The Gastrointestinal Tract Flashcards
What is the function of teeth?
Function in the mastication of bolus
What are the functions of the tongue?
Mechanical processing
Assistance in chewing and swallowing
What are the three pairs of salivary glands?
Parotid
Submandibular
Sublingual
What factors does the saliva have that help with absorption and digestion?
Watery solution Electrolytes Buffers Glycoproteins Antibodies Enzymes Initiation of digestion of complex carbohydrates
What cells does the stomach have that helps with absorption and digestion?
Parietal cells (HCl and intrinsic factor) Chief cells (pepsinogen)
What endocrine functions does the liver have?
Insulin and glucagon
What exocrine functions does the liver have?
Majority of pancreatic secretions
Pancreatic juice secreted into small intestine- carbohydrases, lipases, nucleases, proteolytic enzymes
How is the liver involved in absorption and digestion?
Performs metabolic and haematological regulation and produces bile
Secreted into gallbladder and then into the duodenum via the common bile duct
What role does the large intestine have in absorption?
Re absorption in the large intestine includes- water, vitamins (K, biotin and B5), bile salts
Defaecation reflex triggered by distension of rectal walls
What is the physiology of absorption?
Breakdown of complex carbohydrates, proteins and fats- enzymes are either luminal (secreted by glands) or membrane bound
Absorption of digested nutrients/fluids through the brush border by active transport and diffusion (passive, facilitated, solvent drag)
What is malabsorption?
Difficulty in the digestion or absorption of nutrients from food
What are some causes of malabsorption?
Luminal enzymes -cystic fibrosis -chronic pancreatitis Mucosal -coeliac disease -lactose intolerance Structural -crohns disease -intestinal recession Infective -bacterial overgrowth -parasitic infection Non-GI disease -diabetes mellitus -hyperthyroidism
What is the process of carbohydrate digestion?
Starch/glycogen is broken down into trisaccharides by the helps of luminal digestion and the alpha amylase enzyme
The trisaccharides are then broken down into glucose, galactose and fructose by membrane digestion e.g. sucrase, lactase
What is the process of protein digestion?
Begins in the stomach- the low pH destroys the tertiary and quaternary structure and with the help of pepsin, the proteins are broken down into shorter polypeptides.
The pancreatic proteases produced in the pancreas travel to the duodenum and break the polypeptides down into peptides and amino acids.
These amino acids are then absorbed into the bloodstream at the brush border.
What is the process of fat absorption?
Triglycerides are broken down into lipase and fatty acids by pancreatic lipases.
The small lipids are emulsified by bile salts to form micelles.
The small lipid is then gradually leave the micelles an diffused into the intestinal epithelia.
