Histology of gastrointestinal system

Question 1

Layers of the mucosa

Answer 1

Epithelium- mucus secreting

Question 2

Layers of the mucosa

Answer 2

Lamina Propria-MALTS for immune survailence ( lymphocytes, plasma cells)

Question 3

Layers of the mucosa

Answer 3

Muscularis mucosae-Causes movement of mucosa. Innervated by parasympathetic

Question 4

Submucosa

Answer 4

Very vascular

Question 5

Tunica muscularis

Answer 5

Smooth muscle. Inner=circular m. outer=longitudinal m. Between layers is a parasympathetic myenteric plexus

Question 6

Tunica externa

Answer 6

known as tunica adventitia

Question 7

mucosa structure

Answer 7

stratified squamous in oral cavity, pharynx, esophagus, anal canal. Stomach has secretory glands. small intestine has villi and large intestine has mucus glands

Question 8

Muscularis mucosae

Answer 8

extend into lamina propria and villi

Question 9

Tunica muscularis function

Answer 9

peristalsis which is inherent but regulated by ANS, hormones, environmental influences.

Question 10

Esophagus

Answer 10

upper 1/3 & lower 1/3 have seromucous glands. Upper 1/3 of tunica muscularis contains skeletal muscle, middle 1/3 is mixed, lower 1/3 is smooth muscle.

Question 11

Esophageal sphincter

Answer 11

Physiologic and involved contraction of diaphragm, Aboral peristalsis, Intra abdominal pressure

Question 12

Stomach

Answer 12

Mechanical and chemical functions

Question 13

muscle layers in the stomach

Answer 13

innermost is oblique, inner (middle) circular, outer is longitudinal

Question 14

Gastric glands

Answer 14

1-7 glands that empty into lumen at a single gastric pit. Glands are straight tubular with base, neck , isthmus opening into it

Question 15

Parietal cells

Answer 15

Large, round , eosinophilic cytoplasm. tubulovesicular system, Short microvilli, Carbonic acid is produced in cells which dissociates into hydrogen and bicarbonate ions. Vesicles of tubulovesicular system may bud off into canaliculi so that HCL is produced in lumen of canaliculi

Question 16

Chief cells

Answer 16

basophilic cytoplasm, secrete pepsinogen

Question 17

pepsinogen

Answer 17

stored in zymogen granules and cleaves to become pepsin in low ph

Question 18

Stem cells

Answer 18

replace all kinds of gastric cells by migrating up and down gland

Question 19

Neuroendocrine cells

Answer 19

secrete hormones, serotonin

Question 20

Pyloric region of stomach

Answer 20

mucus secreting pyloric glands to protect duodenum from low ph. Circular layer of tunica muscularis is thick which forms the pyloric sphincter

Question 21

Pyloric region of stomach

Answer 21

also has neuroendocrine cells called G-cells which secrete gastrin into the blood stream

Question 22

gastrin

Answer 22

increases secretion from parietal and chief cells and enhances gastric motility

Question 23

duodenum

Answer 23

villi becomes shorter progressing towards ileum. Brunners glands are specific to duodenum

Question 24

Brunners glands

Answer 24

contain columnar mucus- secreting cells. Secrete lysozyme, May excrete IgA from plasma cells in lamina propria

Question 25

Histopathalogy note

Answer 25

Alcian blue stains acidic mucin but does not stain alkaline mucin.

Question 26

Small intestinal villi

Answer 26

simple columnar epithelium ( enterocytes). These have up to 3000 microvilli per cell

Question 27

goblet cells in small int. villi

Answer 27

mucus secreting

Question 28

paneth cells of small int. villi

Answer 28

At base of crypts with eosinophyilic granules

Question 29

what do secreted materials do?

Answer 29

kill off pathogens which have survived the acidic environment

Question 30

other cells in small intestine

Answer 30

neuroendocrine cells, stem cells, intraepithelial lymphocytes

Question 31

Lacteal

Answer 31

lymphatic vessels of lamina propria

Question 32

brush border of microvilli

Answer 32

stains PAS-Positive due to glycocalyx

Question 33

Duodenum secretions

Answer 33

enterokinase, activates trupsin from trypsinogen in pancreas

Question 34

secretin

Answer 34

promotes secretion of pancreatic juices

Question 35

Cholycystokinin- pancreozymin (CCK)

Answer 35

promotes pancreatic secretions, stimulates gall bladder secretions

Question 36

duodenal papilla/ major duodenal papilla

Answer 36

intersection of bile duct and pancreatic duct. Entry way into duodenum

Question 37

Jejunum & Ileum

Answer 37

devoted to absorption of water and nutrients. increasing number of peyers patches and goblet cells

Question 38

protein digestion in stomach

Answer 38

Denatured by HCL, Hydrolyzed into polypeptide fragments by pepsin

Question 39

Protein digestion in small int.

Answer 39

Pancreatic enzymes, Membrane bound enterocytes, each amino acid is absorbed by a different carrier

Question 40

Carbohydrate digestion

Answer 40

Salivary and pancreatic amylase( converts starch into glucose and maltose)

Question 41

Digestion of lipids

Answer 41

fats emulsified by bile, pancreatic lipases break down triglycerides

Question 42

digestion of lipids

Answer 42

subunits are absorbed by enterocytes and reconstituted before being transfered to lymphatics via lacteals in lamina propria

Question 43

digestion of lipids

Answer 43

triglycerides in smooth ER are coated with proteins and phospholipids to form chylomicrons which are released into intercellular clefts.

Question 44

Chylomicrons

Answer 44

basically a travel vesicle for triglycerides. They are sent to the liver after they're done

Question 45

Large intestine

Answer 45

besides H20 & electrolytes, it absorbs fat soluble vitamins produced by bacteria living in large int.

Question 46

large int. composition

Answer 46

straight tubular glands with absorptive cells, goblet cells, stem cells.

Question 47

teniae coli

Answer 47

longitudinal layer of tunica muscularis

Question 48

Anus

Answer 48

stratified squamous epithelium