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Lines of Defense: Enhancing Immunity Against Pathogens

This educational content outlines the various lines of defense in our body, from physical barriers like skin and mucous membranes to the intricate immune system response involving white blood cells and antibodies.

justin-jenkins
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Lines of Defense: Enhancing Immunity Against Pathogens

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  1. Immunology

  2. LINES OF DEFENSE • We live in a virtual sea of bacteria; we have evolved ways of protecting ourselves. • BARRIERS: Our Goal? Keep the Beasties Out! • 1. SKIN: protected by • many layers of dead dry cells that are leathery. • pores are protected by sweat • sweat washes out pores • contains lytic enzymes which burst whatever beasties that try and get in. • hair shafts protected by oils and lytic enzymes

  3. LINES OF DEFENSE • 2. EYES: Protected by • tears contain lytic enzymes and wash the eyeballs. • 3. EARS: Protected by • Wax: semi-liquid paste that traps beasties and contains lytic enzymes • Cilia: microscopic hairs that ‘wave’ rhythmically and transport the wax out of the ear. • Hairs: help to trap the beasties. • Eardrum: physical barrier keeps beasties out of middle and inner ear.

  4. LINES OF DEFENSE • 4. NOSE & RESPIRATORY SYSTEM: Protected by • Mucus: sticky and has lytic enzymes. • Cilia: transports “dirty” mucous from the lungs back to the throat where it is swallowed. • White Blood Cells: live in the air sacks (alveoli) of our lungs; they eat dirt, debris, and beasties = scavengers. • 5. MOUTH: Protected by • Saliva: contains lytic enzymes • Native Bacteria: normal bacteria that • live in your mouth will attack and destroy the new bacteria (competitive)

  5. LINES OF DEFENSE • 6. STOMACH: Protected by • Hydrochloric Acid (HCl): strong (3M) kills a lot • of bacteria & spores(?) • 7. INTESTINES: Protected by • Small Intestine: digests beasties for food • Large Intestine: is protected by native bacteria (E. coli) that fights off foreigners. • 8. REPRODUCTIVE SYSTEM: Protected by • Male system – not usually any problems. • Female system: • Barrier is at the cervix – mucous plug. • Also native bacteria, acidic environment, and WBC’s.

  6. LINES OF DEFENSE • If the bacteria gets past our physical barriers, then… • IMMUNE SYSTEM: BEASTIES IN BLOOD STREAM • 1. WHITE BLOOD CELLS (WBC’s) are phagocytic; they engulf and digest beasties. • They leave the blood go to the site of infection. • Problem: WBC’s reproduce every 3 hours and when they engulf a beasties they both die. Bacteria reproduce every 20 minutes (under optimum conditions). • Solution: Fever (increased metabolic rate) • This will slow the bacterial reproduction rate down (every 3 hours) so our WBC can keep up!

  7. White Blood Cells • Produced in our bone marrow • Our stem cells can produce several different kinds of bacteria-fighting immune cells.

  8. Phagocytosis • Leukocytes (neutrophils, eosinophils, and macrophages) engulf foreign invaders. • Complement, or complementary proteins help phagocytotic cells engulf foreign cells

  9. Phagocytosis • After phagocytosis, the cell releases a packet of enzymes that destroy the bacteria • Unfortunately the white blood cell dies too.

  10. Lymphocytes-2 kinds • Lymphocytes produce antibodies. • One kind, T cells, find antigens on bacteria, or receives messages from leukocytes, and then signal an attack.

  11. B Cells • T cells pass information along to B cells • B cells produce antibodies • Antibodies can stay on the surface of B cells, or they can be released and travel through the body to attack bacteria.

  12. Antibodies • Are “Y” shaped proteins that targe foreign invaders • Antibodies have specific genes that allow them to “match” certain bacteria and viruses • Antibodies attach and hang on to the foreign invader, and wait for a macrophage to come along and eat the whole thing.

  13. Memory • After an infection is gone, most of your white blood cells that were used, die. • Memory T cells remain though • They hold an imprint of the antigen, and can mobilize B cells super fast if they need to again • Invading pathogens are destroyed before they are even able to multiply. • This is why we rarely get the same infection twice

  14. So why do we have allergies?

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