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The Blood and Immunity

Chapter 10

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Red blood cells deliver oxygen and nutrients and carry waste away.

White blood cells search and destroy foreign invaders.

Key words: AIDS, antibodies, antigen, immune response, immunity, platelets, red blood cells and white blood cells.

Blood – A Multipurpose Fluid

Transportation: Transports materials to and from all the cells of the body

Nutrients and oxygen are supplied to cells to meet their needs.

Wastes are carried away to organs that remove wastes

Chemical messengers produced and released in one part of the body are carried in the blood to other areas for cell activity

Blood – A Multipurpose Fluid

Regulation: Absorbs heat from warm areas of the body and release heat in cooler areas. Maintains a constant Ph and water balance.

Protection: Carries specialized cells and chemicals that defend the body against disease and it has the ability to clot protecting the body from injury.

Components of Blood

Plasma- Clear, straw colored liquid part of the blood (55% of the total blood volume). 90% is water, 10% salts, glucose, amino acids, fatty acids vitamins, enzymes, hormones, waste and proteins

3 types of proteins:

Albumin- keeps water from leaving blood.

Fibrinogen- helps clotting

Globulins- transport proteins and fight infection (antibodies)

Components of Blood

Red Blood Cells (erythrocytes): Red in color and carry oxygen from the lungs to the body and carry carbon dioxide from the body to the lungs. There are 30 trillion red cells in the human body and they are filled with Hemoglobin an iron protein. Red cells are made by the bone marrow and live about 120 days. As they die, they are broken down and removed by the liver and the spleen.

Anemia is a vitamin deficiency where there are too few red blood cells.

Sickle cell anemia is a hereditary disease caused by an abnormal form of hemoglobin not a vitamin deficiency

Components of Blood

White Blood Cells (leukocytes)- defenders of the body. Protect from bacteria and viruses. 60 billion in the mature adult. Normally there are 7,000-10,000/cubic millimeter but when infection is present, they can increase to >30,000. There are five kinds of white blood cells:

Neutrophils-phagocytosis (engulf bacteria)

Monocytes- phagocytosis

Eosinophils- clotting and allergy control

Basophiles- release heparin (anticoagulant) and histamine (inflammatory)

Lymphocytes- immunity

Components of Blood

Platelets- cell fragments involved in blood clotting.

Bits of cytoplasm from large cells in bone marrow

1.5 trillion in adult

200 billion per day, live for 7 days

Blood Clotting

Solidification of blood at the site of an injured blood vessel = clotting

Clotting process

Ruptured platelets and the wall of the injured vessel release enzyme- Thromboplastin

Thromboplastin initiates enzyme controlled reactions that converts prothrombin (protein) into thrombin.

Thrombin converts plasma fibrinogen into strands of fibrin

These strands trap RBC and platelets to form a clot

Clot stops the bleeding and cells re-grow to replace damaged cells

When healing is complete, a plasma enzyme- Plasmin dissolves the fibrin clot

Blood Clotting

Factors that prevent clot formation

Smoothness of the inner wall of the vessel prevents platelets from being activated.

Substances in the blood act as anticoagulants and prevent clot formation e.g. heparin (drug used after surgery to prevent clots)

Blood Clotting Problems

Not enough platelets

Vitamin K deficiency

Hemophilia- hereditary disease where one of the clotting factors is missing.

Clotting without injury- clots form and travel through the circulatory system

Block heart artery- heart attack

Block brain artery- stroke

Block lung artery- reduces oxygen to lungs

Section Review

Name the liquid part of the blood.

What is the function of RBC?

What is the function of WBC?

What plasma protein forms the strands in a blood clot?

The Immune System

Carries out a major part of the protective function of the blood.

Cells on constant patrol

Attacks foreign substances that get past other body defense systems

Defenses Against Infection

Pathogens- viruses, bacteria and organisms that cause disease. Found in:





First-Line Defenses

Physical and Chemical Barriers





Membranes lining the body


Stomach Acid


Second-Line Defenses

Inflammatory Response- When a pathogen gets past the first-line defenses



Warmth and pain

Damaged cells release certain chemicals that increase blood flow to the area that causes increased puffiness and warmth that attract phagocytes (neutrophils and macrophages)

Second-Line Defenses cont.

Macrophages- giant WBC that can ingest large numbers of bacteria.

As the inflammation proceeds, phagocytes ingest the pathogens and any damaged tissue. Pus (mixture of phagocytes, dead cells, bacteria and body fluid) collects in the wound and either drains or absorbs into the body.

Viruses produce and enzyme called Interferon that causes uninfected cells to produce enzymes that block the virus.

Third-Line Defenses

Immune System- recognizes, attacks, destroys and remembers each kind of pathogen and produces antibodies that bind to and inactivate pathogens.

Bone Marrow, WBC, lymph nodes, tonsils, thymus and spleen make up the immune system.

Immunity- ability to fight infection through the production of antibodies or cells that inactivate foreign substances or cells. This is call the immune response.

Antigens- substances that can trigger an immune response.


Cells of the immune system that recognize specific antigens and either produce antibodies or kill foreign cells directly

B lymphocytes or B cells- produce antibodies

T lymphocytes or T cells- attach foreign cells directly

Capable of recognizing different antigens

Primary Immune Response- when and antigen enters the body for the first time antibodies are formed (10-15 days.

Secondary Immune Response- when the same antigen enters the body again the antibodies activate faster

B cells and Antibodies

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T Cells and Immunity

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Types of Immunity

Active- the body produces it’s own antibodies or killer T cells to attach a particular antigen.

Example: chickenpox

Passive- A person is given antibodies obtained from the blood of either another person or an animal. "Borrowed immunity"


Blood Groups

ABO Blood Groups- A persons blood type depends on the antigen that is present on the surface of a RBC:

A = A antigen

B = B antigen

AB = A and B antigen

O = Neither A or B antigen

Blood Groups

Rh Factors- Group of antigens first found on the RBC’s of rhesus monkeys.

85 % humans have Rh antigen = Rh+

15 % have no Rh antigen = Rh-

Transfusions – Person receiving blood must not have antibodies that will react with any A, B or Rh antigens in the donors blood








A, O


B, O

A, B, O



When an organ is transplanted from one person (donor) to another person (recipient), the transplant is recognized by the recipients immune system as foreign and activates antibodies to reject the organ. This process can be lessened if the donor and recipient are closely related or by the use of immune suppressing drugs.

Section Review

What are the two types of Lymphocytes?

Define the term antigen

What happens to an antigen-antibody complex?

What antibodies are in the plasma of a person with type B blood?



Acquired – picked up from other people

Immune Deficiency - breakdown of the bodies immune system

Syndrome – Group of symptoms that indicate disease.


HIV- Human immunodeficiency virus is the cause of AIDS.

HIV attacks the helper T cells of the immune system.

Swollen Lymph glands, fever, weakness and weight loss

Pneumocystis carinii- pneumonia

Kaposi’s sarcoma


How AIDS is spread

Sexually transmitted

Blood to Blood contact

Blood transfusions

IV drug users who share needles





Sexual Abstinence

Protected Sex- Latex condoms

Avoid drug use


No cure however drugs have been developed to treat the disease and prolong life

Immune Disorders

Allergies- Rapid overreaction to and antigen that is not normally harmful. Trigger the release of histamine that induces an inflammatory response. Antihistamines are used to control the reaction

Pollen, hair, dust mites, insect stings, foods

Immune Disorders

Autoimmune Disease- Immune system fails to recognize some of the person’s body cells as "self" and produces antibodies against them.

Juvenile diabetes, rheumatoid arthritis, multiple sclerosis, lupus.

Cancer is a variety of diseases in which cells of the body multiply without control

Section Review

What is the pathogen that causes AIDS?

How can a person infected with AIDS not show any symptoms of the disease?

Name three ways AIDS can be transmitted.

What is histamine?

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