Subtitle

Ch. 31 Notes: Immune System and Disease

• 3F research and describe the history of biology and contributions of scientists;

• 4C compare the structures of viruses to cells, describe viral reproduction, and describe the role of viruses in causing diseases such as human immunodeficiency virus (HIV) and influenza;

• 11C summarize the role of microorganisms in both maintaining and disrupting the health of both organisms and ecosystems

• 10A describe the interactions that occur among systems that perform the functions of regulation, nutrient absorption, reproduction, and defense from injury or illness in animals;

Objectives

• Germs cause many diseases in humans– Germ theory- specific microorganisms cause specific diseases– Disease causing agents are called pathogens• There are different types of pathogens– Bacteria, Viruses, Fungi, Protozoa (Protists), and Parasites

• Pathogens can enter the body in different ways– Via body fluids, through the air, mosquito bites,

contaminated food/water, touch– Vector- anything that carries a pathogen and transmits it

to an organism (mosquitos, rats)

• The immune system consists of organs, cells, and molecules that fight infections– Many body systems protect you from pathogens

• First Line- outer defenses– Skin, physically blocks invading pathogens. Sweat and oil

on skin prevents growth of pathogens–Mucous- traps pathogens in airways

• Second Line: cells and proteins. –White blood cells may engulf, destroy, or cover the invader

with poison– Proteins, like antibodies, can stick to a pathogen and

identify it as an invader. Other proteins called interferons keep healthy cells from being infected with viruses.

antibody

pathogens

• Immunity prevents a person from getting sick from a pathogen– Passive immunity- no immune response. Think DNA immunity-

do not have to be exposed to be immune.• Mothers milk• genetics

– Active immunity- body produces an immune response.

• Part of active immunity:

• The immune system has many responses to pathogens and foreign cells– Nonspecific responses- happen the same way for every

pathogen• Inflammation- swelling of the affected sight, increases blood

flow to affected area

• Fever- speeds up production of white blood cells and interferons

– Specific responses- occur at the cellular level and are different for each pathogen• Cellular immunity- defense against infected body cells using T

cells• Humoral immunity- defense against pathogens in body fluids

using antibodies

• When the immune system is weakened, the body cannot fight off disease– HIV (human immunodeficiency virus)- attacks T cells so that

other pathogens can take over the body.– Can lead to AIDS- acquired immune deficiency syndrome• People die from aids because they cannot fight off other

diseases like pneumonia, viral infections, or fungal infections.• HIV is transmitted through infected body fluids, especially blood

HIV

T cell deadT cell

antibody

activatedB cell