Lecture 13 - Innate Immunity Flashcards
what is innate immunity?
the first and second line of defenses against invaders
what are the two arms of the immune system that work together?
- Innate immunity: immediate defenses; 1st and 2nd line defenses.
- Adaptive immunity: delayed defense; 3rd line defenses. It is developed when you have an infection, and it is not innate.
how do the two arms of the immune system work together?
they work together against foregin invaders with the help of cytokines
what are cytokines?
they are chemical communication signals that promote immune functions
what are the hallmarks/characteristics of innate immunity?
-First and second-line defense
-Inborn immunity: present since birth.
-Initial, immediate defenses against foreign invaders.
-Same responses regardless of the invader: non-specific.
-Same responses regardless of the number of exposures: no memory.
if the barrier is breached in first-line defense, what happens next?
second line defenses are used and kicked in
how are second-line defenses used/kicked in?
-They are kicked in by recognizing pathogen-associated molecular patterns (PAMPs) or microbe-associated molecular patterns (MAMPs) on foreign invaders using pattern recognition receptors (PRRs) on sentinel cells; example: toll-like receptors (TLRs) on phagocytes.
are second-line defenses specific?
they are partially specific; which is about 20 PAMPs
what do PRR’s do?
PRRs detect PAMPs or MAMPs and make a response
what are the two components of innate immunity?
first-line defenses and second-line defenses
what are the components of first-line defenses?
Skin and mucous membranes
what are the 3 barriers at surfaces under first-line defenses?
- Physical
- Chemical
- Biological
what are the two physical barriers of first-line defenses?
-Skin
-Mucous membranes
what are the two layers of the skin?
-Dermis: tough and durable bottom layer
-Epidermis: multi-layers thick top layer
what does the epidermis consist of?
The topmost layer made of dead cells filled with keratin - a water-proof protein that keeps the skin dry
what are the skin’s flushing actions in first-line defenses?
Trying to wash away the invaders by:
-Dead cells flake off, taking away the attached invaders.
-Sweat falls off, carrying away invaders
in the physical barrier of mucous membranes within the first-line defense, what does it line and produce?
Mucous membranes line “tubes” and eyes. They produce sticky mucus that traps and flushes out the invaders.
what are the flushing actions of the mucous membranes?
- Eyes: tears
- Digestive tract:
- Saliva (washes away invaders from mouth/teeth).
- Peristalsis (rhythmic contraction and relaxation of muscles that pushes the invaders toward and out of the anus).
- Vomiting and diarrhea (ways to purge out invaders during infection). - Respiratory tract:
- Mucociliary escalator (cilia push the mucus up away from the lungs and towards the throat and finally the anus).
- Coughing and sneezing (ways to purge out invaders during infection). - Urogenital tract:
- Urination
- Genital secretions
what are the chemical barriers in first-line defense?
They are chemicals that inhibit or kill microbes by secreting antimicrobial chemicals.
what things do the chemical barriers secrete?
-Enzymes (ex: lysozyme in tears, saliva, mucus, sweat, and breastmilk. It breaks down PG wall).
-Salt (in sweat)
-Acids (in stomach and vagina)
-Antimicrobial peptides (ex: defensins)
-Iron-binding proteins (ex: lactoferrin in saliva, mucus, breastmilk, phagocytes, hide away iron from invaders. They bind to iron to keep it away from the invaders).
what are the biological barriers in first-line defense?
The normal microbiota (flora):
-It covers all binding sites with mucus, so the invaders cannot attach.
-Compete for nutrients
-It makes antimicrobial chemicals
-Alters pH, O2, and other parameters.
what are the outcomes of physical + chemical + biological surface barriers?
they are strategically placed to prevent the invasion of deeper tissues
which of the following is NOT a first-line defense in the innate immune system?
1. Mucociliary escalator
2. Skin microbiota
3. Stomach acid
4. Fever
- Fever
what are the components of second-line defenses?
Leukocytes (WBCs)
Protein substances
Inflammation
Fever
what are two kinds of leukocytes?
granulocytes and agranulocytes
what is hematopoiesis?
the formation of blood cells
what do all blood cells arise from?
all blood cells arise from stem cells in the bone marrow
what are the 3 types of granulocytes?
-Neutrophils
-Basophils (in blood) and Mast cells (in tissues)
-Eosinophils
what are the 2 types of agranulocytes?
-Lymphocytes
-Monocytes
what do granulocytes contain?
Cytoplasmic granules
what are neutrophils?
-The most numerous WBCs
what do neutrophils function as?
they function as phagocytes
how many nuclei are in neutrophils?
the nucleus is 3-5 lobed
how do the granules stain in neutrophils? what do they contain?
Granules stain light purple; they contain digestive enzymes and antimicrobials (defensins, etc.)
where are neutrophils located? where do they migrate to during infection?
they are in blood and migrate to tissues during infection
where are basophils and mast cells located? how common are they? what is their function?
-Basophils are in blood and Mast cells are in tissues.
-They are the least common in blood.
-Their function is in inflammatory responses including allergies