Circulatory System

Heartbeat

• The heart beats approximately 100,000 times a day (1^✔ ✔Trusted Source
  A healthy heart is not a metronome: an integrative review of the heart's anatomy and heart rate variability
  
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• The lub-dub sound is due to the blood flowing through the heart chambers during the cardiac cycle (2^✔ ✔Trusted Source
  Physiology, Heart Sounds
  
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• The heartbeat of a woman is faster than that of a man (3^✔ ✔Trusted Source
  Role of biological sex in normal cardiac function and in its disease outcome - a review
  
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Composition of Blood

• Human blood is made up of red blood cells that carry oxygen, white blood cells that fight disease, platelets that help the blood clot, and a liquid portion called plasma (4^✔ ✔Trusted Source
  Blood
  
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Red Blood Cells

• Every second, 5 million red blood cells are removed from the circulatory system (5^✔ ✔Trusted Source
  How Do Red Blood Cells Die?
  
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• The average lifespan of red blood cells is 120 days (5^✔ ✔Trusted Source
  How Do Red Blood Cells Die?
  
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• Red blood cells do not contain a nucleus (6^✔ ✔Trusted Source
  Blood Groups and Red Cell Antigens
  
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White Blood Cells

• There are about 30-40 billion white blood cells present in our body to fight against infective and foreign organisms.

Platelet Production

• Platelets, which form a part of the blood cell component are produced at a rate of 100 billion per day (7^✔ ✔Trusted Source
  Emerging Concepts in Immune Thrombocytopenia
  
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Blood Volume

• An adult human body contains five liters of blood and an infant has about one liter of blood (8^✔ ✔Trusted Source
  Physiology, Blood Volume
  
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Circulation of Blood

• On average, human blood circulates through the whole body every 23 seconds.

Function of the Aorta

• The aorta is the major artery that transports blood from your heart to the rest of your body (9^✔ ✔Trusted Source
  Anatomy, Abdomen and Pelvis: Aorta
  
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Pulmonary Veins

• The pulmonary vein is the only vein in the human body that carries oxygenated blood, while all the other veins of the body carry deoxygenated blood (10^✔ ✔Trusted Source
  Anatomy, Thorax, Lung Veins
  
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Cornea and Blood Supply

• The cornea in the eye is the only part of the body that does not have a blood supply (11^✔ ✔Trusted Source
  Absence of blood and lymphatic vessels in the developing human cornea
  
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Production of Blood Cells

• Each day, an adult can produce one trillion blood cells, including 200 billion red blood cells (12^✔ ✔Trusted Source
  Hematopoiesis
  
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Thickness of Heart

• The left side of the human heart is much thicker and stronger than the right side (13^✔ ✔Trusted Source
  Physiology, Left Ventricular Function
  
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Kidney Filtration

• Each day, the kidneys filter about 1700 liters of blood (14^✔ ✔Trusted Source
  How does the urinary system work?
  
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Smallest Blood Vessel

• Capillaries are the smallest blood vessels in the body; it would take ten of them to equal the thickness of a human hair (15^✔ ✔Trusted Source
  Classification & Structure of Blood Vessels
  
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Length of the Blood Vessel

• An average adult has about 60,000 miles of blood vessels (16^✔ ✔Trusted Source
  Blood and lymphatic vessel formation
  
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