01b Normal GI structure and function

Question 0

Site of bile salt and B12 absorption

Answer 0

Ileum

Question 1

Site of nutrient absorption

Answer 1

Jejunum

Question 2

Lamina propria and contents

Answer 2

Loose connective tissue with lymph and capillaries just below and supporting epithelium. Contains lymphocytes and plasma cells. ALSO CONTAINS HISTAMINE SECRETING ECL CELLS

Question 3

Submucosa

Answer 3

loose collagenous and adipose tissue supporting the mucosa- contains larger blood vessels and lymphatics

*innervated by meissners plexus- mucosal mvmt, BLOOD FLOW, and gland SECRETION

Question 4

Adventitia

Answer 4

Outer layer of connective tissue surrounding GI tract outside of peritoneum

Question 5

Serosa

Answer 5

Simple squamous epithelium (mesothelium) covers tissues within the peritoneal cavity

Question 6

Langerhans cells

Answer 6

Dendritics in skin and mucosa

Question 7

Gland layers in esophagus

Answer 7

Superficial mucosal glands in lamina propria- lubricating mucous

Submucosal seromucous glands– Pepsinogen, Lysozyme, mucous

Question 8

Gastric juice contents

Answer 8

Hydrochloric acid, pepsin, rennin, gastric lipase

Question 9

Gastric pit

Answer 9

Invagination of epithelium with connection to up to 7 Gastric glands
Contain surface mucous cells (thick protective electron dense mucous)

Question 10

Gastric Glands

Answer 10

secrete HCL and enzymes
3parts:
Isthmus- meeting of glands parietal and surface mucous cells
Neck- Neck mucous cells (thin lubricating mucous), parietal (IF and HCL), stem cells
Base- Cheif (pepsinogen), parietal, neck mucous, ECL(histamine), Gastrin and D cells(somatostatin)

Question 11

Parietal cell

Answer 11

Pyramidal cell secreting HCL and IF for B12 absorpton
*Secretory canaliculus - lots of mitochondria and microvilli invaginations
*Tubovesicular network (more of this means less HCL)
*Rich in Mito
“Fried egg appearance”

Question 12

Chief cells

Answer 12

Pepsinogen, rennin, gastric lipase in apical secretory granules (secretion stimulated by secretin)

base of fastric glands

Basophilic from rER, Golgi

Question 13

ECL cells

Answer 13

Histamine secretion (responsive to ACH) 
Located in Lamina propria below gastric glands

Question 14

Auerbach’s plexus

Answer 14

Between the inner circular layer and outer longitudinal layer of muscle
Controls parastalsis

Question 15

ENS

Answer 15

• Independent ANS modulated by brain, but works on its own

* ACH, Norepi, seritonin

Question 16

Esophageal glands

Answer 16

Abundant in submucosal layers (like in duodenum)
Mucous cells(mucous) and Serous cells (pepsinogen, lysozyme)

Question 17

Esophageal muscularis propria

Answer 17

upper 1/3 skeletal-voluntary
Middle 1/3- mixed
Lower 1/3 - smooth, involuntary

Question 18

Stomach epithelium

Answer 18

Simple columnar with surface mucous cells and pits

• Thick electron dense mucous that traps bicarbonate ions
• Gastric glands off of pits that dive into lamina propria

Question 19

EC cells

Answer 19

Secrete serotonin- located in gastric glands

Question 20

A cells

Answer 20

Secrete enteroglucagon

Question 21

Enteroendocrine cells

Answer 21

SECRETE INTO LAMINA PROPRIA

• G cells- gastrin
• EC cells- Serotonin
• D cells- somatostatin
• A cells- Enteroglucagon
• ECL cells- Histamine

Question 22

Secretin

Answer 22

• Stimulates secretion of pepsinogen, rennin, and gastric lipase
• Suppresses gastrin
• Suppresses GI motility

Question 23

Gastric mucosa turn around

Answer 23

3 days

Question 24

Glands in fundus and body

Answer 24

Straight tubular glands

Question 25

glands in cardia and pyloris and cardia

Answer 25

Cardia- Highly coiled glands with shallow pits and lots of enteroendocrine cells
Pyloris- branched glands with prominant mucous neck cells

Question 26

Cephalic phase of digestion

Answer 26

Brain–> Vagus –>ACh–> Gastrin –> histamine 30% HCL

Question 27

Gastric phase

Answer 27

Gell activity from stretch- 60% gastric acid and smooth muscle contraction

Question 28

Intestinal phase

Answer 28

10% gastric acid

Duodenal emptying-
Enterogastric reflex (gastric inhibitory)
CKK and secretin suppress gastric activity (10% acid )