the gastrointestinal system

Question 1

difference between chyme and bolus

Answer 1

a mass of chewed food mixed with saliva that is ready to be swallowed
while
chyme is the semi-fluid mixture of partially digested food and digestive juices that is formed in the stomach. After swallowing, the bolus travels down the esophagus and enters the stomach, where it undergoes further digestion and mixing with gastric juices to form chyme.

Question 2

the six essential activities of the GI system

Answer 2

ingestion, propulsion, mechanical digestion, chemical digestion, absorption, defecation

Question 3

the primary digestive organs

Answer 3

mouth– pharynx,– oesophagus,– stomach,– small intestine– large intestine

all others are accesory digestive organs

Question 4

the three divisions of the small intestine

Answer 4

duodenum
jejunum
ileum

Question 5

is water a class of nutrients

Answer 5

yes

Question 6

main function of the GI tract

Answer 6

to process food

Question 7

basic compositon of saliva in the mouth

Answer 7

water
salivary amylase
mucins

Ions, buffers, metabolites, antibodies, etc

mucins are high molecular weight proteins that secrete mucous to lubricate the mouth and food

Question 8

the four layers of the walls of the GI tract

Answer 8

mucosa,– submucosa,– muscularis externa,– serosa

walls of the GI always have these same 4 layers

Question 9

what releases pepsinogen when stimulated

Answer 9

zymogen granules

Question 10

what converts inactive pepsinogen to pepsin(the active form)

Answer 10

HCl

note that pepsin is a protease.

Question 11

which cells contain the zymogen granules which release pepsinogen

Answer 11

chief cells

Question 12

H/K ATPase function

Answer 12

Pumps H+ and K+ into stomach, Cl- follows passively, creating acidic environment for digestion and nutrient absorption.

Question 13

the main substances that the parietal cell secretes

Answer 13

HCL
Intrinsic factor

note that the intrinsic factor is required for Vitamin B12 absorption in the intestines

Question 14

the three main endocrine cells

Answer 14

G, D and Enterochromaffin-like cells

G cells secrete gastrin , D cells secrete somatostatin, Enterochromaffin-like cells secrete histamine

Question 15

function of gastrin

Answer 15

acts directly on parietal cells to stimulate the secretion of gastric acid (HCl) by parietal cells in the stomach.

Question 16

histamine function

Answer 16

indirectly stimulates parietal cells to release HCl into the stomach lumen

it does this indirectly by stimulating the proton pump( (H+/K+ ATPase) through histamine(H2) receptors on parietal cells.

Question 17

are carbohydrates and proteins absorbed in the small intestines?

Answer 17

no, they are too large

note that fats are not digested nor absorbed in the SI, but carbs and proteins can be partially digested in the SI

Question 18

Sphincter of Oddi function

Answer 18

opens to allow entry of bile into the duodenum

when closed, entry is blocked

Question 19

acinar cells

Answer 19

exocrine gland cells that secrete numerous susbstances, and are found on numerous organs

in the pancreas they secrete pancreatic juice into the pancreatic duct

contain watery alkaline fluid and Hydrogen carbonate, and digestive enzymes

Question 20

trypsinogen activated to trypsin by?

Answer 20

enteropeptidases like enterokinase

Question 21

intestinal juice has a neutral pH, true or false

Answer 21

true

Question 22

non digestible carbohydratre is aka

Answer 22

fibre

Question 23

where does protein digestion begin in the GI tract

Answer 23

the stomach

Question 24

the main enzymes that carry out protein digestion

Answer 24

endopetidase(like pepsin, trypsin…etc): break down bigger protein molecules, from their midpoint

exopetidases: further breaks down peptide fragments produced by endopeptidases into individual amino acids or smaller peptides that can be absorbed by the intestinal epithelium.

Question 25

most abundant dietary fats

Answer 25

triglycerides