Innate Immunity

Question 1

What is a pathogen?

Answer 1

Biological agents capable of producing disease; include viruses, bacteria, and fungi.

Question 2

What are the 3 lines of defense against pathogens?

Answer 2

1) Skin and mucous membranes
2) Innate defense mechanisms
3) Adaptive immunity

Question 3

What is meant by innate defenses?

Answer 3

Defenses that guard equally against a broad range of pathogens.

Question 4

Characteristics of Innate Immunity.

Answer 4

1) Local - wards off pathogen at the point of invasion with little effect anywhere else
2) Nonspecific - acts against broad spectrum
3) Lacks memory

Question 5

What are the 3 types of innate defenses?

Answer 5

1) Protective cells
2) Protective proteins
3) Protective processes

Question 6

How does skin function as an external barrier?

Answer 6

Makes it mechanically difficult for microorganisms to enter the body - toughness of keratin; too dry and nutrient-poor for microbial growth

Question 7

What is the acid mantle?

Answer 7

Thin film of lactic and fatty acids from sweat and sebum that inhibits bacterial growth.

Question 8

Where do you find mucous membranes?

Answer 8

Where “inside meets outside”; digestive, respiratory, urinary, and reproductive tracts

Question 9

What is lysozyme?

Answer 9

An enzyme destroys bacterial cell walls.

Question 10

Neutrophils

Answer 10

Can kill using phagocytosis and digestion; can kill by producing a cloud of bactericidal chemicals

Question 11

What happens when lysosomes degranulate?

Answer 11

They discharge enzymes into tissue fluid causing a respiratory burst - creates a killing zone around neutrophil, destroying several bacteria

Question 12

Eosinophils

Answer 12

Found especially in mucous membranes; it guards against parasites, allergens, and other pathogens - kills tapeworms and roundworms by producing superoxide, hydrogen peroxide, and toxic proteins.

Question 13

Basophils

Answer 13

Secretes chemicals (leukotrienes, histamine, heparin) that aid the mobility and action of other leukocytes.

Question 14

What do leukotrienes do?

Answer 14

Activate and attract neutrophils and eosinophils.

Question 15

What does histamine do?

Answer 15

Increases blood flow (vasodilator)

Question 16

What does heparin do?

Answer 16

Inhibits clot formation that would impede leukocyte mobility.

Question 17

What are the three different types of lymphocytes?

Answer 17

T cells, B cells, Natural Killer cells

Question 18

Monocytes

Answer 18

Emigrate from the blood into connective tissues and transform into macrophages

Question 19

What are antimicrobial proteins?

Answer 19

Proteins that inhibit microbial reproduction and provide short-term, innate immunity to pathogenic bacteria and viruses; two families: interferons, complement system

Question 20

What do interferons do?

Answer 20

Secreted by certain cells infected by viruses; Alert neighboring, activate second-messenger systems within, NK cells & macrophages

Question 21

What is the complement system?

Answer 21

A group of 30 or more globular proteins that make powerful contributions to both innate immunity and adaptive immunity; float around in inactive form, activated by the presence of a pathogen

Question 22

What are the 3 routes of complement activation?

Answer 22

Classical pathway, alternative pathway, lectin pathway.

Question 23

Describe the classical pathway of classical activation.

Answer 23

1) Antigen-antibody complexes form on the pathogen surface
2) Reaction cascade (complement fixation)
3) C3 dissociates into C3a and C3b

Question 24

Describe the alternative pathway of classical activation.

Answer 24

1) C3 dissociates into fragments C3a and C3b
2) C3b binds to pathogen surface
3) Reaction cascade and autocatalytic effect
4) C3 dissociates into C3a and C3b

Question 25

Describe the lectin pathway of classical activation.

Answer 25

1) Lectin binds to carbohydrates in pathogen surface
2) Reaction cascade
3) C3 dissociates into C3a and C3b

Question 26

Describe the course of a fever.

Answer 26

1) Infection and pyrogen secretion
2) Hypothalamic - thermostat is reset to higher set point
3) Onset-body temperature rises
4) Stadium - body temperature oscillates around new set point
5) Infection ends, set point returns to normal
6) Defervescence-body temperature returns to normal

Question 27

Describe inflammation.

Answer 27

The process begins with the release of a variety of proinflammatory chemicals, such as histamin, from injured tissue, immune cells, and infectious organisms. This tiggers mobilization of body defenses, containment and destruction of pathogens, tissue cleanup and repair

Question 28

What do cytokines do during inflammation?

Answer 28

Regulate inflammation and immunity - includes interferon, interleukins, tumor necrosis factor, chemotactic factors, and others

Question 29

Describe the four cardinal signs of inflammation.

Answer 29

Heat: results from hyperemia
Redness: due to hyperemia, and extravasated RBCs in the tissue
Swelling (edema): due to increased fluid filtration from the capillaries
Pain: Direct injury to the nerves, pressure on the nerves from edema.

Question 30

Describe neutrophil behavior in inflammation.

Answer 30

Chemical messengers are released by basophils, mast cells, blood plasma, and damaged tissue. These inflammatory chemicals stimulate leukocyte margination (adhesion to the blood vessel wall), diapedesis (crawling through gaps in the wall), chemotaxis (movement toward the source of the inflammatory chemicals), and phagocytosis (engulfing bacteria or other pathogens).