The Immune System

“Infection Protection” How the body protects itself from disease

Chapter 10 (10-2)

Blood

Blood is a liquid tissue with 3 functions:

1. Transportation

2. Regulation

3. Protection

We have between 4-6 L of blood

Purpose of Blood

Transport Regulation Protection

Purpose of Blood

Transport: To carry nutrients to all cells To carry wastes away from cells to

removal organs To carry hormones (chemical

messengers)

Purpose of Blood

Regulation To absorb heat from one part of the

body and release it in a cooler part. To maintain pH and water levels.

Purpose of Blood

Protection To defend the body against disease-

causing agents. To stop the body from bleeding by

clotting.

Components of Blood

Plasma Erythrocytes or Red Blood Cells Leukocytes or White Blood Cells Platelets

Components of Blood

Plasma

Water – 90% Dissolved Material such as: salts, glucose, amino

acids, fatty acids, vitamins, hormones, wastes Proteins

• Albumin – regulates movement of water out of blood• Fibrinogen – involved in clotting• Globulins – many functions such as:

• Transport Proteins – to move substances • Antibodies – to destroy foreign substances and fight

disease.

Red Blood CellsErythrocytes

Carry oxygen and carbon dioxide Made in the bone marrow 30 trillion in the body Does not contain a nucleus Contains hemoglobin – an iron-

containing protein that causes it to be red and to carry oxygen

Red Blood CellsErythrocytes

Fun Facts:• You have 30 trillion RBCs• They live 120 days – then get destroyed.• New cells are formed at the rate of 2 million

per second (same rate they die)• The liver and spleen removed dead cells

and the iron is recycled.

Anemia

When you have too few RBCs or not

enough hemoglobin (low iron in diet).• Symptoms: not enough oxygen in blood,

you get very tired.• Treatment: Eat more iron, get shots of

vitamin B-12 for pernicious anemia.

Sickle Cell Anemia

Genetic Disorder – when RBCs are not formed correctly because hemoglobin is made wrong:• Symptoms: RBCs are sickle

in shape and get stuck in blood vessels causing pain.

• Treatment: Transfusions help.

Sickle Cell Anemia

White Blood Cells Leukocytes

Colorless blood cells Defend the body from bacteria

and viruses Made in the bone marrow Have a nucleus. They can move on their own or

carried by the blood stream. There are five different kinds of

WBCs.

Five types of White Blood Cells

• Neutrophils – phagocytosis of small particles• Monocytes – phagocytosis of large particles• Eosinophils – release clot-digesting agent, combat

allergy-causing substances• Basophils – release heparin – anti-clotting agent,

and histamine – that causes inflammation• Lymphocytes – produce antibodies that are

involved in the immune response

White Blood Cells Leukocytes

Fun Facts:• You have 60 billion white blood cells.• They are made at a rate of 1 million per

second.• When you have an infection they multiply

and congregate in the area of the infection to attack the invader.

• Pus that forms contains WBCs and bacteria.

Leukemia

A type of cancer that produces

white blood cells. Symptoms include very high

WBC count. Treatment: includes bone

marrow transplants and medications.

Platelets

Cell fragments involved in blood clotting.

Form by pinching off bits of cytoplasm from large cells in the bone marrow.

Do not contain a nucleus. Surrounded by a

membrane.

Platelets

Fun Facts• You have 1.5 trillion platelets• They live for 7 days• They are produced at a rate of 200 billion a

day.

Blood Clotting

Good Clotting - helps you to stop bleeding when you have an injury.

Bad Clotting – when you get a clot within a blood vessel that clogs the vessel. You can have a stroke or heart attack from this.

The process is basically the same…

Blood Clotting

Blood Clotting Video

Blood Clotting

1. Platelets stick to the damaged vessel and break.

2. Broken platelets release thromboplastin.3. Thromboplastin converts prothrombin to

thrombin.4. Thrombin converts soluble fibrinogen to

insoluble fibrin.5. Fibrin forms a web to stop the bleeding.

Blood Clotting

To remove clot

The body activates the enzyme plasmin to dissolve the clot after the skin heals.

The body prevents internal clots by:• Having smooth vessels – platelets don’t

get stuck and break.• Anticoagulants (heparin) in blood prevent

clotting.

Clotting Problems

Internal clots form when the vessels are not smooth – caused by build-up of material in veins and arteries.• Symptoms: Can cause death, strokes,

heart attacks if it blocks blood flow.• Treatment: Heparin can be injected to

dissolve the clot if done quickly.

Hemophilia

Genetic disease where a person is

missing one or more clotting factors.• Symptoms – internal or external bleeding

without ability to clot.• Treatment – injections of missing factors,

blood transfusions.

Blood Clotting

http://www.youtube.com/watch?v=HFNWGCx_Eu4&feature=player_embedded

What Causes Disease?

Viruses and bacteria are pathogens. Pathogens are microorganisms that cause disease.Pathogens are everywhere; in food, in air, in water, inside your body.

Our Immune System has three lines of defense.

How Can We Protect Ourselves From

Pathogens?

First Line of Defense

Physical Barriersprevent entrance of pathogens or trap them and washes them away.

• Skin• membranes• mucus• sweat• urine

Chemical Barriers

kill or inhibit pathogen activity.

•Stomach acid•tears•saliva

Second Line of Defense

If a pathogen gets past first line of defense, it starts an infection.

This activates the second line of defense to have an inflammatory response.

Inflammatory Response

Symptoms:

Swelling, pain, warmth, redness

Cause of Symptoms: Cells that got damaged by infection release

chemicals. These chemicals cause more blood to flow to

area ,which causes symptoms. Macrophages (large white blood cells) come to the

area to ingest bacteria.

As Inflammatory response continues...

Pus forms from mixture of dead cells, white blood cells, bacteria and body fluid.

If pathogen is a virus, damaged cells produce interferon that protects other cells from damage.

Third Line of Defense

If inflammatory response is insufficient, the immune system takes over.

The immune system creates antibodies and other specialized cells to stop pathogens.

Each antibody or specialized cell is made for a specific pathogen.

The Immune Response(The Immune System)

Provides immunity to pathogens

Requires that the body can distinguish between

“self” and foreign material.

Involves production of antibodies and

specialized cells.

Is triggered by an antigen.

Lymphocytes

Cells that recognize antigens and either

a) produce antibodies

b) kill foreign cells

Types of lymphocytesa) B cells

b) T cells

Type of Immune Responses

Primary Immune

Response The first time you are

exposed to antigen. No antibodies for first

five days. Over the next 10-15

days rise in antibodies.

Secondary Immune

Response Second exposure to same antigen. Within 1-2 days

high levels of antibodies are in blood.

Type of Immune Responses

B Cells and Antibodies

B cells are stimulated by helper T cells when they see a bacterial antigen.

Helper T cells only recognize antigen after it is ingested by a phagocyte and has been displayed on phagocyte’s membrane.

B cells then produce plasma cells and memory B cells.

Plasma cells make antibodies. Memory B cells divide to make more plasma

cells without needing helper T cells – secondary response.

T Cells and Antibodies

T cells are stimulated by helper T cells when they see a virus-infected cell (antigen).

Helper T cells only recognize antigen after it is ingested by a phagocyte and has been displayed on phagocyte’s membrane.

T cells then produce killer T cells and memory T cells.

Killer T cells seek and destroy antigen. Memory T cells produce killer T cells without

needing helper T cells – secondary response.

Suppressor T Cells

Shut down the killer T cells when the infection is stopped.

Types of Immunity

Active Immunity Body produces its own

antibodies or killer T cells

Results from having the disease.

Results from use of vaccines containing dead or weakened virus.

Passive Immunity Body receives

antibodies from a source Results from receiving

antibodies from mother’s milk.

Results from vaccine containing only antibodies

Blood Types

Antibodies play a part in blood types, transfusions, and transplants.

There are four different blood types: A,

B, AB, and O. You are a certain blood type if your

blood contains certain antigens.

ABO Blood Types

There are two antigens: A and B If you have blood type A, you have A antigens and

B antibodies. If you have blood type B, you have B antigens, and

A antibodies. If you have blood type AB, you have both A and B

antigens and no antibodies. If you have blood type O, you have neither antigen

and both A and B antibodies.

Transfusions

A blood recipient cannot have antibodies to the antigens he is receiving.

Example:

If you have A blood, you cannot safely receive B or AB blood because you have B antibodies.

Challenge

Which blood type can give blood to anyone?

Which blood type can receive blood from anyone?

Universal Blood Donor

A person with blood type O is called the universal donor. Why?

Answer: His blood contains no antigens so no one will react to it.

Transplants

Transplanted organs trigger the recipient’s immune system to fight these foreign cells - called rejection

To control this effect, the immune system is often suppressed prior to transplant through medications.

Universal Blood Recipient

A person with blood type AB is the universal recipient.

Why?

Answer: His blood contains both antigens and no antibodies, so his blood will not react to any blood type.

AIDS

Acquired Immune Deficiency Syndrome - affects the immune system.

Caused by HIV (human immunodeficiency virus).

Acquired by body fluid transfer. The virus attacks helper T cells. Why is this

bad?

Answer:

Body can’t produce antibodies or killer T cells and can’t fight diseases.

Symptoms: swollen glands, fever, weakness, weight loss, inability to fight common illnesses, fungi, cancers (Kaposi’s sarcoma).

No cure.

Immune Disorders

Allergies – overreaction to an antigen that is not normally harmful. It triggers the inflammatory response – when the body makes histamines. To reduce symptoms – take antihistamines.

Immune Disorders

Autoimmune Diseases – when the body fails to recognize its own cells as self and produces antibodies against its own cells.• Lupus (various organs, kidneys), Multiple

sclerosis (nerves), rheumatic fever (heart and joint tissue)

Immune Disorders

Cancer – body doesn’t recognize foreign cells as foreign and lets them multiply uncontrollably. Suppression of immune system often results in cancer.