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22 Cards in this Set

  • Front
  • Back
what are the two structures of the digestive system?
-The gastrointestinal tract (GI tract)
The pathway from the mouth to the anus

-Accessory digestive organs
Organs involved in grinding food or providing digestive secretions
-Salivary glands
what is the function of the GI tract?
-digest food
-absorb nutrients and water into the blood
-and eliminate waste
what are Components of the gastrointestinal tract?
-Mouth-site where food is moistened and chewed

-Esophagus-tube leading to the stomach

-Stomach-secretes HCI, enzyme: pepsin

-Small intestine-digestion and absorption of nutrients

-Large intestine (colon) – completes absorption of nutrients: water, steroids, and minerals

-Rectum and anus eliminate waste
describe the normal biota of the digestive system? where is it?
-Tongue, teeth, small intestine, colon, rectum
-Heavily colonized with various bacteria
-Oral cavity contains up to 700 different bacterial species
-Esophagus, stomach, duodenum
-“Almost sterile” –how can that be?
-HCI in stomach; peristalsis and the rapid transport of food helps prevent colonization by microbes
what is tooth decay? and its dangers?
Dental Caries (tooth Decay)
-Accumulation of microbes on the surface of the teeth is called dental plaque – biofilm
-The plaque is made up of streptococci (Streptococcus mutans) and filamentous bacteria Actinomyces
-Bacteria hydrolyze the sucrose into glucose and fructose
-Then glucose is used to synthesize dextran (gummy polysaccharide)
-Inside the plaque, bacteria ferment the fructose into lactic acid. Lactic acid damages the enamel of the tooth

-Bacteria invade the dentin
-Bacterial population inside the dentin is composed of Gr+ bacilli and filamentous bacteria (about 300 bacterial species are indentified)
-If not treated, the tooth decay advances to pulp and roots (contain blood vessels and nerves)
-The infection can spread to the neighboring soft tissue
-Prevention of dental caries – reducing the amount of sucrose in the diet and, proper brushing and flossing
What is periodontal disease?
-Initial Stage – gingivitis
-Symptoms: swelling, bleeding of gingival, formation of pockets
-Advanced stage – periodontitis
-Symptoms: tissue destruction, formation of deep pockets, build up of calculus (deposits of CaCO3) loosening of teeth, bone loss
Describe mumps.

- treatment
-Mumps virus – paramyxovirus
-Disease of parotid (salivary) gland (located below the ears)
-The virus is acquired by respiratory rout
-Symptoms: swelling of parotid gland fever, pains during swelling
-Complications: inflammation of testis (possibly sterility), meningitis, inflammation of ovaries
-Available vaccine (MMR)
what is the virulence factors of mumps.
Virulence factors:
-The virus induces the infected cell to fuse with the adjacent cell – a large multinucleate cell is formed (syncytia)
-The virus particles freely pass from one cell to another – evading the antibodies
Describe Gastric ulcer

-Lesions in the mucus membrane of the stomach
-Caused by Helicobacter pylori
-The bacterium can survive in the acidic environment in the stomach by producing urease that neutralizes the acid
-H. polyri causes destruction of the protective mucus layer that leads to the period to the wall
-Symptoms : Abdominal burning pain
How do is Helicobacter diagnosed?
Visually by endoscopy – a flexible tube is inserted through the mouth into the stomach
-ELISA test – blood is tested for the presence of antibodies against Helicobacter
describe Salmonellosis

- cause
- incubation period
- source of infection
-Caused by Salmonella –Gr-, facultative anaerobic rods, there are about 2000 serotyps
-Bacteria invade the intestinal mucous membrane. From there they can enter the lymphatic system.
-Incubation time is 12-36h but it depends on the number of cells ingested.
-Recovery – after few days, typically self-limited infection
-Antibiotics not effective
-Source of infection: poultry, eggs, egg products
describe . Typhoid fever

- cause
-incubation period
Typhoid fever

-Caused by Salmonella typhi
-Bacteria multiply in phagocytic cells. They can be found in blood, urine feces.
-Incubation period is up to 3 weeks.
-Symptoms: Headache, high fever, and diarrhea (after 2nd week)
-Susceptibility: Travel in areas with poor sanitation
-Patients can become chronic carriers of the diseases. They shed bacteria from their gall bladder.
-Treatment: Antimicrobial drugs
Describe Shigellosis (Bacillary Dysentry)

Shigellosis (Bacillary Dysentry)

-Caused by Shigella – facultative anaerobic Gr negative rods
-Bacteria multiply int eh small intestine in the cells of mucous membrane
-Produce the shiga toxin
-Symptoms: severe diarrhea with blood in stool, abdominal cramps and fever.
-Treatment: Fluid and electrotype replacement and antimicrobial treatment
describe Cholera

- cause
- mortality rate
-Causative agent: Vibrio cholera, slightly curved rod with a single polar flagellum
-The bacterium grows on the epithelial cells in the small intestine (does not enter the host cell)
-Produces entertoxin. The enterotoxin causes excessive secretion of water and electrolytes.
-Symptoms: severe diarrhea with sudden loss of fluids, which results in shock, collapse, and even death.
-The blood becomes very vicious.
-Treatment: replacing lost fluid and electrolytes, tetracycline
-Mortality rate:
-Untreated; 50%
-Treated: 1%
describe Cryptosporidiosis

source of infection
-Cryptosporidium hominis (infects humans)
-Contracted by ingestion of the oocysts; drinking or recreational water
-Water contamination – animal waste
-Oocysts develop into sporozoits- embed in the epithelial cells of the intestine
-Symptoms: diarrhea
-Treatment: usually not required in the case of healthy individuals; antidiarrheal agent
Describe Staphylococcal food poisoning

- source of disease
-Caused by Staphylococcus aureus – lives in nasal cavity
-Food provides favorable environment (if left in room temperature) for multiplication of bacteria
-S. aureus can outgrow other competing bacteria (tolerates higher osmotic pressure, higher temperatures, low moisture level).

-Foods such as custards, sauces, processed meats – contaminated and left unrefrigerated
-Toxins are released. Taste and smell of the food is not altered
-Further cooking can eliminate bacteria by not the toxin
-The toxin damages the tissues
-Symptoms of intoxication: abdominal cramps, vomiting, and diarrhea
-The disease is self-limiting, recovery within 24h
describe Amoebic dysentery

- symptoms
_-Causative agent: Entamoeba histolytica
-Contracted by ingestion of cysts in contaminated water
-Trophozoits released from the cysts – multiply in the epithelial cells of large intestine- causing ulcers
-Severe dysentery (blood in stool)
-Can spread to other organs (liver)
-Diagnosis: serological tests, fluorescent antibody tests
-Treatment: metronidazoie
what is hepatitis?
-Hepatitis is an inflammation of the liver caused by an infection with viruses
what viruses cause hepatitis?
There are five known viruses that can cause hepatitis: Hepatitis A, B, C, D, E)
What are symptoms of hepatitis?
-Symptoms include jaundice, abdominal pain, fatigue, nausea, vomiting, appetite loss

Jaundice – yellowing of skin and the whites of eyes
Describe hepatitis A. ( what i had..)

-Causative agent: Single stranded RNA virus, no envelope
-Infection is acquired via oral rout (fecal contamination of food, water, and oysters)
-In 50% of cases symptoms are subclinical
-Symptoms: anorexia, nausea, fever, abdominal discomfort, fever, and chills, and jaundice
-Vaccine is available
Describe hepatitis B.

-Causative agent: Hepatitis B virus (HBV) , double stranded DNA virus with the envelope.
-Transmission: break in the skin- body fluids (blood, saliva, breast milk, and semen)
-Multiples exclusively in the liver
-Symptoms; loss of appetite, fever, joint pains, and jaundice
-10% of patients become carriers (reservoirs of the disease). They are more likely to get liver cancer.
-Vaccination recommended for health care professionals and other high-risk groups.
-Vaccine is obtained by genetic engineering.