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Microbiology > Chapter 12 > Flashcards

Chapter 12 Flashcards

1
Q

The blood:
- whole blood cells

A

White blood cells consist of:
- blood cells -> formed elements suspended in plasma
- plasma -> clear, yellowish fluid
- serum -> essentially the same as plasma, except that it is the clear fluid from clotted blood; used in immune testing and therapy

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2
Q

Hematopoiesis

A

The production of blood cells

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3
Q

Stem cells

A
  • the primary precursor of new blood cell maintained in the bone marrow
    - during development, stem cells proliferate and differentiate into the specialized form and function of mature cells
    - become red blood cells, platelets, and white blood cells
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4
Q

White blood cells (leukocytes)

A
  • granulocytes and agranulocytes, depending on their staining patterns when viewed with a microscope
  • these cells are vitally important to nonspecific and specific immunity
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5
Q

Cytokines:

A
  • critical for cell communication
    • hundreds of small active molecules secreted to regulate, stimulate, suppress, and otherwise control many aspects of cell development, inflammation, and immunity
    • produced by monocytes, macrophages, lymphocytes, fibroblasts, mast cells, platelets, and endothelial cells
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6
Q

First line of defense ————

A
  • first line of defense is inborn, and specific
    - physical and chemical barriers that impede the entry of microbes and foreign agents, whether living or not
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7
Q

Built-in defenses of the mucous membranes

A

Respiratory tract:
- nasal hair traps larger particles
- copious flow of mucus and fluids provides flushing actions
- ciliated epithelium conveys particles trapped in the mucus toward the pharynx
- sneeze reflex expels a large amount of air at high velocity
- foreign matter in the bronchi, trachea, and larynx triggers coughing to eject irritants

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8
Q

Nonspecific chemical defenses

A

• Sebaceous secretions exert an antimicrobial effect
• Specialized glands of the eyelids lubricate the conjunctiva with an antimicrobial secretion
• Lysozyme: an enzyme found in tears and saliva that hydrolyzes the peptidoglycan in the cell wall of bacteria
• High lactic acid and electrolyte concentration of sweat
• Acidic pH and fatty acid content of the skin
• Hydrochloric acid in the stomach
• Digestive juices and bile in the intestines
• Antimicrobial chemical in semen
• Protective pH in the vagina during reproductive years maintained by normal biota

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9
Q

Nonspecific chemical defense -> lysozyme

A
  • an enzyme found in tears and saliva that hydrolysis the peptidoglycan in the cell wall of bacteria
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10
Q

Second line of defense ————

A
  • is generalized and nonspecific defenses that support and interact with specific immune responses
    • phagocytosis
    • inflammation
    • fever
    • antimicrobial proteins
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11
Q

Phagocytosis: cornerstone of inflammation and specific immunity

A

General activities of phagocytes:
- survey the tissue compartments and discover microbes, particulate matter, no injured or dead cells
- ingest and eliminate these materials
- to read immunogenicity information (antigens)

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12
Q

The three types of phagocytes

A
  • neutrophils
  • monocytes
  • macrophages
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13
Q

Neutrophils

A
  • a general purpose phagocyte
  • react early in the inflammatory response to bacteria and other foreign materials and to damages tissue
  • high neutrophil counts in blood is a common sign of a bacterial infection
  • is the primary component of pus
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14
Q

Monocytes lead to macrophages

A
  • monocytes are transformed into macrophages after they migrate out of the bloodstream ad into the tissues
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15
Q

Monocytes lead to macrophages:
Histiocytes

A

Histiocytes: live in a certain tissue and remain there during their life span
- alveolar (lung) macrophages
- Knupffer cells in the liver
- dendritic cells in the skin
- macrophages in the spleen, lymph nodes, bone marrow, kidney, bone, and brain
Other macrophages drift nomadically throughout the MPS

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16
Q

Mechanisms of phagocytic recognition, engulfment, and killing

A

Phagocyte (eating cells):
- physical process of engulfment
- attack and dismantling of foreign cells
- can be an isolated event or as part of the orchestrated events

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17
Q

Events of phagocytosis

A
  • chemotaxis
  • ingestion
  • phagolysosome formation
  • destruction
  • excretion
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18
Q

Chemotaxis

A

Phagocytes migrate into a region of inflammation with a deliberate sense of direction, attracted by a gradient of stimulant products from the parasite and host tissue at the site of injury.

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19
Q

Adhesion

A

Phagocytes use their PRRs to recognize PAMPs on foreign cells. This receptor interaction causes the two to “stick” together

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20
Q

Engulfment and phagosome formation

A

Once the phagocyte has made contact with its prey, it extends pseudopods that enclose the cells or particles in a pocket and internalize them in a vacuole called a phagosome. it also secretes more cytokines to further amplify the innate response

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21
Q

Phagolysosome -> formation and killing

A
  • in a short time, lysosomes migrate contact with its prey, it extends pseudopods that enclose the cells or particles in a pocket and internalize them in a vacuole called a phagosome. It also secreted more cytokines to further amplify the innate responses
22
Q

Destruction

A

Two separate systems of destructive chemicals await the microbes in the phagolysosome. The oxygen-dependent system (known as the respiratory burst, or oxidative burst) involves several substances that were described in chapters 6 and 9. Myeloperoxidase, an enzyme found in granulocytes, forms halogen ions (OCl−) that are strong oxidizing agents.

23
Q

Elimination

A

The small bits of indigestible debris are released from the macrophage by Exocytosis

24
Q

Signal molecules on microbe surfaces

A

Pathogen-associated molecular patterns (PAMPs):

• Signal molecules found on microbial surfaces recognized by phagocytes and other defensive cells
• Molecules shared by many organisms, but not present in mammals
• Serve as “red flags” for phagocytes and other cells of innate immunity
• Bacterial PAMPs: peptidoglycan and lipopolysaccharide
• Viral PAMPs: double-stranded RNA

25
Q

Receptors in the host:
- pattern recognition receptors (PRRs)

A
  • found in phagocytes, dendritic cells, endothelial cells, and lymphocytes
  • recognize and bind PAMPs
  • cells possess PRRs whether they have encountered PAMPs before or not
26
Q

Receptors in the host:
Inflammasomes

A
  • PRRs found writhing the cytoplasm of phagocytic cells of the innate immune system
  • recognize PAMPs once they have been phagocytosed
  • recognition leads to the release of signals that initiate and regulate information
27
Q

Steps of phagocytosis

A

1) chemotaxis by phagocyte
2) adhesion of bacteria
3) engulfment into phagocytic vacuole
4) phagosome (what will break down the bacteria)
5) phagolysosome formation
6) killing and destruction of bacterial cells
7) release of residual debris

  • when we leave things behind the immune system is able to start recognizing them (like when we leave something behind and someone is able to find us)
28
Q

Inflammatory response: a complex reaction to injury

A

Easily identifiable by a classic series of signs and symptoms:
- rubor: redness caused by increase circulation and vasodilation in the injured tissue
- calor: warmth caused by the heat given off by the increased flow of blood
- tumor: swelling caused by the fluid escaping into the tissues
- dolor: pain caused by the stimulation of nerve endings
- loss of function

29
Q

Inflammatory response

A
  • some chronic diseases, such as cardiovascular disease, are caused by chronic inflammation
  • can be local or systemic
  • come researchers believe that aging is the consequence of increasing inflammation in multiple body systems
30
Q

Factors that elicit inflammation

A
  • trauma from infection
  • tissue injury or necrosis due to physical or chemical agents
  • adaptive immune reactions
31
Q

Chief functions of inflammation

A
  • to mobilize and attract immune components to the site of injury
  • to set in motion mechanisms to repair tissue damage and localize and clear away harmful substances
  • destroy microbes ad block their further invasion
32
Q

The inflammatory response is?

A
  • a powerful defensive mechanism
  • a means for the body to maintain stability and restore itself after injury
  • has the potential to cause tissue injury, destruction, and disease
33
Q

The stages of inflammation
- injury/immediate reactions

A

Injury/immediate reactions: Following an injury, early changes occur in the vasculature (arterioles, capillaries, venules) in the vicinity of the damaged tissue. These changes are controlled by nervous stimulation, chemical mediators, and cytokines released by blood cells, tissue cells, and platelets in the injured area. Some mediators are vasoactive—that is, they affect the endothelial cells and smooth muscle cells of blood vessels—and others are chemotactic factors, also called chemokines, that affect white blood cells.

34
Q

The stages of inflammation
- vascular reactions

A
  • vascular reactions: In quick succession, the blood vessels in the vicinity dilate (widen), then constrict, and then dilate again. The wide-narrow-wide sequence is thought to be for the purpose of flushing irritants (such as bacteria) away from the area, then the narrowing is an attempt to stem blood leaving the blood vessels, followed by a long-term dilation to bring helpful blood components to the site. The overall effect of vasodilation is to increase the flow of blood into the area, which facilitates the influx of immune components and also causes redness and warmth.
    Some substances cause the endothelial cells in the walls of postcapillary venules to contract and form gaps through which blood-borne components exude into the extracellular spaces. The fluid part that escapes is called the exudate.
35
Q

The stages of inflammation:
- edema and pus formation

A

Edema and pus formation: Accumulation of this fluid in the tissues gives rise to local swelling and hardness, called edema. The fluid contains varying amounts of plasma proteins, such as globulins, albumin, the clotting protein fibrinogen, blood cells, and cellular debris. Depending on its content, the fluid may be clear (called serous), or it may contain red blood cells or pus. Pus is composed mainly of white blood cells and the debris generated by phagocytosis. In some types of edema, the fibrinogen is converted to fibrin threads that enmesh the injury site. Within an hour, multitudes of neutrophils responding chemotactically to special signaling molecules converge on the injured site.

36
Q

The stages of inflammation:
- resolution/star formation

A
  • resolution/scar formation: Repair is the last step and results either in complete resolution to healthy tissue or in formation of scar tissue, depending on the tissue type and the extent of the damage. Note here that macrophages are
    pictured leaving the blood vessels in a process called diapedesis (dye′′-ah-puh-dee′-sis). Meanwhile, differentiated stem cells in the area begin to divide and repopulate the damaged site with new cells to replace those that were damage
37
Q

Diapedesis

A
  • the migration of WBCs out of blood vessels into tissues
  • WBCs are actively motile and readily change shape
  • endothelial cells lining venues contain complex adhesive receptors that capture WBCs and transport them into extracellular spaces
38
Q

Chemotaxis

A
  • migration of cells in response to a specific chemical stimulus
  • cells swarm from many compartments to the site of infection and remain there to perform general and specific immune functions
39
Q

Benefits of edema and leaky vessels

A
  • influx of fluid dilutes toxic substances
  • fibrin clot can trap microbes to prevent further spread
  • neutrophils aggregated at the inflamed site are involved in phagocytosing and destroying bacteria, dead tissues, and particulate matter
  • Pus
  • Pyogenic
40
Q

Benefits of edema and leaky vessels
Pus
Pyogenic

A

Pus: the accumulation of a white, gooey mass of cells, liquefied cellular debris, and bacteria
Pyogenic: bacteria such as streptococci, staphylococci, gonococci, meningococci that stimulate the formation of pus

41
Q

Fever

A

Abnormally elevated body temperature:
- nearly universal symptom of infection
- associated with certain allergies, cancers, and other organic illnesses
- if the cause is unknown, its called fever of unknown origin (FUO)
Body temperature is maintained around 37C (98.6F) by the hypothalamus:
- low-grade fever: 37.7 - 38.3C or 100-101F
- high-grade fever: 40-41.4C or 104-106F

42
Q

Pyrogens

A
  • substances that rest hypothalamic thermostat to a higher setting:
    - Exogenous pyrogens: products of infectious agents such as viruses, bacteria, protozoans, fungi, endotoxin, blood, blood products, vaccines, or injectable solutions coming from outside the body
    - endogenous pyrogens: liberated by monocytes, neutrophils, and macrophages during phagocytosis such as interleukin- 1 and tumor necrosis factor
43
Q

Benefits of fever

A

Inhibits multiplication of temperature-sensitive microorganisms such as the poliovirus, cold viruses, herpes zoster virus, and systemic and subcutaneous fungal pathogens

Interferes with the nutrition of bacteria by reducing the availability of iron

Increases metabolism and stimulates immune reactions and naturally protective physiological processes:
• Speeds up hematopoiesis, phagocytosis, and specific immune reactions

44
Q

Antimicrobial products: interferon

A

• Small proteins produced naturally by certain white blood and tissue cells
• Originally thought to be directed against viruses, but is involved in defenses against microbes and immune regulation and intercommunication
• Interferons alpha and beta: produced by lymphocytes, fibroblasts, and macrophages
• Interferon gamma: produced by T cells

45
Q

Antimicrobial products: interferon
- biological activities of interferon

A

• Bind to cell surfaces and induce changes in genetic expression; exact results vary
• All three IFNs can inhibit the expression of cancer genes and have tumor suppressor effects
• IFN alpha and beta stimulate phagocytes
• IFN gamma is the immune regulator of macrophages and T and B cells

46
Q

Characteristics of interferons

A
  • Binding of viruses and other microbes to receptors on a host cell, signals the cell to produce interferon
  • Interferon molecules are rapidly secreted into the extracellular space, binding to other host cells
  • Binding of interferon induces the production of proteins in the cell that inhibits viral multiplication:
    • Degrade viral RNA
    • Prevent translation of viral proteins
    Not microbe-specific
    Valuable treatment for a number of virus infections
47
Q

Antimicrobial products: complement

A
  • Named for its property of “complementing” immune reactions
  • Consists of over 30 blood proteins that work in concert to destroy bacteria and certain viruses, parasites, and nearby cells
    Cascade reaction:
    • Sequential physiological response
    • First substance in a chemical series activates the next substance, which activates the next, and so on
48
Q

The four stages of the complement cascade

A

Initiation: C3 protein, either free or bound to a pathogen membrane, is hydrolyzed into two fragments, C3b and C3a

Activation and cascade: further enzymatic action; C3b protein cleaves the protein C5 into C5a and C5b

Polymerization: C5b fragment is now free to form a complex with C6, C7, and C8 called the membrane attack complex (MAC)

Membrane attack: MAC is positioned on and forms pores in the offending cell’s membrane, causing it to lose structural integrity:
• Leads to inappropriate flow of water and ions in and out of the cell, and eventual of the lysis of the cell

49
Q

Pyrogens

A

Pyrogens are what triggers the body’s temperature system to respond to triggers

50
Q

Complement pathways

A
  • Classical complement pathway: initiated by binding to the antibodies that are already bound to microbes
  • Alternative complement pathway:
    • Does not require antibody to get started
    • Initiated by the presence of foreign cell antigens
    • Quicker response than the classical pathway
51
Q

The steps in alternative complement pathways at a single site

A

1) initiation: C3 hydrolysis
2) activation: C3b cleaves C5 into C5a and C5b
3) polymerization: C5b, C6, C7, C8, and multiple C9s together form the membrane attack complex
4) membrane attack: cells swells and bursts

52
Q

Antimicrobial products:
- antimicrobial peptides

A

Short proteins of 12 to 50 amino acids:
• Defensin and others
Able to insert themselves into bacterial membranes
Can create a pore in the membrane:
• If enough pores form, the cell lyses
Also have an effect on other actions of nonspecific and specific immunity

Researchers are looking for ways to turn these antimicrobial peptides into therapeutic drugs

Microbiology (23 decks)

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