Biology 107

Lecture Notes: Defenses against disease I.

Reading: Chapter 43 in text.

The human body possesses two mechanisms which protect it from potentially dangerous invaders

• Nonspecific defenses :

• Specific defenses :

Nonspecific defenses against infection

• The skin and mucous membranes provide first-line barriers to infection
• Lysozyme:

• Phagocytic cells, inflammation, and antimicrobial proteins function early in infection

Microbes that penetrate the skin or mucous membranes encounter amoeboid white blood cells capable of phagocytosis

· Phagocytic and natural killer cells

o Neutrophils

o Monocytes:

o Macrophages:

o Eosinophils:

o Natural killer cells:

• The inflammatory response
• A local inflammatory response occurs when there is damage to a tissue due to physical injury or entry of microorganisms
• Chemical signals in the inflammatory response
• Histamine:

• basophils and mast cells:

• Prostaglandins :

• Migration of phagocytic cells into the injured area is also a result of increased blood flow and increased leakage from the capillaries

• Antimicrobial proteins
• complement proteins :

• Interferons :

How immunity arises

• The immune system is the body’s third line of defense. It is distinguished from nonspecific defenses by:
• Specificity
• Diversity
• Self/nonself recognition
• Memory
• Lymphocytes provide the specificity and diversity of the immune system
• Humoral immunity:

• cell-mediated immunity:

• B cells

• T cells

Antigen:

Antibody:

• Clonal selection :

• effector cells:

• memory cell:

• primary and secondary immune responses:

• immunological memory

• Lymphocyte development gives rise to an immune system that distinguishes self from nonself
• self tolerance

• autoimmune disorders

• The role of cell surface markers in T cell function and development

· The major histocompatibility complex