Innate Immunity Flashcards
Chapter 15
Define Species resistance
Properties that protect an organism from infection by pathogens of other different organisms
Define Innate Immunity
What type of immunity is always active, nonspecific, rapid, and able to work against a variety of pathogens?
Innate Immunity
What are the main cells of the bodies so-called 3rd line of defense?
Lymphocytes
How is the bodies 3rd line of defense different from the first 2?
The 3rd line is composed of lymphocytes which respond to unique pathogens and alter the bodies defenses to be more effective to said pathogens. So the 3rd line is specific whereas the first 2 or nonspecific.
What structures work to prevent pathogens from entering the body in the first place?
2 points
- Skin
- Mucous membranes
Which layer of sknin contains hair follicles, glands, and nerve endings?
The dermis
What makes the skin an effective defense against pathogens?
2 nonspecific answers
- Its physical structure
- Its chemical components
What 2 characteristics of innate immunity does the skin illustrate? How?
- Barriers: tightly packed epithelial cells act as a barrier to pathogens
- Clearance: outermost dead cells slough off, taking any microorganisms with them
The epidermis contains defensive cells called what?
Dendritic Cells
What cells devour pathogens non-specifically while also playing a role in adaptive immunity?
where are these cells located?
Dendritic cells in the epidermis
What fibers give skin strength and the pliability to prevent skin penetration?
Collagen
What are the skins chemical defenses against pathogens?
Name the 2 structures (not how the defense works itself)
- Dermal cells
- Sweat glands
How do sweat glands chemically protect against pathogens?
Perspiration from sweat glands contain salt, antimicrobial peptides, and the enzyme lysozome. The salt draws water from invading cells, effectively killing them.
3 components not as important, just how salt kills pathogens
What are antimicrobial peptides?
Positively charged chains of amino acids that act against microorganisms
What class of antimicrobial peptides do sweat glands secrete?
Dermcidines
Explain dermcidins?
Broad-spectrum antimicrobial peptides that act against gram-negative and positive bacteria & fungi
How does lysozyme in perspiration defend against pathogens?
Lysozome is an enzyme that breaks down cell walls of bacteria. Without a cell wall, bacteria is more easily destroyed by the bodies other defenses
How does sebum protect the skin?
- Its oily nature keeps the skin pliable
- Fatty acids in sebum lower the pH of the skin to 5 while also destabilizing cells’ membranes.
What characteristics of the skin make it a inhospitable environment to most microorganisms?
4 points
- Salt
- Antimicrobial peptides
- Lysozome
- Acidity
Where is bacteria that finds the skin a suitable environment typically abide?
2 points
- In crevices around hairs
- In the ducts of glands
Where are mucous membranes located?
generally speaking
In any body cavity open to the outside environment
How are epithelial cells in mucous membranes different from skin epithelial cells?
3 pointss
- Form a thin layer, sometimes only one cell thick (skin iss thick)
- Are alive and play roles in bodily functions (skin are dead so they can slough off eventually)
- Moist surface (skin is dry)
Why is the number of resident microbiota much higher on mucous membranes than on the skin?
Because mucous surfaces are very moist, which is conducive to bacterial growth
What do dendritic cells underneath the mucous epithelium do?
- Devour invaders
- can extend pseudopods between epithelial cells to “sample” the lumen (mucous membrane)
What is the lacrimal apparatus?
Generally speaking
A group of structure that produce & drain away tears
How are the eyes protected against pathogens?
2 things
- Tears which are carried away by the Lacrimal apparatus
- Lysozome in tears (which destroys bacteria)
How does the microbiome affect the bodies 2nd line of defense?
It stimulates it and boosts the body’s production of antimicrobial substances
Why is using antimicrobial products not necessarily wise?
Because it removes all microbes from your body, including those part of your microbiota, potentially making you more senstitive to infection.
When does the bodies second linne of defense come into play?
Once a pathogen has successfully penetrated the skin or a mucous membrane
What is a major difference between the bodies first and second line of defense?
Think overall function of disease fighting
The second line has no “barriers” like the first line.
involves cells, chemicals, and processes
When blood clots, what is the remaining liquid called?
Serum
What does transferrin do?
A transport protein that transports iron in plasma to cells
What do we call excess iron that is stored in the liver?
Ferritin
What are the main and secondary functions of iron-binding proteins?
Main: transporting and storing iron
Secondary: Sequestering iron so it is unavailable to microorganisms
How do some bacteria get around iron-binding proteins sequestering of iron?
iron-binding compounds
By secreting their own iron-binding compounds called siderophores, which have a greater affinity for iron than the bodies iron related proteins, allowing the bacteria to steal iron from the body
What are formed elements?
Cells and cell fragments that are suspended in blood plasma
What is hematopoiesis?
Process in which stem cells in the bone marrow of larger bones with hollow cavities produce 3 types of formed elements
What are the 3 formed elements produced during hematopoiesis?
- Erythrocytes
- Platelets
- Leukocytes
What are erythrocytes? What do they do?
Fancy name for red blood cells. They carry oxygen & carbon dioxide in the blood.
What are platelets? What is their function?
Platelets are pieces of megakaryocytes and they aid in blood clotting
What are leukocytes also called?
White blood cells
Leukocytes are divided into what two groups?
- Granulocytes
- Agranulocytes
What are the 3 granulocytes?
- Basophil
- Eosinophil
- Neutrophil
What are the two agranulocytes?
- Monocytes
- Lymphocytes
Define granulocytes
?
What granulocyte stains blue with the basic dye methylene blue?
basophils
What granulocyte stains red/orange with the acidic dye eosin?
Eosinophils
What granulocyte stains lilac with a mixture of acidic & basic dyes?
Neutrophils
What are neutrophils also known as?
Polymorphonuclear Leukocytes (PMNs)
What is diapedesis?
Which granulocytes are phagocytic?
Neutrophils & Eosinophils
Basophils not phagocytic
What are agranulocytes
Explain monocytes
Are large agranulocytes with slightly lobed nuclei
Explain Lymphocytes
The smallest leukocytes and have nuclei that nearly fill the cells
What lymphocytes function in innate defense?
Natural Killer Lymphocytes
What do monocytes mature into after leaving the blood via diapedesis?
Marcophages
What are macrophages?
Phagocytic cells in the bodies second line of defense that devour foreign objects
How are macrophages often named?
Based on their location in the body
bc they specialize for each body tissue
What are alveoli?
Small pockets at the end of respiratory passages where oxygen and carbon dioxide exchange
What is a differential white blood cell count? What can it serve as a sign of?
The proportion of leukocytes in blood and can signal the presence of disease
What are the 6 steps of phagocytosis?
- Chemotaxis
- Adhesion
- Ingestion
- Maturation
- Killing
- Elimination
What is chemotaxis?
The movement of a cell toward a chemical stimulus or away from a chemical stimulus
Positive Chemotaxis is?
Movement towards a chemical stimulus
Negative Chemotaxis is?
Movement away from a chemical stimulus
What chemicals attract phagocytic leukocytes?
4 points
- microbial secretions
- parts of microbial cells
- components of damaged tisssues & white blood cells
- chemotactic factors
List chemotactic factors
3 points
- defensins
- peptides from complement
- chemokines
What does the chemotaxis phase of phagocytosis aim to achieve?
Bring the phagocytic cell towards the site of an infection
What is the adhesion phase of phagocytosis?
2nd phase in which the phagocytic cell attempts to attach to microorganisms via binding receptors
How can bacteria hinder the 2nd phase of phagocytosis?
From virulence factors like capsules that hinder adhesion and make the bacteria slippery
How are pathogens more easily phagocytized?
covered in 2 different things
When they are covered with antimicrobial proteins like complement proteins, or antibodies
What is opsonization?
What do phagocytes do once they adhere to pathogens?
They extend pseudopods to surround the microbe
What is a phagosome?
A food vessicle made inside phagocytes as they internalize a microbe
What are phagolysosomes formed from and what do they do?
Formed when lysosomes add digestive chemicals to maturing phagosomes. They use substances to destory the engulfed microbes.
Phagolysosomes are also known as?
a residual body
Phagolysosome formation kills most pathogens in what amount of time?
30 minutes
What happens when phagocytes cannot complete digestion of a microbe?
They eliminate the remains of the microbe via exocytosis
How do phagocytes know to leave the bodies own healthy cells unharmed?
2 points
- cytoplasmic membrane receptors that detects microbe surface components that are not present on the body’s cells
- Opsonins that provide a signal to phagocytes
Why do eosinophils not phagocytize? What do they do instead?
Because it’s not their usual mode of attack. They secrete antimicrobial chemicals that adhere to the surface of parasitic helminths and secrete toxins that weaken and or kill them.
What is eossinophilia?
An abnormally high number of eosinophils in the blood
What might be two explanations for eosinophilia?
- Helminth infestation
- patients have allergies
