Exam 1 Lecture 4 Flashcards
Bacteria vs Immune Response
Immune system usually wins most of the time
True or false: Most of the bacteria that live on our planet are capable of beating the human immune system
False; most have evolved to live in other niches
What traits to some bacteria have that they can use to get around our immune system?
- Virulence factors 2. Host defenses previously disrupted which make it easier for bacteria to cause infection
There is a ______ of human and pathogens
co-evolution
Disease = (2 things)
- Lack of tolerance AND 2. Lack of Resistance
Resistance
The ability to eliminate a pathogen once it has entered our bodies
Tolerance
Bacteria can be in the host but not cause infection
True or false: we get sick every time a bacteria enters our bodies
False; normally, no. ex) normal microbiota
2 major types of immunity
Innate and adaptive
Innate immunity
first line of defense rapid responses to a broad range of microbes germline encoded receptors and responses early warning and defense system
Adaptive Immunity
Primary response takes time Targeted to specific microbes Clonally rearranged receptors Provides immunologic memory
External defenses
Part of innate immunity Physical and chemical barriers Mucous membranes
Internal defenses
Part of innate immunity: complement; phagocytic cells; pattern recognition receptors; inflammatory response
Innate immunity time scale:
Hours
Adaptive immunity examples
Humoral response (antibodies) Cell-mediated response (T cells)
Adaptive immunity time scale
Days
Examples of physical and chemical barriers
Skin, tears, saliva, respiratory (mucus and cilia trap and remove organisms)
How can microbiota protect us?
They compete with pathogens for nutrients, produce antimicrobials, and influence the immune system
If pathogens manage to breach initial external defenses, where might they end up?
gastrointestinal tract mucosa or respiratory tract
Stomach
contains acidic pH which can kill many microorganisms
Helicobacter pylori
adapted to acidic pH in stomach, cleaves urea to form NH3 which, as a base, acts as a buffer to resist harsh stomach acid
Mucus
viscous; contains antimicrobial molecules
How many layers of mucus are found in the GI tract?
2: outer and inner mucus layer
True or false: the inner mucus layer is essentially sterile
True
Cell surface mucins prevent:
pathogen binding
The ___ and ___ influence components of the mucus barrier
Microbiota; immune system
What do Goblet cells secrete?
Mucins
What do Paneth cells secrete?
Antimicrobial defensins and other proteins
What is the function of M-cells?
They sample contents of the stomach and deliver antigens from the gut lumen to the immune system.
Two parts of the Innate Immune System?
External (physical, chemical and mucous) and Internal Defenses (Complement, Phagocytes, PRRs and Inflammatory Response
What is the Complement System made up of?
It is a family of proteins present in blood and tissues that contains enzymes, receptors, and regulatory proteins
What does the Complement System do when activated and the 3 outcomes of activation?
It links the innate and adaptive systems.
- Inflammation and Opsonization
- Opsonization
- Pathogen Lysis (Membrane Attack Complex)
3 pathways of complement activation?
- Classical
- Lectin
- Alternative
