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Fake Scabs

In this activity, students learn about scabs, as they make fake ones.

Most people would agree that scabs aren't very appealing, but have a critical job in our bodies. Without scabs, germs could enter our bodies through open cuts and scrapes. A scab is a special cover created by our blood to prevent germs from getting into our blood and circulatory system while the skin re-forms underneath.

Blood has 4 main components:

  • Plasma: ~55% of total blood volume
  • Red blood cells (erythrocytes): ~44% of blood by volume
  • White blood cells (leucocytes): remaining blood volume
  • Platelets (thrombocytes): remaining blood volume

Plasma is the liquid portion of blood, composed of 90% water, salts, lipids and hormones, especially rich in proteins (mainly albumin), immunoglobulins (antibodies), clotting factors and fibrinogen. Plasma functions in transporting blood cells and nutrients; regulating the body’s water and mineral; irrigating tissues; defending against infections; and coagulating blood.

Red blood cells carry oxygen from the lungs to body tissue.

White blood cells function in immunity by engulfing "invaders" in the body and platelets, are suspended in plasma.

In combination with platelets, clotting factors, proteins and enzymes in plasma control hemorrhaging (bleeding; when blood exits an artery, tissue or vein).

When a blood vessel is broken platelets bind to the edges of the cut and to each other and trigger the enzyme thrombin to catalyse the formation of the protein fibrin from fibrinogen in the plasma.

Fibrin forms tough insoluble strands, bonding platelets and red blood cells into a clot at the hemorrhage site to block bleeding. It is the platelets and weblike structure of fibrin strands that form the bulk of a scab.

Creating fake scabs is creative way to cement in the ideas of the structure and function of blood, clotting and scabs in blood's role in protecting the body.

Fake scabs are a great creative addition to costumes! Use extra caution when heating and pouring wax, and remind students never to pour extra wax down the sink! An extra pair of adult hands is useful for this activity.

Objectives

  • Explain why scabs are important, mechanically and immunologically (in defending the body).

  • Describe the 4 main components of blood.

  • Discuss the process of clotting and scab formation.

Materials

  • Per Class or Group:
    hot plate
    large pot with water
    large coffee tin, bent at the rim to create a pouring spout OR heat proof glass measuring cup with spout
    blocks of wax/parffin
    red food colouring or dye
    aluminum foil
    cocoa powder
    oatmeal
    popsicle sticks or wooden coffee stir sticks
    vaseline

Key Questions

  • What are the components of blood?
  • Which blood components are responsible for scab formation?
  • Why are scabs important?
  • What role does clotting play in stopping bleeding?
  • What could happen if blood did not clot?
  • What role do scabs play in body defenses?
  • What could happen if scabs did not cover wounds?

What To Do

  1. Create a safe wax-melting station in your classroom. Wax can be messy, so you may want to cover tables. Set up a pot ¼ full of water on the hotplate and turn on the heat.
  2. Break the wax into manageable pieces and put into the coffee tin. Place the tin into the pot of hot water and melt the wax, stirring occasionally with wooden stick.
  3. Once wax has melted, add the food colouring or other red dye and stir well.
  4. WHILE WAX MELTS, students should prepare the rest of their scab materials by cutting a small piece of aluminum foil (10cm square) and scrunching up the edges into a small bowl shape.
  5. ​​In each students’ bowl, place:
  • A teaspoon of cocoa powder.
  • A pinch of oatmeal ground up with your fingers to make it powdery.
  1. Pour a little bit of wax into each student’s foil bowl.
  2. Stir the wax, cocoa and oatmeal with a wooden stick, and then spread it out in the bowl to let it cool completely before peeling off the foil. If you poke gently at the wax while it hardens you’ll get a nice rough texture.
  3. Stick the scab on to a body surface using Vaseline as a temporary adhesive.

Teacher Tip: Applying the fake scab to the body is easier when wax is still warm and can conform to body contours.

WARNING: Be sure to monitor that  students do not apply fake scabs when they are still too hot or pliable, as they may burn or crumble upon application.

Extensions

  • What other bodily processes are triggered by a cut? HINT: pain?
  • Investigate clotting deficiencies. HINT: What is hemophilia?
  • Investigate how donated blood is used.
  • Investigate blood typing. A, B, AB, O ect.

Other Resources

American Society of Hematology | Blood Basics

TedEd |Video| How a Wound Heals Itself

Canadian Blood Services | Donation

TedEd |Video| Why do Blood Types Matter?