Lecture # 5 Digestion: regulation and secretion

Question 1

When the pH of the stomach is increased by the use of antacid medication to avoid GERD, over time the stomach may not be acidic enough. Which of the following might occur?

Answer 1

decreased protein digestion

Question 2

Which specialized cell of the gastric epithelium secretes a hormone?

Answer 2

G-cells; gastrin cells, secretions go towards the blood.

Question 3

Enteroendocrine cells secrete hormones into the intestinal lumen. (T/F)

Answer 3

False, into the blood stream all endocrine cells makes secretions, hormones, that go to the blood

Question 4

Enterohepatic recirculation of bile salts

Answer 4

the circulation of bile salts from the liver, to the gallbladder, to the common bile duct, back to the liver.

Question 5

How many grams of bile salts are required for daily fat reabsorption?

Answer 5

20-30 g

Question 6

Bile production is a function of the endocrine portion of the liver.

Answer 6

False

Question 7

Where are bile salts generated from?

Answer 7

Bile salts are synthesized from cholesterol and modified by taurine or glycine in the liver, forming conjugated bile salts (covalent modification). Hepatocytes secrete 0.7 L/day of bile into billiary canaliculi

Question 8

Lechithin

Answer 8

phospholipid

Question 9

Why are positive and negative charges added to bile salts?

Answer 9

To make them more soluble in water

Question 10

What is responsible for the yellow color of bile?

Answer 10

Bilirubin, from hemoglobin

Question 11

How are drugs, and hormones eliminated?

Answer 11

They are converted to glutathione and glucaronic acid, and secreted with bile salts.

Question 12

Why is conjugation of bile salts important?

Answer 12

important for micelle formation. Important for bile salt storage in the gallbladder. Lecithin is important for micelle formation.

Question 13

What is bile composed of?

Answer 13

conjugated bile salts, electrolytes, water, cholesterol, lecithin, steroid hormones, billirubin diglucuronide, drugs glucronides, glutathionylated drugs.

Question 14

What are the four types of bile salts? What are the primary bile salts? Secondary Bile salts? How are primary bile salts converted to secondary bile salts?

Answer 14

Cholic, chenodeoxycholic, deoxycholic, and lithocholic acid. 2) cholic and chenodeoxycholic 3) deoxycholic and lithocholic 4) by intestinal bacteria.

Question 15

What is the role of CCK in digestion?

Answer 15

Secreted by I cells of the duodenum, CCK induces the release of bile from the gallbladder and potentiates the vagus nerve endings on the gallbladder wall.

Question 16

Where are bile salts reabsorbed?

Answer 16

from the terminal illeum and recirculated back to the liver.

Question 17

What controls smooth muscle contraction of the gallbladder?

Answer 17

Impulses from the vagus nerve.

Question 18

How does the consumption of plant sterols or stanols lower blood cholesterol?

Answer 18

Plant sterols (have double bonds) or stanols (do not have double bonds) ( are similar to cholesterol. They inhibit the reabsorption of bile salts, and cause the body to use blood cholesterol to synthesize bile salts, which lowers cholesterol. (two grams of sterols and stanols are needed to be consumed/day to reduce cholesterol by 10%)

Question 19

Cholestyramine

Answer 19

synthetic drugs. ;Binds to bile salts in the G.I tract, excreted to the liver, and causes the body to use cholesterol in the blood to form more bile salts.

Question 20

How many grams of sterols and stanols are available in whole foods?

Answer 20

0.25 g of sterols and stanols in whole foods.

Question 21

Where is the majority of water reabsorbed?

Answer 21

The stomach and large intestine

Question 22

Where are the majority of macronutrients reabsorbed?

Answer 22

lipids, monosaccharides, amino acids, small peptides, are absorbed in the jejunum of the small intestine

Question 23

Where are short chain fatty acids absorbed?

Answer 23

acetic acid (2C), butyric acid 3C), and propionic acid (4) . Absorbed in the large intestine. Produced by microbes.

Question 24

What molecules can cross the membrane of enterocytes with ease?

Answer 24

water and small lipids. takes advantage of concentration gradient.

Question 25

What molecules need carrier proteins to be transported across the plasma membrane?

Answer 25

Glucose (GLUT) , fatty acids (Fatty acid transporter or CD36) both dependent on concentration gradient and the amount of transporters on the concentration gradient.

Question 26

Both active transport and pinocytosis (a form of endocytosis) require chemical energy in the form of ATP. (T/F)

Answer 26

true; ATP is needed to move the cytoskeleton in pinocytosis.

Question 27

Na+/K+ ATPase

Answer 27

Protein that transports sodium and potassium against their concentration gradient. Energy is supplied by ATP,