5b.) The Intestines Flashcards
Define absorption
Movement of electrolytes, water and nutrients form the gut lumen to blood
Compare the jejunum and ileum in terms of:
- Where they are
- The thickness of their intestinal walls
- Length of vasa recta
- Number of arcades
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Describe the blood supply to the intestines
SMA gives off following branches:
- Jejunal and ileal arteries: jejenum & ileum
- Ileocolic: terminal ileum, caecum
- Right colic: ascending colon
- Middle colic: transverse colon
Ileocoli, right colic and middle colic anastomose to form the marginal artery
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Describe the venous drainage of the intestines
- Superior rectal vein becomes IMV when it comes out of pelvis
- Inferior mesenteric vein joins the splenic vein
- Splenic vein adn superior mesenteric vein join to form the portal vein which forms behind the neck of the pancreas
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Describe the properties of chyme once it has left duodenum, include:
- Tonicity
- pH
- Digestion
- Isotonic
- Neutral
- Digestion nearly complete
Absorption requires a large surface area; describe 3 structural features of intestines that increase surface area
- Plicae circulares (permanent intestinal folds)
- Villi
- Microvilli
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State the 3 main epithelial cell types in intestines and what each one does
- Enterocytes (most)= absorptive cells
- Goblet cells= mucus secreting
- Enteroendocrine= produce hormones
How often is the mucosa of intestinal glands shed?
Constantly shed evey 3-6 days
Describe the structure of intestinal glands (crypts of Lieberkuhn)
???
Only monosaccharides can be absorbed; true or false?
True
State the three monosaccharides that can be absorbed
- Glucose
- Fructose
- Galactose
Glucose can only be absorbed alongside Na+; true or false
True
State 3 common dietary carbohydrates
- Starch (polysaccharide)
- Lactose (disaccharide)
- Sucrose (disaccharide)
Describe the structure of starch
Consists of:
- Amylose: straight chains of glucose with alpha 1-4 bonds
- Amylopectin: branched chains of glucose with alpha 1-4 bonds on straight chains and alpha 1-6 bonds on branch points
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Which bonds, in starch, can salivary and pancreatic amylase break?
What do you end up with once they have broke these bonds?
Salivary and pancreatic amylase can break alpha 1-4 bonds:
- In amylose: this produces the disaccharide MALTOSE
- In amylopectin: this produces shorer but still branched chains of glucose called ALPHA DEXTRINS
![](https://s3.amazonaws.com/brainscape-prod/system/cm/291/356/797/a_image_thumb.png?1572006801)
What enzyme is required to break alpha 1-6 bonds (in branches of amylopectin in starch)?
Isomaltase
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State the monosaccharide components of maltose
2 x glucose
Summarise starch digestion
- Salivary and pancreatic amylase break alpha 1-4 bonds in produce:
- Maltose from amylose
- Alpha dextrins from amylopectin
- Isomaltase required to break alpha 1- bonds in amylopectin
![](https://s3.amazonaws.com/brainscape-prod/system/cm/291/371/924/a_image_thumb.png?1572019409)
State the monosaccharide components of lactose
Glucose and galactose
State the monosaccharide components of sucrose
Glucose and fructose
What enzyme breaks lactose into it’s monosacchardie components?
Lactase
(Lactose -> glucose + galactose)
What enzyme breaks sucrose into its monosaccharide components?
Sucrase
Glucose + fructose