Siebecker Lecture 1

Question 0

What are pancreatic enzymes responsible for?

Answer 0

Breaking down big particles down into smaller particles.

Question 1

Digestion occurs by enzymes from which 2 areas?

Answer 1

• Pancreatic enzymes (& bile) in lumen

- Brush border enzymes on the membrane

Question 2

What are brush border enzymes responsible for?

Answer 2

Breaking down small particles into single units

Question 3

Digestion occurs through 2 main methods:

Answer 3

-Mechanically chewing
-Chemically through acids and enzymes
These break food down into the smallest particles.

Question 4

Absorption occurs through ________. What is a possible consequence?

Answer 4

Transporters. Transporters can get overwhelmed/saturated and can become too small to accommodate food particles or the number of transporters can be reduced.

Question 5

In pancreatic secretion, what do acinar cells secrete, duct cells?

Answer 5

Acinar cells: digestive enzymes

Duct cells: water and bicarb

Question 6

What does the main pancreatic duct drain?

Answer 6

Enzymes, water, and bicarb into the small intestine

Question 7

What do the Islets of Langerhans secrete?

Answer 7

hormones (insulin and glucagon) into the blood

Question 8

What is the purpose of pancreatic secretion of water and bicarb?

Answer 8

Neutralize acid from the stomach

Question 9

What stimulates the secretion of pancreatic enzymes, and what purpose does this serve?

Answer 9

Stimulated by Neuroendocrine System; digestion of food

Question 10

What are the 3 Pancreatic Phases?

Answer 10

Cephalic, Gastric, and Intestinal

Question 11

What happens during the Cephalic Phase?

Answer 11

Vagus nerve stimulates pancreatic secretion in response to conditions reflexes: Smell, Taste, Chewing, and Swallowing.

Question 12

What happens during Gastric Phase?

Answer 12

Vagus nerve stimulates gastric distension.

Question 13

What is the most important phase for the pancreas?

Answer 13

Intestinal Phase

Question 14

What happens during Intestinal Phase?

Answer 14

Digestive products trigger release of hormones that control secretions.

Question 15

Where is CCK released from?

Answer 15

It is released from the I cells by fat and protein (peptides/amino acids)

Question 16

What is the purpose of CCK?

Answer 16

Stimulates enzyme and bile secretion for digestion.

Question 17

Where is Secretin released from?

Answer 17

It is released from S cells by H+ (acid) and fat.

Question 18

What is the purpose of Secretin?

Answer 18

Stimulates water and bicarbonate secretion to neutralize acid.

Question 19

What do saccharides need for absorption?

Answer 19

Brush border enzymes to be broken down into monosaccharides for absorption.

Question 20

Humans do not make enzymes that break down which 2 types of sugars?

Answer 20

Oligosaccharides and fiber. Only bacteria make enzymes that can break these bonds. Use of prebiotics (a-galactosidase) feed these bacteria.

Question 21

Which dietary carbs are digestible by humans?

Answer 21

Starch (amylose and amylopectin), Sucrose (table sugar), Lactose (milk sugar), Trehalose (mushrooms, honey, shrimp, algea), Glucose (honey, fruit, vegetables), and Fructose (HFCS/agave/honey, fruit, vegetables).

Question 22

Most enzymes come from the brush border and act in the brush border, which one comes from the pancreas and acts in the duodenal lumen?

Answer 22

Amylase. Its substrate is starch and end products are dextrins, maltotriose, and maltose

Question 23

What are characteristics of the SGLT 1?

Answer 23

Transports glucose and galactose and uses active transport (requiring ATP/energy)

Question 24

What does GLUT 5 transport and by what means?

Answer 24

Fructose; through facilitated diffusion (easily saturated)

Question 25

What does GLUT 2 transport?

Answer 25

Glucose, galactose, and fructose

Question 26

What is the purpose of GLUT 2 transport?

Answer 26

It is the backup transporter for fructose when GLUT 5 is overwhelmed. It transports out enterocytes into the blood through facilitated diffusion.

Question 27

What is a consequence of disaccharides or larger carbohydrates remaining in the small or large intestines?

Answer 27

They can not be digested or absorbed, so they become food for the resident bacteria which can result in carbohydrate malabsorption.

Question 28

What are consequences of carbohydrate malabsorption?

Answer 28

Carbohydrates get fermented by bacteria which creates gas and the carbohydrates sitting in the intestine will have an osmotic effect drawing H2O. Gas + H2O will trigger: bloating, constipation/diarrhea, pain, nausea, flatulence, belching, GERD and fatigue.

Question 29

What are the 3 types of gas produced by bacteria?

Answer 29

Hydrogen, Methane, and Hydrogen Sulfide

Question 30

Which lactose malabsorption is genetic and which is a result of damage?

Answer 30

Primary - Congenital (rare): Genetic (born without lactase) | Secondary - Acquired (common): Damage (loss of lactase after weaning)

Question 31

What are the 2 phases of small intestine protein digestion?

Answer 31

Pancreatic enzymes in lumen of small intestine | Brush border enzymes

Question 32

What are the 5 pancreatic enzymes and what do they do?

Answer 32

Trypsin, Chymotrypsin, Elastase: breakdown protein into polypeptides (2-6 amino acids long) Carboxypeptidase A & B: breakdown polypeptides into amino acids

Question 33

What is the brush border enzyme and what does it do?

Answer 33

Aminopeptidases: breaks peptides (2-3 long) into amino acids

Question 34

Why can peptides able to be absorbed?

Answer 34

They are digested into amino acids inside the enterocyte.

Question 35

What activates Trypsin?

Answer 35

Enteropeptidase/Enterokinase (from the brush border) released by the detergent action of bile (fat helps protein digestion)

Question 36

What does Trypsin activate?

Answer 36

It activates chymotrypsin, elastase, and carboxypeptidase A & B. (It does NOT activate aminopeptidase).

Question 37

What is the transporter of peptides? And what gets absorbed?

Answer 37

PEPT1; amino acids, di & tri peptides (unlike di & tri saccharides), this is due to the presence of peptidases within the enterocytes.

Question 38

What is the gate function within the tight junctions?

Answer 38

It regulates passage of micro & macro molecules through the paracellular space between cells.

Question 39

What is the fence function within the tight junctions?

Answer 39

It keeps microbiotia and large substances out, for our protection.

Question 40

What is the consequence of increased intestinal permeability?

Answer 40

Prolonged/Constant opening of tight junctions allow unintended items through (paracellularly). Absorption of unintended items can also occur through the cell itself (transcellular) - think bacteria via lipid rafts.

Question 41

What does intestinal permeability cause?

Answer 41

It causes systemic symptoms and is a main cause of food reactions.

Question 42

How is it possible to have increased intestinal permeability without GI symptoms?

Answer 42

There are many other causes of intestinal permeability that do not involve GI damage and opening of tight junctions. (i.e. hormonal disregulation and traumatic brain injury)

Question 43

What are the consequences of stress on digestion?

Answer 43

Stress inhibits digestion by lowering HCl, bicarbonate, bile, and enzymes and increasing intestinal permeability.

Question 47

CCK and Secretin release are what type of process?

Answer 47

Parasympathetic processes

Question 48

Stress (sympathetic) will ________ secretion.

Answer 48

Inhibit