Chapter 3 Flashcards Preview

Surgery > Chapter 3 > Flashcards

Flashcards in Chapter 3 Deck (38):
1

What are natural immune barriers in the body?

Skin
Resp epithelium
GI and GU adaptations

2

How does the skin protect with immunity?

First line of defense
Mechanical barrier that provides an unfavorable environment for microbial growth with its acidic pH (5-6) and relative lack of water

3

How does the respiratory tract protect against infection?

Mucous blanket contains IgA, which captures inhaled particles and steadily rolled toward the mouth by motion of the cilia
Particles are expelled by coughing
Additional protection is offered by the secretory immunoglobulin A (S-IgA)

4

How do GI adaptations protect against infection?

Acidic pH prevents growth of most bacteria in the stomach, keeping it essentially sterile
Peristalsis and a nl motility pattern keep the bacterial population of the small bowel constant

5

How do GU adaptations protect against infection?

Urinary tract is normally sterile except at the urethral orifice
Urine also contains IgA, which prevents bacterial adherence to the urothelium

6

How do normal microflora of the GI tract contribute to host defense?

Occupy potential epithelial binding sites, which limits pathologic microbial penetration. This is known as colonization resistance or tropism

7

What are the leukocytes responsible for phagocytosis?

Macrophages
Monocytes
Granulocytes

8

Where are macrophages heavily concentrated?

Lungs
Liver
Spleen

9

What is chemotaxis?

In this case, where circulating phagocytes migrate to areas of inflammation by following a gradient of chemoattractant molecules

10

Opsonization

A process by which opsonins (immunoglobulins and complement) bound to the surface of microbes interact with receptors on the phagocyte and promote ingestion

11

What is the major histocompatibility complex?

The MHC helps macrophages and antigen-presenting cells

12

What are the MHC subdivided into?

Class I
Class II

13

What does the antigen-MHC class II complex do?

It binds to T lymphocytes that express the CD4 molecule and are known as helper T cells

14

What do helper T cells do?

Interact with antigen-presenting macrophages and proliferate into a subpopulation of T-cell clones that recognize the specific antigen(s) and amplify the immune response

15

Effector cells

Consist of monocytes, macrophages, granulocytes and cytotoxic T cells that express the CD8 molecule

16

What is the humoral response dependent upon?

Immunoglobulins and complement

17

What do immunoglobulins do?

Protect the host from infection by
(a) neutralizing viruses and bacterial toxins
(b) inhibiting microbial attachment to host cells
(c) opsonizing pathogens for elimination by phagocytes
(d) activating the complement cascade

18

What is the first immunoglobulin produced in the initial response to antigen and is a potent activator of the complement?

IgM

19

What is transported across the placenta from the mother to the fetus and protects the newborn until the 4th mo of life?

IgG

20

What is the MC immunoglobulin deficiency?

IgA

21

What does S-IgA do?

Acts as first line of defense against pathogens by preventing bacterial adherence to the mucosal epithelium of the respiratory, GI, and GU tracts

22

What is the complement system?

A nonspecific defense system that allows for an immediate response to invading organisms

23

Who should be screened for complement deficiencies?

Pts with recurrent infections

24

Definition of viruses

Obligate intracellular pathogens composed of a central core of genetic material (DNA or RNA) surrounded by a protein coat (the capsid), which protects the nucleic acid and serves as a vehicle of transmission from one cell to another

25

How do viruses cause dz?

Cell lysis or by interfering with nl cell machinery to cause cellular dysfunction

26

Why can bacterial superinfection occur with viruses?

Impaired phagocytic capacity of virally infected macrophages or polymorphonuclear leukocytes (PMNs) rendering the host more vulnerable to bacterial infection

27

When can viruses be implicated in surgical diseases

Appendicitis (enterovirus)
Ulcerative colitis (CMV)
Intussusception (adenovirus)

28

What are the three general shapes of bacteria?

Spheres
Rods
Spirals

29

What is an example of a bacterial species that invades tissue?

S. pneumoniae

30

What are the two subdivisions of bacteria that produce toxins

Exotoxins and endotoxins

31

What do protein exotoxins cause?

Hemolysis of RBCs
WBC death
Necrosis of tissues
Degradation of intercellular substances
Clotting of plasma

32

What are some surgical diseases resulting from bacterial exotoxins?

Necrotizing fasciitis caused by C. perfringens, S. pyogenes, and S. aureus
Toxic megacolon caused by C. diff

33

What are endotoxins?

Macromolecular complexes of phospholipids, polysaccharide and protein, which form the outer layer of the cell wall of gram-neg bacteria

34

Molds

Multicellular fungi that form long filaments called hyphae and reproduce by forming spores

35

Yeasts

Unicellular fungi that reproduce by budding

36

What are the three main mechanisms by which fungi can gain access to human tissues and cause dz?

Inhalation
Inoculation of the subcutaneous tissues
Colonization of mucosal surfaces

37

What are other RFs for fungal infection besides being immunocompormised?

Prolonged hospitalization
IV cannulae
Prolonged or broad-spectrum antibiotic administration
Hyperalimentation
Immunosuppressive drugs
Burns
Trauma
Malnutrition

38

How to determine proper selection of antimicrobial therapy?

Know
(a) the MC pathogens causing the specific infection
(b) the MOA of the selected agent
(c) the mechanisms of resistance to the selected agent
(d) potential SEs
(e) sensitivity patterns of the most common microbes in the environment