What is the immune system The bodys defense

What is the immune system? • The body’s defense against disease causing organisms (pathogens – Bacteria, virus, fungi), malfunctioning cells, and foreign particles.

Vocabulary • Antigen- A foreign molecule on the surface of a pathogen that induces an immune response. • Antibody- a protein produced by the body's immune system when it detects harmful substances, called antigens. • Macrophage- large “eating cell” • Pathogen- something that causes a disease / illness.

• ANTIGENS against us. ANTIBODYS identify and attack ANTIGENS.

Two Divisions of the Immune System 1) Cell-mediated immune system: Controlled by the WBCs. - Phagocytes (Macrophages) – eat invaders - T-cells, B-cells (produce Ab) and K-cells (kill invaders) 2) Antibody-mediated immune system (Humoral): Controlled by antibodies. • This represents the third line of defense in the immune system

Three Lines of Defense • First Line of Defense: – Innate – Non-specific – Natural barriers to keep pathogens out! – Ex: Skin, mucus membranes, secretions • Second Line of Defense: – Innate – Non-specific – Rapid local response to pathogen after it has entered – Ex: Phagocytes (macrophages), inflammatory response, fever • Third Line of Defense: – Acquired – Specific to an antigen – Specifically target and attack invaders that pass the first two lines of defense. – Ex: Macrophages, Helper T cells, B-cells, antibodies, & Killer T

st 1 Line of Defense

The First Line of Defense ~Skin~ - The dead, outer layer of skin, known as the epidermis, forms a shield against invaders and secretes chemicals that kill potential invaders. - You shed between 40 – 50 thousand skin cells every day!

Defense ~Mucus and Cilia~ - As you breathe in, foreign particles and bacteria bump into mucus throughout your respiratory system and become stuck. - Hair-like structures called cilia sweep this mucus into the throat for coughing or swallowing Don’t swallowed bacteria have a good chance of infecting you?

nd 2 Line of Defense

The Second Line of Defense ~The Inflammatory Response~ - Injured body cells release chemicals called histamines, which begin an inflammatory response - Capillaries dilate - Temperature rises - Wound become red, swollen, and warm. - WBCs flock to infected area like sharks to blood. - If enough microbes survive the Inflammatory response then a fever is triggered.

The Second Line of Defense ~Macrophages~ - If invaders actually get within the body, then your white blood cells (WBCs) begin their attack - WBCs normally circulate throughout the blood, but will enter the body’s tissues if invaders are detected

rd 3 Line of Defense Antibody-mediated immunity

Cells • T-Cells: T cells do not recognize free-floating antigens. Rather, their surfaces contain specialized antibody-like receptors that see fragments of antigens on the surfaces of infected or cancerous cells. – Helper T cells: Coordinate immune responses by communicating with other cells. – Killer T cells: These cells directly attack other cells carrying certain foreign or abnormal molecules on their surfaces. – Memory T cells: remember and destroy the pathogen.

• B cells belong to a group of white blood cells known as lymphocytes and produce a specific antibodies.

The Third Line of Defense ~Antibodies~ - Most infections never make it past the first and second levels of defense - Those that do trigger the production and release of antibodies - Each antibody binds only to one specific binding site, known as an antigen Specific

Antibody Production - B-cells produce antibodies that are equipped to find that specific antigen and attach.

White Blood Cells ~Phagocytes~ • These white blood cells are responsible for eating foreign particles by engulfing them Lysosomes

White Blood Cells ~Phagocytes~ • Once engulfed, the phagocyte processes the antigens and shows them on the outside to the T-cells

T-Cells T- Cells are helper cells that recognize the antigen flag on the macrophage They call out to the B-cells

B-Cells • B-cells produce Y-shaped antibodies, these antibodies attach to the specific antigen and tag them for destruction.

K cells Now it is easy for killer K cells to destroy all the germs because they have been tagged by the T and B- cells. K- cells come in and destroy all the germs .

M-Cells • If the same pathogen invades again then…. • M-cells remember the enemy pathogen and help activate the immune system much faster

Bell Ringer # 1 What is immunity? A. The body's ability to produce cells that inactivate foreign cells or substances. B. The body's ability to regulate homeostasis through feedback loops. C. The body's ability to produce the "fight or flight" response. D. The body's ability to use the endocrine system to fight disease

Bell Ringer # 2 White blood cells are an important part of the human immune response. Two types of white blood cells, neutrophils and macrophages, act as phagocytes. Phagocytes perform which of the following functions in the human body? A. They produce antibodies. B. They bind to antigens and develop into plasma cells. C. They form a barrier against pathogens. D. They engulf and destroy bacteria.

• Which statement best describes an immune response? • A) It always produces antibiotics. • B) It usually involves the recognition and destruction of pathogens. • C) It stimulates asexual reproduction and resistance in pathogens. • D) It releases red blood cells that destroy parasites

After an initial infection, B-cells recognize the measles virus. How is this helpful in human immune response? • A. The B-cells use this recognition to defend the body against other pathogens, such as bacteria. • B. The B-cells more quickly recognize and respond to any other virus that invades the body. • C. The B-cells produce antibodies more quickly if the measles virus is encountered again. • D. The B-cells transfer this recognition to T-cells, which will then devour the viruses.