Small Intestines, Liver and Pancreatic Secretions

Question 1

Describe the process of bile production?

Answer 1

Synthesises bile salts which are used in the small intestine for the emulsification and absorption of lipids, cholesterol, phospholipids and lipoproteins

Question 2

Describe metabolic regulation?

Answer 2

Regulates levels of carbohydrate, lipids, amino acid in blood

Question 3

What does the liver store?

Answer 3

Glycogen, fat, vitamins (A, B12, D, E, and K), copper and iron

Question 4

How does the liver detoxify substances?

Answer 4

Hepatocytes remove ammonia and convert to urea

Question 5

Describe the phagocytosis function of the liver?

Answer 5

Kupffer cells phagocyte worn-out and dying red and white blood cells, some bacteria

Question 6

What proteins does the liver produce?

Answer 6

Albumins, fibrinogen, globulins, heparin, clotting factors

Question 7

How does the liver activate vitamin D?

Answer 7

The skin, the liver, and kidneys participate in synthesising the active form of vitamin D

Question 8

Describe tehe secretions of the liver?

Answer 8

Each day hepatocytes secrete 800 to 1000 ml of bile, a yellowish, brownish, or olive green liquid

• Partially an excretory product, partially a digestive secretion
• has pH of 7.6 to 8.6

Question 9

Describe the composition of bile?

Answer 9

consists mostly of

1. water and bile acids (cholic acid)
2. bile salts (sodium and potassium salts)
3. cholesterol
4. phospholipids (lecithin)
5. bile pigments (bilirubin)
6. several ions

Question 10

What is the function of bile salts?

Answer 10

emulsification – breakdown of large lipid globules into a suspension of droplets about 1μm in diameter, and in absorption of lipids following their digestion
- Cholesterol is made soluble in bile by bile salts and lecithin

Question 11

Describe the pancreas?

Answer 11

1. retroperitoneal gland 2. 12 -15 cm long, 2.5 cm thick 3. lies posterior to the greater curvature of the stomach

Question 12

What are the parts of the pancreas?

Answer 12

a head, body, and a tail

Question 13

How is the pancreas connected to the duodenum?

Answer 13

1. hepatopancreatic ampulla 2. accessory pancreatic duct

Question 14

Describe the portions of the pancreas?

Answer 14

1. exocrine portion - secrete digestive enzymes into the intestine 2. endocrine portion - secrete insulin and glucagon into the bloodstream

Question 15

What are the cells of the exocrine portion?

Answer 15

acini - 99% of the pancreas are small clusters of glandular epithelial cells

Question 16

What are the secretions of the exocrine portion?

Answer 16

1. cells within the acini secrete a mixture of fluid and digestive enzymes called pancreatic juice
2. cells within the ducts secrete NaHCO3 solution

Question 17

Describe the cells of the endocrine portion?

Answer 17

1% are organised as clusters called pancreatic islets (islets of Langerhans)

Question 18

How much pancreatic juice is produced daily?

Answer 18

1200 - 1500 ml

Question 19

Describe the composition of pancreatic juice?

Answer 19

consisting of water, Na+, K+, Cl-, sodium bicarbonate (NaCO3) and several enzymes - Pancreatic juice is a clear, colourless liquid

Question 20

What make pancreatic juice slightly alkaline?

Answer 20

Sodium bicarbonate - pH (7.1 - 8.2)

Question 21

What are the functions of sodium bicarbonate?

Answer 21

1. Buffers acid gastric juice in chyme
2. Stops the action of pepsin from the stomach
3. Creates the ideal pH for action of digestive enzymes in the small intestine

Question 22

Name enzymes present in pancreatic juice?

Answer 22

1. pancreatic alpha amylase
2. pancreatic lipase
3. nucleases
4. proteolytic enzymes
5. trypsin inhibitor

Question 23

Describe pancreatic amylase?

Answer 23

carbohydrate enzyme that breaks down certain starches - almost identical to salivary amylase

Question 24

Describe pancreatic lipase?

Answer 24

1. the principal triglyceride-digesting enzyme 2. breaks down certain complex lipids, releasing fatty acids that can easily be absorbed

Question 25

Describe nucleases?

Answer 25

break down nucleic acids - ribonuclease and deoxynuclease

Question 26

Describe proteolytic enzymes?

Answer 26

1. break down proteins 2. secreted in form of zymogens e.g. trypsinogen, chymotrypsinogen, proelastase In the duodenum and enterokinase converts trypsinogen to trypsin 4. trypsin converts other zymogens to chymotrypsin, carboxytrypsin and elastase

Question 27

Pancreatic secretions are regulated by?

Answer 27

by neural and hormonal mechanisms

Question 28

What is the innervation of acinar and duct cells?

Answer 28

the sympathetic and parasympathetic nerves

Question 29

During the cephalic and gastric phases parasympathetic impulses are transmitted along?

Answer 29

vagus nerve

Question 30

What do the parasymapthetic nerve impulses stimulate?

Answer 30

increased secretion of pancreatic enzymes

Question 31

Describe the response to the presence of fatty acids and amino acids in the duodenum?

Answer 31

1. the I cells of duodenal mucosa secrete cholecystokinin into the blood 2. Cholecystokinin (CCK) stimulates a pancreatic secretion that is rich in digestive enzymes

Question 32

Describe the response to the presence of acidic chyme in the intestinal lumen?

Answer 32

1. jejunal S cells release secretin into the blood 2. Secretin stimulates the flow of pancreatic juice that is rich in bicarbonate ions

Question 33

Describe the intestinal phase?

Answer 33

1. In response to fatty acids and amino acids in chyme, the I cells of duodenal mucosa secrete cholecystokinin into the blood - Cholecystokinin (CCK) stimulates a pancreatic secretion that is rich in digestive enzymes 2. In response to acidic chyme (low pH) in the intestinal lumen, jejunal S cells release secretin into the blood - Secretin stimulates the flow of pancreatic juice that is rich in bicarbonate ions