Adventist Youth Honors Answer Book/Health and Science/Blood and the Body's Defenses

Blood and the Body's Defenses
Health and Science
General Conference
Skill Level 2
Year of Introduction: 2000

1. Have the Microscopic Life honor. edit

Instructions and tips for earning the Microscopic Life honor can be found in the Nature chapter.

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

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

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

Blood cells are treated with a staining agent before they are photographed so that identifiable features will stand out.

1. Red Blood Cells are responsible for transporting oxygen to other cells in the body, and for collecting carbon dioxide from them for disposal. Red blood cells can be identified by their donut-shape.

2. Platelets are the blood cell fragments that are involved in the cellular mechanisms that lead to the formation of blood clots. Platelets appear in most of the photographs above as tiny, irregular, bluish specks.

3. Neutrophils, are a type of white blood cell which travel to infected tissue and surround bacteria, rendering them harmless to the body. The picture above shows two neutrophils surrounded by multiple red blood cells. Neutrophils have segmented nuclei and small granules that stain purple.

4. Eosinophils, are a second type of white blood cells and are responsible for combating infections by parasites. Eosinophils are filled with large granules that stain red.

5. Basophils are a third 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. Basophils have large, dark granules in the cell that may cover the nucleus.

6. Lymphocytes are a fourth 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. Lymphocytes have no granules, and they have very large nuclei that take up nearly all of the cell's area.

7. Monocytes, are a fifth 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. Like neutrophils, monocytes have no granules, but their nuclei take up only about half the cell's area. A monocyte's nucleus often has an indentation in it.

4. 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? edit

Prepared microscope slides are offered for sale at many scholastic supply houses. Many retailers offering such slides have an Internet presence. Before spending money on this, check with a local high school biology teacher. They will have microscopes and very well may have slides on hand already.

The charts below show the expected distribution of the different types of cells. It is possible that you may not see any eosinophils or basophils in your sample since they are so rare and you're only looking at 100 white blood cells.

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

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

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

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. Well before the date of the blood drive, have the Pathfinders advertise the event (this is a good opportunity to earn the Lettering and Poster Making honor). Be sure to announce the blood drive in church for several weeks. On the day of the event, 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). edit

This downloadable movie clip shows blood flowing through a capillary, but it's very short. Its shortness does make for a quick download (56Kbytes). It is best to play the movie in "loop" mode.

This much longer (11 Mbytes) movie clip also shows blood flowing through a capillary.

Visit a medical lab where blood tests are performed. edit

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

Visit a blood bank. edit

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

6. What two gases 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. edit

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.

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

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.

8. 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? edit

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. 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 separated 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-      

9. 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? edit

  • Joseph's brothers dip his coat in blood before returning to their father. Genesis 37:12-36.
  • The Nile turns to blood during the showdown between Moses and Pharaoh. 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 Elijah 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.

10. List 10 specific health habits that can help your body stay healthy and fight off infection. Find a reference from the Spirit of Prophesy that supports each one of these. Keep a record for three weeks of how often you repeat these 10 habits. edit

  • 1. Proper Diet. "When we feed on flesh, the juices of what we eat pass into the circulation. A feverish condition is created, because the animals are diseased; and by partaking of their flesh we plant the seeds of disease in our own tissue and blood." Healthful Living, p 212
  • 2. Fresh Air. "The effects produced by living in close, ill-ventilated rooms are these: The system becomes weak and unhealthy, the circulation is depressed, the blood moves sluggishly through the system because it is not purified and ventilated by the pure, invigorating air of heaven. The mind becomes depressed and gloomy, while the whole system is enervated, and fevers and other acute diseases are liable to be generated."—Healthful Living, p 212.
  • 3. Get Plenty of Sleep. Your immune system replenishes itself while you sleep, so not getting enough sleep robs it of the time it needs to fully recharge. The amount of sleep a person needs varies from one individual to another, but most people need eight hours per night. If you wake up exhausted, you're not getting enough sleep.

"They may be weary, but how sweet is rest after a proper amount of labor. Sleep, nature's sweet restorer, invigorates the tired body and prepares it for the next day's duties."—Child Guidance, pp 341,342.

  • 4. Avoid Caffeine. Caffeine interferes with your ability to get to sleep, so it should be avoided - especially after noon.

"The stimulating diet and drink of this day are not conducive to the best state of health. Tea, coffee, and tobacco are all stimulating, and contain poisons. They are not only unnecessary, but harmful, and should be discarded if we would add to knowledge, temperance."—Review and Herald, Feb. 21, 1888.

  • 5. Do Not Drink Alcohol. "Alcohol and tobacco pollute the blood of men, and thousands of lives are yearly sacrificed to these poisons."—Health Reformer, November, 1871.
  • 6. Do Not Use Tobacco. See above.
  • 7. Be Happy. A cheerful heart does good, like a medicine.

"Let the sunshine of love, cheer, and happy content enter your own hearts, and let its sweet influence pervade the home. . . . The atmosphere thus created will be to the children what air and sunshine are to the vegetable world, promoting health and vigor of mind and body."—Sons and Daughters of God, pg 168.

  • 8. Regular Exercise. "In many cases the sickness of children can be traced to errors in management. Irregularities in eating, insufficient clothing in the chilly evening, lack of vigorous exercise to keep the blood in healthy circulation, or lack of abundance of air for its purification, may be the cause of the trouble. Let the parents study to find the causes of the sickness and then remedy the wrong conditions as soon as possible."—Adventist Home, pg 263.
  • 9. Regular Bathing. Taking a bath or a shower regularly washes pathogens from your skin and thus, away from your body.

"Persons in health should . . . by all means bathe as often as twice a week. Those who are not in health have impurities of the blood. . . . The skin needs to be carefully and thoroughly cleansed, that the pores may do their work in freeing the body from impurities; therefore feeble persons who are diseased surely need the advantages and blessings of bathing as often as twice a week, and frequently even more than this is positively necessary."—Testimonies to the Church, Volume III, p. 70.

  • 10. Wear Clean Clothing. Clothes that are worn day after day accumulate dirt and bacteria. Change into clean clothing every day and keep the "nasties" away.

"It is important also that the clothing be kept clean. The garments worn absorb the waste matter that passes off through the pores; if they are not frequently changed and washed, the impurities will be reabsorbed."—Child Guidance pg 109.

  • 11. Keep Your Home Clean. Bacteria love dirt. Keep it out of your house. Allow plenty of sunshine to enter your house during the day, and allow fresh air in as often as possible. Sunshine kills many forms of bacteria, and stale air harbors it.

"I have often seen children's beds in such a condition that the foul, poisonous odor constantly rising from them was to me unendurable. Keep everything the eyes of the children rest upon and that comes in contact with the body, night or day, clean and wholesome. This will be one means of educating them to choose the cleanly and the pure. Let the sleeping room of your children be neat, however destitute it may be of expensive furniture."—Child Guidance pg 109.

11. Define the following terms related to the body's defenses edit

  • 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 pathological 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: a chemical released by basophils and mast cells (which are very similar to basophils) and causing an immune response. In some cases, the response is unwarranted because the invading substance is harmless. In this case, the response is known as an allergic reaction. Histamines cause inflammation of the tissue, watery eyes, itching, runny nose, and sneezing.
  • Antihistamine: a drug that suppresses the release of histamine. Examples include the prescription drugs Clarinex, Allegra, and Zyrtec, and the over-the-counter drugs Claratin and Benadryl.

12. 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. edit

Poison ivy is shown in the picture on the left. Poison 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 transfer 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. Unconsciousness.

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 antihistamine such as Benadryl.
  3. Do not scratch

13. 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. edit

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 influenza, 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.

14. 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. edit

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.


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

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.

16. What is AIDS? How is it spread? Is there a cure? Why is it so devastating? edit

AIDS is an acronym for acquired immunodeficiency syndrome or acquired immune deficiency syndrome and is defined as a collection of symptoms and infections resulting from the specific damage to the immune system caused by infection with the human immunodeficiency virus, commonly called HIV. Although treatments for both AIDS and HIV exist to slow the virus' progression in a human patient, there is no known cure.

AIDS is the most severe manifestation of infection with HIV. HIV is a retrovirus that primarily infects vital components of the human immune system such as certain T cells and macrophages. It also destroys T cells. As T cells are required for the proper functioning of the immune system, when enough T cells have been destroyed by HIV, the immune system barely works, leading to AIDS.

The symptoms of AIDS are primarily the result of conditions that do not normally develop in people with healthy immune systems. Most of these conditions are infections caused by bacteria, viruses, fungi and parasites that are normally controlled by the elements of the immune system that HIV damages. Nearly every organ system is affected.

Three main transmission routes of HIV have been identified:

  1. Sexual route. The majority of HIV infections have been, and still are, acquired through unprotected sexual relations. Sexual transmission occurs when there is contact between sexual secretions of one partner with the rectal, genital or mouth mucous membranes of another.
  2. Blood or blood product route. This transmission route is particularly important for intravenous drug users, hemophiliacs and recipients of blood transfusions and blood products. Health care workers (nurses, laboratory workers, doctors etc.) are also concerned, although more rarely. Also concerned by this route are people who give and receive tattoos and piercings.
  3. Mother-to-child route (vertical transmission). The transmission of the virus from the mother to the child can occur in utero during the last weeks of pregnancy and at childbirth. Breast feeding also presents a risk of infection for the baby. In the absence of treatment, the transmission rate between the mother and child was 20%. However, where treatment is available, combined with the availability of Cesarean section, this has been reduced to 1%.

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

Leviticus 11:36-38

Leviticus 13:6

Leviticus 11:25

Leviticus 13:45-47

Deuteronomy 23:12

References edit

  • Much of the information (and in some cases the text) of this chapter were drawn from the Wikipedia articles on Blood, Blood Type, AIDS, Histamine, Antihistamine, Basolphils, Eosinophils, Nuetrophils, Lymphocytes, Monocytes, Poison Ivy, Poison Oak, and others.