This week: Protection from Pathogens

esophagus

stomach

Taking in food and oxygen exposes us to pathogens

Pathogen: a disease causing agent

Ebola

E. coli

Fungus from soil

Phage virus

various pathogens

The Immune System

• Non-specific:–barriers

• Specific:–B-cells -> antibodies

–T-cells

Fig 43.2

Non-Specific Immune SystemBarriers: Skin-

DryInhospitableCompetitionSecretions (lysozyme)

Hairs and Mucus (protect openings)Traps particles, swallowed

Stomach acidkills pathogens

Fig 43.2

Skin protects us from most pathogens

Fig 43.2

esophagus

stomach

Stomach acidkills pathogens

Hairs and Mucus (protect openings)Traps particles

Non-Specific Immune SystemBarriers: Skin-

DryInhospitableCompetitionSecretions (lysozyme)

Hairs and Mucus (protect openings)Traps particles, swallowed

Stomach acidkills pathogens

Fig 43.2

The Immune System

• Non-specific:–barriers

• Specific:–B-cells -> antibodies

–T-cells

Fig 43.2

The Specific Immune System

B-cells and T-cells move through the circulatory system scanning for pathogens

B-cells develop in bone marrowT-cells in the thymus

B-cells make and secrete antibodies

Fig 43.14

Constant region

Variable region

An Antibody

Fig 43.10

Antibodies recognize and bind to antigens

Fig 43.10

Marked fordestructionby WBC

B-cells make antibodies that bind to antigens marking them for destruction

Fig 43.19

Fig43.14

Each B-cell/antibody recognizes a specific antigen

Fig43.13

B-cell DNA rearranges to

make a unique and random gene

Fig43.14

Each B-cell/antibody recognizes a specific antigen

Marked fordestructionby WBC

B-cells make antibodies that bind to antigens marking them for destruction

Fig 43.19

Fig43.21

Antibody binding to antigens can lead to...

Neutralization Engulf and Destroy

What about damaged or abnormal cells?

•Viral infections•Cancer cells•Non-functional cells

T-cells recognize and destroy abnormal cells

Fig 43.18

Helper T-cells activate B-cells and Killer T-cells

CB 43.17

Killer T-cells recognize and destroy abnormal cells

Fig 43.18

Helper T-cells activate B-cells which produce antibodies

CB 43.19

Fig 43.15

It can take 7-14 days to produce sufficient antibodies to eliminate a pathogen

Memory B-cells make the response to a second exposure more rapid

This is how vaccines work.

Fig 43.14

Vaccines work via memory B-cells that make the response to a second exposure more rapid

Fig 43.15

Next: Vaccines, when politics and science collide...