How Bacteria Make Us Sick

1. How Bacteria Make Us Sick

2. Exposure • A bacterial cell has to first enter our body, this can happen through: Ingestion A break in the skin (Cut or wound)

3. Inside Our Body • Warm (37 C) • Moist • Lots of food! (sugars) • This makes our insides the ideal breeding ground for bacteria

4. Once inside • The bacteria begin to reproduce…Very Quickly!

5. How Bacteria Cause Illness 1. They can produce Enzymes • Ex: Helicobacter pylori produces an enzyme that neutralizes stomach acids…unfortunately it also destroys the lining of the intestinal wall

6. 2. Some produce toxins (poisons) that kill cells. Clostridium botulinum bacteria produce botulinum toxin, the most powerful toxin known to humankind. They cause the disease called botulism Exotoxins are poisons released by live bacteria. Endotoxins are poisons released when the bacteria die.

7. 3. Body Becomes Overwhelmed Too many bacteria interrupt normal bodily functioning

8. The Human Immune System Vide

9. What is the immune system? • The body’s defense against disease-causing organisms, malfunctioning cells, and foreign particles

10. Entering your body Microorganisms can enter the body via your: • Pores (skin and hair follicles) • Mouth (food, water, inhalation) • Eyes • Nose • To help prevent microorganisms from entering your body and to help fight against them if they do enter, your body has three lines of defense mechanisms

11. The First Line of Defense- Physical and Chemical Barriers~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!

12. The First Line of 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?

13. Saliva contains many chemicals that break down bacteria • Thousands of different types of bacteria can survive these chemicals, however The First Line of Defense~Saliva~ What’s the first thing you do when you cut your finger?

14. The First Line of Defense~Stomach Acid~ • Swallowed bacteria are broken down by incredibly strong acids in the stomach that break down your food • The stomach must produce a coating of special mucus or this acid would eat through the stomach!

15. The First Line of Defense~Tears~ • Contain an enzyme called lysozyme • Destroys peptidoglycan in cell walls of bacteria

16. The Second Line of Defense- Nonspecific Response to Infection~White Blood Cells~ • 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

17. White Blood Cells ~Phagocytes~ • These white blood cells are responsible for eating foreign particles by engulfing them • Once engulfed, the phagocyte breaks the foreign particles apart in organelles called ________ Lysosomes

18. The Second Line of Defense~Interferons~ • Virus-infected body cells release interferons when an invasion occurs • Interferon – chemical that interferes with the ability of viruses to attack other body cells What happens to already infected cells?

19. White Blood Cells~T-Cells~ • T-Cells, often called “natural killer” cells, recognize infected human cells and cancer cells • T-cells will attack these infected cells, quickly kill them, and then continue to search for more cells to kill