Innate immunity lecture

Question 1

Natural resistance or Species resistance is due to?

Answer 1

Physiological processes of humans that are incompatible with those of the pathogen
– Correct chemical receptors not present on human cells
– Conditions may be incompatible for pathogen’s survival

Question 2

Innate Immunity is?

Adaptive Immunity is?

Answer 2

Innate Immunity: First Line of defense (lack specificity and
memory) no need for activation, always present.
• Adaptive Immunity (Memory and specificity) needs
activation.

Question 3

The Role of Skin in Innate Immunity

Answer 3

– Skin composed of two major layers
– Epidermis
* Multiple layers of tightly packed cells
* Few pathogens can penetrate these layers
* Shedding of dead skin cells removes microorganisms
* Epidermal dendritic cells phagocytize pathogens
– Dermis
* Collagen fibers help skin resist abrasions

Question 4

The Role of Skin in Innate Immunity: Skin has chemicals that defend against pathogens

Answer 4

1) Perspiration secreted by sweat glands
* Salt inhibits pathogen growth
* Antimicrobial peptides
* Lysozyme destroys cell wall of bacteria
2) Sebum secreted by sebaceous (oil) glands
* Helps keep skin pliable
* Lowers skin pH to a level inhibitory to many bacteria

Question 5

The Role of Mucous Membranes in Innate Immunity

Answer 5

– Mucous membranes line all body cavities open to
environment
– Two distinct layers
1) Epithelium
– Thin outer covering of the mucous membranes
– Epithelial cells are living
– Tightly packed to prevent entry of pathogens
– Continual shedding of cells carries away microorganisms
2) Deeper connective layer that supports the epithelium

Question 6

The Role of Normal Microbiota in Innate Immunity

Answer 6

– Microbial antagonism
* Normal microbiota compete with potential
pathogens
– Normal microbiota make it hard for pathogens to
compete
– Consume nutrients
– Create an environment unfavorable to other
microorganisms
– Help stimulate the body’s second line of defense
– Promote overall health by providing vitamins to host

Question 7

Defense Components of Blood

Answer 7

– Plasma

• Mostly water containing electrolytes, dissolved gases, nutrients, and proteins
• Serum is the fluid remaining when clotting factors are removed
• Includes iron-binding compounds, complement proteins, and antibodies

Question 8

Defense Components of Blood: Cells and cell fragments in plasma are called formed elements
– Three types of formed elements

Answer 8

1) Erythrocytes
– Carry oxygen and carbon dioxide in the blood
2) Platelets
– Involved in blood clotting
3) Leukocytes
– Involved in defending the body against invaders
– Divided into granulocytes and agranulocytes

Question 9

Defense Components of Blood
– Granulocytes
– Neutrophils and eosinophils

Answer 9

1) Granulocytes
– Contain large granules that stain different colors
– Three types
* Basophils – stain blue with basic dye methylene blue
* Eosinophils – stain red/orange with acidic dye eosin
* Neutrophils – stain lilac with mix of acidic and basic
dyes
2) Neutrophils and eosinophils
– Phagocytize pathogens
– Capable of diapedesis

Question 10

Defense Components of Blood

– Agranulocytes

Answer 10

– Cytoplasm appears uniform under a light microscope
– Two types
1) Lymphocytes
– Most involved in adaptive immunity
2) Monocytes
– Leave the blood and mature into macrophages

Question 11

Lab analysis of leukocytes

Answer 11

– Differential white blood cell count can signal signs of disease
– Increased eosinophils indicate allergies or parasitic worm infection
– Bacterial diseases often show increase in leukocytes and neutrophils
– Viral infections show increase in lymphocytes

Question 12

Describe Phagocytosis

Answer 12

– Cells capable of phagocytosis are called phagocytes
– Phagocytosis is not completely understood 
– Can be divided into six stages
1) Chemotaxis 
2) Adherence 
3) Ingestion
4) Maturation 
5) Killing
6) Elimination

Question 13

Describe Nonphagocytic Killing: Killing by eosinophils

Answer 13

– Attack parasitic helminths by attaching to their surface
– Secrete toxins that weaken or kill the helminth
– Elevated eosinophils often indicative of a helminth
infestation
– Eosinophil mitochondrial DNA and proteins form
structure that kills some bacteria

Question 14

Nonphagocytic Killing: Killing by natural killer (NK) lymphocytes

Answer 14

– Secrete toxins onto surface of virally infected cells and tumors
– Differentiate normal body cells because they have membrane proteins similar to the NK cells

Question 15

Nonphagocytic Killing – Killing by neutrophils

Answer 15

– Produce chemicals that kill nearby invaders

– Generate extracellular fibers called neutrophil extracellular traps (NETs) that bind to and kill bacteria

Question 16

Nonspecific Chemical Defenses Against Pathogens

Answer 16

– Toll-like receptors (TLRs)
– Integral membrane proteins produced by phagocytic
cells
– Bind pathogen-associated molecular patterns
(PAMPs)
– Initiate defensive responses
– Apoptosis
– Secretion of inflammatory mediators
– Production of stimulants of adaptive immune response
– NOD proteins
– Cytosolic proteins that bind PAMPs

Question 17

Nonspecific Chemical Defenses Against Pathogens: Interferons

Answer 17

– Released by host cells to nonspecifically inhibit the
spread of viral infections
– Cause many symptoms associated with viral infections
– Two types
1) Types I (alpha and beta)
2) Type II (gamma)

Question 18

Nonspecific Chemical Defenses Against Pathogens

– Complement

Answer 18

– Set of serum proteins designated numerically according to their order of discovery
– Complement activation results in lysis of the foreign cell
– Complement can be activated in three ways
1) Classical pathway
2) Alternative pathway
3) Lectin pathway

Question 19

What happens in Complement: Inactivation of complement

Answer 19

Body’s own cells withstand complement cascade

– Proteins on many cells bind and break down activated complement proteins

Question 20

Inflammation is?

Answer 20

– Nonspecific response to tissue damage from various causes
– Characterized by redness, heat, swelling, and pain
– Two types
1) Acute
2) Long-lasting (chronic)

Question 21

Acute inflammation is?

Answer 21

– Develops quickly and is short lived
– Is typically beneficial
– Is important in the second line of defense
– Dilation and increased permeability of the blood vessels
– Migration of phagocytes
– Tissue repair

Question 22

Fever is

Answer 22

– A body temperature over 37°C
– Results when pyrogens trigger the hypothalamus to increase the body’s core temperature
– Various types of pyrogens
– Bacterial toxins
– Cytoplasmic contents of bacteria released by lysis
– Antibody-antigen complexes

Question 23

Explain the production of fever in response to infection

Answer 23

1) Chemicals secreted by phagocytes travel in blood to hypothalamus
2) Hypothalamus secretes prostaglandin, which resets hypothalamic thermostat
3) Nerve impulses cause shivering, higher metabolic rate, inhibition of sweating, and vasoconstriction
4) These processes increase body temperature to the point set by the hypothalamic thermostat

Question 24

What are the body’s first line and second line of defense?

Answer 24

First line of defense
1) Skin 
2) Mucous membranes
3) Normal microbiota 
Second line of defense
1) Blood
2) Phagocytosis
3) Non-phagocytic killing
4) Non specific chemical defenses against pathogens
5) Inflammation
6) Fever

Question 25

Antimicrobial substances: Both skin and mucous membranes are protected by a variety of antimicrobial substances including?

Answer 25

1) Lysozyme
- Enzymes that degrade peptidoglycan
- Found in tears, saliva, blood and phagocytes
2) Peroxidase
- Found in saliva, body tissues, & phagocytes
- breaks down hydrogen peroxide to produce reactive oxygen
3) Lactoferrin
- Sequesters iron from microorganisms (iron essential for microbial growth)
- Found in saliva, some phagocytes, blood & tissue fluids
4) Defensins
- Antimicrobial peptides inserted into microbial membrane
- Found on mucous membranes and phagocytes

Question 26

WBC’s leukocytes are divided into 4 categories

Answer 26

1) Granulocytes
2) Dendritic cells
3) Mononuclear phagocytes (involved in diff. modality of host defense
4) Lymphocytes

Question 27

Cells of the immune system are?

Answer 27

Always found in normal blood

• numbers increase during infection
• some cells play dual roles in both innate and adaptive immunity
• Blood cell formation called hematopoiesis
• blood cells including immune cells originate from hematopoietic stem cells in bone marrow
• blood cells stimulate to differentiate by colony- stimulating factor

Question 28

Cells of the innate immune system

Answer 28

Neutrophil
Macrophage
Dendritic cell

Question 29

Soluble factors of innate immune system

Answer 29

Lysozyme
NOD
TLR

Question 30

Granulocytes

Answer 30

• Contain cytoplasmic granules
• Divided into 3 types
  1) Neutrophils
  2) Basophils
  3) Eosinophils