Presentation on theme: "KEY CONCEPT Germs cause many diseases in humans."— Presentation transcript:
1 KEY CONCEPT Germs cause many diseases in humans.
2 Germ theory states that microscopic particles cause certain diseases. Germ theory proposes that microorganisms cause diseases.proposed by Louis Pasteurled to rapid advances in understanding disease
3 Koch’s postulates support the theory. Disease-causing agents are called pathogens.
4 There are different types of pathogens. Bacteria are single-celled organisms.cause illness by destroying cellsrelease toxic chemicals
5 Viruses are genetic material surrounded by a protein coat. force host cells to make more virusesvery small
6 Fungi can be multicellular or single-celled. take nutrients from host cellsoccur in warm and damp places
7 Protozoa are single-celled organisms. use host cells to complete their life cyclestake nutrients from host cell
8 Parasites are multicellular organisms. grow and feed on a hostpossibly kill the host
9 Different pathogen cause common infectious diseases.
10 Pathogens can enter the body in different ways. Pathogens can be transferred by direct or indirect contact.Indirect contact does not require touching an infected individual.touching an infected surfacebreathing in infected air
11 Vectors carry a pathogen and transmit it into healthy cells. Direct contact requires touching an infected individual. Includes:kissingsexual intercoursehand shakingtick
12 KEY CONCEPT 31.2 The immune systems consists of organs, cells, and molecules that fight infections.
13 Many body systems protect you from pathogens. The immune system is the body system that fights off infection and pathogens.Many other tissues and systems help the immune system.Skin is a physical barrier to infection.Mucous membranes trap pathogens entering the body.The circulatory system transports immune cells.
14 Cells and proteins fight the body’s infections. White blood cells attack infections inside the body.Phagocytes engulf and destroy pathogens.T cells destroy infected cells.B cells produce antibodies.
15 Three types of proteins fight off invading pathogens. Complement proteins weaken pathogen membranes.Antibodies make pathogens ineffective.Interferons prevent viruses from infecting healthy cells.antibodypathogens
16 Immunity prevents a person from getting sick from a pathogen. In all immunity, pathogens are destroyed before you get sick.Passive immunity occurs without an immune response.mother’s milkgeneticsActive immunity occurs after a specific immune response
17 KEY CONCEPT 31.3 The immune system has many responses to pathogens and foreign cells.
18 Many body systems work to produce nonspecific responses. Nonspecific responses are the same for every pathogen.In inflammation, blood vessels become leaky.white blood cells move toward infection and damaged tissuecapillary wallextracellular spacewhite blood cellcharacterized by swelling, redness, and pain
19 In fever, body temperature increases. Low fevers stimulate white blood cells to mature.High fevers can cause seizure, brain damage, and even death.
20 Cells of the immune system produce specific responses. Specific immune responses begin with the detection of antigens.Antigens are surface proteins on pathogens.Each pathogen has a different antigen.virusantigens
21 There are two specific immune responses. Cellular immunity uses T cells to destroy infected body cells.pathogenantigensT cellreceptorsactivated T cellsmemory T cells
22 There are two specific immune responses. Humoral immunity uses B cells to produce antibodies.B cellT cellpathogenmemory B cellsactivated B cellsantibodies
23 Both responses produce memory cells. B cellT cellspecialized T and B cellsprovide acquired (active) immunity
24 The immune system rejects foreign tissues. Tissue rejection occurs in organ or tissue transplants.Tissue rejection is the result of an immune response.immune system detects protein markers on the donor tissuemakes antibodies against the donor’s tissue
25 KEY CONCEPT 31.4 Living in a clean environment and building immunity help keep a person healthy.
26 Many methods are used to control pathogens. Antibiotics and antiseptics cause pathogens to burst.
27 Antiseptics kill pathogens outside of the body. do not target specific pathogensexamples include vinegar and soapAntibiotics kill pathogens inside the body.target one specific bacterium or fungusnot effective against viruses
28 Antibiotic resistance can cause medicines to become ineffective. Some bacteria in a population have genes that make them immune to antibiotics.These bacteria spread the gene, making the antibiotics useless.A bacterium carries genes for antibiotic resistance on a plasmid.A copy of the plasmid is transferred through conjugation.Resistance is quickly spread through many bacteria.
29 Vaccines artificially produce acquired immunity. Vaccines also control pathogens and disease.given to prevent illnesscontain the antigen of a weakened pathogen
30 Vaccination provides immunity. stimulates a specific immune response Antigens in a vaccine trigger an immune response, and memory B cells are made.1memory B cellscauses memory cells to be producedA memory B cell is stimulated when the real pathogen binds to it.2allows immune system to respond quickly to infectionThe B cell quickly activates and makes antibodies that fight the pathogens before you get sick.3has such a fast response, a person will not get sick
31 KEY CONCEPT 31.5 An overactive immune system can make the body very unhealthy.
32 Allergies occur when the immune system responds to harmless antigens. An allergy is an response to a harmless antigen.Allergies are caused by allergens.Allergens are antigens that cause an allergic reaction.Allergens cause inflammation responses.
33 There are many different allergens. food, e.g. peanuts, milk, wheat, etc.airborne, e.g. pollen, dust mite feces, mold, etc.chemical, e.g. nickel, medicine, bee stings, etc.
34 Allergens can cause anaphylaxis. Anaphylaxis is an extreme inflammation response.Blood vessels and airways become too porous.If not treated immediately, anaphylaxis can cause death.
35 In autoimmune diseases, white blood cells attack the body’s healthy cells. Autoimmune diseases are failures of the immune system.White blood cells cannot recognize healthy cells.White blood cells attack healthy body cells.Tissues fail because of attack.