Physiological Function Of The Digestive System Flashcards
What is the function of the digestive system?
To breakdown carbs, fats and proteins into smaller monomers for energy and molecules synthesis
What are the 6 main functions of the digestive system?
Ingestion: material emerged digestive tract via mouth
Mech processing: crushing and shearing material easier to propel
Digestion: chem breakdown of food into small organic drags for absorption
Secretion: release of water, acids, enzymes, buffers and salts to aid digestion
Absorption: movement of organic subs, electrolytes, vitamins, and water across digestive epithelium to interstitial fluid
Excretion: removal of waste products
What are the functions of the oesophagus, stomach, SI and LI?
Oesophagus: transit
Stomach: storage, acid/breakdown of physical breakdown (secrets intrinsic factor)
SI: duo; fat, prot, carb digest and absorb
Jeje; water and electrolyte abs
il; bile slate transport and B12 abs
LI: colon; storage, water and electrolyte transport
Redfin and anus: defecation
What function of the specialised cells of the stomach have?
Mucus: protects against acidity
Parietal cells: HCl and intrinsic fac
ECL cells: histamine to stim parietal cells
Chief cells: secrets pepsin and gastric lipase
D cells: somatostatin to inhib gastric acid
G cells: gastric, stim parietal cells to secrete gastric acid and chief cells pepsin
What are the functions of the LI?
Reab of water and compaction of insatiable contents into faeces
Absorb vitamins
Store fecal matter prior to defecation
What are the two main types of GI muscle movements with a brief explanation?
Serene ration: facilitates mixing of contents aiding absorption
Peristalsis: facilitates spears movement of gut contents
What is the defecation reflex?
Increases peristalsis throughout large intestine
Relaxation of internal sphincter and concomitant contraction of outer sphincter
Defecation occurs only with voluntary relax of the external sphincter via the pundendal never or when the internal Pa exceeds 55mgHg
What are the main functions of the Liver?
Secretes bile and digestive fluid Metabolises proteins, carbs and fats Stores glycogen, vitamins and minerals Synth blood clot fac Removes waste and toxic mater from blood The blood col Destroys old RBCs
How does the liver synthesise bile salts?
From cholesterol via p450 oxidation to cholic acid or chenideoxycholic acid
Primary bile salts: cholic acid becomes either glycocholic or taurocholic acid with glycine or taurine
What is the physiological function of bile salts?
Solubilises polar lipids during digestion
Antibacterial properties
Denaturing proteolysis
pH for enzyme function
How is bile stored?
Bile is secretes by hepatocytes
Stored in the gallbladder from the common hepatic duct
Concentrates the bile
Bile salts secretion controlled by conc on blood
More in blood more secretes (and CCK)
What is the function of the exocrine pancreas?
Aq: neutralise the duo content,
Prevents damage to duo mucosal by acid and pepsin
Beings pH to optimal range for pancreatic enzymes
Enzymatic: enzymes for digestion
What is the mechanism of pancreatic secretion during the cephalic phase?
Stim from smell or taste, to the vagus nerve activating the G cell to secrete gastrin
The vagus nerve also act the ductal cells and acinar cells to produce water and bicarb and enzymes respectively
What is the mechanism of pancreatic secretion during the intestinal phase?
Acid, fat and protein enters the intestines
Acid activated the S cells to secrete secretin which activates ductal cells to produce water and bicarb
Fat and proteins act I cells to produce CCK which activates the vagus nerve (vagovagal reflex) to act the duct and acinar cells to prod water, bicarb and enzymes
What pancreatic enzymes do acinar cells secrete?
Trypsinogen Chymotrypsinogen Carboxypeptidase Amylase Lipase Ribonuclease
