Non-Specific Defenses April 3, 2015

Body fights disease in 2 ways 1. Non-specific defense system  Protects body from all foreign substances 2. Specific defense system (aka immune system)  Attacks particular, previously encountered foreign substances Try to organize the list from the do now into the two systems – we will double check later! Today, we are focusing on nonspecific defenses. Next class: Immune system

Surface Barriers Skin and mucus membranes prevent pathogens from entering body  Tightly bound cells provide physical barrier  Acidic secretions in skin, vagina, and stomach inhibit bacterial growth  Mucus in respiratory and digestive tracts trap bacteria  Saliva and tears contain an enzyme – lysozyme – that destroys bacteria.

Cellular Defenses The body has specialized cells that destroy foreign material  Phagocytes (macrophages & neutrophils) – engulf and digest foreign particles, such as bacteria and viruses

Cellular Defenses The body has specialized cells that destroy foreign material  Phagocytes (macrophages & neutrophils) – engulf and digest foreign particles, such as bacteria and viruses  Natural killer cells (a type of lymphocyte) – destroy cancer / virus infected cells by releasing chemicals that destroy cell membranes. Watch me! Watch me 2!

Inflammation Inflammation occurs when an area that is damaged or infected becomes red, warm, swollen, and painful. Occurs when damaged cells release chemicals that increase blood flow, make blood vessels leaky, and attract leukocytes. How does it protect the body?  prevents spread of pathogens to nearby tissue  helps rid body of pathogens and dead cells  Helps speed healing

Fever Fever is when the body’s temperature becomes elevated due to infection Occurs when white blood cells release chemicals that reset the body’s thermostat How does it protect the body?  reduces bacterial growth by causing the liver & spleen to take up nutrients  increases metabolic rate to speed the healing process Why do we get the chills when we have a fever?

Turn and Talk Review the list of defenses we made during the do now and categorize them as specific or non-specific defenses. Then, review for exit ticket!

Exit Ticket 1. Which of these describes NK (natural killer) cells? a) Immune cells that release chemicals to kill specific, previously encountered pathogens b) Immune cells that release chemicals to kill any pathogen it encounters c) Immune cells that engulf and destroy specific, previously encountered pathogens d) Immune cells that engulf and destroy any pathogen it encounters

Exit Ticket 2. Which of these does not characterize the inflammatory response? a) blood capillaries become leaky b) affected areas become warm and red c) reduces nutrients available to pathogens d) speeds healing

Exit Ticket 3. How does a fever help the body fight disease? a) by raising body temperature above the tolerance of pathogens b) by decreasing the nutrients available to pathogens c) by reducing pathogen’s metabolic rate d) by increasing blood flow to infected areas

Exit Ticket 3. How does a fever help body fight disease? a) by raising body temperature above the tolerance of pathogens b) by decreasing the nutrients available to pathogens c) by reducing pathogen’s metabolic rate d) by increasing blood flow to infected areas

Exit Ticket 4. Describe three ways the skin and mucus membranes fight disease (2 are required, one is EC) Extra credit: Name a phagocyte