Term
| 4 functions of the stomach |
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Definition
storage of food
secretes gastric acid (HCL)
Mixing action+ acid conver food into semi-solid paste =chyme
Chyme released slowly into stomach |
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Term
| Where does the digestion of proteins begin? Enzymes involved? |
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Definition
in the stomach
Secretes pepsinogen (inactive)
activated under acidic conditions to pepsin |
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Term
| What are the 4 regions of the stomach? |
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Definition
1. Cardiac: narrow strip around esophageal sphincter
2. Fundus (upper region)
3. Body (largest)
4. Pyloric region- continuous w/ small intestine |
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Term
| What does the pyloric region of the stomach have? |
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Definition
Pyloric antrum: muscular region, most mixing
Pyloric canal: narrowing
Pylorus/Pyloric Sphincter: thick band of smooth muscle |
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Term
| What are the inner lining of the stomach called? What do they do? |
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Definition
Rugae- numerous longitudinal folds
Allows for stomach expansion
-stomach expands to hold about a gallon
Rugae disapear when stretched |
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Term
| What is the histology of the mucosa layer in the stomach? |
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Definition
simple columnar epithelium
typical lamina propria and muscularis mucosa
Gastric pits |
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Term
| What is the histology of the submucosa layer of the stomach? |
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Definition
| most regions of stomach contain large numbers of gastric glands that extend into the submucosa |
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Term
| What is the muscularis externa? |
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Definition
Smooth muscle
extra oblique layer of smooth muscle |
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Term
What are gastric pits?
What extends from from there base?
In fundus and body? |
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Definition
cup shaped invaginations into mucosa
long tubular gastric glands extend from base of pits
In fundus and body gastric glands contain mostly three cell types:
1. mucous neck cells: mucos
2. parietal cells: secrete gastric acid (HCL) and intrinsic factor (allow absorption of V.B12)
3. Chief Cells- secrete pepsinogen |
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Term
| What are enteroendocrine cells? |
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Definition
secrete various hormones
scattered along lining of alimentary canal
also present in gastric glands |
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Term
| What are the pyloric region of the stomachs enteroendocrine cells called? |
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Definition
G cells that secrete hormone gastrin
Stimulates gastric acid secretion |
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Term
What is the longest portion of the alimentary canal?
What is it the site of?
% of subdivisions? |
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Definition
small intestine
site of most enzymatic digestion and absorption of nutrients and fluid
3 subdivisions
Duodenum 5%
Jejunum 35%
ileum 60% |
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Term
What does the duodenum receive from what two things?
What is the opening called? |
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Definition
digestive enzymes and bile
1. main pancreatic duct: transport "pancreatic juice" containing enzymes to duodenum
2. Common bile duct: transport bile to duodenum, join before connecting w/duodenum
-raised area on inner surface where hepato-pancreatic ampulla opens into duodenum |
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Term
| What are and what are the purpose of the modifications of the small intestine? |
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Definition
All increase surface area
1. circular folds (plicae circulares)
-transverse ridges of mucosa and submucosa
2. Villi- finger-like projections of the mucosa
- covered w/simple columnar epithelium
-contain blood vessels and lacteals (lymphatic capillaries)
3. Microvilli- apical surface of absorptive cells; further increase surface area for absorption |
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Term
| What are the absorptive cells in the small intestine, and function? |
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Definition
Uptake digested nutrients
Simple columnar epithelium |
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Term
| Other than simple columnar epithelium what else does it have? |
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Definition
goblet cells secrete mucus that lubricates chyme
enteroendocrine cells secrete hormones that influence many digestive processes |
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Term
| What are intestinal crypts? |
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Definition
crypts of lieberkuhn
epithelial cells secrete "intestinal juice" watery fluid that mixes with chyme (1.5 L/day)
Basal cells: divide to replace old/defective epithelial cells
-push up cells from base of crypts toward tip of villi where old cells slough off (takes 20 days) |
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Term
| Main functions of the large intestine? |
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Definition
absorb most remaining water and electrolytes (400mL/day enters, only 100 mL is lost)
Small amount of digestion by bacteria (residue entering colon has few nutr)
Contractions of muscularis externa force feces toward the rectum |
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Term
| THe large intestine is divided into: |
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Definition
cecum
vermiform appendix
colon
rectum
anal canal |
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Term
What are and where are?
1. Cecum-
2. Vermiform appendix-
3. Colon-
4. Rectum-
5. Anal Canal- |
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Definition
1. Cecum- blind pouch, inferior to junction of ileum/asc colon
2. Vermiform appendix- contains lymphoid tissue, neutralizes pathogens
3. Colon- divided into distinct segments (asc, trans, desc, sigmoid)
4. Rectum- straight portion, desc along the inferior half of sacrum
5. Anal Canal- the last subdivision of large intestine |
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Term
| What are other special features of the large intestine? |
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Definition
teniae coli- "ribbons" three longitudinal strips of thicken muscularis externa (equally spaced around circumference)
haustra- tension of teniae coli cause colon to "pucker" into repeating sacs=hastrae
and epiploic appendages- fat filled pouches of visceral peritoneum that hang (unknown signfigance) |
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Term
1. What is absent in the large intestine?
2.What is it lined with?
3. What is the lymphoid tissue?
4. What is present?
5. What is the epithelium changes at anal canal? |
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Definition
1. villi
2. simple columnar epithelial tissue
3. lamina propria and submucosa (abundant GALT)
4. Intestinal crypts
-straight rectangular tubes and numerous goblet cells (mucos to lube feces)
5. Becomes stratified squamous epithelium |
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Term
| What are anal columns/valves? |
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Definition
mucosa folded into longitudinal and circular ridges
Opposing columns line-ip to close off anal canal along with; valves-circular folds inferior to columns |
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Term
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Definition
valleys between colomns
during defecation passing feces squeezes out a lubricating mucos from sinuses
allows route for escape of gases |
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Term
| What are the hemorrhoidal veins? |
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Definition
surround anal canal/anus
both internal and external |
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Term
| what is the internal anal sphincter? |
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Definition
| thick band of smooth muscle |
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