USMLE Step 1 Physiology Review 57 04 Jejunum & Small Intestine

USMLE Step 1 Physiology Review 57 04 Jejunum & Small Intestine

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Play USMLE Audio MP3 57 04 Jejunum & Small Intestine Below

Begin 57 04 Jejunum & Small Intestine Transcription

Now for some questions on the jejunum and the secretions of the jejunum. This substance stimulates gallbladder contraction, pancreatic secretion, and retards stomach emptying?

  • Cholecystokinin or CCK from the I cells of the jejunum

This secretion inhibits gastric acid secretion, pepsinogen secretion, pancreatic secretion, inhibits gallbladder contraction, causes insulin release and glucagon release?

  • Somatostatin produced by the D cells

This inhibits gastric acid secretion and stimulates insulin release?

  • Gastric Inhibitory peptide or GIP from the neuronal cell bodies of the jejunum

What six things are absorbed in the small intestine that is the duodenum, the jejunum and the ileum. List them alphabetically.

  • First, Bile acids, Second, carbohydrates, Third, Ionic Calcium and Iron in the 2+ form only, Fourth lipids, Fifth proteins, Sixth vitamins.

Student doctor please pause the tape and summarize the information discussed on the secretions by different cells in the jejunum.

  • Cholecystokinin or CCK from the I cells of the jejunum stimulates gallbladder contraction, pancreatic secretion, and retards stomach emptying. Somatostatin produced by the D cells inhibits gastric acid secretion, pepsinogen secretion, pancreatic secretion, inhibits gallbladder contraction, causes insulin release and glucagon release. Gastric Inhibitory peptide or GIP from the neuronal cell bodies in the jejunum inhibits gastric acid secretion and stimulates insulin release. Six things are absorbed in the small intestine that is the duodenum, the jejunum and the ileum. There are bile acids, carbohydrates, Ionic Calcium and Iron in the 2+ form only, lipids, proteins, and vitamins.

Okay now for some more questions. In what form are the carbohydrates including the starches and the sugars absorbed in the small intestine?

  • Only in the form of monosaccharides

And what are the monosaccharides? There are three)

  • Glucose also called Dextrose, Fructose also called Laevulose, and Galactose.

In what form are proteins absorbed?

  • In the form of amino acids, dipeptides and tripeptides

In what form are lipids absorbed?

  • In the form of fatty acids, monoglycerides, and cholesterol

What types of vitamins are absorbed?

  • Both water soluble and fat soluble vitamin are absorbed in the small intestine

One vitamin however is absorbed in one place only, what is the vitamin and where is it absorbed?

  • Vitamin B12 absorbed in the ileum

How are bile acids reabsorbed?

  • They are reabsorbed from secreted bile salts in order to recycle them

And this happens where?

  • In the ileum only

And what two ions are absorbed in the small intestine?

  • Ionic Calcium and Iron in the 2+ form only

What does the large intestine absorb?

  • Water

Student doctor please pause the tape and summarize the information discussed on the jejunum since the last summary.

  • The first question in this section was about the form in which carbohydrates including the starts and the sugars absorbed in the small intestine. And this will be the last of gastrointestinal physiology. Carbohydrates including the starches and the sugars absorbed in the small intestine only in the form of monosaccharides. The monosaccharides are Glucose also called Dextrose, Fructose also called Laevulose, and Galactose. Proteins are absorbed in the form of amino acids, dipeptides and tri-peptides. Lipids are absorbed in the form of fatty acids, monoglycerides, and cholesterol.  Both water soluble and fat soluble vitamins are absorbed in the small intestine. One vitamin, however, Vitamin B12, is absorbed in the ileum only. Bile acids are reabsorbed from secreted bile salts in order to recycle them and this happens in the ileum only. Ionic Calcium and Iron in the 2+ form only absorbed in the small intestine. The large intestine absorbs water.

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