digestive system

Question 1

tubular gastrointestinal tract

Answer 1

mouth, esophagus, stomach, small intestine, large intestines and rectum

Question 2

accesory organs

Answer 2

liver, pancreas, gall bladder

salivary glands

Question 3

four layes tunics of the GI tract

Answer 3

1. ) mucusa
2. ) submucosa
3. ) muscularis
4. )Serosa

Question 4

saliva

Answer 4

99.5% water,  0.5% solutes
mucous, lysozyme, urea, amylase, lingual lipase, bicarbonate ions
Produced by parotid gland
cleanses mouth and teeth
dissolves food to begin digestion
mucus lubricates food for swallowing
lysozyme destroys bacteria
amylase: initiates starch digestion
lingual lipases is activated in the stomach

Question 5

digestive processes of the oral cavity

Answer 5

mastication (chewing)
salivary amylase
deglutition (swallowing)

Question 6

gastric secretions

Answer 6

hydrochloric acid
pepsinogen
pepsin
mucus

Question 7

hydrochloric acid

Answer 7

.  hydrochloric acid: 	
destroys bacteria in food
acid pH denatures proteins
converts pepsinogen to pepsin
inhibits gastrin secretions
stimulates secretin and CCK secretions

Question 8

pepsinogen

Answer 8

inactive form of pepsin (prevents pepsin from digesting proteins in chief cells where it is produced)

Question 9

pepsin

Answer 9

breaks peptide bonds in proteins –> peptides

Question 10

mucus

Answer 10

protective barrier, prevents digestion of stomach wall

Question 11

the hormone gastrin

Answer 11

stimulates 
parietal cells to secrete HCl
chief cells to secrete pepsinogen
Function:
increased secretion of gastric juice
decreased pH of gastric contents
indirectly: increased motility of the stomach and gastric emptying

Question 12

time of stomach emptying

Answer 12

stomach generally empties 2 to 4 hours after a meal
fluids: least time
carbohydrates less time than proteins
fats spend the longest time in the stomach
fatty acids in chyme stimulate CCK release which delays gastric emptying

Question 13

intrinsic factor

Answer 13

is required for absorption of vitamin B12
is required for erythropoiesis

pernicious anemia:
inadequate production of intrinsic factor leads to insufficient erythropoiesis

Question 14

movements within the small intestine

Answer 14

segmentation
localized contraction of circular muscle fibers in regions that contain food
mixes chyme with digestive juices
brings food into contact with mucosa for absorption
peristalsis
successive muscle contractions similar to but weaker than those in esophagus and stomach
pushes chyme forward through small intestine

Question 15

types of glandular tx in the pancreas

Answer 15

endocrine 
pancreatic islets 
alpha cells secrete glucagon 
beta cells secrete insulin 
exocrine 
-acini: acinar cells secrete pancreatic juices

Question 16

liver lobule flow

Answer 16

hepatocytes secrete bile into bile canaliculi which join to form bile ducts

Question 17

bile

Answer 17

produced by hepatocytes

Question 18

bile salts role in digestion

Answer 18

Break down
emulsify dietary fats in chyme (aqueous environment)
break down large lipid globules into small droplets (larger surface area for digestion)
Transport lipids to the lymph
“Micelles”

Question 19

bilirubin

Answer 19

is formed from the breakdown of hemoglobin (from “heme” portion )
liver removes waste bilirubin from the blood and secretes it in bile
intestinal bacteria in the GI tract breakdown bilirubin to form urobilinogen
– urobilin (stercobilin) - gives feces brown colour

Question 20

functions of the liver

Answer 20

carbohydrate metabolism 
lipid metabolism 
protein metabolism 
detoxification 
excretion of bilirubin 
synthesis of bile salts 
storage: glycogen, vitamins, iron
phagocytosis 
activation of vitamin D

Question 21

the gallbladder

Answer 21

storage and concentration of bile until bile required by small intestine

Question 22

the large intestine

digestive process

Answer 22

mechanical:
Haustra – pouches on large intestine =haustral churning
peristalsis
mass peristalsis
defecation reflex
chemical
** bacterial
fermentation of any remaining carbohydrates
bilirubin stercobilin
production of vitamin K and some B vitamins

Question 23

movements in the large intestine

Answer 23

haustral churning moves contents to next haustra
peristalsis moves contents along length of intestine
mass peristalsis is a strong contraction that pushes contents into sigmoid colon and rectum

Question 24

flatulence

Answer 24

A factor of these variables:
The bacteria in your colon

Type of food consumed

Motility time