Honors Biology Semester One

What is an infectious disease? What is a noninfectious disease? Germ Theory Theorized by Louis Pasteur Proposed that specific microorganisms (pathogens/germs) cause diseases Hypothesized that if pathogens were eliminated from the body, the person wouldn’t get sick Koch’s Postulates Pg. 941

Bacteria Single-celled organisms Release chemicals that are toxic to the host or destroy healthy body cells Examples: Food Poisoning, strep throat, ear infections Viruses Disease-causing strands of DNA or RNA surrounded by protein coats So small that they couldn’t be seen until the electron microscope was invented Take over healthy cells, force it to stop normal activities, and produce more viruses Examples: flu, cold, AIDS Fungi Can be multi or single-cellular Pierce healthy cells and take the cell’s nutrients Fungal infections normally occur in warm/damp places Examples: Athlete’s foot

Protozoa Single-celled organisms that prey on other cells Need healthy cells to complete their life cycles Example: Malaria Parasites Grow and feed on a host Some kill the host (why is this NOT the best idea?); some drain the body’s resources without killing the host Examples: Heartworm, hookworms, pinworms

With your table partner, make a list of ways pathogens might enter the body: Now, read from the bottom half of pg. 943 through 944 and list all the ways that pathogens can be transmitted:

Think of your body as a castle during a battle in medieval times…what might that entail? Immune system A body system that fights off infection and pathogens Several lines of defense Relies on physical barriers first; if those fail, immune system cells travel through the lymphatic and circulatory system to the sight of infection

First line of defense is the skin (castle’s outer wall) Physically blocks invading pathogens Secretes oil and sweat making the skin hypertonic (what does this mean?) and acidic, an environment that many pathogens can’t survive However, the skin has openings like the eyes, nose, ears, mouth, and excretory organs These organs are further protected by mucous membranes meant to trap pathogens before they enter the body Sometimes, the first line of defense fails, and the immune system gets to work!

White Blood Cells 6 different types Basophils Mast cells Neutrophils Macrophages Lymphocytes (T cells and B cells) Eosinophils Refer to Fig on pg. 946 for function of each type of WBC Proteins Three types Complement Proteins Antibodies Interferons Read pg. 947 to determine functions of each protein type; take notes! Phagocytes

Occurs without the body undergoing an immune response Transferred between generations through DNA and between mother & child Some diseases can pass between species; some can’t Genetic immunity is what a species has when they are immune to a pathogen that can’t harm members of that species Inherited immunity is when pathogen-fighting antibodies in a mother’s immune system are passed to the unborn baby through the umbilical cord or through breast milk to infants

Body-produced immunity in response to a specific pathogen that has infected or is infecting the body Occurs after your immune system reacts to a pathogen invasion and keeps you from becoming sick by a particular pathogen more than once

Body responds to pathogens and foreign particles with specific and nonspecific responses Specific responses differ slightly for each pathogen; nonspecific responses are the same for every pathogen Nonspecific Responses Inflammation is characterized by swelling, redness, pain, itching, and increase warmth at the affected site Occurs when a pathogen enters the body or when body’s other tissues become damaged Fevers develop when mast cells or macrophages release chemicals that cause the hypothalamus (part of which system?) to increase the body’s temperature Fever goes away when the chemicals are no longer being made by the mast cells

Low fevers stimulate the production of interferons, which prevent viruses from reproducing Low fevers also make white blood cells mature faster, which is important because only mature WBCs can destroy pathogens High fevers (103°F or above) are dangerous because at that point, the hypothalamus can not longer regulate body temperature, so enzymes that control chemical reactions in the body stop functioning High fevers can cause seizures, brain damage, and in extreme cases, death.

When the immune system detects a pathogen, it triggers an immune response Two types of specific immune responses: Cellular Humoral 4 total groups 2 groups will make a poster over cellular immunity 2 groups will make a poster over humoral immunity Everyone will make a Double Bubble Map comparing and contrasting cellular and humoral immunity

Occurs when the recipient’s immune system makes antibodies against the protein markers on the donor’s tissue Why it’s important to find a “match” for organ/tissue donation

Read on page 955 & 956, and list ways that pathogens are controlled; be ready to discuss!

Oversensitivity to a normally harmless antigen Allergens are antigens that cause an allergic reaction Steps of an allergic reaction: 1. Allergen enters body 2. Mast cells or basophils release histamine – a chemical that causes nonspecific immune responses 3. Eosinophils sometimes also play a role in allergic reactions Scientists aren’t sure what causes some individuals to suffer from allergies, while others do not.

Leukemia HIV Both of these diseases weaken the immune system in different ways…many times, individuals who have these types of diseases die from complications of them, not the disease itself.

Germs cause many diseases in humans. The immune system consists of organs, cells, and molecules that fight infections. The immune system has many responses to pathogens and foreign cells. Living in a clean environment and building immunity help keep a person healthy. An overactive immune system can make the body very unhealthy. When the immune system is weakened, the body can’t fight off diseases.