Digestive System IV

Question 1

Characteristics of undifferentiated crypt cells (3)

Answer 1

• located in basal portion of gland
• give rise to other types of epithelial cells
• intestinal epithelium replaced every few days

Question 2

Characteristics of goblet cells (2)

Answer 2

• secrete protective mucin

- increase in numbers caudally in intestine

Question 3

Characteristic of enteroendocrine cells

Answer 3

important in hormonal regulation of GI function

Question 4

Characteristics of paneth cells (3)

Answer 4

• only found in base of gland
• have apical membrane bound granules
• probably control the microflora of the crypts

Question 5

Characteristics of globular leukocytes (3)

Answer 5

• have large eosinophilic globules
• small heterochromatic nucleus
• intraepithelial as well as in lamina propria

Question 6

Characteristics of M cells (3)

Answer 6

• located over lymphatic areas or nodules
• apical surfaces have blunt microvilli or ridges
• take up antigens by endocytosis

Question 7

Characteristic of intraepithelial lymphocytes

Answer 7

common throughout intestine

Question 8

Characteristics of enterocytes (intestinal absorptive cells) (3)

Answer 8

• numerous on surface of villi in small intestine, luminal surface in large intestine, and glands of both
• columnar w/ apical microvilli
• glycocalyx covering microvilli serve as anchorage site for digestive enzymes

Question 9

Functions of intestinal enterocytes (5)

Answer 9

• active uptake of small molecules
• resynthesis of triglycerides from fatty acids that diffused into the cell
• formation of glycoprotein droplets (chylomicrons)
• (neonates) takes IgG into absorptive cells in jejunum and ileum
• protease resistant IgAs from mucosal yphatic tissue are passed into lumen to fight foreign invaders

Question 10

Order of lipid absorption in enterocytes

Answer 10

1. lipids broken down in gut lumen
2. resulting glycerol, fatty acids, and monoglycerides diffuse across the plasmalemma of apical microvilli
3. resynthesis of triglycerides by SER
4. protein synthesis by RER
5. synthesis of glyco- and lipoproteins by golgi
6. assembly into chylomicrons
7. exocytosis of chylomicrons at basolateral cell membrane and diffusion into capillaries

Question 11

3 secretions of enterocytes

Answer 11

• enzymes secreted to glycocalyx
• active movement of ions at basal membrane
• chylomicrons released at lateral membrane by exocytosis

Question 12

What must be intact for peristalsis to occur?

Answer 12

intrinsic interneurons

Question 13

What does the submucosal plexus in the T. submucosa do?

Answer 13

• sensory to epithelium

- motor to muscularis mucosae and blood vessels

Question 14

What does the myenteric plexus in the T. submucosa do?

Answer 14

• coordinates peristalsis
• stretch receptors
• motor to T. muscularis and blood vessels

Question 15

What 3 things make up the intestinal mucosal barrier?

Answer 15

mucous
bicarbonate
apical junctions (seal lumen)

Question 16

Characteristics of large intestines (3)

Answer 16

• site of microbial action
• epithelium absorbs or secretes H2O and electrolytes, secretes mucus, absorbs products of fermentation in non-ruminant herbivores
• forms fecal mass

Question 17

Anorectal line

Answer 17

marks the separation between rectum and anal canal

epithelium changes from simple columnar to stratified squamous

Question 18

Anal canal

Answer 18

short terminal segment of digestive tract that is lined by stratified squamous epithelium

Question 19

Where does the anal canal terminate?

Answer 19

anus

Question 20

Anal columns

Answer 20

longitudinal folds which alternate with sinuses

continuous with rectal columns and sinuses in ruminants but not present in horse

Question 21

Anocutaneous line

Answer 21

point at which stratified squamous epithelium becomes keratinized
it is a mucocutaneous junction

Question 22

External anal sphincter is made of what kind of muscle?

Answer 22

skeletal muscle

Question 23

Internal anal sphincter is made of what kind of muscle?

Answer 23

thickening of the circular layer of the smooth muscle of the T. muscularis

Question 24

Anal sacs (or perianal sinuses)

Answer 24

located on either side of the anal canal between the external and internal anal sphincters
ducts from the anal sacs open into the anal canal at the anocutaneous line

Question 25

Anal glands

Answer 25

modified tubular sudoriferous glands (apocrine sweat) associated w/ anal canal
open directly into the anal canal
secretes lipid in carnivores, mucus in pig
gland morphology is coiled tubular

Question 26

Perisaccular glands (glands associated w/ anal sac)

Answer 26

secrete into neck of anal sac or directly into its duct

gland morphology is coiled tubular

Question 27

Glands of the perianal zone

Answer 27

located in cutaneous area around anus

third most common site of tumors in dogs

Question 28

Name the 2 glands of the perianal zone

Answer 28

tubular sudoriferous glands (coiled tubular)

circumanal glands

Question 29

Name the 2 types of circumanal glands

Answer 29

superficial - large sebaceous glands usually associated w/ hairs
deep - hepatoid cell masses located deep to sebaceous glands

Question 30

Characteristics of the gall bladder (5)

Answer 30

• stores and concentrates bile, resorbs Na+ and water
• no muscularis mucosae
• may contain mucous and/or serous glands
• tunica muscularis disorganized
• may contain goblet cells

Question 31

Characteristics of extrahepatic bile ducts

Answer 31

• connect liver lobes w/ gall bladder and duodenum
• structure similar to gall bladder
• T. muscularis may be discontinuous