Chapter 15: Innate immunity

Question 1

Species resistance

Answer 1

-we are naturally resistant to most plant and animal pathogens due to our anatomy and physiology being incompatible with those of the pathogen

ex: lacking certain chemical receptors or pH/ temperature, first line of defense

Question 2

What does innate immunity mean?

Answer 2

First two lines of defenses in your body that are present at birth
-is always active, nonspecific, and rapid, and works against a large range of pathogens
-but humans don’t have innate/natural resistance to a number of pathogens therefore they cause diseases

Question 3

How many lines of defense/immunity are there?

Answer 3

three

Question 4

What is the 1st line of defense?

Answer 4

-defense is composed chiefly of external physical barriers and associated chemicals and processes.
ex: skin and mucous, tight junctions, and acid in your stomach. sweat secretions
-this line of defense is non-specific

Question 5

What is the 2nd line of defense?

Answer 5

-is internal and composed of protective cells, bloodborne chemicals, and processes that inactivate or kill invaders
examples:
-WBC (neutrophils, monocytes, eosinophils ,and basophils)
-fever (temperature)
- interferons (Alpha, Beta)
- inflammatory response
- complement system

** these are all non-specific

Question 6

What is the 3rd line of defense?

Answer 6

-also called adaptive immunity, and is resistance against pathogens that act more effectively upon subsequent infection of same pathogen
examples:
-WBC (lymphocytes, T-cell, B-cells)

** these are specific

Question 7

lysozyme

Answer 7

is an enzyme that destroys the cell walls of bacteria by cleaving the bonds between the sugar subunits of the peptidoglycan wall

Question 8

What is a differential white blood cell count?

Answer 8

measures the percentage of each type of white blood cell (WBC) that you have in your blood

Question 9

What are the five major types of white blood cells?

Answer 9

1. Neutrophils
2. lymphocytes
3. monocytes
   4.eosinophils
4. basophiles

Question 10

How to remember the five major types of white blood cells?

Answer 10

Never Let Monkeys Eat Bananas

Question 11

Diapedesis

Answer 11

where white blood cells change and travel through intact blood vessels by squeezing between lining cells and travel to other parts of the body

Question 12

How does phagocytosis help fight diseases/infections?

Answer 12

phagocytes engulf and destroy foreign particles in the body

Question 13

Neutrophiles

Answer 13

-makes up 65% of WBC and cane be made without being sick

Question 14

Steps in Phagocytosis

Answer 14

1. chemotaxis of phagocyte to microbe
2. Adhesion

3.Ingestion of microbes by phagocytes

4. Fusion of a series of vesicles including lysozymes

5.killing of microbes by enzymes and other chemicals

6. elimination (exocytosis)

Question 15

Interferons

Answer 15

-are protein molecules released by host cells to non-specifically inhibit the spread of viral infections
-interfere with viral replication/ progression
-can cause muscle aches, malaise, chills, fever, headache

Question 16

Type I Interferons (Alpha and Beta)

Answer 16

-infected monocytes and macrophages will secrete alpha interferon and fibroblast (undifferentiated cells) will secrete beta interferon
-produced with the infection, and hours later will lead to AVP (anti-viral protein)
-they can act on cells that secrete them, cells infected, and trigger protective steps in neighboring cells

Question 17

Steps for Type I Interferons

Answer 17

1.Virus infects cell
2.viral component triggers activation of type I IFN gene
3. If N-a and -B are released and bind to receptors on the same and nearby cells
4. Binding activates genes for antiviral proteins, though AVPs remain inactive at this time
5. Later the infected cell may die releasing viruses
6. If the cell is infected, viral components activate the AVPs
7. Active AVPs degrade mRNA and bind to ribosomes which stop protein synthesis preventing viral replication

Question 18

Type II (Gamma) Interferon

Answer 18

-is produced by activated T lymphocytes and natural killer lymphocytes. It regulates the immune system as in its activation of phagocytotic activity
-produced several days after an infection to stimulate WBC and phagocytes

Question 19

complement

Answer 19

-a group of serum proteins designated numerically which can result in lysis of a foreign cell
-can be activated in 3 ways

Question 20

What are the three ways complement system can be activated?

Answer 20

1. Classical pathway
2. alternative pathway
3. lectin pathway

Question 21

Classical pathway

Answer 21

-requires pre-made antibodies (already had the infection)
-antibodies bind to foreign substances called antigens and this binding begins a series of enzyme activities called complement cascade

Question 22

Alternative pathway

Answer 22

-activation occurs independent of antibodies
-is activated by endotoxin and/ or foreign glycoproteins and it uses factors B,D and P (properdin) and C3b
-the alternative pathway is useful in the early stages of an infection before the adaptive immune response has created the antibodies needed to activate the classical pathway

Question 22

Lectin Pathway

Answer 22

-activation is independent of antibodies
-we produce lectin which binds to mannose, a carbohydrate on the surface of foreign cells to activate the cascade

Question 23

All three pathways lead to what?

Answer 23

complement cascade

Question 24

Complement cascade MAC (membrane attack complex)

Answer 24

1. C1 (only found in classical) binds the cell with antibodies (If classical activation)
2. Activated C1 cleaves C2 –> C2a + C2b and C4 –> C4a + C4b
3. C2a and C4b form an enzyme that cleaves C3 –> C3a + C3b (opsonization)
4. C2a + C3b + C4b –> C5 convertase
5. C5 convertase cleaves C5 into –> C5a + C5b (Inflammation)
6. chemotaxis and inflammation and C5b + C6, C7, C8, C9
7. membrane attack complex forms, which puts a circular hole in pathogens membrane

** need to get to C3b by any method, after that pathway is the same in every method

Question 25

The inflammatory response

Answer 25

1. A cut penetrates the epidermis barrier and bacteria invade
2. damaged cells release prostaglandins, leukotrienes, and histamine
3. Prostaglandins and leukotrienes make vessels more permeable. histamine causes vasodilation increasing blood flow to the site
4. macrophages and neutrophils squeeze through walls of blood vessels
5. increased permeability allows antimicrobial chemicals and clotting proteins to seep into damage tissue but also results in swelling
6. blood clot forms
7. more phagocytes move to site and devour bacteria
8. accumulation of damaged tissue and leukocytes form pus
9. stem cells repair the damaged tissue, blood clot reabsorbed or falls off

Question 26

Production of a fever

Answer 26

1. chemicals secreted by phagocytes travel in blood to hypothalamus
2. hypothalamus secretes prostaglandins which reset hypothalamic thermostat
3. Nerve impulses causes shivering, higher metabolic rate, inhibition of swelling, and vasoconstriction
4. these processes increase the body temp to the point set by the hypothalamic thermostat