Phases of gastric secretion

Question 1

What are the 3 phases of gastric secretion?

Answer 1

Cephalic, Gastric, intestinal

Question 2

What is the composition of bile and how much is produced a day?

Answer 2

Yellow/green - alkaline
- bile salts
- pigments
- cholesterol
- neutral fats
- phospholipids
- electrolytes

Question 3

What are cholic acid and chenodeoxycholic acid?

Answer 3

2 principle bile salts

Question 3

What is bilirubin and how does intestinal bacteria affect it?

Answer 3

main bile pigment (waste product of hemoglobin)
- converts bilirubin into stercobilin (feces brown color)

Question 4

What is the liver’s role in digestion?

Answer 4

produces bile (a cholesterol derivative)

Question 4

What is the function of the gallbladder?

Answer 4

a storage organ for bile
- contracts to release bile

Question 4

What is bile and why is it needed?

Answer 4

is a fat emulsifier
- breaking fat down into easier absorbable portions

Question 5

What is the meaning of amphipathic?

Answer 5

hydrophilic and hydrophobic

Question 6

What happens when the hepatopancreatic sphincter is closed?

Answer 6

digestion is not occurring
- bile back up through cystic duct and is stored in gallbladder

Question 6

How does the muscular walls affect the gallbladder?

Answer 6

releases bile into the duodenum
- bile expelled into cystic duct the bile duct

Question 7

What is the major stimulus of gallbladder contractions?

Answer 7

CCK

Question 8

What is CCK secreted by and what does it respond to?

Answer 8

small intestine, lipids and peptides

Question 8

What are the 2 main hormones that regulate bile in the small intestine?

Answer 8

secretin and CCK

Question 9

What is the role of CCK?

Answer 9

stimulates gallbladder contractions
- stimulates secretion of pancreatic juice
- relaxes hepatopancreatic sphincter

Question 10

How are bile salt conserved?

Answer 10

recycling (90-95%) through the enterohepatic circulation

Question 10

What is the function of the ileum when it comes to bile transportation?

Answer 10

ileum (bile transporter reabsorbs 95% of bile salts) to blood to liver (via hepatic portal vein) to new bile

Question 11

What are gallstones and why are they painful?

Answer 11

They are sharp and in gallbladder/ ducts. When we release bile (the liver contracts) the gallbladder touch the sharp sides

Question 12

What is obstructive jaundice? And what are other causes of jaundice?

Answer 12

It’s caused by excess bilirubin
- the gallstones block the duct causing bilirubin and bile build up
- Alcoholism, fatty liver disease, hepatitis

Question 12

What are the treatments of gallstones and what is its effect?

Answer 12

removing the gallbladder
- causes common bile duct to expand to hold more bile

Question 12

What is acini and what do they mediate?

Answer 12

secretory acinar cells clustered around ducts
- mediate exocrine function of pancreas

Question 12

What are the 4 basic types of enzymes needed to digest food?

Answer 12

• DNA/ RNA
• protein
• lipids
• carbohydrates

Question 13

What is the composition of pancreatic juice and what is the function of its alkalinity?

Answer 13

1200-1500 ml/day
- water + electrolytes (bicarb; pH8) + enzymes
- i) neutralize acidic chyme ii) create optimal pH for intestinal and pancreatic enzymes

Question 14

What is a precursor form and what enzyme is released in that form?

Answer 14

an inactive form (activated once in the duodenum)
- proteolytic enzymes

Question 15

What form is amylase, lipase and nucleases in?

Answer 15

active form but require ions or bile for optimal activity

Question 16

What class are membrane-bound enteropeptidase in?

Answer 16

brush border enzymes

Question 16

What are the 3 types of cells in a gastric gland?

Answer 16

Parietal (secretes HCl and intrinsic factor) + chief cells (secrete pepsinogen) + enteroendocrine cells (secrete hormones and paracrines)

Question 17

What is the function of secretin and what’s it triggered by?

Answer 17

stimulates pancreatic duct cells to secrete bicarb-rich juice - acidic chyme

Question 18

What is the function of CCK of the pancreas and what’s it triggered by?

Answer 18

stimulates pancreatic acinar cells to secrete enzyme-rich juice - proteins and lipids

Question 19

How does the parasympathetic nervous system affect secretion?

Answer 19

vagal stimulation of secretory activity - primarily during cephalic and gastric secretion

Question 19

What are the 2 regulations of pancreatic secretion?

Answer 19

secretin and CCK

Question 20

Where are most enzymes manufactured in the intestine?

Answer 20

brush border enzymes

Question 21

What are most intestinal juices made of?

Answer 21

water + mucus

Question 21

What are the requirements for optimal intestinal digestive activity?

Answer 21

i) optimal liver & pancreatic function and ii) regulated chyme delivery to stomach - neutralize stomach HCl and contents of stomach are hypertonic

Question 21

What is segmentation and what is it initiated by?

Answer 21

contractions of smooth tissue in small intestine for digestion - intrinsic pacemaker cells in circular muscle

Question 22

What is the pace of segmentation in the duodenum and ileum and why is one faster?

Answer 22

duodenum (12-14/ min), ileum (8-9/ min) - duodenum at top faster to push food down

Question 22

What determines the intensity of segmentation?

Answer 22

long and short reflexes and hormones

Question 23

What is the function of motilin?

Answer 23

initiates peristalsis starting in proximal duodenum

Question 23

What do ileal motility (increases) and ileocecal sphincter (relaxes) respond to?

Answer 23

i) gastroileal reflex (initiated by stomach; long reflex) ii) gastrin

Question 24

What are the important hormones and paracrines?

Answer 24

CCK - gastrin - histamine - intestinal gastrin - motilin - secretin - somatostatin

Question 25

What is a catabolic reaction and what is the most important process called?

Answer 25

chemical digestion - hydrolysis (water + breakdown)

Question 25

What are the monosaccharides?

Answer 25

glucose, fructose, galactose

Question 26

What monosaccharide makes sucrose, lactose and maltose?

Answer 26

S - glucose + fructose L - glucose + galactose M - glucose + glucose

Question 27

What are the 3 digestive enzymes of carbohydrates?

Answer 27

salivary amylase, pancreatic amylase, and intestinal brush border enzymes