Lecture 45 & 46 - Digestion & Nutrient absorbtion

Question 1

Epithelium in the gut is an effective barrier for ________and their related _____

Answer 1

Epithelium in the gut is an effective barrier for pathogens and their related toxins

Question 2

The control systems of the gut involves the :

Answer 2

CNS, ENS, Hormones and muscle

Question 3

True or False:

Endocrine system acts on a minute time-scale

Answer 3

True

Question 4

ENS lines the intestinal, lined the same way from mouth to anus.

What controls the mucosal epithelial cells?

Answer 4

Submucous plexus - contains arteries/arterioles and ENS nerves

Question 5

What lies superficial to the submucous plexus?

Answer 5

deep muscular plexus

Question 6

True or False.

The ENS is completely autonomous

Answer 6

True

Question 7

True or False.

The PNS controls the regulation of motility and water and salt transport in the gut

Answer 7

False.

It’s the ENS

Question 8

What is the state after a meal

Answer 8

Fed state

Question 9

What happens in the fed state?

Answer 9

Stomach relaxes
Segmentation - push content/mixing
Peristalsis - propagates in anal direction

Question 10

What happens in the fasted state?

Answer 10

Migrating motor complex, slowly propagating constriction that moves along whole length of small intestine

Question 11

What happens in the mass movement contraction?

Answer 11

Defacation (colon, rectum

Question 12

True and False

The peristalsis that occurs in the esophagus is controlled by the ENS

Answer 12

False.

Its by the PNS - by a means of swallowing

Question 13

The final motor activity is the sum of the:

Answer 13

pacemaker activity and the neural activity

excitation and inhibition

Question 14

True or False

Salivation, gastric acid secretion, gastric peptide secretion - the beginnings of the fed state can be started by cephalic input (i.e the sight of food)

Answer 14

True

Question 15

The basic food groups are:

Answer 15

Carbohydrates
Proteins
Fats
Vitamins and minerals

Question 16

Predominant location of breakdown and absorption is the…

Answer 16

Duodenum and jejunum

Question 17

Digestion requires contact between food particles and digestive enzymes.

As such, vigorous ______ _____ for mixing and physical breakdown of foods exist.

Answer 17

Digestion requires contact between food particles and digestive enzymes.

As such, vigorous motor activity for mixing and physical breakdown of foods exist.

Question 18

Digestion is mostly dependent on enzymes released from _____ ______

Answer 18

Digestion is mostly dependent on enzymes released from exocrine pancreas

Question 19

The gut epithelium changes depending on the function of the tract at each point

The gut epithelium can be described as a monolayer of enterocytes

Answer 19

The gut epithelium changes depending on the function of the tract at each point

The gut epithelium can be described as a ______ of _______

Question 20

Enterocytes have an apical surface exposed to the ______

Answer 20

Enterocytes have an apical surface exposed to the Lumen

Question 21

Gut epithelial cells have a ______, where stem cells are produced

They then migrate to the _____ tip (in small intestine)

Answer 21

Gut epithelial cells have a crypt, where stem cells are produced

They then migrate to the villus tip (in small intestine)

Question 22

True or False

There is a change from secretory to absorptive (water) as cells migrate from the crypt to the villi tip

Answer 22

True

Lasts 3-8 days

Question 23

Amylase digests?

and where is it released?

Answer 23

Sugars, starches

Salivary and pancreatic

Question 24

Glucose and galactose are transported by the ___-_____ ___ ________(SGLT) across the apical membrane of enterocytes

Answer 24

Glucose and galactose are transported by the sodium-glucose linked transporter SGLT across the apical membrane of enterocytes

Question 25

Glucose and galactose are transported across the basolateral membrane by ____ _

Answer 25

Glucose and galactose are transported across the basolateral membrane by GLUT 2

Question 26

Fructose crosses the apical membrane with ____ _

Answer 26

Fructose crosses the apical membrane with GLUT 5

Question 27

Proteins are digested to _____ _____ and ___ ______

Answer 27

Proteins are digested to amino acids and short peptides

Question 28

What is an endopeptidase? What is an example?

Answer 28

Endopenetidases are responsible for breaking peptide bonds within an amino acid chain Pepsin

Question 29

What is an exopeptidase? What is an example?

Answer 29

An exopeptidase is any peptidase that catalyzes the cleavage of the terminal (or the penultimate) peptide bond; the process releases a single amino acid or dipeptide from the peptide chain Carboxypeptidases

Question 30

Which cells are responsible for the secretion of Pepsin

Answer 30

Chief cells

Question 31

What activates the chief cells?

Answer 31

acid pH (about 2), produced in stomach by H+ secretion from parietal cells - stimulated by Gastrin

Question 32

From what is Trypsin secreted?

Answer 32

pancreas yo

Question 33

What activates trypsin, chymotrypsinogen and procarboxypeptidase?

Answer 33

CCK - released from the duodenum enteroendocrine cells

Question 34

How do single AAs cross the apical membrane?

Answer 34

via Na+ transporters also cross the basolateral membrane via Na+ transporters

Question 35

How do di-and tr-peptides cross the apical membrane?

Answer 35

via H+ coupled transporters usually broken to AA's within the cells consequently

Question 36

Fats are broken by ______ in the mouth

Answer 36

lipase

Question 37

You need ___to absorb the fats. How does ____ help?

Answer 37

Bile Bile salts coat fat droplets and together with mixing motility emulsify them.

Question 38

What is the role of secretin?

Answer 38

Secretin is a hormone that both controls the environment in the duodenum by regulating secretions of the stomach and pancreas, and regulates water homeostasis throughout the body.

Question 39

What is the role of cholecytokinin?

Answer 39

CCK is a peptide hormone of the gastrointestinal system responsible for stimulating the digestion of fat and protein. Cholecystokinin, is synthesized by I-cells in the mucosal epithelium of the small intestine and secreted in the duodenum, the first segment of the small intestine, and causes the release of digestive enzymes and bile from the pancreas and gallbladder, respectively.