GI Reflexes

Question 1

What are the two reflexes in the colon?

Answer 1

Gastroileal reflex

Gastrocolic reflex

Question 2

What is the gastroileal reflex?

Answer 2

Food in stomach triggers the release of gastrin and the motor activity in the ileum increases and the ileocecal sphincter relaxes, so the ileal contents move into the large intestine in anticipation of a new meal.

Question 3

What is the gastrocolic reflex?

Answer 3

Mass peristalsis- Food in the stomach triggers mass movement of colon contents, starting halfway through transverse colon, all the way to the rectum.

Question 4

How many species of bacteria live in the large intestine?

What do they do?

Answer 4

800+

fermenting cellulose and indigestible carbs

Question 5

Other than advancing chyme, what three things does the large intestine do?

Answer 5

1- Intestinal gas- H2, CO2, N2, CH4
2- Decomposition of bilirubin
3- Synthesize the B vitamins and vitamin K

Question 6

The intestines absorb back __L of fluid a day. __L from water we drink, and __L from internal secretions

Answer 6

9L
2L
7L

Question 7

The Small intestine- absorbs ____ of fluid back and the large intestine absorbs ___ back; about _____ is excreted through feces a day

Answer 7

~8L
~1L
10cc

Question 8

What is a vitamin?

Answer 8

Small dietary compounds that are necessary for metabolism, absorbed unchanged, some we eat, some we make

Question 9

What is, and what are the fat-soluble vitamins?

Answer 9

Absorbed with other lipids, need fat in the diet or can’t be absorbed
ADEK

Question 10

What do vitamin A and D do?

Answer 10

A- visual pigment, antioxidant,

D- Calcium absorption

Question 11

What do vitamin E and K do?

Answer 11

E- antioxidant, wound healing

K- Clotting

Question 12

What are the water-soluble vitamins and what do they do?

Answer 12

B-complex (Not B12)- Function as coenzymes

C- promotes collagen formation, Hb synthesis, sound CT structure

Question 13

What is a free radical?

Answer 13

• Free radicals- chemical particles with an odd number of electrons. We produce them naturally, but also xrays, nitrites. We produce some, but vit C, K, E help.

Question 14

What are minerals? How does our body use them? Which two minerals are used differently?

Answer 14

Inorganic elements that plants extract from soil and water and are introduced to food web. Not used as fuel, but both are essential to our ability to use nutrients. Fe and Ca are unusual that they are absorbed in proportion to the body’s needs, whereas the other minerals are absorbed at a fairly constant rate, leaving the kidneys to excrete the excess.

Question 15

Feces are ___% water and ____% solids.

Answer 15

75%

25%

Question 16

What makes up the solids of feces?

Answer 16

Solids are 30% bacteria, 30% undigested dietary fiber, 10-20% fat, the remainder is proteins, dead cells, mucus, and salts

Question 17

Which 4 hormones control the large intestine?

Answer 17

Gastrin
GIP
Secretin
CCK

Question 18

Where is gaskin secreted?

Answer 18

By enteroendocrine cells in duodenal mucosa

Question 19

What stimulates GIP?

Answer 19

Glucose, fatty acids, amino acids

Question 20

What does GIP do?

Answer 20

↑ Insulin secretion

↓ HCl production

Question 21

What stimulates secretin?

Answer 21

Acidic chyme

Question 22

What does secretin do to the gastric area?

Answer 22

↓ gastric secretion

↓ gastric mobility

Question 23

What does secretin do to protect the colon?

Answer 23

↑ pancreatic juice rich in bicarb ions (↑pH)
↑ bile secretion
↑ intestinal mucus secretion

Question 24

What stimulates CCK?

Answer 24

Fatty chyme

Question 25

What does CCK do?

Answer 25

↑ pancreatic juice rich in digestive enzymes
Stimulates ejection of bile from the gallbladder (a bag of smooth muscle)
Relaxes the sphincter of Oddi- hepatopancreatic duct so bile can be released