AY Honors/Blood and the Body's Defenses/Answer Key

Have the Microscopic Life honor.

The PDF of answers to the Microscopic Life honor can be found Here.

Name two major constituents of blood. What is the percentage of each in normal blood?

Human blood consists of about 45% blood cells, and 55% plasma.

Be able to draw pictures of and name the 7 types of blood cells and indicate what each type does.

1. Neutrophils, are a type of white blood cell which travel to infected tissue and surround bacteria, rendering them harmless to the body. The picture below shows two neutrophils surrounded by multiple red blood cells.

2. Monocytes, are a type of white blood cell which also travel to infected tissue and turn into macrophages. As macrophages, these cells kill germs (including cancer cells) and start the production of antibodies.

3. Eosinophils, are a third form of white blood cells and are responsible for combatting infections by parasites.

4. Lymphocytes are type of white blood cell involved in the human body's immune system. There are two broad categories of lymphocytes, namely T cells and B cells. T cells are especially important in cell-mediated immunity, which is the defense against tumor cells and pathogenic organisms inside body cells. They are also involved in rejection reactions. B cells, in the presence of an antigen (a substance that stimulates an immune response), can become much more metabolically active and differentiate into plasma cells, which secrete large quantities of antibodies.

5. Basophils are a fifth type of white blood cell which store histamine, a chemical that is secreted by the cells when stimulated in certain ways (histamine causes some of the symptoms of an allergic reaction). Basophils tend to appear in specific kinds of inflammatory reactions, particularly those that cause allergic symptoms.

6. Red Blood Cells are responsible for transporting oxygen to other cells in the body, and for collecting carbon dioxide from them for disposal.

7. Platelets are the blood cell fragments that are involved in the cellular mechanisms that lead to the formation of blood clots.

Observe some preserved human blood under a microscope. Count 100 white blood cells and draw a graph showing the number of each of the five types of white blood cells you found. Which type is most common? Which type is least common?

White Blood Cell Distribution chart

White Blood Cell Type	Range
Neutrophils	50-70%
Lymphocytes	15-40%
Monocytes	2-8%
Eosinophils	1-4%
Basophils	0.4-1.0%

Reference for white blood cell distribution: Family Practice Notebook

Do at least one of the following and report on what you observed.

Observe blood being drawn from someone's arm by a medical professional.

This requirement can be met by organizing a blood drive for your church. Blood donation organizations will not accept blood from minors, but there are still ample opportunities for the Pathfinders to help in other ways. This is an excellent way to meet the Community Service requirements for the AY curriculum.

Invite the organization to have a blood drive at your church. The Pathfinders should help set everything up, greet people, hand out paper work to the donors, serve cookies and juice, and clean up afterwards.

With the help of an experienced person, observe blood flowing through some capillaries (either on video tape or in a living organism such as a hamster cheek-pouch, frog skin, or goldfish tail, using a microscope).

This website has a short movie clip showing blood flowing through a capillary, but it's very short. Its shortness makes for a quick download though (56Kbytes). It is best to play the movie in "loop" mode.

Here is another website with an online movie of blood flowing through a capillary. The movie file is 11 Mbytes long.

Visit a medical lab where blood tests are performed.

Talk to your personal physician or a doctor in your church to find out where the local medical labs are.

Visit a blood bank.

Contact your local Red Cross to arrange a visit. You can find your local chapter at their website.

What two gasses are transported by the red blood cells? Explain why blood appears blue/green in your veins, but if you cut yourself, the blood that comes out is bright red. Explain why a lack of iron in your diet might make you have yellowish-colored blood.

Red blood cells transport oxygen to the rest of the body and carry the carbon dioxide away. Blood carrying oxygen appears bright red. When you cut yourself, your blood is exposed to oxygen in the air, and this is sufficient to cause it to turn color. When little oxygen is present is the blood, it is still red, but it is much darker, tending more towards black. Blood is neither blue nor green inside your veins, but it looks this way sometimes because the veins themselves and pigment in your skin impart a bluish tint.

Blood carries oxygen by letting it bind loosely with iron. Without sufficient iron in the blood, its oxygen carrying capacity is reduced. Since oxygen is what makes the blood bright red, it cannot assume this color without iron. Blood plasma is yellow, so when the red cells cannot impart their color to the blood with full power, the underlying color of the plasma has a greater influence.

Explain how blood clots when you are injured. How does typical "First Aid" help in the process?

Blood clotting occurs in two stages called primary hemostasis and secondary hemostasis. Primary hemostasis begins immediately after the wall of a blood vessel is broken. Platelets in the blood bind to a protein called collagen which is found in the vessel wall. Normally the collagen is hidden from the platelets, but when the blood vessel is broken, it becomes exposed. When the platelets bind with the collagen, it forms a plug which slows the flow of blood through the break in the blood vessel.

Secondary hemostasis takes place over the next couple of hours. A protein in the blood called fibrinogen is converted to fibrin which is long and string-like. The fibrin forms a mesh which makes the clot larger, eventually sealing the break in the blood vessel.

Typical first aid for bleeding concentrates on slowing and stopping the flow of blood from the wound. If the blood is allowed to pool around the wound instead of flowing out of it, more platelets and fibrinogen is available on the scene and the clot can form more quickly.

What does it mean to be a blood donor? If possible, know your blood type. What types of blood can be donated to you? Which blood types cannot be donated to you? Why?

Being a blood donor means that a person allows his or her blood to be drawn so that it can be used at a later time. Sometimes the blood is used by another person, and sometimes the blood is used by the donor herself. Often when a person is scheduled for surgery and has plenty of advance notice, she has the opportunity to bank some of her own blood. This is called an autologous donation. Autologous blood donations do not need to be screened for things like AIDS or hepatitis because the person cannot contract a disease from herself. If she has the disease, she has the disease. If she doesn't, she won't contract it from her own blood. However, if the blood donation is not autologous, it is carefully screened for all types of potential diseases so that the person receiving it does not contract it from the transfusion.

Before donating blood, the donor must fill out an extensive questionaire. If the donor has traveled in certain foreign countries recently (where tropical diseases are common, for instance), or if the person is at high risk for contracting AIDS, the blood donation will not be accepted. Blood is also not accepted from people who have ever had cancer, hepatitis, or any number of other diseases.

Once the forms have been filled out, the blood type is tested, and then the donor lies on a table. A tube is inserted in an arm vein (this may involve a little pain, but it is brief and not severe), and the donor is then asked to squeeze a rubber ball. The amount of time spent lying on the table depends on how quickly a pint of blood can be extracted, but it ranges between five and twenty minutes. When a pint of blood has been extracted, the tube is removed and the donor may slowly sit up. The wound is bandaged, and free cookies and juice are served to replenish the donor's body fluids and restore sugar.

Blood typing can be done at home or in the classroom. Sargent-Welch sells blood typing kits that will test the blood type of 50 individuals for about $1.00 per person. These kits are made for educational settings.

Health Hometest has kits you can buy for testing a single person for about $10.00.

Nobelprize.org has an online "Blood Typing Game" for determining the blood type of a virtual patient.

The ABO and Rh blood typing systems categorize blood according to the way antigens and antibodies behave in a person's blood.

ABO Groups:

• Blood Group A: Persons with type A blood have type A antigens on the surface of their red blood cells and type B antibodies in their blood plasma.
• Blood Group B: Persons with type B blood have type B antigens on the surface of their red blood cells and type A antibodies in their blood plasma.
• Blood Group AB: Persons with type AB blood have both type A and type B antigens on the surface of their red blood cells and neither type A nor type B antibodies in their blood plasma.
• Blood Group O: Persons with type O blood have neither type A nor type B antigens on the surface of their red blood cells and they have both type A and type B antibodies in their blood plasma.

Rh Factor:

• Rh Positive blood has Rh antigens on the surface of the red blood cells, and does not have Rh antibodies in the blood plasma.
• Rh negative blood does not have Rh antigens on the surface of their red blood cells. It does not naturally have Rh antibodies in the blood plasma, but it can develop them if exposed to Rh positive antigens (if for instance, Rh+ blood is given to an Rh- patient).

The ABO group and Rh factor are combined to specify the blood type. So a person with type AB+ (pronounced AB positive) blood has type AB blood and is Rh positive.

The blood plasma and corpuscles (red cells, white cells, and platelets) are seperated in donated blood before it is transfused into a patient. This removes most of the donor's antibodies from the blood since the antibodies are present in the plasma. Because antibodies attack cells with a specific antigen marker, people with type A antibodies cannot receive blood that has type A antigens. If a person with type A antibodies receives blood with type A antigens, the patient's blood will attack the donated blood causing it to clump together and eventually break down. When the cells break down, they can release toxins that could possibly kill the patient. The same holds for type B and type Rh antigens and antibodies.

Blood compatibility chart

Recipient Blood Type	Donor must be
AB+	Any blood type
AB-	O-	A-	B-	AB-
A+	O-	O+	A-	A+
A-	O-	A-
B+	O-	O+	B-	B+
B-	O-	B-
O+	O-	O+
O-	O-

Tell two stories in the Bible in which blood is involved. From what you know about blood, why do you think that the Bible uses blood as a symbol of God's saving power?

• Joseph's brothers dip his coat in blood before returning to their father. Genesis 37:12-36.
• Moses turns the Nile into blood. Exodus 7:14-24.
• During Passover the angel of death passes over houses marked with blood. Exodus 12:1-30.
• Blood is taken into the Most Holy Place on the Day of Atonement. Leviticus 16
• The priests of Baal cut themselves in their contest with Elija on Mount Carmel. 1 Kings 18:16-40.
• King Ahab bleeds to death in his chariot. 1 Kings 22:29-40.
• The Last Supper is a symbol of Christ's body and blood. Luke 22:7-32.
• Jesus's side is pierced on the cross and blood and water flows out. John 19:28-37.
• The saints' robes washed in the blood of Jesus. Revelation 7:15

Blood is responsible for collecting waste from all over our bodies. In this sense, it literally washes us on the inside, just as Christ's blood washes away our sins.

Define the following terms related to the body's defenses:

• Immunology: a broad branch of biomedical science that covers the study of all aspects of the immune system in all organisms.
• Pathogen: a biological agent that causes disease or illness to its host.
• Inflammation: a pathalogical condition of any part of the body. It is manifested outwardly by redness and swelling, attended with heat and pain.
• Antibody: a protein used by the immune system to identify and neutralize foreign objects like bacteria and viruses. Each antibody recognizes a specific antigen unique to its target.
• Memory Cells: are a type of lymphocte (also known as memory B cells) that are formed following primary infection. When a B cell is activated by recognizing a specific antigen, it quickly reproduces to form antibody producing plasma cells and long-lived memory cells. The memory B cells are specific for the antigen that first stimulated their production.
• Immunity: a state of having sufficient biological defenses to avoid infection, disease, or other unwanted biological invasion.
• Vaccine: a medication given to stimulate the body's production of antibodies and provide immunity against a disease, prepared from the agent that causes the disease, or a synthetic substitute.
• Allergy: an immune malfunction whereby a person's body is over-sensitive to a substance that is harmless to most people, causing the immune system to attack it.
• Histamine:
• Antihistamine:

Poison ivy and poison oak are often encountered by active Pathfinders. Be able to identify poison ivy and poison oak, and know how to avoid having allergic reactions to them, and explain what to do if you get an allergic reaction to either of them.

Poison Ivy

Poison ivy is shown in the picture on the left. Poisin Oak is on the right. Learn to identify these by sight. Poison ivy most often grows on "disturbed" ground, including stream banks, roadsides, and the edge of woods. Both these plants contain an oil called urushiol which causes allergic reactions if it comes into contact with your skin. Contact can be made directly (by touching the plant) or indirectly (by touching something that has touched the plant, such as a clothing, a friend, or a pet).

The best way to avoid having an allergic reaction to either of these is to avoid them. In order to avoid them, you must be able to recognize them. If you do come into contact with either of these, wash the affected areas with hot soapy water as soon as possible. Wash clothes in hot water too. If your pet has contacted poison ivy or poison oak, wash him in hot soapy water to remove the oil from his fur. The oil will not harm your pet (most animals are not allergic to urushiol), but your pet can easily tranfer the oil to you.

If you still get an allergic reaction, treatment depends on the severity of the reaction.

Seek emergency medical treatment under the following conditions:

1. Swelling of the throat.
2. Difficulty breathing.
3. Weakness or dizziness.
4. Bluish lips.
5. Unconciousness.

You should see a doctor if any of the following apply:

1. A large area of the body is affected.
2. Rash on the face.
3. Rash around the eyes, mouth, or genitals.
4. A rash with pus.

You may otherwise self-treat:

1. For minor rashes, apply Calamine lotion (not Caladryl), zinc oxide, or a mix of 3 teaspoons of baking soda with one teaspoon of water.
2. Take an over-the-counter anithistamine such as Benadryl.
3. Do not scratch

Make a list of as many as possible of the infectious diseases that you have had. Which ones are you now immune to? Explain why or why not.

A person acquires immunity to diseases he is exposed to either by contracting the disease or by receiving a vaccination. Vaccinations are weakened forms of the disease-causing pathogen, and they stimulate the immune system to develop a defense against that particular pathogen.

Some diseases, such as infleunza, mutate frequently, and the immune system having developed a defense against one strain is not prepared for the new, mutated strain. This is why flu shots are given annually. The vaccine is developed to combat this years version of the flu.

Other diseases such as tetanus and diphtheria require booster shots every 10 years to maintain the body's immunity.

From your personal medical records, list all of the vaccinations that you have had and determine from your doctor when your next vaccination should be.

Encourage your Pathfinders to ask their parents about their immunization records. These days pediatricians usually send immunization records home with the parents, so they should have them somewhere at home.

In the United States, the Centers for Disease Control (CDC) recommends that vaccinations be given according to the schedule below. For a more up-to-date schedule, visit the CDC's website.

Write or tell about one infectious disease (at least 250 words).

An infectious disease is any sickness caused by a biological agent (such as a virus, bacteria, or parasite) as opposed to being caused by a physical agent (such as a burn or a cut).

Here is a list of infectious diseases common today: AIDS, measles, tuberculosis, malaria, pertussis (whooping cough), tetanus, meningitis, chicken pox, influenza (the flu), and hepatitis.

Other infectious diseases have been largely eliminated through the use of vaccines, including polio, smallpox, and diphtheria.

Find three Biblical references that have to do with cleanliness and the control of or spread of disease.

Leviticus 11:36-38

Levitcus 13:6

Leviticus 11:25

Leviticus 13:45-47

Deuteronomy 23:12

References

• Wikipedia articles on Blood and Blood Type