Skin & hair are made of keratin. The body s defenses Ch 9. Sticky Mucus Lines Passages Into Body. Bio 11 (De Anza) - Schinske

Size: px

Start display at page:

Download "Skin & hair are made of keratin. The body s defenses Ch 9. Sticky Mucus Lines Passages Into Body. Bio 11 (De Anza) - Schinske"

Chrystal Thompson
7 years ago
Views:

1 The body s defenses Ch 9 Skin & hair are made of keratin Dead Keratinized Epidermal Cells virus antibody Keratin is a durable, waterproof protein Sebaceous glands & sweat glands secrete antimicrobials Sebaceous glands (around hair) secrete oily ( sebum ) that is acidic Sticky Mucus Lines Passages Into Body Sweat has enzymes ( lysozymes ) that digest bacteria Acidic Gastric Juice Protects One of the Main Body Entrances Diarrhea & Vomiting Purge Digestive System of All Materials Vomiting Sneezing serves a similar purpose for respiratory system Gastric Juice ph ~2.0 Diarrhea

2 The 2nd line of defense White blood cells and defensive proteins Act when an invader penetrates the body s external barriers Nonspecific combat all invading microbes The 2nd line of defense: White blood cells White Blood Cells (cells that fight infection) Phagocytes Eat Invaders Natural Killer (NK) Cells Problem: How do NK cells know which cells to kill? Key to Immunity: Recognizing self vs. non-self Self Cells Granules contain chemicals to burst cell or cause it to commit suicide (apoptosis) NK cell is unharmed, looks for other abnormal cells Like Spies Eliminating DoubleAgents Nonself Cell Tell abnormal (infected or cancerous) cells to commit suicide How do NK cells know which cells to kill? NK Cell Attacks If: Cell has no HLA proteins Cell has different HLA proteins NK cells are one of our main natural defenses against cancer Even though cancer cells start from our own body cells, they make strange HLA proteins. NK cells recognize and force cancer cells to commit suicide! Abnormal HLA proteins HLA = Protein markers on cell surfaces Your HLA proteins are unique to you, just like your fingerprints & DNA! Like wearing uniforms for identification

3 Another defense mechanism: Inflammation Poison oak on the hand Any type of tissue injury triggers the inflammatory response Sx: Redness, warmth, swelling and pain Inflammation brings defenses & repairs to a specific area Need Help Here! Like Putting Up Signs & Opening Gates to Attract Help Responding cells eat microbes & release histamine Histamine makes vessels leaky to bring nutrients & more defenses to area = swelling, redness Antihistamines (ex. Benadryl) block effects of histamine What happens when you cut your finger? Platelets Platelets and and clotting clotting proteins proteins promote promote scabbing scabbing Injured Injured cells cells release release chemicals chemicals that that trigger trigger nonspecific nonspecific defenses defenses Phagocytes Phagocytes move move in in What happens when you cut your finger? Phagocytes Phagocytes engulf engulf bacteria bacteria Tissue Tissue heals heals What happens when you cut your finger? Fever is a whole-body reaction to speed up repairs Possible Benefits: Defensive cells move faster Phagocytes eat faster Cells divide faster Interferons enhanced

4 Protective proteins: Interferons Protective proteins: Complement Plasma proteins that automatically assemble, create holes in the membrane of bacteria and cause them to burst Infected cells send messages about viral infection to neighboring cells Proteins called Interferons tell other cells to produce substances that interfere with viral reproducton All of these defenses are nonspecific Overview of the body s defenses Recap: External barriers Physical barriers How do these defenses work? Food poisoning Chemical barriers Secretions - inhibit growth of microbes Intro to immune system 3:16 Common, usually mild symptoms Caused by eating food contaminated with viruses or bacteria How does your body respond? Salmonella

5 1st line of defense The 2nd line of defense Vomiting Diarrhea & Vomiting purge digestive system of toxic materials Phagocytes Eat Invaders Diarrhea Protective proteins: Complement Why non-specific? Plasma proteins that automatically assemble, create holes in the membrane of bacteria and cause them to burst Which defenses work against bacteria and viruses? Bacteria Viruses Inflammation phagocytes Complement NK cells The immune response in action How does our immune system respond when we get a cold?

6 How does the body respond to a viral infection? The common cold A contagious viral disease of the upper respiratory track Primarily caused by rhinoviruses The most common infectious disease in humans Cold viruses live only in the nose The major point of entry the nose 1st line of defense mucous membranes of the nose From the nose, the virus is transported to the back of the nasopharynx Cold viruses attach to cells lining the nasopharynx How a cold virus infection occurs The virus attaches to a receptor located on the surface of nasal cells. After attaching to the receptor, the virus is taken into the cell, where it starts an infection How a viral infection occurs Virus binds to the plasma membrane The virus is taken into the cell where it starts an infection Viral RNA is integrated into the cell genome The infected cell manufactures new virus. The infected cell eventually ruptures and dies, releasing newly made virus Nonspecific defenses Cold symptoms are due mainly to the body's response to the viral infection. The immune system responds by activating the inflammatory response This causes mucus secretion. Virus-infected cells also produce interferon Interferon stimulates healthy cells to make antiviral proteins Limitations of nonspecific immunity Need another defense system to target those specific particularly nasty invaders. Sometimes too many invaders will enter body for phagocytes, NK cells, etc. to eliminate them quickly enough. Plus, those nonspecific defenses have their efforts spread widely, not focused. Specific Defenses

The Immune System. 2 Types of Defense Mechanisms. Lines of Defense. Line of Defense. Lines of Defense

The Immune System. 2 Types of Defense Mechanisms. Lines of Defense. Line of Defense. Lines of Defense The Immune System 2 Types of Defense Mechanisms Immune System the system that fights infection by producing cells to inactivate foreign substances to avoid infection and disease. Immunity the body s ability