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Biology 245 > Nonspecific Host Defense > Flashcards

Nonspecific Host Defense Flashcards

1
Q

Susceptibility

A

Lack of resistance to a disease

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2
Q

Immunity

A

Ability to ward off disease

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3
Q

Innate Immunity

A

Defenses against any pathogen

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4
Q

Adaptive Immunity

A

Immunity, resistance to a specific pathogen

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5
Q

Immune System

A

immune system also includes fast-acting components collectively called the innate or nonspecific system

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6
Q

innate immunity

A

first line of defense

  • intact skin
  • Mucous membranes and their section
  • normal microbiota

second line of defense

  • phagocytes
  • inflammation
  • fever
  • antimicrobial substances
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7
Q

Adaptive Immunity

A

Third line of defense

  • specialized lymphocytes: T cells and B cells
  • antibodies
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8
Q

Physical Factors

A 
Skin
Epidermis
consists of tightly packed cells with
◦Keratin, a protective protein
Mucous membranes Mucus: Traps microbes
 Ciliary escalator: Microbes trapped in mucus are
transported away from the lungs
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9
Q

Specialized Mucosa

A

mucus reduces mobility of pathogen

specialized mucosae include stomach (acidic)
and respiratory tract (cilia beat mucus away from lungs)

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10
Q

Lacrimal apparatus

A

Washes eye

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11
Q

Saliva

A

Washes microbes off

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12
Q

Urine

A

Flows out

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13
Q

Vaginal secretions

A

Flows out

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14
Q

Normal Microbiota and Innate Immunity

A

Microbial antagonism/competitive exclusion:
Normal microbiota compete with pathogens or alter the environment
Commensal microbiota: One organism (microbe)
benefits and the other (host) is unharmed
◦May be opportunistic pathogens

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15
Q

surveillance

A

cells/proteins of the immune
system travel throughout the body [they are
present in all fluid compartments

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16
Q

recognition

A

crucial step; cells and protein

components of the immune system examine surface markers (PAMPS) to distinguish self from nonself

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17
Q

destruction

A

usually by phagocytosis

neutrophil or macrophage

18
Q

blood vessels

A

contains blood which is composed of fluid (plasma) and “cells” (erythrocytes, leukocytes and platelets)
fluid component leaks from capillaries to ECF (sometimes leukocytes follow)
b) b) extracellular compartment – contains extracellular fluid
(ECF) that “washes” the cells of body tissues

19
Q

lymphatic vessels

A

collects the “washings” (now called
lymph) and delivers it back to the blood by connections with veins near the heart as lymph travels through the lymphatic vessels, it passes
through lymph nodes where immune cells (leukocytes) are present in large numbers

20
Q

Red Blood Cells

A

Transport O2 and CO2

21
Q

White Blood Cells:

A

Neutrophils:Phagocytosis

Basophiles: Histamine

Eosinophils:
Kill parasites

Monocytes:
Phagocytosis

Dendritic cells: Phagocytosis

Natural killer cells: Destroy target cells

T cells:
Cell-mediated immunity

B cells:
Produce antibodies

22
Q

Platelets

A

Blood clotting

23
Q

Percentage of each type of white cell

A 
Neutrophils
60–70%
Basophils
0.5–1%
Eosinophils
2–4%
Monocytes
3–8%
Lymphocytes
20–25%
24
Q

Lymphocytes

A

3rd line of defense; these cells have no role in
the 2nd line of defense
T lymphocytes (T cells) – kill virus infected cells and cancer cells
B lymphocytes (B cells) – produce antibodies for ‘marking’ pathogens

25
Q

Phagocytosis

A

Ingestion of

microbes or particles by a cell, performed by phagocytes

26
Q

Inflammation

A
  • Redness
  • Pain
  • Heat
  • Swelling (edema)
  • Acute-phase proteins activated (complement, cytokine and kinins)
  • Vasodilation (histamine, kinins, prostaglandins, and leukotrienes)
  • Margination and emigration of WBCs
  • Tissue repair
27
Q

Benefits of Inflammation

A

a) attracts leukocytes to site of infection b) creates optimum conditions for leukocyte function c) localizes (traps) pathogen; prevents spreading to other areas d) creates optimum conditions for tissue repair

28
Q

Histamine

A

Vasodilation, increased permeability of blood vessels

29
Q

Kinins

A

Vasodilation, increased permeability of blood vessels

30
Q

Prostaglandins

A

Intensity histamine and kinin effect

31
Q

Leukotrienes

A

Increased permeability of blood vessels, phagocytic attachment

32
Q

Inflammatory Response

A

a) cytokines released by cells of damaged
tissue or macrophages (upon pathogen
binding)
b) b) cytokines produce vasodilation (redness,
heat) and increased permeability of capillaries cytokines also act as chemoattractants to
recruit leukocytes (see diapedesis, below) to the site of infection
c) exudate (fluid) now leaves highly permeable capillaries to accumulate in tissue (swelling or edema)
d) increased pressure in tissue due to swelling causes pain
e) diapedesis: migration of neutrophils and monocytes across capillary wall to tissue
f) monocytes become macrophages in tissue

33
Q

Fever: Advantage/disadvantages

A

Advantages
◦Increases transferrins ◦Increases IL–1 activity ◦Produces Interferon

Disadvantages
◦Tachycardia ◦Acidosis ◦Dehydration ◦44–46°C fatal

34
Q

systemic (not local) response to limit growth

(multiplication) of microbes

A

pyrogens are secreted when leukocytes or
macrophages bind pathogen
Lipid A from GN bacteria is also a pyrogen
b) b) pyrogens circulate to hypothalamus and
raise set point for body temperature

c) increased temperature causes liver (and macrophages) to sequester iron and zinc
d) growth of bugs is inhibited by:
increase in temperature (growth of bugs is inhibited and leukocyte function improves)
limited iron and zinc

35
Q

interferon

A

antiviral protein released by cells infected with virus interferon inhibits synthesis and assembly
of virions in neighboring (healthy) cells
upon entry into healthy cell, virus cannot reproduce and the cell remains uninfected

36
Q

Alpha IFN and Beta IFN

A

Causes cells to produce antiviral proteins that inhibit viral replication

37
Q

Gamma IFN

A

Causes neutrophils and macrophages to phagocytize bacteria

38
Q

Complement & 3 mechanisms for complement

A

i) forms membrane attack complex (MAC) and
causes cell death
ii) ii) binds to surface of pathogen and ‘marks’
it for destruction by phagocytes
iii) iii) promotes inflammation

39
Q

Complement must be activated (complement fixation) by one of two mechanisms before it can destroy pathogens

A

a) classical pathway – binding of antibody to pathogen b) alternative pathway – direct binding of complement to pathogen

40
Q

Effects of Complement Activiation

A

Opsonization or immune adherence: Enhanced
phagocytosis
Membrane attack complex: Cytolysis Attract phagocytes

41
Q

Some Bacteria Evade Complement

A
  • Capsules prevent C activation
  • Surface lipid-carbohydrates prevents MAC formation
  • Enzymatic deigestion of C5a.

Biology 245 (3 decks)

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