Microbial disease Flashcards
Where is the mucus layer thinner: the colon or the jejunum?
Jejunum
Dendritic cells play a central role in adaptive immunity? Why then do some types of microbes seek them out?
Some microbes can “hijack” dendritic cells for transport throughout the body using them as Trojan horses. This process is called leukocyte trafficking.
(Dendritic cells are found mixed with epithelial cells in mucosa, skin, and many organs. They are phagocytic, often migratory, antigen-processing and antigen-presenting cells that play a central role in adaptive immunity. Because they’re phagocytic and migratory they are frequently used as “Trojan horses”).
What is septic shock?
The systemic interaction of microorganisms and their products (toxins) with a spectrum of host cells and chemical mediators results in a clinical syndrome recognized as sepsis or septic shock. The host mediators and amplification systems initiating the syndrome vary with the type of organism and the nature of the infectious process (local or systemic). Regardless of the specific cause, the major elements of septic shock form a continuum, including (1) hemodynamic derangements (reduced blood pressure and increased heart rate), (2) abnormal body temperature, (3) progressive hypoperfusion of the microvasculature, (4) hypoxic injury to susceptible cells, (5) quantitative adjustments in blood leukocytes and platelets, (6) DIC, (7) multiple organ failure, and (8) death.
Animals dying of septic shock typically have evidence of fluid in the body cavities, pulmonary edema, petechial hemorrhages, congestion of the liver and intestines, and dehydration. Common microscopic lesions include acute necrosis of renal tubules, centrilobular hepatocytes, cardiac myocytes, adrenals, and tips of intestinal villi.
When a microbe accesses an animal’s body via the alimentary system there are three particular epithelial sites where the microbe can “cross” and gain access to deeper tissues. What are these three epithelial sites?
Tonsillar epithelium
Villus epithelium
M cells in Peyer’s patches
Fill in the blank: New and/or altered __________ allow microbes to more efficiently or rapidly establish infection, evade host defenses and develop resistance to treatments (e.g., antibiotic resistance).
Virulence factors
The skin is an important biologic as well as physical barrier. Which of the following is NOT a feature of skin that protects against microbial invasion?
(a) Continual shedding of surface squames
(b) Its acidity
(c) Its dryness
(d) Its thickness
(e) Its normal population of commensal microbes
(f) Secretion of sebum
(g) The presence of sweat glands
(g) The presence of sweat glands
What does viremia mean?
The condition of having viruses circulating in the bloodstream.
What is an exotoxin?
A toxin secreted by live (usually Gram-positive) bacteria
Where in the body, in general terms, are dendritic cells located?
They are found mixed with epithelial cells in mucosa, skin, and many organs. They are phagocytic, often migratory, antigen-processing and antigen-presenting cells that play a central role in adaptive immunity. However, because they’re phagocytic and migratory they are frequently used as “Trojan horses” to allow infection of lymphoid tissues (leukocyte trafficking).
The larger an inhaled particle, the further into the conducting airways it will pass before finally contacting a mucosal surface and being trapped in mucus. True or false?
False. Larger inhaled particles are generally trapped by mucus covering the nasal turbinates. It’s the smaller particles that may travel further down the conducting airways before being trapped.
From the list below choose particles that are small enough that, if inhaled, they may reach the exchange parts of the respiratory system (e.g., alveoli) and NOT be trapped in the conducting airways. Choose any that apply.
(a) 100 µm diameter
(b) 20 µm diameter
(c) 5 µm diameter
(d) 1 µm diameter
(e) 0.1 µm diameter
(d) 1 µm diameter
(e) 0.1 µm diameter
Where is the mucus layer thicker: the colon or the jejunum?
Colon
What are M cells, where are they found, and what is their purpose?
M(icrofold) cells are modified crypt epithelial cells found within the small intestine overlying GALT (e.g., Peyer’s patches). They act as the interface between materials in the intestinal lumen and the lymphoid nodules of GALT. They transfer antigens from the intestinal lumen across the mucosa to dendritic and immune cells (macrophages and lymphocytes) in GALT. To achieve this they are not covered by mucus, unlike the majority of intestinal epithelial cells. This makes them efficient at antigen transfer, but also makes them “easy targets” for microbial entry.
Which three body systems are the most common portals of entry by microbes gain entry to an animal’s body?
Alimentary / Digestive
Respiratory
Urogenital
A phagocytic, often migratory, antigen-processing and antigen-presenting cell is termed a __________ .
Dendritic cell
Where in the body, in general terms, are dendritic cells located?
They are found mixed with epithelial cells in mucosa, skin, and many organs. They are phagocytic, often migratory, antigen-processing and antigen-presenting cells that play a central role in adaptive immunity. However, because they’re phagocytic and migratory they are frequently used as “Trojan horses” to allow infection of lymphoid tissues (leukocyte trafficking).
