Biology Unit 10 Explanation & Notes

Section 31.1 Pathogens and Human Illness

Name as many diseases caused by germs as you can think of:

One of the most deadly was the Spanish flu that killed between 20 and 50 million people in the 1920s. An infectious disease (flu, polio) is passed from one person to another caused by germs. A noninfectious disease (cancer, heart disease) cannot be passed onto a healthy person.

Pathogens are disease-causing agents that make a person ill. Bacteria, viruses, fungi, protozoa, and parasites are all different types of pathogens that attack, invade, or drain the nutrients of healthy cells and can enter the body through direct or indirect contact.

Look around and find 5 “infected” surfaces: ___________________________________________________.

A vector is anything carries a pathogen and transmit it into healthy cells such mosquitoes (malaria) and fleas (Black Plague).

Section 31.2 Immune System

The immune system fights infection and pathogens. It uses physical barriers to block pathogens and protective cells to attack invading pathogens.

Outside Defense: SKIN – provides a physical barrier and secretes oil and sweat which kills many pathogens

MUCOUS MEMBRANE – hairlike cilia coated with sticky solution to trap pathogens entering openings (eyes, nose, mouth, etc.)

Inside Defense: WHITE BLOOD CELLS – find and kill pathogens inside the body; phagocytes are cells that destroy pathogens by surrounding and engulfing or “eating” them.

LYMPHOCYTES – white blood cells that start the immune response; one type is T cells that destroy infected body cells and another type is B cells that make proteins which weaken pathogens looking to infect body cells.

PROTEINS – attacks and defends against pathogens; antibodies are proteins made by B cells that can weaken pathogens or clump them together so that easily “eaten” by phagocytes

Passive Immunity occurs without the body undergoing an immune response and can be transferred by DNA or mother and child through the umbilical cord and mother’s milk. Active immunity produces a response to a specific pathogen infecting the body. Once sick, your immune system will look out for the same pathogen again to prevent the same illness.

Section 31.3 Immune Responses – zombie survival!

There are two general responses to invading pathogens:

Inflammation – a nonspecific response that involves swelling, redness, pain, and itching of the infected area

Fever – an increase in the body’s temperature in order to increase the amount of white blood cells attacking pathogens

Aside from the general responses there are more specific immune responses from the body and they rely on identifying problem cells. Antigens are protein markers on the surfaces of cells or viruses that the immune system can identify as foreign cells. Think of antigens as like the uniform of a soldier that shows which side they are on. After the attack, memory cells that are specialized T and B cells “remember” an antigen from a previous invading pathogen and responds quickly before illness occurs.

Here is how to think about the two types of specific responses:

Humoral Immunity Cellular ImmunityResponse depends on antibodies that clumps

pathogens

Response depends on T cells that blows up infected cells

B cells bind to pathogens and steal it’s antigens; then T cells

bind to stolen antigens and activate B cells which creates

antibodies that clumps pathogens; phagocytes eat

the clumps

Phagocytes eats pathogens and steals antigens; T cells bind to stolen antigens and

gets activated to make memory and activated cells;

activated T cells causes infected cells to burst

Zombie Stranger Analogy Zombie Parents AnalogyTo protect you and your

loved ones, you must “wipe out” any strange zombies (pathogens) before they infect anyone!

Oh no, a zombie (pathogen) bit your parents and now they

are infected! They must be “put down” before they infect

anyone else!

Partner up! Complete pg. 8 and 9

Section 31.4 Immunity and Technology – controlling pathogens

Scientists have developed several methods to aid our immune system in killing pathogens. Antiseptics are chemicals, like soap, vinegar, and rubbing alcohol that kills pathogens. For example, rubbing alcohol weakens the cell membranes causing them to burst. Antibiotics also help the immune system by targeting bacteria and fungus.

However, overuse of antibiotics can lead to antibiotic resistance which occurs when bacteria mutate so that they are no longer affected by antibiotics.

Another method of treatment that scientists use is to prevent illness in the first place. A vaccine is a substance that contains the antigen of a pathogen which will produce memory cells in your immune system. You won’t get sick because the pathogens are weakened and not able to reproduce. If you have been vaccinated and a pathogen enters your body, your immune system will right away fight the infection and prevent illness.

Question: Why do you need a flu vaccine every year? SKIP pg. 21-22

Section 31.5 Overreactions of the Immune System

Show of hands: Who has an allergy? What are they?

Over half the people in the United States has an allergy. An allergy is an oversensitivity to a normally harmless antigen. Allergens are antigens that cause an allergic reaction by the immune system; basically it causes it to overreact.

White blood cells respond to allergens by releasing histamine, a chemical that causes a nonspecific immune response, usually inflammation. This is an unnecessary response because the inflammation does not benefit the person, only irritates! If your body is severely irritated, you can experience anaphylaxis which is when the immune system releases so much histamine that your airways tighten and blood leaks out the vessels. Question: Why do you think pollen irritates?

Sometimes, your immune system can’t tell the difference between harmful cells and healthy cells. Autoimmune diseases are the result of your body’s immune system inability to tell the difference between healthy and unhealthy cells. Examples are type 1 diabetes and multiple sclerosis (MS).

Section 31.6 Diseases That Weaken the Immune System

There are diseases that attack your immune system leaving you vulnerable to other diseases. Leukemia is when bone marrow produces abnormal white blood cells that do not mature. This causes the marrow to keep making white blood cells leaving red blood cell counts low and your immune system weakened. This would leave opportunistic infections to make a person sick that otherwise a healthy immune system could fight off.

Another immune attacking disease is the human immunodeficiency virus (HIV). HIV infects T cells making them unable to active B cells thus making your immune response weak. It could take several years before HIV finally infects more T cells than the bone marrow can replace and opportunistic infections occur such as AIDS. The picture shows an infected T cell with HIV cells forming.

Acquired immune deficiency syndrome (AIDS) is the last stage of a declining immune system which is the result of an HIV infection. Fungal infections, tuberculosis, pneumonia, and viral infections can all be opportunistic infections that eventually lead to death. Treatment is expensive and complicated and only slows not cure the disease.

PARTNER UP! – complete pg 25-27

Section 32.2 Digestive System

The major function of digestion is to break down foods into smaller molecules that the body can use. Think of the digestive system, a collection of organs that break down food into cellular pieces, like a “disassembly line” that moves the food in one direction. The first place that digestion begins is in the mouth where chewing breaks down the food and saliva starts the chemical breakdown of food. From there, the esophagus, a tube connecting the mouth to the stomach, uses peristalsis or the rhythmic, involuntary contractions of the smooth muscles that pushes food down.

Question: do you think it matters how many times you chew before swallowing your food?

Mechanical and Chemical DigestionMouth

Mechanical – chewing shreds and grinds food Chemical – salivary amylase breaks down sugarsStomach

Mechanical – smooth muscle contractions further breaks down food mixed with digestive juices

Chemical – hydrochloric acid and pepsin break down proteins

Small IntestineMechanical – muscular contractions breaks down

food further mixing it with bile and enzymesChemical – enzymes, bile, and hormones complete

digestion of proteins, sugars, and fatsSKIP pg. 35-36

Section 32.3 – Absorption of Nutrients

In order for your body to get nutrients from the food you eat you need to absorb them. Absorption is the process by which nutrients move out of the digestive organs into the circulatory and lymphatic systems. This occurs in the small intestine where the lining, villi, and microvilli absorb most of the nutrients.

The lining is in folds because it increases the surface area for nutrients to pass through as well as slowing the passage of nutrients. The villi are small finger-like projections that are covered with cells containing microvilli which are tiny projections that further expand the surface area and absorb nutrients.

DRAW IT! Draw the lining, villi, and microvilli!

Section 32.4 – Excretory System

The excretory system eliminates nonsolid wastes through sweat, urine, and exhalation to maintain homeostasis in the body. Excess water, salts, toxins, carbon dioxide, minerals, and vitamins are all expelled by the lungs, skin, kidneys, and bladders. When you breathe out, your lungs exhale CO2 and water to balance oxygen levels in your blood. The skin releases excess water and salts and also cools your body to maintain body temperature. DRAW IT! Pg. 986

The kidneys are organs that eliminate waste by filtering and cleaning the blood which produces urine. Urine travel through in the ureter, which is a tube that carries urine from each kidney to the bladder. The urinary bladder is a sac like organ that stores up to half a liter or 2 cups of urine.

Inside the kidney are nephrons which are individual filtering units that filter the blood materials, reabsorb some materials back into the blood, and excrete waste as urine. Each kidney has about 1 million nephrons!

If a person who has failing kidneys cannot find a donor, then they will go through dialysis. Dialysis is when the person’s blood is cleaned and chemically balanced through a machine and then returned to the body. This process needs to be done three times a week. Why do you think that is?

PARTNER UP pg. 39

Section 33.2 – Muscular System

Blink Test – see if you can get your partner to involuntarily blink by clapping in front of their face (not too close!) Were you able to control the blink or did you blink uncontrollably?

The muscular system moves bones at joints and pushes blood, food, and fluids throughout the body. The heat created from muscle contractions (flexing) helps keep a normal body temperature and shivers involuntarily when you are cold. The muscle fibers are muscle cells that contract when they are stimulated by the nervous system by pulling and letting go. The following are three types of muscles in your body:

Skeletal Muscle – muscle that is attached to the skeleton by tendons (connective tissue from muscle to bone or other muscle tissue); slow-twitch for endurance (kick) and fast-twitch muscles or sprinting (blink)

Smooth Muscle – involuntary muscle that regulates blood flow and also moves food through digestive system; slow but last longing

EXCRETORY SYSTEM SKETCH

Cardiac Muscle – involuntary heart muscles that look like smooth and skeletal muscles and uses large amounts of ATP; rate is controlled by signals from the brain

Muscle structure

Myofibrils are long strands of proteins found in a muscle fiber that contain a set of patterned filaments (ropes). Myofibrils are divided into sarcomeres which are sections that contain all the needed filaments to contract that section of the muscle. Actin filaments are thin protein fibers that are pulled to cause muscle contraction and attached at each end of the sarcomere. Myosin filaments are the protein fibers that pull actin and are attached at the middle of the sarcomere.

List examples of voluntary and involuntary muscles: