Tag Archives: science

Blood

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  • The average human body has about 1.3 gallons (5 L) of blood
  • It accounts for 7% of total body weight
  • Veins are large blood vessels carrying deoxygenated blood to the lungs. The lungs oxygenate the blood with oxygen from the air. Then, the blood goes into arteries. Arteries are large blood vessels that carry the newly oxygenated blood to every corner of the body

This is a map of major arteries and veins in the human body.

  • If one of these arteries or veins is cut open, the victim may bleed out within several minutes. Bleeding to death is called desanguination (massive loss of blood) or exsanguination (complete loss of blood)
  • Alcoholics or those with liver disease are particularly at risk for de/exsanguination because an impaired liver reduces the blood’s clotting ability

Bleeding (scientifically known as Hemorrhaging (America)/Hæmorrhaging (Britain))

  • Class I – loss of 0-15% (0-0.75 L) of a victim’s blood; vital signs stable; transfusions and saline solutions not necessary; just to be safe, victim should not engage in vigorous physical activity
  • Class II – loss of 15-30% (0.75 L-1.5 L) of a victim’s blood; victim experiences a faster heartbeat; skin cools and appears pale; victim appears dazed or irritable; saline solutions may be necessary
  • Class III – loss of 30-40% (1.5 L-2 L) of a victim’s blood; blood pressure drops; heart rate increases; victim goes into shock; victim is mentally deficient, dazed, has difficulty moving, is hard to understand, and acts strangely; saline solutions and blood transfusions necessary
  • Class IV – loss of 40% (+2 L) or more of a victim’s blood; victim passes out; saline and blood; heart goes into ventricular tachycardia (the heart beats unsustainably fast); transfusions necessary; require resuscitation to prevent death;
  • A cancer patient was found with just 25% (0.9 L) of her blood in her system and survived. She lost the blood over a period of weeks, not all at once
  • Donating blood about takes 8-10% (0.4-0.5 L) of a person’s blood
  • The average woman loses 1 cup (0.24 L) of blood during menstruation
  • Redheads do not bleed faster than other hair types

The Color of Blood

  • Humans and other mammals have red blood because of a compound called hemoglobin. Blood from veins is darker red than blood from arteries because arterial blood is oxygenated. Veins appear blue because of the light-scattering properties of skin, not because the blood is actually blue.
  • Victims of carbon monoxide poisoning have bright red blood
  • Victims of cyanide poisoning have bright red blood in their veins
  • Skinks have green blood
  • Squid, cuttlefish, snails, slugs, and horseshoe crabs have blue blood
  • Sea squirts and sea cucumbers have blood that turns yellow when exposed to oxygen

Blood Types

  • Blood types are determined by the presence or absence of antigens – substances that trigger an immune reaction to foreign objects in the body. An A blood type has A antigens, a B blood type has B antigens, an AB blood type has both A and B antigens, and an O blood type has neither A nor B antigens on red blood cells, but A and B antigens in the plasma
  • Type O can donate to A, B, AB, and O; Type A can donate to A and AB; Type B can donate to B and AB; AB can donate to AB
  • The universal blood cell receiver is AB
  • There is a third antigen called the Rh factor, which can be present (creating a + blood type) or absent (creating a – blood type)
  • The universal red cell donor is O negative
  • The universal plasma donor is AB positive
  • O+ and A+ are the most common blood types
  • B- and AB- are the least common blood types

Blood types are inherited through the parent. This Red Cross chart will help you figure out someone’s blood type

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Reprinted from Reference for Writers