Midterm Exam Week 1 Flashcards
(91 cards)
Why do warm-blooded, long-lived mammals have complex immune defenses?
Infectious agents such as bacteria thrive and can divide rapidly in warm-blooded creatures.
What is the role of commensal microflora in host defense mechanisms?
Microflora provide molecular signals for immune system development in each person.
Lactobacillus acidophilus
Major component of vaginal microflora
Metabolism of glycogen by L. acidophilus creates a vaginal pH of 5, resulting in the prevention of yeast colonization (which can often cause vaginitis- an inflammation of the vagina that can result in discharge, itching, and pain)
Vaginitis
inflammation of the vagina that can result in discharge, itching, and pain
Eye is protected against infections by which of the following?
a. the mucous membranes that cover their surface
b. the secretion of complement proteins
c. the release of slightly acidic secretions
d. the secretion of lysozyme onto their surface
e. interferons produced by immune cells
lysozyme (innate immunity)
Which statement about the complement system is true?
a. These proteins are involved in innate immunity and not acquired immunity.
b. These proteins are secreted by cytotoxic T cells and other CD8 cells.
c. This group of proteins includes interferons and interleukins.
d. These proteins are one group of antimicrobial proteins acting together in cascade fashion.
e. These proteins act individually to attack and lyse microbes.
antimicrobial cascade
Different initations:
1. Alternative- innate
2. Classical- adaptive
3. Leptin- innate (same as classical but no Ab)
Same efffects: C3a/C5a- inflammation
1. opsonization (C3b) and phagocytosis
2. leukocyte recruitment- neutrophils, monocytes (C3a, C5a)
3. MAC (polymeric protein complex)- microbe lysis
Which cells and which signaling molecules are responsible for initiating an inflammatory response?
a. phagocytes: lysozymes
b. phagocytes: chemokines
c. dendritic cells: interferons
d. mast cells: histamines
e. lymphocytes: interferons
mast cells: histamines
Mast cells are in most tissues, particularly in close contact with the external environment (skin, airways, and intestine) for early pathogen recognition
Within seconds of stimulation, mast cells can undergo degranulation, rapidly releasing pre‐formed mediators from cytoplasmic granules, including histamine
Inflammatory responses may include which of the following?
a. clotting proteins migrating away from the site of infection
b. increased activity of phagocytes in an inflamed area
c. reduced permeability of blood vessels to conserve plasma
d. release of substances to decrease the blood supply to an inflamed area
e. inhibiting the release of white blood cells from bone marrow
Inflammation includes
- inc phagocyte activity (neutrophils, monocytes)
- inc vessel permeability (leukocyte diapedesis/migration to tissue)
- inc blood supply to inc imm response
Which of the following is most likely to be recognized by a particular TLR that defends against some viruses?
a. lipopolysaccharides
b. double‐stranded DNA
c. double‐stranded RNA
d. glycoproteins
e. phospholipids
TLRs are key feature of innate immunity: pattern recognition receptors (PRRs) for PAMPs
Recognized PAMPs include
-LTA (gram pos bacteria)
-LPS (gram neg bacteria)
-flagellin (bacteria)
-ssRNA and dsRNA (viruses)
PAMP recognition activates signaling pathways and induces production of cytokines and chemokines
Histamines trigger dilation of nearby blood vessels, and increase in their permeability. Which of the signs of inflammation are therefore associated with histamine release?
a. redness and heat only
b. swelling only
c. pain
d. redness, heat, and swelling
e. all of the signs of inflammation
4 Cardinal Signs of Inflammation: 1. Calor (heat) 2. Dolor (pain) 3. Rubor (redness) 4. Tumor (swelling) Histamines trigger THREE Dilation-> more warm blood-> heat/redness More permeability-> more fluid leakage-> swelling
One reason that pathogenic microorganisms have an advantage in the host they infect is because they:
a. have previously been encountered through natural exposure
b. have previously been encountered through vaccination
c. strengthen the host’s immune response
d. reproduce and evolve more rapidly than the host can eliminate them
e. reproduce and evolve more slowly than the host can eliminate them.
Pathogenic microorganisms reproduce and evolve more rapidly than the host can eliminate them
Which of the following is not a characteristic of inflammation?
a. inactivation of macrophages
b. increased vascular permeability and edema
c. vasodilation
d. pain
e. influx of leukocytes.
4 Cardinal Signs of Inflammation
1. Calor (heat)
2. Dolor (pain)
3. Rubor (redness)
4. Tumor (swelling)
Inflammation-> neutrophils die-> release contents and form NETs
Inflammation is associated w/leukocyte recruitment (IL8), vasodilation, vessel permeability
Macrophages produce cytokines that initiate/regulate inflammation
Which of the following pairs is mismatched?
a. lymphocytes: innate immune response
b. natural killer cell: kills virus‐infected cells
c. macrophage: phagocytosis and killing of microorganisms
d. erythrocyte: oxygen transport
e. eosinophil: defense against parasites.
Lymphocytes are part of adaptive immunity (B and T cells), although NK cells are innate.
NK cells kill virus-infected cells and phagocytosed microbes.
Macrophages phagocytose and kill microorganisms when classically activated (innate immunity). Alternative activation allows macrophages to control inflammation and repair tissues/inc fibrosis (adaptive immunity).
RBCs are the only cells without MHC I; however, NK cells do not kill them because NK cells are in tissues, NOT circulation.
Eosinophils are associated w/IL5 and help defend against extracellular parasites (helminths)
Examples of granulocytes include all of the following except:
a. neutrophil
b. monocyte
c. basophil
d. eosinophil.
e. All of the above are examples of granulocytes.
FOR MY MEMORY: MEB'N Mast cells Eosinophils Basophils Neutrophils
Monocytes/macrophages are not granulocytes.
The most abundant type of leukocyte in human peripheral blood is:
a. eosinophil
b. basophil
c. neutrophil
d. monocyte
e. lymphocyte.
Neutrophils, fundamental to INNATE immunity
Low levels inc risk of bact/fung infection
-neutropenia
-chronic granulomatous disease (NADPH oxidase defect-> ineffective phagolysosome)
-leukocyte adhesion deficiency syndrome (LFA-1 defect, impaired stabilization of T cells binding to ICAM-1 on APCs, umbilical cord sep. delay)
Koch’s Postulates
- Infected tissue shows presence of microorganisms not in healthy tissue
- Microorganism isolated, grown in pure culture
- Injected in healthy tissue/animal, causes disease
- Microorganism isolated, shown to be identical to 1
Gram-positive bacterial wall structure
Stains purple
thick peptidoglycan layer
Lipoteichoic acid (recognized by TLR2:6)
TLR1,2,6 recognizes LPS for G+
Gram-negative bacterial wall structure
Stains pink
thin peptidoglycan layer
LPS (recognized by TLR4:4)
Host defense mechanism for extracellular pathogens
NK cells, T cells- perforin
Complement- MAC
Neutrophils, Macrophages- phagocytosis
Granulocytes- degranulation
Host defense mechanism for intracellular pathogens
only eliminated by cellular immune response, NO ABS
tissue damage caused by inflammation (ex- tuberculosis)
Germ-free animals
C-section
don’t have any commensal microflora
Intracellular Bacteria
shielded from Abs
disease mechanism due to host immune response
Ex: Mycobacterium tuberculosis, Legionella pneumophila
Extracellular Bacteria
Replicate outside host cells (circulation, conn tissue, airways, GI tract)
Induce inflammation (resulting in tissue destruction) and produce toxins (endotoxin from cell wall, secreted exotoxins)
Ex: staphylococcus aureus, Clostridium tetani, Neisseria meningitidis, Escherichia coli
Immune System Components
Fixed Elements (lymphoid organs)
Primary: bone marrow, thymus
Secondary: spleen/lymph nodes, mucosal immune tissues
Mobile Elements
Immune cells
Soluble/humoral components: antibodies, complement, acute phase proteins, etc.
