Innate immunity (First line)

Two types of immunity

Innate immunity (keeps pathogens out) and Adaptive immunity (Destroy specific pathogens)

How many lines of defense do humans have against pathogens

3

Which lines of defense are associated with innate immunity

Physical, Chemical, Cellular

Which lines are associated with adaptive immunity

Chemical

How is the skin a front-line physical barrier against microbial pathogens

The skin has keratin which is resistant to bacterial enzymes and the skin is shed

What is sebum and how does it act as a chemical barrier against pathogens

It is an oil produced by skin glands; it creates an inhospitable environment for pathogens to live

How does sweat act as a chemical barrier against pathogens

It contains antimicrobial peptides, salt, and lysozyme which are not good for pathogen survival

What is lysozyme and where can it be found

It is an enzyme that cleaves NAM and NAG in peptidoglycan. It is found in mucus, sweat, saliva, urine, and tears

What are antimicrobial peptides and how do they cause destruction of microbes

It damages plasma membranes, cell wall synthesis

Where can anti-microbial peptides be found

Skin, epithelial cells, immune cells

How are tears, nasal hairs, and saliva a front-line barrier

They catch and wash away microbes

How do mucous membranes act as physical font-line defense

It lines the tracts and traps debris. It can also contain antimicrobial peptides

What is the ciliary escalator and how does it help prevent infections

By removing the mucus (and thus the pathogen)

What is peristalsis

Muscular contractions that moves food down/prevents it from coming up

Why is gastric juice such an effective line of defense

It is extremely acidic and thus many pathogens cannot tolerate the environment

How does urination help defend against infections and why is it an effective chemical barrier

It is slightly acidic but it also contains lysozyme inhibiting microbial growth/destruction of microbes

What does normal microbiota mean

Bacteria that live in your body which outcompete microbial pathogens from binding to sites

Two examples of normal microbiota providing a front-line barrier against pathogens

Lactobacilli break down glycogen producing lactic acid (lowers the pH so microbial pathogens cannot survive)

Where are complement proteins found

They are produced in the liver and found in blood, lymph and tissue fluid in their inactive forms

How is the complement system activated

By enzymatic reactions

3 means by which the complement system can destroy microbes

Opsonization: The coating of a pathogen with opsonin that allow for easier phagocytosis and the destruction of the pathogen

Inflammation: The activation of the mast cells that cause degranulation and release inflammatory chemicals

Membrane Attack Complex (MAC): Leads to cell lysis and death of the pathogen

What are cytokines and what are their functions

They are proteins that communicate between cells; They bind to receptors and stimulate the production of chemical mediators

Endothelial cells

They line the vessels in the body

Acute phase proteins

They are produced by liver and secreted into the blood in response to inflammatory signals