Chapter 21: The Immune System. Hans Buchner – German bacteriologist who in the 1880s proposed that anti-bacterial proteins existed in blood…. start of.

Chapter 21:The Immune System

Hans Buchner – German bacteriologist who in the 1880s proposed that anti-bacterial proteins existed in blood…. start of the

modern understanding of immunity

Human Anatomy and Physiology, 7eby Elaine Marieb & Katja Hoehn

Copyright © 2007 Pearson Education, Inc.,publishing as Benjamin Cummings.

Figure 21.1: Overview of innate and adaptive defenses, p. 789.

Innatedefenses

Surface barriers• Skin• Mucous membranes

Internal defenses• Phagocytes• Fever• NK cells• Antimicrobial proteins• Inflammation

Humoral immunity• B cells

Cellular immunity• T cells

Adaptivedefenses

(a)

(b)

Human Anatomy and Physiology, 7eby Elaine Marieb & Katja Hoehn

Copyright © 2007 Pearson Education, Inc.,publishing as Benjamin Cummings.

Figure 21.2: Phagocytosis, p. 791.

Innate defenses Internal defenses

Lysosome

Microbe adheres to phagocyte.

Phagocyte forms pseudopods thateventually engulf the particle.

Phagocytic vesicle isfused with a lysosome.

Microbe in fused vesicleis killed and digested bylysosomal enzymes withinthe phagolysosome, leavinga residual body.

Indigestible andresidual materialis removed byexocytosis.

Phagocytic vesiclecontaining antigen(phagosome).

Residual body

Acidhydrolaseenzymes

Phagolysosome

(a) (b)

1

2

3

4

5

Human Anatomy and Physiology, 7eby Elaine Marieb & Katja Hoehn

Copyright © 2007 Pearson Education, Inc.,publishing as Benjamin Cummings.

Figure 21.4: Phagocyte mobilization, p. 794.

EndotheliumBasement membrane Capillary wall

Inflammatorychemicals diffusingfrom the inflamedsite act as chemotactic agents

Innate defenses Internal defenses

Neutrophils enter blood from bone marrow

Margination

Diapedesis

Positivechemotaxis

1

2

3

4

Human Anatomy and Physiology, 7eby Elaine Marieb & Katja Hoehn

Copyright © 2007 Pearson Education, Inc.,publishing as Benjamin Cummings.

Figure 21.12: Types of acquired immunity, p. 806.

Active Passive Active Passive

Acquiredimmunity

Naturallyacquired

Artificiallyacquired

Infection;contactwithpathogen

Antibodiespass frommother tofetus viaplacenta;or to infantin her milk

Vaccine;dead orattenuatedpathogens

Injectionof immuneserum(gammaglobulin)

Human Anatomy and Physiology, 7eby Elaine Marieb & Katja Hoehn

Copyright © 2007 Pearson Education, Inc.,publishing as Benjamin Cummings.

Figure 21.14: Mechanisms of antibody action, p. 809.

Inactivates by

Antigen Antibody

Fixes and activates

Enhances Enhances Leads to

Phagocytosis

Chemo-taxis

Nucleus

Histaminerelease

Inflammation Cell lysis

Agglutination(cell-boundantigens)

Precipitation(soluble antigens)

Neutralization(masks dangerousparts of bacterialexotoxins; viruses)

Complement

Antigen-antibodycomplex

Adaptive defenses Humoral immunity

The Immune Response in the body occurs in two ways:

Nonspecific Immunity

Specific Immunity