Blood and Immunity

I. Blood Is the liquid tissue of transport in humans Average human has 5-6 liters of blood Blood is composed of: red blood cells white blood cells platelets plasma

Blood serves as a transport medium that helps to maintain homeostasis for all cells of the body. Ex: hormones are secreted into blood to help regulate certain activities in the body.

(A) Plasma Consists of 90% water Plasma contains: proteins antibodies nutrients enzymes hormones clotting factors

(B) Red Blood Cells Also known as Erythrocytes. 30 trillion red blood cells in human body. Transports O 2 from lungs to body tissue (cells). Transports CO 2 to the lungs from the body tissue. Lack a nuclei when mature. Contain hemoglobin.

(C) White Blood Cells Also known as Leukocytes. 60 billion white blood cells in the body. WBC’s are larger than RBC’s WBC’s contain a nucleus. Main purpose is to fight off disease.

Types of White Blood Cells Phagocytes Lymphocytes

Phagocytes Engulf and destroy bacteria at the site of infection by the process of phagocytosis. This is the normal defense against disease for the body.

Lymphocytes Produce antibodies which act against foreign molecules known as antigens. An antigen-antibody reaction is referred to as an immune response

(D) Platelets Are smaller than RBC’s and WBC’s. Play a key role in blood clot formation. 1.5 trillion platelets in the blood.

III. Diseases Is any condition that prevents the body from working as it should. As a result the body may fail in maintaining homeostasis.

Diseases in Humans may result from: 1. Pathogens 2. Inheritance 3. Microorganisms 4. Pollutants 5. Organ Malfunction 6. Harmful Lifestyle

1. Pathogens Are potentially dangerous disease-causing organisms in the air, water and food we take in every day. Ex: viruses, bacteria, fungi, and parasites.

2. Inheritance Defective genetic traits can be passed from parent to offspring. Ex: Sickle-cell anemia - in this disease the hemoglobin is flawed and as a result the red blood cells may get twisted and out of shape. The red blood cells cannot carry oxygen in this state.

3. Microorganisms Microorganisms that cause disease include certain fungi, bacteria, protozoa, and viruses. Some diseases caused by microorganisms may be passed from one person to another. Therefore, these diseases are known as infectious diseases.

4. Pollutants Are chemical agents present in the environment that may upset the body’s normal functioning and produce disease. Ex: Asbestos PCB’s

5. Organ Malfunction Diseases may develop when one or more of the body’s organs malfunction. Ex: Kidney failure - The kidneys no longer filter the blood to remove toxins. As a result, a Dialysis machine is used.

6. Harmful Lifestyles The way one lives can be an important factor in causing disease. Ex: tobacco alcohol drugs unsafe sexual experiences

IV. Immune System Defends our bodies against invaders. Each invader, usually a bacterium or virus, has a specific protein molecule attached to its surface called an antigen. When the immune system detects an antigen, it produces antibodies that bind to the antigen. The antibody then destroys the antigen.

Active Immunity Results when antibodies are produced by the body in response to a foreign substance (antigen) in the body. Ex: A person gets chicken pox 1. Antibodies are produced by the body (lymphocytes) to fight the disease-causing organism (antigen). 2. After the illness is over, antibodies against the disease remain in the blood and protect against re-infection.

Passive Immunity Develops when an individual receives antibodies from an outside source (medication). This provides temporary immunity to a particular disease. However, the “borrowed” antibodies are gradually destroyed and the immunity they provide ends.

Vaccinations- Scientists have developed vaccines by using weakened pathogens to stimulate the immune system to react. Antibiotics- Chemicals produced outside the human body, usually by fungi, that can be given to a person to kill the bacteria causing an infection

A Closer Look At White Blood Cells

B-cells Respond to specific antigens by producing antibodies that will bind only to the antigen. Memory B cells remain in the body in case you encounter the same invading microorganism again. This is why you usually only get chicken pox once (active immunity )

Killer T-cells Detect infected cells with the antigen in it. The killer T-cells attach to the cell membrane of your infected body cell. It then punches holes into the membrane of the infected cell, injecting poison into it. As a result, the infected cells are killed and the invaders in these cells are destroyed.

Helper T-cells Assist both B-cells and Killer T-cells. Without Helper T-cells, the immune system cannot do its job effectively. Helper T-cells are destroyed by the human immunodeficiency virus (HIV), which results in the disease called AIDS.

V. Diseases of the Immune System

Allergic Reactions Results from the over activity of the immune system to common substances such as dust, mold, pollen, or certain foods. The immune system begins to make antibodies, which causes the body to release substances, including histamines. This causes many allergic reactions such as: extra fluid in nasal pathways, difficulty breathing, and hives (inflammation). Allergies are treated with antihistamines which are drugs that stop the release of histamine.

Dust Mite Living in rugs and furniture, these tiny arthropods can cause major problems if you are allergic.

Autoimmune Diseases Results from when the immune system begins to attack normal body tissue. The body is literally rejecting its own tissue. Ex: Rheumatic fever Lupus

Immunodeficiency Diseases Ex: AIDS (Acquired immuno- deficiency syndrome) Develops when the HIV virus destroys the Helper T-cells and the body is no longer able to protect itself from diseases that may attack it.

VI. Disorders of Blood

Anemia A condition in which blood cannot carry sufficient amounts of oxygen to body cells. This is due to reduced amounts of hemoglobin and/or red blood cells.

Leukemia A form of cancer in which the bone marrow produces non-functional white blood cells.

VII. Blood Types Blood Type AntigenAntibodies AAanti-B BBanti-A ABA and Bnone O anti-A and anti-B

Transfusion- when a person receives blood from an outside source Donor (donates blood) Recipient (receives blood) type O type A or Otype A type B or Otype B type A, B, AB, or O type AB

Keep in mind: The person receiving the blood, look at the antibody for their blood type; and the person donating the blood, look at the antigen for their blood type. Type O- universal donor Type AB- universal recipient

VIII. Human Lymphatic System

Intercellular Fluid All cells of the body are bathed in a colorless, watery fluid called intercellular fluid (ICF). All substances exchanged between the blood and the body cells must diffuse through the ICF. Excess ICF is drained from the tissues by vessels of the lymphatic system.

Lymphatic System 1.Excess ICF is returned back to the blood by a system of vessels called the lymphatic system.. 2.Tiny lymph vessels are present in all body tissue.

3. Excess ICF diffuses into lymph vessels and is now called lymph. 4. These small lymph vessels join larger lymph vessels and ultimately join into the thoracic duct, which is the largest lymphatic vessel in the body.

5.Lymph from the thoracic duct is emptied into a large vein in the neck. 6.It is in this way that fluid lost from the blood is returned to the blood. 7.Lymph vessels in the villi of the small intestine are called lacteals.

8. Major lymph vessels have enlarged regions called lymph nodes in which lymphocytes (WBC’s) destroy bacteria and other foreign substances from the lymph before the fluid is returned back into the blood.