Intestine 2 (test 1)

Question 1

Where does enterocyte proliferation occur?

Answer 1

In the Crypts

Question 2

What are 2 compensatory reaction to enterocyte loss?

Answer 2

1. Flattening of remaining enterocytes
2. Increased Mitotic rate of crypt epithelial cells

Question 3

The mucosal phase of digestion is mediated by WHAT?

Answer 3

ENTEROCYTES

Question 4

The delivery phase of digestion involves what?

Answer 4

Lymphatics and Blood

Question 5

The mucosal phase of digestion involves what?

Answer 5

Surface (microvilli) and Cellular (enterocytes)

Question 6

The intraluminal phase of digestion involves what?

Answer 6

Pancreatic and Biliary: break down food

Question 7

What are some causes of secretory diarrhea?

Answer 7

Bacterial Exotoxins, Inflammatory Mediators (prostaglandins, eiconsinoids, histamine, kinins, cytokines–>influence enteric nerve reflexes)

Question 8

How does bacterial exotoxins cause secretory diarrhea?

Answer 8

They affect secretion/ absorption (active cAMP and gAMP) of Na+, Cl- and therefore water

Question 9

What is the most common cause of diarrhea in neonatal calves?

Answer 9

ETEC!

Question 10

T or F

ETEC destroys enterocytes while it causes disease

Answer 10

FALSE, ETEC uses pili (fimbrae) to attach to the enterocytes (apical) and secrete exotoxins that cause secretory diarrhea

Question 11

Why does ETEC only infect neonates in the first week of their lives?

Answer 11

Because ETEC needs the receptors involved in colostrum absorption (FcRN) in order to attach to the enterocytes and these receptors go away quickly after the neonate is born.

Question 12

Why do animals die from ETEC infection?

Answer 12

Because of the HYPERsecretory diarrhea which results in DEHYDRATION, electorlyte imbalances, and acidosis.

Question 13

Where does ETEC attach or infect?

Answer 13

ON the apical portion of the microvilli at the FcRN receptors (think passive transfer receptors)

Question 14

What are two effects of enterotoxins from ETEC?

Answer 14

1. inhibits coupled Na-CL uptake and water absorption in the villi-cGMP pathway
2. Stimulates secretion of Cl- in crypts-cAMP pathway

Question 15

Where does rotavirus and coronavirus set up shop?

Answer 15

they infect, proliferate in, and DESTROY Mature Villous enterocytes

Leads to villous atrophy–>malabsorptive (osmotic) diarrhea

Enterocyte damage–>exudative diarrhea

Question 16

How does Rota and Corona viruss cause diarrhea? What type of diarrhea is it?

Answer 16

Villi become denuded, contracted, and may fuse (villous atrophy)–>malabsorption (osmotic diarrhea)

Enterocyte Damage–>exudative diarrhea

Question 17

How do villi compensate for enterocyte damage from rota and corona viruses?

Answer 17

Crypt (immature) enterocytes proliferate in response–>villi will be normal again in ~7 days

Question 18

When would you see Rotavirus in calves?

Answer 18

Between 0-2 weeks of age

Question 19

When would see coronavirus in calves?

Answer 19

Between 0-3 weeks

Question 20

T or F

Coronavirus and Rotavirus desrupt the crypts in the small intestine

Answer 20

FALSE, They attack mature enterocytes on the apical portion of the villi, thus the crypt cells remain intact

Question 21

What cells does rotavirus and coronavirus attack and where?

Answer 21

They attack MATURE enterocytes in the Small intestine leading to osmotic (loss of absorptive surface area) and exudative diarrhea (mucosal damage)

Question 22

What is specific to rotavirus that corona virus does not do?

Answer 22

Rotavirus additionally impairs disaccharidases in the brush border–>leading to maldigestion of carbohydrates

Question 23

T or F

Cats can be infected with parvovirus

Answer 23

TRUE, but it is called panleukopenia, cat distemper, or feline enteritis.

Question 24

What are clinical signs of parvo infection?

Answer 24

Diarrhea-Bloody, Fetid (FOUL smelling)

Vomiting

Fever

Depression

Dehydration

Question 25

Define fetid

Answer 25

Something smelling extremely unpleasant

Question 26

What cells does parvovirus infect?

Answer 26

Rapidly DIVIDING cells

Intestinal crypts–>diarrhea

Bone Marrow–>panleukopenia

Lymphoid follicles–>lymphopenia

Question 27

Where does parvovirus first repicate?

Answer 27

In the lymphoid tissue of the oropharynx–>viremia–>dissemination to rapidly dividing cells of GI tract, bone marrow

Question 28

Parvo infection leads to loss of enterocytes. What three events occur because of this damage?

Answer 28

1. loss of absorptive surface area–>malabsorption–> osmotic diarrhea
2. loss of fluid, electrolytes, plasma proteins into the lumen–> exudative diarrhea
3. loss of mucosal barrier (ulceration)–>secondary bacteremia, endotoxemia

Question 29

Parvo infections in young animals can lead to additional lesions, what are they?

Answer 29

Puppies infected at <2week old: Myocarditis (+/- lesions in the liver, kidney, lung, blood vessels

Kittens infected in Utero: congenital cerebellar hypoplasia

Question 30

T or F

With parvo infection you will see defined crypts

Answer 30

False, parvo attacks the rapidly dividing cells found in the crypts leading to diffuse villous atrophy and crypt dropout

Question 31

What will you see grossly with parvo infection?

Answer 31

The small intestine will be segmentally dark red

Question 32

what will you see microscopically with parvo infection?

Answer 32

Severe villous atrophy

crypt dropout

Question 33

Coccidiosis is an intracellular or extracellular parasite?

Answer 33

Intracellular

Question 34

What type of enterocolitis do you see in calves, kittens, puppies, lambs, kids, piglets and poultry with coccidiosis?

Answer 34

Calves, Kittens, puppies–>hemorrhagic enterocolitis

Lambs, kids–>proliferative enterocolitis

Piglets–>fibronecrotic enterocolitis

Poultry–>hemorrhagic/fibrinonerotic enterocolitis

RARE in horses

Question 35

What 3 things help determine the severity of coccidiosis disease?

Answer 35

1. Infective dose
2. Host immune status
3. site of development (species virulence)
   - villi vs. crypts

Lyse enteroctyes