Digestion in the gastrointestinal tract – basic characteristics. Digestion of carbohydrates, proteins and fats

Question 1

General Characteristics of the Gastrointestinal System - 1

Answer 1

MOUTH

mechanical breakdown of carbohydrates into simple sugars using amylase enzyme/ mouth/ teeth/ saliva

Question 2

General Characteristics of the Gastrointestinal System - 2

Answer 2

PHARYNX

takes food from mouth to osephagus

nasopharynx -> oropharynx -> laryngopharynx

Question 3

General Characteristics of the Gastrointestinal System - 3

Answer 3

OSEPHAGUS

takes food from pharynx to stomach

using peristalsis

• upper osephagal sphincter + lower osephagl sphincter

Question 4

General Characteristics of the Gastrointestinal System - 4

Answer 4

STOMACH

x3 smooth muscle layers to force food to mix with gastric acids/ enzymes to form chyle

• pars cardiaca
• pars fundus
• pars corpora
• pars pylorica with antrum + sphincter

Question 5

General Characteristics of the Gastrointestinal System - 5

Answer 5

SMALL INTESTINE

absorption + digestion of nutrients

• duodenum
• jejunum
• illeum

Question 6

General Characteristics of the Gastrointestinal System - 6

Answer 6

LARGE INTESTINE

absorption of water
excretion of feces

• cecum = connected to small intestine
• colons - ascending/ transverse/ descending/ sigmoid
• rectum = stores feces
• anus = releases feces

Question 7

General Characteristics of the Gastrointestinal System - accessory organ 1

Answer 7

SALIVARY GLANDS

• production of saliva to help break down food in mouth

parotid/ submandibular/ sublingual

Question 8

General Characteristics of the Gastrointestinal System - accessory organ 2

Answer 8

LIVER

Question 9

General Characteristics of the Gastrointestinal System - accessory organ 3

Answer 9

GALL BLADDER

storage of bile from the liver
to be released into small intestine

• collum
• corpus
• fundus

Question 10

General Characteristics of the Gastrointestinal System - accessory organ 4

Answer 10

PANCREAS

production of digestive enzymes / bicarbonates to be released into small intestine

endocrine function - insulin/ glucagon

head/ neck/ tail

Question 11

Physiologic Anatomy of the Gastrointestinal Wall - 1

Answer 11

TUNICA MUCOSA = innermost lining

sublayers:

• epithelium = barrier/ secretion/ absorption via goblet cells
• lamina propria
• muscularis mucosa = muscular movements

Question 12

Physiologic Anatomy of the Gastrointestinal Wall - 2

Answer 12

TUNICA SUBMUCOSA

dense connective tissue
vessels
nerves

glands
immune cells
lymphatics

Question 13

Physiologic Anatomy of the Gastrointestinal Wall - 3

Answer 13

TUNICA MUSCULARIS EXTERNA

• inner circular layer = control diameter of lumen
• outer longitudinal layer = controls length of movement

Question 14

Physiologic Anatomy of the Gastrointestinal Wall - 4

Answer 14

TUNICA SEROSA = outermost layer

serous membrane coating external layers of organs
= connective tissue + mesothelium

Question 15

NERVE SUPPLY

Answer 15

ENS

• myenteric auerbach plexus = between circular + longitduinal layers = controlling motility
• submucosal meisner plexus = between tunica submucosa controlling absorption + secretion

SNS = inhibits GI tract
PNS = stimulates GI tract

Question 16

BLOOD SUPPLY - 1

Answer 16

abdominal aorta

• a. mesenterica superior = small intestine
• a. mesenterica inferior = large intestine
• celiac trunk = stomach/ liver/ spleen/ pancreas

Question 17

BLOOD SUPPLY - 2

Answer 17

portal vein
- collects blood from GI tract taken to liver

hepatic vein
- collects blood from liver, takes back to inferior vena cava

Question 18

Digestion of carbohydrates - 1

Answer 18

MOUTH

Question 19

Digestion of carbohydrates - 2

Answer 19

STOMACH

carbohydrate digestion stops in the stomach as environment is too acidic so salivary amylase is now inactive

Question 20

Digestion of carbohydrates - 3

Answer 20

PANCREAS

pancreas secretes amylase into small intestine

to break continue carbohydrate digestion

Question 21

Digestion of carbohydrates - 4

Answer 21

SMALL INTESTINE

brush border enzymes help convert disaccharides to monosaccharides

• maltose into glucose (maltase)
• sucrose into glucose + fructose (sucrase)
• lactose into glucose + galactose (lactase)

Question 22

Digestion of carbohydrates - 5

Answer 22

ABSORPTION

monosaccharides are absorbed into enterocytes to be taken to bloodstream

Question 23

Digestion of proteins - 1

Answer 23

mouth
nothing significant happens here for proteins

Question 24

Digestion of proteins - 2

Answer 24

STOMACH

HCl in stomach activates pepsinogen -> pepsin for protein digestion

Question 25

Digestion of proteins - 3

Answer 25

SMALL INTESTINE

pancreatic enzymes
- trypsinogen
- chymotrypsinogen

these are inactive enzymes but once released into small intestine they become active
function to digest proteins

Question 26

Digestion of proteins - 4

Answer 26

amino acids absorbed into enterocytes small intestinal epithelial cells taken to bloodtstream

Question 27

Digestion of fats - 1

Answer 27

MOUTH

• lingual lipase starts process

Question 28

Digestion of fats - 2

Answer 28

STOMACH

• gastric lipase

lipolysis: triglycerides -> diglycerides + fatty acids

Question 29

Digestion of fats - 3

Answer 29

SMALL INTESTINE

when fat enters small intestine then liver forms

bile functions emulsify fats into smaller globules so lipase action acts on a greater SA for more ROR digestion

Question 30

Digestion of fats - 4

Answer 30

ABSORPTION

fatty acids converted micelles to be transported by enterocyte small intestine epithelial cells to be absorbed into bloodstream