Stomach

Stomach

• what is it? what does it connect?

enlargement of the GI tract 

connects the esophagus to the duodenum 

Functions

• what does it form?

• what does it hold?

mixes saliva, food, and gastric juice to form chyme

serves as a reservoir for chyme release into the small intestine

secretes gastric juice, contains HCI, pepsin, intrinsic factor, and gastric lipase 

secretes gastrin into blood 

Vocab: What is chyme?

semifluid mixture of partly digested food and digestive secretions found in the stomach and small intestine during digestion of a meal.

(F) What digestion continues?

What digestion begins? By what enzyme?

digestion of starch and triglycerides continues

digestion of proteins, by the enzyme pepsin begins 

(F) Intervals of the stomach does what?

forces a small quantity of chyme into the duodenum 

Anatomy: What are the four main regions of the stomach

cardia, fundus, body, and pyloric part

(A) Cardia

surrounds the attachment point of the esophagus to the stomach 

(A) Fundus

rounded portion superior to the cardia

(A) Body

large central portion of the stomach

(A) Pyloric part

• what are its three regions?

pyloric antrum, pyloric canal, and pylorus

(A) Pyloric antrum

first region, connect to the body of the stomach

(A) Pyloric canal

second region, a canal that leads to the third regions 

(A) Pylorus

third region, around the pyloric sphincter and connects to the duodenum 

(A) Pyloric sphincter

• function 

valve between the stomach and duodenum

regulates passage of chyme and prevents the backflow 

(A) Lesser curvature

concave medial border

(A) Greater curvature

convex lateral border

Rugae of mucosa

gastric folds of the mucosa and submucosa, allows the stomach to expand 

(H) Mucosa

• epithelium - what are they called?

  • what unique histological characteristics does it have?

• what layers?

nonciliated simple columnar epithelium (called surface mucous cells)

• gastric pits 

• gastric glands 

Lamina propria

Muscularis mucosae

Mucosa: Gastric Pits

upper indentation, opening of the gastric gland

Mucosa: Gastric Glands

inward fold, forms columns of secretory cells

(H) Submucosa

• what tissue?

• what does it contain?

areolar connective tissue

• contains LV and BV

(H) Muscularis externa

• what unique histological characteristic does it have? what does it allow?

• layers 

inner oblique: allows for more effective churning and mixing food 

middle circular

outer longitudinal 

Muscularis externa 

• activity 

• result

peristalsis

churn and physically break down food and mix with gastric juice, forming chyme

force chyme through pyloric sphincter

(H) Serosa

• what is it composed of? what layer is it?

mesothelium 

visceral layer of the peritoneum 

Mucosa: What cells are in the gastric pits?

• What do they secrete? function?

surface mucous cells

secrete mucus, protective barrier, prevents digestion of stomach wall

Mucosa: What are the cells of the gastric glands?

mucous neck cells, parietal (oxyntic) cells, chief (zymogenic) cells, and G cells 

(GG) Mucous neck cells 

• what do they secrete?

• function?

secrete mucus and absorption

forms a protective barrier

absorbs some water, ions, some short chain fatty acids

(GG) Parietal cells 

• what is another name for them?

• what do they secrete?

oxyntic cells 

• secrete hydrochloric acid and intrinsic factor

Parietal/ oxyntic cells

• Hydrochloric acid function

kills microbes, denatures proteins, converts pepsinogen into pepsin

Parietal/ oxyntic cells

• Intrinsic factor function 

needed to absorb vitamin B12, used in RBC formation 

(GG) Chief cells 

• what is another name for them?

• what do they secrete?

• how does it activate? then what is its function?

zymogenic cells

secretes pepsinogen and gastric lipase 

hydrochloric acid activates, converts into pepsin and breaksdown proteins into peptides 

splits triglycerides into fatty and mono

(GG) G cells 

• what do they secrete? into where?

• function?

gastrin, a hormone, into the blood stream

stimulates parietal cells to release HCI and chief cells to secrete pepsinogen

increases motility of the stomach