Ward: Small and Large Intestine Secretion and Absorption

Question 1

Two components of the pancreas

Answer 1

acini

islets of Langerhans

Question 2

Pancreatic secretions

Answer 2

proteolytic enzymes
carbohydrate enzyme (pancreatic amylase)
pancreatic lipase
cholesterol esterase

Question 3

List the three proteolytic enzymes released from the pancreas

Answer 3

trypsin
chymotrypsin
carboxypolypeptidase

Question 4

What activates trypsinogen to trypsin?

What activates chymotrypsinogen to chymotrypsin?

Answer 4

enterokinase

trypsin

Question 5

Released from glandular cells and inhibits the activation of trypsin inside the secretory cells, in the acini and in the pancreatic ducts

Answer 5

trypsin inhibitor

Question 6

In pancreatic acinar cells, enzymes are condensed into vacuoles and concentrated to form (blank), which can fuse with the apical membrane and rupture to release its contents

Answer 6

zymogen granules

Question 7

Enzymes of the pancreas are secreted by (blank)

Answer 7

acini

Question 8

When the pancreas releases pancreatic enzymes, it also releases (blank) and (blank)

Answer 8

water; bicarbonate ions

Question 9

The (blank) and (blank) concentrations in pancreatic secretion are approximately similar to that of plasma, but (blank) ion secretion is lower. The (blank) ion secretion increases with secretion rate

Answer 9

Na+; K+; Cl-; bicarbonate

Question 10

How is bicarbonate secreted from pancreatic cells?

Answer 10

Na/H+ exchanger pumps H+ in
H+ forms H20
H20 combines with CO2 to form bicarb which is shuttled out into the lumen in exchange for Cl-

Question 11

As Cl- moves down its concentration gradient into the lumen, (blank) follows, which pulls water with it into the lumen.

Answer 11

Na+; H20

Question 12

What is HCO3 secretion dependent upon?

Answer 12

The availability of Cl- in the lumen. Ultimately the opening of Cl- channels on the apical membrane.

Question 13

As secretory rate increases, conc. of bicarb (blank)

Answer 13

increases

Question 14

As concentration of bicarb in the lumen increases, the concentration of Cl- (blank)

Answer 14

decreases

Question 15

4 stimuli important for stimulating pancreatic secretion

Answer 15

1. ACh
2. gastrin
3. CCK
4. secretin

Question 16

released from parasympathetic vagus nerve terminals in the ENS

Answer 16

ACh

Question 17

released during the gastric phase of the stomach

Answer 17

gastrin

Question 18

secreted by duodenal mucosa when food enters the duodenum

Answer 18

CCk

Question 19

secreted when low pH products enter the stomach (neutralizes pH)

Answer 19

secretin

Question 20

ACh and CCK activate (blank), while secretin activates (blank)

Answer 20

Ca+ stores; cAMP

Question 21

During the cephalic and gastric phases, ACh and gastrin cause relatively (blank) pancreatic secretion

Answer 21

little

Question 22

Pancreatic secretion is increased considerably when chyme enters the duodenum, in response to the hormones (blank) and (blank).

Answer 22

CCK; secretin

Question 23

released from S cells in the mucosa of the upper small intestine. The stimulus for release is gastric acid and long chain fatty acids.

Answer 23

secretin

Question 24

The release of (blank) during the intestinal phase of pancreatic secretion increases the pH of the luminal contents so it is more optimal for pancreatic enzymes

Answer 24

bicarbonate

Question 25

Released from I cells within the mucosa of the duodenum and upper jejunum. The stimulant that causes the release appears to be proteoses and peptones

Answer 25

CCK

Question 26

Two important functions of the secretion of bile into the GI tract

Answer 26

1. emulsifies large fat particles into smaller ones | 2. serves as a means of excretion of waste products

Question 27

Two primary bile acids from cholesterol

Answer 27

cholic acid | chenodeoxycholic acid

Question 28

Constituents of bile

Answer 28

``` Bile acids Phospholipids Cholesterol Bile pigments Inorganic ions ```

Question 29

Major phospholipid found in bile

Answer 29

lecithins

Question 30

Most important bile pigment

Answer 30

bilirubin

Question 31

Bile secreted from the liver can flow into the terminal bile duct, to the hepatic duct, to the common bile duct where it can have one of two fates

Answer 31

1. goes to gallbladder via cystic duct | 2. empties directly into duodenum via the sphincter of Oddi

Question 32

The rate of secretion of bile is related to the amount of bile delivered to the liver by (blank)

Answer 32

hepatic circulation

Question 33

Bile acids are taken up from the bowel by the (blank) and transported back to the liver.

Answer 33

enterohepatic circulation

Question 34

3 pathways involved in bile absorption

Answer 34

1. passive diffusion 2. terminal ileum absoprtion 3. bacteria in terminal ileum and colon decongugate bile salts to bile acids

Question 35

derived from the metabolic breakdown of hemoglobin from aged RBC’s within the reticuloendothelial system to hemin and globin

Answer 35

bilirubin

Question 36

How is bilirubin transported to the liver?

Answer 36

bound to albumin

Question 37

Some bilirubin is extracted in the liver via and active anion transport system, conjugated with (blank) and secreted.

Answer 37

glucuronic acid

Question 38

Some of the bilirubin glucuronide is reduced by bacteria to (blank) and excreted in the feces.

Answer 38

urobilinogen

Question 39

Some bilirubin is passed to the systemic circulation, oxidized to form (blank) and excreted in the urine.

Answer 39

urobilin

Question 40

So, bilirubin can form bilirubin glucuronide, urobilinogen, or urobilin. If it forms bilirubin glucuronide, it's secreted in the (blank). If it forms urobilinogen, it's excreted in the (blank). If it forms urobilin, it's excreted in the (blank).

Answer 40

intestine feces urine

Question 41

T/F: secretion of electrolytes can be bile acid dependent or bile acid independent.

Answer 41

True

Question 42

As bile acids move towards the distal ileum, primary acids are converted to secondary acids. Hydrophobic acids are absorbed (blank), whereas hydrophilic acids are absorbed by (blank). A minor fraction are not absorbed but transported to the colon.

Answer 42

passively; Na+ active transport system

Question 43

Absorbed bile acids are transported to the (blank) where they are actively extracted from the blood and re-secreted

Answer 43

liver

Question 44

3 components of bile

Answer 44

bile salts phospholipids cholesterol

Question 45

What can these lead to? Too much absorption of water from bile (too concentrated). Too much cholesterol in bile, leading to precipitation. Too much absorption of bile acids from bile. Inflammation of the epithelium.

Answer 45

formation of gall stones

Question 46

found extensively in the duodenum between the pylorus and papilla of Vater, secrete mucus

Answer 46

Brunner's glands

Question 47

``` What do these do the Brunner's glands? (i) tactile stimuli (II) irritating stimuli (iii) vagal stimulation (iv) GI hormones ```

Answer 47

cause them to release mucus

Question 48

What is the function of mucus in the small intestine?

Answer 48

to protect the intestinal wall from digestion by gastric juices

Question 49

Secretion of Brunner’s glands is inhibited by (blank), which can lead to the duodenal bulb being unprotected. This is thought to be one of the factors leading to peptic ulcers

Answer 49

sympathetic stimulation

Question 50

Secrete extracellular fluid in the small intestine, which is rapidly reabsorbed by the villi. This solution acts as a carrier for absorption of nutrients

Answer 50

crypts of Lieberkuhn

Question 51

(blank) line the mucosa of the large intestine, while (blank) are not present.

Answer 51

Crypts of Lieberkuhn; villi

Question 52

(blank) stimulation results in copious amounts of mucus secretion.

Answer 52

parasympathetic

Question 53

protects the lining of the large intestine from acid that is formed deep in feces. It also provides a medium for the formation and binding of fecal material

Answer 53

mucus

Question 54

Cl- secretion in the large intestine is under (blank) regulation

Answer 54

cAMP

Question 55

Responsible for numerous pandemic infections of extreme diarrhea and dehydration across the globe, resulting in millions of deaths

Answer 55

cholera