GI System Flashcards
Desribe the gi tract
Assembly line
List the 6 essential activities in GI
Ingestion
Propulsion
Mechanical digestion
Chemical digestion
Absorption
Defecation
List the GI primary organs
Mouth
Pharynx
Oesophagi
Stomach
Small intestine
Large intestine
List The GI secondary accessory
Teeth
Tongue
Salivary glans
Gallbladder
Liver
Pancreas
What does an adequate diet include
Lipids
Carbs
Proteins
Vitamins
Minerals
Water
Largest gland in the mouth
Salivary gland located anterior to ears
Basic composition of saliva
Water
Salivary amylase
Muffins
Ions
Buffers
Role of Saliva
Salivary amylase breaks down starch
Mucin - lubricating mouth
Moistens and converts into bouls to be easily swallowed
What are the 3 modifications of stomach wall
Circular
Longitudinal
Oblique
Role of stomach
Greater churning/ mixing ability
Mechanical breakdown if foodstuff into smaller pieces
Define mucus
Glycoprotein in stomach used for lubrication
Explain role of bicatbonate
Generates ph gradient to protect stomach wall from digestion by gastric acid
Recall:
Where is mucus secreted, stimulus release and function
Source: mucous neck cell
Sfr- tonic secretion, increasing with stomach irritation
Function- physical barrier between lumen and epithelium
Recall-
Source of secretion for bicarbonate with stimuli for release and function
Source- mucous neck cell
Sfr- secreted with mucous
Function- buffers gastric acid to prevent damage to epithelium
Recall-
Source of secretion for HCl, stimuli for release and function
Source - parietal cells
Sfr- ACh, gastrin, histamine
Function- activates pepsin and kills bacteria
Recall-
Source of secretion for intrinsic factor, stimulus for release and function
Source- parietal cells
Sfr- ACH, Gastrin, Histamine
Function- binds to b12 to permit absorption
Recall
Source of histamin
/ Stimulus for Release
and function of histamine
Source- enterochromaffin like cells
Sfr- ACH/gastrin
Function - Stimulate gastric acid secretion
Recalle source of pepsinogen/gastric lipase , stimuli for release and function
Both released by chief cells
Both stimulates byACh, acid, secretin
Pespin- proteins
Gastric lipase - fats
Recalls source stimulation for release and function of somastatin
D cells source
Sfr- acind in stomach
Function- stops gastric acid secretion
Recalls source stimulation for release and function of gastrin
Source - G cells
Stimuli for release a ACh peptides and amino acids
Function- stimulate gastric acid secretion
List 3 reasons to why gastric juice does not digest stomach wall
Mucous barrier by epithelial cells
Alkaline mucous barrier
Tight junction between epi cells prevent acid leaking
State turnover for GI epi cells
Every 3 days
How is the Stomach Surface Area increased
Finger like projections called villi & invaginations called crypts
Describe relationship between surface area and absorption
Increased SA= Increased absorption
Where does absorption take place
Small Intest
State what happens in the duodenum
Enteroendocrine cells secrete peptide bile added to chyme
Role of the liver
Synthesis and secretion if bile
What are bile salts composed of
Cholesterol
Role of bile/liver
Emulsification of fat globules
Decrease size of droplet= increase sa
Role of gallbladder
Concentrates and stores bile
When will bile be stored in gallbladder
When sphincter of oddi closes bile cannot enter duodenum
Role of pancreas
Have acinar cells which secrete pancreatic juice into pancreatic duct containing HC03
What is pancreatic juice made of
Water
Organic subs
Enzymes
Inorganic subs
Describe the intestinal juice
Neutral PH
Medium for digestion and absorption
Contains digestive enzymes made from epi cells in si
How is glucose absorbed
Active transport
What cannot be digestedin stomach
Cellulose also known as fibre
Explain what happens to proteins
Broken down to dipeptides and single amino acids and join with sodium for transport
Explain the role of emulsification in lipid digestion
Bile increases lipid droplets solubility and digestibility by breaking them down to smaller pieces
What does pancreatic lipase break TAGs down into
2 fatty acids
1 monoglyceride
Where do FAs rapidly absorb into
Portal vein
Steps in lipid absorption
Emulsification
Micelle formation
Hydrolysis
Absorption
Restedification
Lipoprotein formation/transport
How do lipids reach blood stream
Absorbed by intestinal mucosa
Broken down into chylomicrons
Moved into lymphatic system
Emptied in venous blood
How and where are vitamins absorbed
Jejenum and ileum
Passive diffusion
What happens to vitamins once absorbed
Transported ti liver and fatty tissue by chylo/lips
Explain the difference between absorption of vitamins and b12
Watee soluble vitamins diffuse into blood
B12 remains with intrinsic factor
Recall how b12 is absorbed
Remains with intrinsic factor
Absorbed via endocytosis
