30" r="5" fill="#dc2626" />
      <text x="270" y="48" font-size="12" fill="#dc2626" font-weight="700" text-anchor="middle">120 mmHg</text>

      <circle cx="500" cy="183" r="4" fill="#64748b" />
      <text x="495" y="175" font-size="11" fill="#64748b" font-weight="600" text-anchor="end">~5</text>

      
      <circle id="tracker-dot" cx="122" cy="162" r="7" class="pulse-dot" />
    </svg>
  </div>

  <div class="callout">
    Re-pumping prevents sluggish circulation and maintains high metabolic rates.
  </div>

  <script>
    const steps = [
      { btn: 'btn-0', zone: 'zone-0', cx: 122, cy: 162 },
      { btn: 'btn-1', zone: 'zone-1', cx: 270, cy: 30 },
      { btn: 'btn-2', zone: 'zone-2', cx: 410, cy: 152 }
    ];

    let current = 0;
    const dot = document.getElementById('tracker-dot');

    function setStep(idx) {
      current = idx;
      steps.forEach((s, i) => {
        const b = document.getElementById(s.btn);
        const z = document.getElementById(s.zone);
        if (i === idx) {
          b.classList.add('active');
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        } else {
          b.classList.remove('active');
          z.classList.remove('active');
        }
      });
      dot.setAttribute('cx', steps[idx].cx);
      dot.setAttribute('cy', steps[idx].cy);
    }

    steps.forEach((s, i) => {
      document.getElementById(s.btn).addEventListener('click', () => setStep(i));
      document.getElementById(s.zone).addEventListener('click', () => setStep(i));
    });

    setInterval(() => {
      setStep((current + 1) % steps.length);
    }, 3500);
  </script>
</body>
</html>

The Double Circulatory System and Gas Exchange Relationship

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <title>Double Circulatory System</title>
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
      font-family: system-ui, -apple-system, sans-serif;
    }

    body {
      background: #ffffff;
      color: #1e2945;
      padding: 10px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      min-height: 100%;
      user-select: none;
    }

    /* Controls Bar */
    .controls {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
      width: 100%;
      max-width: 480px;
      margin-bottom: 8px;
    }

    .step-btn {
      width: 28px;
      height: 28px;
      border-radius: 50%;
      border: 1px solid #cbd5e1;
      background: #f8fafc;
      color: #64748b;
      font-size: 13px;
      font-weight: 700;
      cursor: pointer;
      display: flex;
      align-items: center;
      justify-content: center;
      transition: all 0.25s ease;
    }

    .step-btn.active {
      background: #0284c7;
      color: #ffffff;
      border-color: #0284c7;
      box-shadow: 0 0 0 3px rgba(2, 132, 199, 0.2);
    }

    .play-btn {
      padding: 4px 10px;
      border-radius: 14px;
      border: 1px solid #cbd5e1;
      background: #f8fafc;
      color: #334155;
      font-size: 12px;
      font-weight: 600;
      cursor: pointer;
      display: flex;
      align-items: center;
      gap: 4px;
    }

    /* Diagram Grid Layout */
    .circuit-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      grid-template-rows: auto auto auto;
      gap: 10px;
      width: 100%;
      max-width: 480px;
      position: relative;
    }

    .node {
      border-radius: 12px;
      padding: 10px 8px;
      display: flex;
      align-items: center;
      gap: 8px;
      cursor: pointer;
      transition: all 0.25s ease;
      position: relative;
      border: 2px solid transparent;
    }

    .node-num {
      width: 22px;
      height: 22px;
      border-radius: 50%;
      background: rgba(0, 0, 0, 0.08);
      font-size: 12px;
      font-weight: 800;
      display: flex;
      align-items: center;
      justify-content: center;
      flex-shrink: 0;
    }

    .node-icon {
      font-size: 20px;
      line-height: 1;
      flex-shrink: 0;
    }

    .node-content {
      display: flex;
      flex-direction: column;
      overflow: hidden;
    }

    .node-title {
      font-size: 13px;
      font-weight: 700;
      line-height: 1.2;
      white-space: nowrap;
    }

    .node-sub {
      font-size: 11px;
      opacity: 0.8;
      font-weight: 500;
      white-space: nowrap;
    }

    /* Deoxygenated (Blue) styling */
    .deox {
      background: #f0f9ff;
      border-color: #bae6fd;
      color: #0369a1;
    }

    /* Oxygenated (Red) styling */
    .ox {
      background: #fef2f2;
      border-color: #fecaca;
      color: #b91c1c;
    }

    /* Transition nodes (Lungs / Body) */
    .trans-lungs {
      background: linear-gradient(135deg, #f0f9ff 40%, #fef2f2 100%);
      border-color: #cbd5e1;
      color: #1e2945;
    }

    .trans-body {
      background: linear-gradient(135deg, #fef2f2 40%, #f0f9ff 100%);
      border-color: #cbd5e1;
      color: #1e2945;
    }

    /* Active Highlight State */
    .node.active {
      transform: translateY(-2px);
      box-shadow: 0 4px 12px rgba(0, 0, 0, 0.12);
    }

    .deox.active {
      border-color: #0284c7;
      background: #e0f2fe;
    }

    .ox.active {
      border-color: #dc2626;
      background: #fee2e2;
    }

    .trans-lungs.active, .trans-body.active {
      border-color: #7c3aed;
    }

    /* Connector arrow badges */
    .arrow-badge {
      font-size: 11px;
      font-weight: 700;
      padding: 2px 6px;
      border-radius: 8px;
      background: #f1f5f9;
      color: #475569;
      margin: 0 auto;
      text-align: center;
    }

    /* Legend */
    .legend {
      display: flex;
      justify-content: center;
      gap: 16px;
      width: 100%;
      max-width: 480px;
      padding: 6px 12px;
      background: #f8fafc;
      border-radius: 8px;
      border: 1px solid #e2e8f0;
      margin-top: 8px;
    }

    .legend-item {
      display: flex;
      align-items: center;
      gap: 6px;
      font-size: 12px;
      font-weight: 600;
      color: #475569;
    }

    .dot-blue {
      width: 9px;
      height: 9px;
      border-radius: 50%;
      background: #0284c7;
    }

    .dot-red {
      width: 9px;
      height: 9px;
      border-radius: 50%;
      background: #dc2626;
    }

    @media (max-width: 380px) {
      .node-title { font-size: 12px; }
      .node-sub { font-size: 10px; }
      .node-icon { font-size: 18px; }
      .circuit-grid { gap: 6px; }
    }
  </style>
</head>
<body>

  
  <div class="controls">
    <button class="step-btn active" data-step="0">1</button>
    <button class="step-btn" data-step="1">2</button>
    <button class="step-btn" data-step="2">3</button>
    <button class="step-btn" data-step="3">4</button>
    <button class="step-btn" data-step="4">5</button>
    <button class="step-btn" data-step="5">6</button>
    <button class="play-btn" id="playBtn">
      <span id="playIcon">⏸</span> Auto
    </button>
  </div>

  
  <div class="circuit-grid">
    
    <div class="node deox active" data-step="0">
      <div class="node-num">1</div>
      <div class="node-icon">🫀</div>
      <div class="node-content">
        <div class="node-title">Right Heart</div>
        <div class="node-sub">Deoxygenated</div>
      </div>
    </div>

    
    <div class="node ox" data-step="4">
      <div class="node-num">5</div>
      <div class="node-icon">🫀</div>
      <div class="node-content">
        <div class="node-title">Left Heart</div>
        <div class="node-sub">Oxygenated</div>
      </div>
    </div>

    
    <div class="node deox" data-step="1">
      <div class="node-num">2</div>
      <div class="node-icon">↗️</div>
      <div class="node-content">
        <div class="node-title">Pulm. Artery</div>
        <div class="node-sub">To Lungs</div>
      </div>
    </div>

    
    <div class="node ox" data-step="3">
      <div class="node-num">4</div>
      <div class="node-icon">↙️</div>
      <div class="node-content">
        <div class="node-title">Pulm. Vein</div>
        <div class="node-sub">From Lungs</div>
      </div>
    </div>

    
    <div class="node trans-lungs" data-step="2">
      <div class="node-num">3</div>
      <div class="node-icon">🫁</div>
      <div class="node-content">
        <div class="node-title">Lungs</div>
        <div class="node-sub">Gains O₂</div>
      </div>
    </div>

    
    <div class="node trans-body" data-step="5">
      <div class="node-num">6</div>
      <div class="node-icon">👤</div>
      <div class="node-content">
        <div class="node-title">Body & Organs</div>
        <div class="node-sub">Loses O₂</div>
      </div>
    </div>
  </div>

  
  <div class="legend">
    <div class="legend-item">
      <span class="dot-blue"></span> Deoxygenated
    </div>
    <div class="legend-item">
      <span class="dot-red"></span> Oxygenated
    </div>
  </div>

  <script>
    let currentStep = 0;
    let isPlaying = true;
    let timer = null;

    const stepButtons = document.querySelectorAll('.step-btn');
    const nodes = document.querySelectorAll('.node');
    const playBtn = document.getElementById('playBtn');
    const playIcon = document.getElementById('playIcon');

    function showStep(idx) {
      currentStep = (idx + 6) % 6;
      stepButtons.forEach((btn, i) => {
        btn.classList.toggle('active', i === currentStep);
      });
      nodes.forEach(node => {
        const stepNum = parseInt(node.getAttribute('data-step'), 10);
        node.classList.toggle('active', stepNum === currentStep);
      });
    }

    function nextStep() {
      showStep(currentStep + 1);
    }

    function startAuto() {
      stopAuto();
      isPlaying = true;
      playIcon.textContent = '⏸';
      timer = setInterval(nextStep, 3000);
    }

    function stopAuto() {
      isPlaying = false;
      playIcon.textContent = '▶';
      if (timer) clearInterval(timer);
    }

    stepButtons.forEach((btn, i) => {
      btn.addEventListener('click', () => {
        showStep(i);
        stopAuto();
      });
    });

    nodes.forEach(node => {
      node.addEventListener('click', () => {
        const stepNum = parseInt(node.getAttribute('data-step'), 10);
        showStep(stepNum);
        stopAuto();
      });
    });

    playBtn.addEventListener('click', () => {
      if (isPlaying) {
        stopAuto();
      } else {
        nextStep();
        startAuto();
      }
    });

    // Start playback
    startAuto();
  </script>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="1:1">
  <title>Human Double Circulatory System</title>
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; }
    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
      background: #ffffff;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      min-height: 100%;
      padding: 12px;
    }
    .diagram-svg {
      width: 100%;
      max-width: 440px;
      height: auto;
      display: block;
    }
    .flow-line {
      fill: none;
      stroke-width: 6;
      stroke-linecap: round;
    }
    .flow-blue { stroke: #2563eb; }
    .flow-red { stroke: #dc2626; }
    
    .pulse-blue {
      fill: none;
      stroke: #93c5fd;
      stroke-width: 6;
      stroke-linecap: round;
      stroke-dasharray: 18 36;
      animation: flowForward 2.4s linear infinite;
    }
    .pulse-red {
      fill: none;
      stroke: #fca5a5;
      stroke-width: 6;
      stroke-linecap: round;
      stroke-dasharray: 18 36;
      animation: flowForward 2.4s linear infinite;
    }
    @keyframes flowForward {
      to { stroke-dashoffset: -54; }
    }
    .node-box {
      fill: #ffffff;
      stroke-width: 2;
    }
    .label-title {
      font-size: 13px;
      font-weight: 700;
      letter-spacing: 0.3px;
    }
    .label-sub {
      font-size: 11px;
      font-weight: 600;
    }
    .tag {
      font-size: 11.5px;
      font-weight: 700;
      text-transform: uppercase;
      letter-spacing: 0.5px;
    }
  </style>
</head>
<body>

  <svg class="diagram-svg" viewBox="0 0 400 440">
    <defs>
      
      <marker id="arrow-blue" viewBox="0 0 10 10" refX="6" refY="5" markerWidth="6" markerHeight="6" orient="auto-start-reverse">
        <path d="M 1 2 L 8 5 L 1 8 z" fill="#2563eb" />
      </marker>
      <marker id="arrow-red" viewBox="0 0 10 10" refX="6" refY="5" markerWidth="6" markerHeight="6" orient="auto-start-reverse">
        <path d="M 1 2 L 8 5 L 1 8 z" fill="#dc2626" />
      </marker>
    </defs>

    
    <rect x="75" y="12" width="250" height="24" rx="12" fill="#eff6ff" stroke="#bfdbfe" stroke-width="1.5"/>
    <text x="200" y="28" text-anchor="middle" fill="#1d4ed8" class="tag">Low Pressure Gas Exchange</text>

    
    
    <path id="path-pulm-art" class="flow-line flow-blue" d="M 160 185 C 120 155 120 100 160 76" marker-mid="url(#arrow-blue)" />
    <path class="pulse-blue" d="M 160 185 C 120 155 120 100 160 76" />
    
    
    <path id="path-pulm-vein" class="flow-line flow-red" d="M 240 76 C 280 100 280 155 240 185" />
    <path class="pulse-red" d="M 240 76 C 280 100 280 155 240 185" />

    
    <polygon points="127,126 123,138 135,133" fill="#2563eb" />
    <polygon points="273,134 277,122 265,127" fill="#dc2626" />

    
    
    <path id="path-syst-art" class="flow-line flow-red" d="M 240 255 C 280 285 280 340 240 364" />
    <path class="pulse-red" d="M 240 255 C 280 285 280 340 240 364" />

    
    <path id="path-syst-vein" class="flow-line flow-blue" d="M 160 364 C 120 340 120 285 160 255" />
    <path class="pulse-blue" d="M 160 364 C 120 340 120 285 160 255" />

    
    <polygon points="273,306 277,318 265,313" fill="#dc2626" />
    <polygon points="127,314 123,302 135,307" fill="#2563eb" />

    
    <g transform="translate(140, 52)">
      <rect width="120" height="46" rx="10" class="node-box" stroke="#94a3b8" fill="#f8fafc" />
      <text x="60" y="28" text-anchor="middle" fill="#0f172a" class="label-title">🫁 Lungs</text>
    </g>

    
    
    <rect x="135" y="175" width="130" height="90" rx="14" fill="#ffffff" stroke="#cbd5e1" stroke-width="2" />
    
    
    <path d="M 136 189 A 13 13 0 0 1 149 176 L 198 176 L 198 264 L 149 264 A 13 13 0 0 1 136 251 Z" fill="#eff6ff" stroke="#bfdbfe" stroke-width="1.5" />
    <text x="167" y="212" text-anchor="middle" fill="#1e40af" class="label-title">Right</text>
    <text x="167" y="234" text-anchor="middle" fill="#3b82f6" class="label-sub">Deox</text>

    
    <path d="M 202 176 L 251 176 A 13 13 0 0 1 264 189 L 264 251 A 13 13 0 0 1 251 264 L 202 264 Z" fill="#fef2f2" stroke="#fecaca" stroke-width="1.5" />
    <text x="233" y="212" text-anchor="middle" fill="#991b1b" class="label-title">Left</text>
    <text x="233" y="234" text-anchor="middle" fill="#ef4444" class="label-sub">Oxygen</text>

    
    <rect x="165" y="164" width="70" height="20" rx="6" fill="#1e2945" />
    <text x="200" y="178" text-anchor="middle" fill="#ffffff" style="font-size: 11px; font-weight: 700;">HEART</text>

    
    <g transform="translate(140, 342)">
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</body>
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UK-GCSE-SCIENCE-BIO-TS-03

Child standards (2)

Aligned learning resources

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