🎤 Headliner: Bony fish have a single circulation while mammals rock the double circulation!

• 🚫 No U-turn Allowed! Mammals have valves in their veins & heart. This ensures blood flows only ONE way - from arteries, to capillaries, to veins.
• 🌬 Breather Break at Lungs: Mammals send their blood to the lungs for an oxygen party. But this party has a bouncer (low pressure) to keep the alveoli capillaries from over-partying and bursting.
• 💓 The Heart's Two Rooms: After the lung party, blood comes back to the heart for round two! Mammals have a 2-room heart (left and right). No mixing of oxygen-rich and oxygen-poor blood!
  • Left Room Magic: Welcomes oxygen-rich blood and sends it to organs (except lungs). This party needs HIGH energy (pressure). Kidneys are VIP guests since they filter blood and need extra pressure.
  • Right Room Beats: Welcomes oxygen-poor blood and sends it back to the lung party.
• 🔄 Twice the Fun! Blood in mammals takes two laps around the heart for a full round. It's a DOUBLE circulation party!
  • Pulmonary Circuit: Oxygen-poor blood? No worries! This circuit takes you to the lungs to get refreshed.
  • Systemic Circuit: Once refreshed, this circuit sends the blood to the body's dance floor (organs).

• 🌊 Gill Gala: Fish send their blood to the gills for some O₂ fun. Water flows over gill filaments. Here, oxygen from water RSVPs to the blood party, while carbon dioxide leaves.
• 💥 Pressure Support: Thanks to water, fish can pump blood at high pressure to the gills. No risk of bursting capillaries since water's got their back!
• 🔄 One Round Only! After the gill gala, oxygen-rich blood visits another organ. But post-party, it becomes tired and oxygen-poor. So, it returns to the heart to get energized for the next gill party. Hence, just a SINGLE circulation tour!