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Microbiology > Lecture 12: Innate Immunity > Flashcards

Lecture 12: Innate Immunity Flashcards

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1
Q

What is susceptibility?

A

Likelihood of acquiring/lack of resistance to a disease

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2
Q

What is resistance?

A

Ability to ward off disease

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3
Q

What is innate resistance?

A

Resistance due to physiological processes of humans that are incompatible with those of the pathogen

Chemical receptors for pathogens are not present on human cells

Temperature and pH may be incompatible with those necessary for the pathogens survival

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4
Q

What is acquired resistance?

A

Resistance to an infectious agent due to prior contact with that agent

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5
Q

What is nonspecific resistance?

A

Innate, defense against any pathogens

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6
Q

What is specific resistance?

A

Acquired, defense against specific pathogens

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7
Q

What is the first line of defense?

A

A surface protection composed of anatomical and physiological barriers that keep microbes/ pathogens from entering the body

-physical barriers (intact skin)
-microbiota barrier (normal microbiota (flora))
-chemical barriers (mucous membranes and their secretions)

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8
Q

Discuss the mechanical factors of intact skin

A

Epidermis
-outer layer composed of multiple layers of tightly packed cells
-few pathogens can penetrate these layers
-shedding of dead skin cells removes attached microorganisms

Dermis
-contains protein fibers called collagen and keratin
-give skin strength and pliability to resist abrasions that could introduce microorganisms

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9
Q

Discuss the mechanical factor - mucous membrane

A

Line all body cavities open to the outside environment (oral cavity, digestive system,.)

Two distinct layers:
(1) Epithelium: thin, outer covering of the mucous membranes
-tightly packed
-shed continually
-used for absorption
-contain goblet cells which produce sticky mucus that traps bacteria and pathogens

(2) Depper connective layer that supports the epithelium

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10
Q

Discuss the mechanical factor - ciliary escalator

A

Microbes trapped in mucus are transported away from the lungs

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11
Q

Discuss the mechanical factor - lacrimal apparatus

A

Tears: washes eyes

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12
Q

Discuss other mechanical factors like saliva, urine, vaginal secretions

A

Saliva: washes microbes off

Urine: flows out

Vaginal secretions: flow out

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13
Q

Discuss chemical factor, perspiration

A

Perspiration secreted by sweat glands

salt- inhibits growth of pathogens

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14
Q

Discuss chemical factor, low pH

A

skin (3-5) and gastric juice (1.2-3.0)

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15
Q

Discuss chemical factor, lysozyme

A

Lysozyme destroy cell wall bacteria

in tear, saliva, nasal secretions, tissue fluids

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16
Q

Discuss chemical factor, sebum

A

Sebum secreted by sebaceous (oil) glands (fatty acid)

Helps keep skin pliable

Lowers the pH of the skin

Fungistatic

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17
Q

Discuss chemical factor, transferrins

A

Transferrins in blood find iron, making iron unavailable for bacterial growth

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18
Q

Discuss microbial antagonism/ competitive exclusion when normal microbiota compete with pathogens

A

normal microbiota compete with pathogens:

Secrete antimicrobial substances that limit pathogen growth

Consumption of nutrients makes them unavailable to pathogens

Create an environment unfavorable for other microorganisms by changing pH

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19
Q

What is the immune system?

A

A healthy immune system is responsible for:

-surveillance of the body
-recognition of foreign materials
-destruction of entities deemed to be foreign

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20
Q

Discuss neutrophils and eosinophils?

A

Can phagocytize pathogens

Are capable of diapedesis

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20
Q

What are the body compartments with immune functions?

A

The reticuloendothelial system (RES)

The extracellular fluid (ECF) surrounding tissue cells

The blood stream

The lymphatic system

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21
Q

What is the composition of whole blood?

A

Composed of cells and portions of cells within a fluid called plasma

Plasma is mostly water containing electrolytes, dissolved gases, nutrients, and proteins
- after clotting, remaining fluid is called serum (therapy and testing)
- plasmas proteins include complement proteins and antibodies
-the cells and cell fragments in plasma are called formed elements

Buffy coat: white layer, 1%, WBCs

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21
Q

What are granulocytes and their three types?

A

Contain large granules that stain different colors based on the dye used

3 types:
Basophils
Eosinophils
Neutrophils

22
Q

What are the three types of formed elements?

A

Erythrocytes: carry oxygen and carbon dioxide in the blood

Platelets: involved in blood clotting

Leukocytes: involved in defending the body against invaders
2 groups: Granulocytes and Agranulocytes

23
Q

What is hematopoiesis?

A

Production of blood cells

23
Q

What are neutrophils?

A

Stain lilac with a mixture of acidic and basic dyes

24
Q

What are basophils?

A

Stain blue with the basic dye methylene blue

24
Q

What are eosinophils?

A

Stain red/orange with the acidic dye eosin

24
Q

What is the reticuloendothelial system?

A

Tissues of the body are permeated by a support network of connective tissue fibers that interconnect nearly cells to create a massive network surrounding all organs

25
Q

What are agranulocytes?

A

Cytoplasm appears uniform under a light microscope

2 types:
lymphocytes
monocytes

26
Q

What are lymphocytes?

A

Most involved in specific immunity

27
Q

What are monocytes?

A

Leave the blood and mature into macrophages

27
Q

What are the functions of Leukocytes aka WBCs,

Eosinophils

A

Toxic to parasites, some phagocytosis

28
Q

What are the functions of Leukocytes aka WBCs,

Basophils

A

Produce histamine

28
Q

What are the functions of Leukocytes aka WBCs,

Neutrophils

A

Phagocytic

29
Q

What are the functions of Leukocytes aka WBCs,

lymphocytes

A

Involved in specific immunity

Natural killer lymphocytes (NK cells): secrete toxins onto the surface of virally infected cells and tumors

30
Q

What are the functions of Leukocytes aka WBCs,

monocytes

A

phagocytic as mature macrophages

fixed macrophages in lungs, liver, bronchi

wandering macrophages roam tissues

31
Q

What are macrophages?

A

Phagocytic cells of the second line of defense

All macrophages (plus monocytes attached to endothelial cells) = mononuclear phagocytic system

31
Q

What is the purpose of the differential white blood cell count test?

A

Can signal signs of disease

-Allergies or parasitic worm infection: increased eosinophils

-bacterial diseases: often show increase in leukocytes and in neutrophils

-viral infections: show increase in lymphocytes

31
Q

What are wandering macrophages?

A

Leave the blood via diapedesis

Phagocytize throughout the body

32
Q

What are fixed macrophages?

A

Do not move throughout the body

Often phagocytize within a specific organ
- include Langerhans cells (epidermis), alveolar macrophages (lungs) microglia (central nervous system), Kupffer cells (liver)

33
Q

Second line of defense:

phagocytosis

A

Phago: eat

Cyte: cell

Ingestion of microbes or particles by a cell, performed by phagocytes

33
Q

Second line of defense

Inflammatory response

A

-Redness
-Pain
-Heat
-Swelling (edema: leakage of fluid into tissues)
-Acute-phase proteins activated (complement cascade , cytokines, kinins)
-Vasodilation (histamine, kinins, prostaglandins, leukotrienes)
-Margination and emigration of WBCs
-Tissue repair/scarring

33
Q

What is the second line of defense?

A

Operates when pathogens succeed in penetrating the skin or mucous membranes

nonspecific defense:
-composed of cells, antimicrobial chemicals, and processes

-many of these components are contained or originate in the blood

-no physical barriers

34
Q

What are the phases of phagocytosis?

A
  1. Chemotaxis and adherence of microbe to phagocyte
  2. Ingestion of microbe by phagocyte
  3. Formation of a phagosome
  4. Fusion of the phagosome with a lysosome to form a phagolysosome
  5. Digestion of ingested microbe by enzymes
  6. Formation of residual body containing indigestible material
  7. Discharge of waste materials
35
Q

What are the major events in inflammatory response?

A
  1. Injury/immediate reactions
  2. Vascular reactions
  3. Edema and Pus formation
  4. Resolution/ Scar formation
36
Q

What is diapedesis?

A

Passage of blood cells through intact blood vessel walls

36
Q

Second line of defense

What are interferons (IFNs)

A

Protein molecules released by host cells, appear later in the course of infection
-nonspecifically inhibit the spread of viral infections
-particularly effective against RNA viruses
-cause many symptoms associated with viral infections

Alpha IFN (by epithelium and leukocytes & Beta IFN (by fibroblasts)
-cause cells to produce antiviral proteins that inhibit viral replication
-present early in the infection

Gamma IFN (by T cells and NK cells)
-causes neutrophils and macrophages to phagocytize bacteria

37
Q

What are the benefits of fevers?

A

Enhances the effects of interferons

Inhibits growth of some microorganisms

May enhance the performance
-of phagocytes
-cells of specific immunity
-and the process of tissue repair

37
Q

What is a fever?

A

Abnormally high body temperature

Nearly universal symptom of infection

Hypothalamus normally set body temperature at 37 C.

Pyrogens (ie endotoxin) cause phagocytes to release interleukin-1
-hypothalamus releases prostaglandins that reset the hypothalamus to a high temperature
-body increases rate of metabolism and shivering to raise temperature
-when IL-1 is eliminated (degraded by enzymes) body temperature falls

Crisis: shaking chills, falling body temp, intense sweating, low BP, may result in death

37
Q

Alpha IFN (by epithelium and leukocytes & Beta IFN (by fibroblasts)

A

-cause cells to produce antiviral proteins that inhibit viral replication
-present early in the infection

38
Q

Gamma IFN (by T cells and NK cells)

A

-causes neutrophils and macrophages to phagocytize bacteria

39
Q

What is interferon therapy?

A

Interferon is not virus specific

Synthesis in response to one cell type will also protect against other cell types

Produced industrially as a treatment for virus infections

Many viral infections don’t respond to interferon therapy at all

Only a slight effect is seen with those viral infections that do respond

39
Q

Second line of defense

Complement system

A

The system that enhances (complements) immune reactions

Serum proteins activated in a cascade: more than 26 proteins

Effects of complement activation:
- Opsonization: enhanced phagocytosis
-Membrane attack complex (MAC): cytolysis
- Trigger inflammation

39
Q

What are some bacteria that evade the complement system?

A

Capsules prevent C activation

Surface lipid-carbohydrates prevent MAC formation

Thick peptidoglycan makes it harder for MAC to form

Enzymatic digestion of C5a

40
Q

Interferons:

Protein molecules released by host cells, appear later in the course of infection

A

-nonspecifically inhibit the spread of viral infections
-particularly effective against RNA viruses
-cause many symptoms associated with viral infections

Microbiology (17 decks)

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