Lecture #10 Flashcards
What does innate immunity mean? (innate immune system)
Defences present at birth
How does the defences work in an innate immune system?
Non-specific defences, meaning they act against most microbes in the same way
Does the innate immune system have a memory component? (do they remember viruses?)
No, they cannot recall previous contact with a foreign microbe
When is the innate immune system present?
Always, from birth to death
When does the innate immune system respond?
Responds rapidly to an infection, and is active before the infection occurs
What are two barriers that the innate immune system uses to keep viruses out?
- Physical barriers
2. Chemical barriers
What are the secondary barriers the innate immune system uses to keep viruses out? What type of symptoms does that include?
Cellular defences: inflammation, fever and molecular defences
What are 3 types of physical barriers in the innate immune system?
- Skin
- Mucous membrane
- Fluid flow
What are 3 reasons that the skin is able to work as a physical barrier for the innate immune system?
- The outer layer of the skin consists of dead cells and protective protein called keratin
- Layers constantly shed removing microbes
- The skin is very dry, inhibiting microbial growth
Is the skin a good defence for the immune system?
Yes excellent and rarely is penetrated by microbes
What type of infection is able to grow on the skin? Explain it
Fungi, eating dead skin cells
Where do most infections occur in regards to the skin?
Underneath the skin
Some microbes that are able to eat dead skin cells and oils cause what?
Body Odour
Where are skin infections most commonly found?
Moist areas of the skin or in a moist environment
What is a mucous membrane
The membranes involved in fluid exchange
Is a mucous membrane more or less protective than skin?
Less
Where can mucous membrane be found?
Tracts such as digestive, reproductive and respiratory
What does the mucous membrane secrete? What does that help?
Secretes mucous (glycoprotein), which helps to keep the membrane from drying and cracking
How does the mucous membrane work to keep microbes out?
- The mucous traps microbes
2. Cilia then moves the mucous containing microbes away
What are mucocilary escalators?
The movement of mucous by cilia
What is fluid flow? What are examples of it?
Secretions that move microbes away and out of the body
ex. saliva, tears, urine and vaginal secretions
Regarding fluid flow, how does it connect to tracts?
Every tract has its own ability to get microbes out
What are 5 types of chemical barriers?
- Acidity of body fluids and skin
- Lysosomes
- The normal microflora
- Lactoferrin
- Defensins
Why does the skin and stomach fall into the chemical barrier category of the innate immune system?
Stomach: Hydrochloric acid with a pH of 2 therefore the low pH destroys bacteria and toxins
Skin: Fatty acids and lactic acid create a pH of 3-5 therefore prevent the growth of microbes
What does a lysozyme do to be considered a chemical barrier in the innate immune system?
It is an enzyme that degrades peptidoglycan (found in bacterial cell walls)
Where is the enzyme lysozyme found?
In sweat, tears, saliva and nasal secretions
What is normal microflora and why is it considered a chemical barrier for the innate immune system?
Functions to prevent the growth of pathogens.
This causes ‘all the seats in the room to be taken’ therefore the bacteria have no where to stay
How does normal microflora prevent the growth of pathogens?
Competitive exclusion and microbial antagonism
When is normal microflora acquired?
Right after birth
What is lactoferrin?
Iron binding proteins found in milk and mucus
Why is lactoferrin a chemical barrier?
It limits the iron available to microorganisms therefore slows the growth of microorganisms allowing the immune system to kill them a lot easier
What are defensins and what do they do that they are part of the chemical barrier category of the innate immune system?
Short polypeptides that pike holes in microbial membranes
Where do defensins come from?
Produced by epithelial cells
What is the second line of defences for the innate immune system?
Cellular defences which are leukocytes
What are leukocytes and when do they increase?
White Blood Cells, increase in numbers in response to infection
What are phagocytes?
White blood cells that use phagocytosis to eat microbes
What are two types of leukocytes?
- Granulocytes
2. Agranulocytes
What are granulocytes?
White blood cells with large granules in their cytoplasm and are visible under the light microscope
What are 3 types of granulocytes?
- Basophils
- Eosinophils
- Neutrophils
What are basophils?
A subgroup of leukocytes that is a weak phagocyte that secrete chemo-attractants (to attract other cells)
What do basophils also release (besides chemo-attractants) and what does it do?
Histamines, which cause allergies and inflammation
What do eosinophils do?
Destroy large pathogens and produce extracellular digestive enzymes to attack the parasite
What do neutrophils do for the innate immune system?
They are strong phagocytes that can leave the blood, enter the infected tissue and destroy foreign microbes and particles via phagocytosis
What is the difference between granulocytes and agranulocytes?
Granulocytes- you can see granules under a microscope
Agranulocytes- cannot or hard to see granules under light microscope
What are 3 types of agranulocytes?
- Monocyte
- Dendrite cells
- Lymphocytes
What is the connection between monocytes and macrophages?
Monocytes- initially not phagocytic (baby) and when they leave the blood and enter the tissue they become macrophages
What are macrophages and what do they do?
Mature monocytes and strong phagocytes, they are often found in organs and filter out invading pathogens as blood passes through
What do dendrite cells do?
found in the tissue and in skin, they present foreign material cells to the adaptive immune system (present antigens)
What is a lymphocyte and what are 3 types
Type of white blood cell (leukocyte) that is an agranulocyte.
- Natural killer cells
- B lymphocytes
- T lymphocytes
What do natural killer cells do?
Go around looking for any cells that display unusual proteins in the plasma membrane and kill the infected body and tumor cells
What are T and B lymphocytes part of?
Adaptive immunity
During an infection, what type of cells move to the infected area?
Monocytes and granulocytes
What are the 4 stages of phagocytes moving to an infection
- Chemotaxis
- Adherence
- Ingestion
- Digestion
What occurs in chemotaxis stage?
Phagocytes are attracted to the foreign particles, damaged cells,etc
What occurs in the adherence stage?
Phagocyte attaches to the foreign particle (it has to see something abnormal for it to be able to grab on)
What occurs in the ingestion stage?
Pseudopods extend and engulf the particle which then the particle becomes trapped in the phagosome
What occurs in the digestion stage?
Digestive enzymes enter the phagosome, which then takes 20-30 minutes to kill the bacterium
What are some signs and symptoms of inflammation?
Pain, redness, heat, swelling and loss of function
What 3 things does inflammation do?
- Destroys the injurious agent
- Prevents spreading of injurious agent
- Repairs and replaces damaged tissue
What are 4 stages of inflammation?
- Tissue damage
- Vasodilation
- Phagocytosis
- Tissue repair
What does vasodilatation mean? What does it allow in the infection sense?
Blood vessels open so that blood can reach affected areas, allowing more white blood cells to access area
What occurs during vasodilation?
WBC bring nutrients for faster healing which causes the symptoms but allows for fibrinogen clot formation
What is fibrinogen and when does it play a role?
Fibrinogen- an inactive protein factor in blood that waits for tissue damage, plays a role in inflammation
What does fibrinogen clot formation do for inflammation?
Segregates the affected area and prevents the spread of infection (isolates everything)
What occurs during phagocytosis? Tissue repair step?
Phagocytes destroy invading microbes
Tissue repair is when new cells are produced
What is a fever and what part of the brain controls it?
An increase in body temperature
Controlled by the hypothalamus of the brain
What triggers a fever? What do they all have in common?
Toxins, lps and chemicals produced by the immune system (they all reset the body’s thermostat)
What are 4 things that result from a fever being caused?
- Muscle contractions (shivering)
- Increased temp
- Faster phagocytosis (do to #2)
- Slows growth of heat limited microbes
What does increased temperature in a fever do to help you get better?
Causes faster metabolism which promotes healing
What is the temperature of a fever that can cause death?
43 degrees
What is the complement system?
A system composed of roughly 30 proteins that circulate in the blood and work together as a cascade (one triggers the next,etc). They can be triggered by surface molecules of invading microbes which then result in a complement cascade
What is an example of a surface molecule that can trigger complement system?
Lipopolysaccharide
What are the 3 stages of the complement system?
- Opsonization
- Enhance Inflammation
- Cytolysis
What occurs in the opsonization stage of the complement system?
C (complement) proteins attach to microbes and act as a flag to attract a phagocyte which allows increase of phagocytosis by 1000x
What occurs in the enhance inflammation stage of the complement system?
Increases blood vessel permeability which attracts phagocytes to infection site
What occurs in the cytolysis stage of the complement system?
Formation of tthe membrane attack complex which pokes holes in the bacterial cell membrane
What is interferon and what does it do?
Is proteins that is released by infected cells to warn neighbouring cells and interferes with viral replication
What is the benefit of releasing interferon?
Allows the neighbouring cells time to produce anti viral proteins
What are 4 downsides of interferon proteins?
- Do not help cells already infected
- Only effective for a short period of time
- Causes side effects
- Can be toxic to organs
What are the side effects of interferon proteins?
Nausea, vomiting, fatigue, headache and fever
