Chapter 10

Discuss the functions of VIP. What is this hormone structurally similar to?

similar to GIP, Secretin, glucagon plays a role in increasing water and electrolyte secretion from the pancreas. Stimulates lipolysis, glycogenolysis, and insulin. Relaxes smooth muscle, inhibits gastric secretion that is induced by histamine and pentagastrin.

What is the function of motilin?

simulate gastric motor activity and regulates contractions that occur every 2 hrs following a meal

Explain the physiological role of gastrin

stimulate the secretion of HCL and pepsinogen within the fundus of the stomach (digestive of proteins)

How does the consumption of fats influence the digestive process?

the ingestion of fast also inhibits gastric acid secretion and motility

What effect does fasting have on gastrin level?

fasting decreases circulating gastrin levels as well as the number of gastrin binding sites.

What is the nature of the relationship between CCK and the pancreas?

regulate growth of the endocrine portion of the pancreas, simulate secretion of pancreatic enzymes and secretin- induced pancreatic

What is the primary stimulus for gastrin secretion? When was this hormone isolated?

-isolated in 1964, Food is the I stimulus for gastrin release,

What is the major role of the gastrointestinal hormones?

-stimulate the secretion of digestive hormones -to facilitate the conversion of food molecules into the smallest constituents that are than transported throughout the body by the circulatory system

Name and discuss three (3) GI hormones and their physiological roles

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Name and discuss three (3) endocrine pathophysiologies of the GI tract

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Name four (4) chemical stimuli that can lead to the release of GI hormones?

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Name the types of cells in which GI hormones are synthesized?

1. Enterochromaffin-Like (ECL): D (Somatostatin, G(gastrin), S(secretin) 2. Argyrophilic 3. Argentaffin

Name the two targets of gastrin

1. Histamine- releasing ECL cells 2. Acids- secreting parietal cells

Name the accessory organs of the digestive system. What is secreted by these organs and what is the function of these substances?

1. Pancreas- secretes insulin and glucagon (metabolism of carbohydrates), exocrine, breaks down carbohydrates 2. Gallbladder- reservoir (Stores) for bile salts (excerted by the live- source of bile), emulsify fats within the intestines

Discuss the five (5) biological effects of gastrin

1. Stimulate lower esophageal sphincter pressure 2. Relaxation of pyloric sphincter 3. Stimulate pancreatic secretion 4.Enchance motor activity in the intestine 5. Stimulate secretion of pancreatic bicarbonate and H20

Discuss the three (3) physiological effects of CCK in response to a meal. What is the potential for CCK in a pharmaceutical sense

1. contraction of the gallbladder 2. relaxation of the sphincter of oddi 3.inhibition of gastric emptying Has a role as a satiety hormone

When was CCK discovered and by whom? What is the function of CCK? What cell type is CCK localized to? Explain how CCK becomes physiologically active

1928, Ivy and Oldberg, cause contraction and emptying of the gallbladder, localized to the I cells of the intestinal mucosa and the 7th amino acid from the carboxy terminus must be sulfated in order for the molecule to be physiologically active

What type of loop system controls the release of secretion and bicarbonate ions? What is the function of bicarbonate?

An endocrine closed loop system, maintaining the balance of acids and bases in the body as an acid buffer. Neutralizes H+ which raises the pH causing a decrease in releasing secretin

Name the four (4) molecular forms of gastrin. Which of these forms is physiologically relevant?

Component I- big big gastrin (not circulating) Component II- big gastrin Component III- gastrin 17 (Physiologically relevant form Component IV- gastrin 14

Discuss substance P (SP)

Composed of 11 amino acid residues. The first neuropeptide found in the brain and gut. Function as a physiological modulator of smooth muscle activity in gut tissue. Role in intestinal peristalsis.

Discuss the uniqueness of the frog Rheobatrachus silus. What kind of human disease is linked to the used of NSAIDs and why does this condition occur?

Female Rheobatrachus silus swallow fertilized eggs which develop in her stomach. Tadpoles secrete PGE2 which inhibits gastric acid secretion. Nonsteroidal anti -inflammatory drugs can lead to peptide ulcers by removing protective covering of mucosa

What is the source of secretin and when is it released?

Found in granular S cells of the small intestine Is stimulated by a decrease in the pH of the duodenum to HCL from the stomach

Discuss the localization and function of GIP. Name three (3) organs/tissues on which GIP has a direct metabolic effect.

GIP is localized to certain k cells of the duodenum and ileum in dogs and humans. GIP is insulintropic; potentials insulin releases in response to glucose adipose, muscle, liver, GI Tract, brain

Newborns have low proteolytic activity. What is the probable source of the GI hormones they use to breakdown milk proteins

Milk- newborns have low proteolytic activity and are able to move easily milk or baby formula. GI hormones present in breast milk may stimulate the release of gastric secretion in the infants digestive tract

Name the cells that release secretin. What stimulates the release of secretin? Which pH value is not conducive to the release of secretin?

S cells, simulated by a decrease in the pH of the duodenum to HCL from the stomach, above pH of 4.5

What are the two forms of SST?

S14- found in D cells of pancreatic islets and gastric atrium S28- found in the epithelial D cells of the small intestines and colon

a. Bulbogastrone b. Urogastrone c. GLP-1 d. Villikinin e. Enkephalins f. Neurotensin g. Peptide YY h. Neuropeptide

a. Bulbogastrone b. Urogastrone- B form: composed of 53 amino acids with 3 internal sulfide bonds and suppresses secretion of gastric acid. y form: lacks an arginine residue in the C-terminal portion c. GLP-1(Glucagon like peptide)- intestinal peptide and encoded in the proglucagon gene. Proglucagon gene is expressed(A cells, L cells, certain neurons). Released after ingestion of food. Stimulates insulin secretion, inhibits glucagon secretion, pharmacologically used to lower insulin levels. d. Villikinin- stimulates motility of the villous in small intestines. Only active in mucosa of the small intestine. Levels increase in human urine and following a meal. Does not exhibits characteristics of other GI hormones e. Enkephalins- found in ECL and nerve cells affilated with digestive tract, stimualtes gastric acid secretion, stimulates acid release from parietal cells, regulate motility and secretion. f. Neurotensin- localized to the N cells within the mucosa of the ileum, communicate with lumen of the intestine via microvilli g. Peptide YY- localized to the intestine, released in the blood following a meal h. Neuropeptide- regulates activity of other nerves, maintains tone of smooth muscle, regulates local blood flow and epithelial transport