HSCI 100 Immune system

Infectious agents

Microbes: microscopic organisms such as bacteria and viruses that can cause disease

Pathogens: microscopic organisms + fungus, parasites and prions(misfolded proteins)

Infection: when pathogen colonizes a tissue that can support its

growth

A pathogen is contagious if it can spread

the 3 lines of immune defense

1. Non-specific physical and chemical barriers

2. Non-specific inflammatory response and

proteins

3. A specific and adaptive or learned response

from the T and B cells

Innate

first 2 lines of defense

No memory (does not “learn”)

Non-specific

Fast

Adaptive/Acquired

3rd line of defense

Memory (learns)

Primed

Specific

Slow (days to weeks)

1st line of defense

physical and chemical barriers:

tears, skin, saliva, large intestine, respiratory tract, stomach and bladder.

2nd line of defense

internal defenses

Inflammation

Cellular phagocytosis

Natural killer cells

Complement system

Organs of the immune system

Lymphatic organs

Primary– Red bone marrow– Thymus gland

Secondary Lymph nodes, spleen, Peyer’s patches, tonsils, and appendix