Anatomy #4: Blood.

We are back on track with lessons. We’ve had a month or so to get over illnesses and now we are heading back on track with lessons and more – rather than just doing worksheets and play. Not that there’s anything wrong with worksheets and play, but I still like to try and get lessons in so the kids learn some organized things and have to focus on learning.

We are on blood and the circulatory system.

There are some great YouTube videos on this whole process and they can be found here. We watched all three. They made for some fun viewing and introduced the topic to the kids in a way that I can’t.

The I borrowed the following information about blood from this website:

What are the components of blood?

The components of blood can be divided into plasma and cells. When blood is placed in a container and spun at high speeds in a process called centrifugation, the heavier and denser cells settle at the bottom while the lighter plasma remains on top. Plasma is composed of water, ions like sodium, potassium and calcium, and proteins like albumin and globulins.

The cell component consists of white blood cells, red blood cells and platelets.


  • White blood cells (WBCs). White blood cells, also called leukocytes, are made in the bone marrow but undergo maturation in the thymus. They are bigger than red blood cells. When you have a cold or a fever, these cells are activated and they hone in to the infection. Think of them as your personal army against invaders like bacteria and viruses. When a WBC called macrophage encounters an enemy, it “eats” up the enemy and digests it. Other WBCs are called lymphocytes. T lymphocytes are called killer cells because they destroy the invaders. B lymphocytes are also called plasma cells because they produce globulins or antibodies. Antibodies attach to invaders and mark them for destruction by macrophages and lymphocytes.
  • Red blood cells (RBCs). If red blood cells are removed from blood, it would appear light yellow. This is because it derives its red color from red blood cells or erythrocytes. RBCs contain a structure called heme, which has iron. Blood appears red due to the reaction of iron and oxygen. RBCs are mainly produced in the bone marrow but they can also be manufactured by the liver, kidneys and spleen. When you breathe in, oxygen enters the lungs. The red blood cells in the blood then get the oxygen molecules by binding them with heme. When the red blood cells reach your other tissues, they release the oxygen they are carrying.
  • Platelets. Platelets are from big cells called megakaryocytes, which are present in the bone marrow. Therefore, they are not really cells but are cell fragments made of cytoplasm. A proof that they are not cells can be observed through electron microscopy—they do not contain nuclei, mitochondria and ribosomes. However, platelets are still important because they contain alpha and dense granules. When you get a cut, platelets release these granules in order to prevent bleeding and seal your cut through the process called clotting.


While I was reading the information to the kids, I had them draw a picture of what I was reading. Abby just drew some blobs on the page (her normal point of view if I’m asking her to draw) but Nicholas actually got some of the ideas into his drawing. The red cells were red, the white cells were white (I had given them yellow paper) and he wrote p’s all over the page for plasma. He drew some lines for the platelets. I’ll take that.

Then we got to have some real fun and look at blood under our microscope. This was a totally unexpected activity. Nicholas had cut his knee outside during playtime and wanted to look at the blood, so we did. They thought it was really cool.

Everyone was a little upset that they didn’t get to put anything onto our big skeleton with this lesson – but I promised them that we’d learn how blood fits into our skeleton at the next lesson and they could color it in then.

Abby practiced drawing the letter B today, and coloring our big B. Nicholas practiced writing the word blood – and then had to do his word wall for other words that have the “oo” in the middle of them.

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