Blood is mostly a liquid called plasma with three main kinds of cells floating in it: red blood cells, white blood cells, and platelets. Each part has a different job, like carrying oxygen, fighting germs, or helping your blood clot when you get a cut.

Main parts of blood

  • Plasma : The yellowish liquid that makes up about half or a bit more of your blood; it is mostly water but also carries sugars, fats, proteins, hormones, salts, and vitamins. Plasma is what transports nutrients, waste products, and many signaling chemicals around the body.
  • Red blood cells : Cells packed with hemoglobin that give blood its red color and carry oxygen from the lungs to the rest of the body and carbon dioxide back to the lungs. They make up most of the solid part of blood and are crucial for delivering energy to tissues.
  • White blood cells : A group of different immune cells (like lymphocytes, neutrophils, monocytes, eosinophils, and basophils) that patrol the body to find and destroy germs or abnormal cells. They help control infections and coordinate the body’s immune defenses.
  • Platelets : Tiny cell fragments that rush to a damaged blood vessel and help form clots so bleeding slows and scabs can form. They work together with special proteins in plasma called clotting factors to seal wounds.

Rough percentages

  • Plasma: about 55–60% of total blood volume.
  • Cells and platelets together: about 40–45% (most of this is red blood cells, with white cells and platelets making up a much smaller fraction by volume).

Mini FAQ: what makes up blood?

  1. Is blood just cells?
    No; blood is a mixture of a watery fluid (plasma) and different types of cells and cell fragments.
  1. What’s inside plasma?
    Water, dissolved nutrients like glucose and fats, salts, hormones, antibodies, and clotting proteins all ride in plasma.
  1. Why are there different white blood cells?
    Different white blood cells specialize in different tasks, such as targeting bacteria, parasites, or coordinating longer-term immune memory.

Information gathered from public forums or data available on the internet and portrayed here.