• 11 parts
  • Checked October 2026

Components of Blood Diagram

A tube of spun blood: plasma, buffy coat and red cells, with what each layer holds.

Components of Blood Diagram

Name Date

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1 2 3 4 5 6 7 8 9 10 11
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Write the name of each numbered part.Answer key

  1. Plasma
  2. Buffy coat
  3. Erythrocytes (red blood cells)
  4. Water
  5. Plasma proteins
  6. Other solutes
  7. Albumins
  8. Globulins
  9. Fibrinogen
  10. Leukocytes (white blood cells)
  11. Platelets

Drawn for this site on 2026-10-03 from plain geometry. Licence: own work.

Each numbered ring is a button. Use the arrow keys to move between them and Enter to choose. Names are read out in Study, and once a part is answered.

Next step Next: the blood cells, kind by kind

All 11 parts on the diagram

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  1. Plasma The liquid part of blood. It is about 55 percent of the blood and stays on top after spinning.
  2. Buffy coat A thin layer of white blood cells and platelets. It settles between the plasma and the red cells.
  3. Erythrocytes (red blood cells) Red blood cells, packed at the bottom. Their share of the blood is called the hematocrit.
  4. Water Plasma is mostly water. Everything else in plasma is dissolved or carried in it.
  5. Plasma proteins Proteins dissolved in the plasma. The three groups are albumins, globulins and fibrinogen.
  6. Other solutes Everything else dissolved in plasma: salts, nutrients, gases, hormones and wastes.
  7. Albumins The most common plasma proteins. They help hold water in the blood by osmotic pressure.
  8. Globulins A group of plasma proteins. Antibodies are globulins, called gamma globulins or immunoglobulins.
  9. Fibrinogen The plasma protein that forms blood clots. It turns into threads of fibrin.
  10. Leukocytes (white blood cells) The white blood cells of the immune system. They help the body fight infection.
  11. Platelets Tiny pieces of very large cells. They help blood clots form.

How this list was compiled: Every name read on 2026-10-03 and kept only where two independent sources give it. (1) Wikipedia, text only: Blood, Blood plasma, Buffy coat, Blood fractionation and Hematocrit, https://en.wikipedia.org/wiki/Blood_fractionation : the three layers of spun blood, plasma as about 55 percent of blood and mostly water, the plasma proteins, the buffy coat of leukocytes and platelets. (2) U.S. National Cancer Institute, Dictionary of Cancer Terms, https://www.cancer.gov/publications/dictionaries/cancer-terms : plasma, albumin, fibrinogen, platelet, leukocyte, erythrocyte and hematocrit. (3) Henry Gray, Anatomy of the Human Body (1918, public domain), The Blood, https://www.theodora.com/anatomy/the_blood.html : plasma and the three kinds of corpuscle, the red ones biconcave disks. (4) Three books read by full-text search at archive.org: a 1946 volume of a medical technology journal and a 1986 book on red cell metabolism (the buffy coat of leukocytes and platelets between the red cells and the plasma), and a study guide to a college physiology textbook (plasma water as the carrier; albumins, globulins and fibrinogen; antibodies as gamma globulins; electrolytes, nutrients, gases, hormones and wastes), https://archive.org/details/sim_american-journal-of-medical-technology_1946-03_12_2 , https://archive.org/details/redcellmetabolis0000unse , https://archive.org/details/studyguideforshe0000harl_v1v9 . The drawing is our own. Licence: own work

The drawing: Drawn for this site on 2026-10-03 from plain geometry. Own original drawing; nothing traced or copied. Not to scale. Licence: own work

How it works

When a tube of blood is spun in a centrifuge, it separates into three layers. The heaviest part, the red blood cells, sinks to the bottom, the plasma stays on top, and a thin buffy coat lies between them.

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The three layers

Plasma is the top layer, about 55 percent of the blood. The buffy coat is the thin band under it. The erythrocytes are packed at the bottom.

What each layer holds

Follow the lines from a layer to its tiles. Plasma is mostly water, with plasma proteins and other solutes. The proteins come in three groups: albumins, globulins and fibrinogen. The buffy coat holds the leukocytes and the platelets.

  • The drawing is not to scale: the real buffy coat is far thinner than drawn here.

Questions and answers

What are the components of whole blood after centrifugation?

Three layers. Plasma, the liquid, is on top. The buffy coat, a thin band of white blood cells and platelets, is in the middle. The erythrocytes, or red blood cells, are packed at the bottom.

What is the buffy coat?

The thin layer between the plasma and the red cells in a tube of spun blood. It holds most of the white blood cells and the platelets.

What is plasma made of?

Mostly water. Dissolved in it are the plasma proteins (albumins, globulins and fibrinogen) and other solutes such as salts, nutrients, gases, hormones and wastes.

What does hematocrit mean?

It is the share of the blood that is made up of red blood cells: the bottom layer of the tube compared with the whole column.

How do I drag the labels to identify the components of whole blood after centrifugation?

Name the three layers first, top to bottom: plasma, buffy coat, erythrocytes. Then place what each one holds. This drawing is our own, made for practice.

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