TOPIC TWO TOPIC TWO

Homeostasis in OrganismsHomeostasis in Organisms

A. HomeostasisA. Homeostasis 1. 1. Photosynthesis Photosynthesis is carried out by plants, and is carried out by plants, and

algae (autotrophs). It takes the radiant energy of algae (autotrophs). It takes the radiant energy of the sun and puts it in the bonds of sugar the sun and puts it in the bonds of sugar molecules. Photosynthesis occurs in the molecules. Photosynthesis occurs in the chloroplast of plant cells.chloroplast of plant cells.

Plants absorb carbon dioxide from the air. Too much carbon dioxide will

cause the Earth to heat up(the greenhouse effect). Animals can eat

the sugar made to use as energy

chloroplastschloroplasts

Energy rich organic compounds.

a. Plants have a. Plants have stomates, stomates, small holes in their small holes in their leaves that let them exchange the gasses used leaves that let them exchange the gasses used in photosynthesis. in photosynthesis. Guard cells Guard cells open and close open and close the stomates.the stomates.

2. Living things use energy produced by 2. Living things use energy produced by Aerobic Aerobic respiration respiration whichwhich requires oxygen, and requires oxygen, and anaerobic anaerobic (no oxygen) respiration.(no oxygen) respiration. Aerobic Aerobic (no (no oxygen) respiration yields more ATP (energy) for oxygen) respiration yields more ATP (energy) for a molecule of sugar than a molecule of sugar than anaerobic anaerobic (no oxygen) (no oxygen) respiration.respiration.

a. When humans are forced to get energy from a. When humans are forced to get energy from anaerobic respiration, we produce lactic acid anaerobic respiration, we produce lactic acid that damages muscles (“the burn” you feel that damages muscles (“the burn” you feel during exercise).during exercise).

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3. 3. Photosynthesis and Aerobic Respiration are Photosynthesis and Aerobic Respiration are opposite reactions! opposite reactions! They are also important in They are also important in cycling oxygen, carbon, hydrogen and water cycling oxygen, carbon, hydrogen and water through the environment.through the environment.

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4. These two chemical reactions (photosynthesis 4. These two chemical reactions (photosynthesis and respiration) use and respiration) use enzymes enzymes whichwhich are are catalysts catalysts – they affect the rates of chemical reactions.– they affect the rates of chemical reactions.

1) 1) lock and key model lock and key model – one type of enzyme fits – one type of enzyme fits one type of molecule. Change its shape and the one type of molecule. Change its shape and the enzyme will no longer work.enzyme will no longer work.

2) 2) very high temperatures very high temperatures cause proteins and cause proteins and enzymes to lose their shape so that they no enzymes to lose their shape so that they no longer work properly. longer work properly.

B. Immune System:B. Immune System: 1. The job of the immune system is to protect 1. The job of the immune system is to protect

the body against the body against pathogens; pathogens; an organism that an organism that invades the body, causing diseaseinvades the body, causing disease

a. Types of pathogens include viruses, a. Types of pathogens include viruses, bacteria, and parasites.bacteria, and parasites.

Special white blood cells make antibodies, that mark the invader for future killing by other cells.

2. 2. White Blood Cells White Blood Cells are the main are the main components of the immune system. Different components of the immune system. Different white blood cells white blood cells have different roles.have different roles.

3. 3. Antigens Antigens cause an immune response. cause an immune response. Antibodies Antibodies are proteins made by white blood are proteins made by white blood cells to attack antigens. cells to attack antigens. Each antibody attacks Each antibody attacks a specific antigen as determined by its shape.a specific antigen as determined by its shape.

4. A 4. A vaccine vaccine is an injection of a dead or weakened is an injection of a dead or weakened pathogen. This causes the body to make antibodies pathogen. This causes the body to make antibodies against that pathogen.against that pathogen.

a. Vaccines only prevent diseases. They are not cures a. Vaccines only prevent diseases. They are not cures

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5. 5. Antibiotics Antibiotics are drugs used to stop infections are drugs used to stop infections by by bacteriabacteria. Ineffective against viruses.. Ineffective against viruses.

When an antibiotic binds to a bacterial enzyme, it may alter the activate site of the enzyme and prevent it from reacting with its substrate.

How an Antibiotic May Inactivate a Bacterial Enzyme

C. Diseases and Disorders: C. Diseases and Disorders: a condition, other a condition, other than injury, that prevents the body from than injury, that prevents the body from working as it shouldworking as it should

1. Diseases and disorders and how its 1. Diseases and disorders and how its disrupts homeostasis.disrupts homeostasis.

a. (AIDS, cold, flu, chicken pox) virusesa. (AIDS, cold, flu, chicken pox) viruses

b. (strep throat, food poisoning, syphilis) b. (strep throat, food poisoning, syphilis) bacteriabacteria

c. (athlete’s foot, ringworm) fungusc. (athlete’s foot, ringworm) fungus

d. (tapeworm, leeches) parasitesd. (tapeworm, leeches) parasites

The adult tapeworm lives in the small intestine of the dog or cat. It is hooked onto the intestinal wall by a structure called a rostellum

which is sort of like a hat with hooks on it. The tapeworm also has six rows of teeth to grab on with. Most people are confused about

the size of a tapeworm because they only see its segments which are small; the entire tapeworm is usually 6 inches or more.

e. (Down’s Syndrome, sickle cell) genetic e. (Down’s Syndrome, sickle cell) genetic disordersdisorders

Sickle cells

Normal red blood cells

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f. (heart attack, diabetes) organ malfunctionf. (heart attack, diabetes) organ malfunction

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g. (smoking, drug use, exposure to sun) high g. (smoking, drug use, exposure to sun) high risk behaviorrisk behavior

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