physiology of the small intestine and accessory organs Flashcards
types of cells in pancreas
exocrine (99%)
endocrine (1%)
what do exocrine cells do in pancreas
- secretion of enzyme rich fluid into duodenum
- breaks down digestible food
what do endocrine cells do in pancreas
- release of hormones into bloodstream that affect carbohydrate metabolism
(insulin, glucagon, somatostatin)
what type of structure is the pancreas
similar to salivary glands
what to acinar cells do in pancreas
secrete enzymes and fluid into the duct system
what does the pancreatic duct fuse with
the bile duct on entry to duodenum
what controls composition of pancreatic juice
local nerves and hormones
what is the composition of pancreatic juice
- aqueous component
- enzymatic component
why is the pancreas a very dangerous organ to injure
due to the potency of its enzyme contents
how much of the aqueous component is secreted each day (pancreas)
200-800ml
what is the aqueous component rich in
bicarbonate (pH 8)
what does the aqueous component do
helps to neutralise acidic chyme as it enters the duodenum
what stimulates the secretion of the aqueous component
secretin
what makes up the enzymatic component (pancreas)
- proteolytic enzymes
- pancreatic amylase
- lipolytic enzymes
what do proteolytic enzymes do in pancreas
breakdown proteins
what does pancreatic amylase do
breaks down starch
what does lipolytic enzymes do in pancreas
digest fat
examples of proteolytic enzymes in pancreas
trypsin, chymotrypsins, carboxypeptidases
what and where is proteolytic enzymes activated
activated in duodenum by enterokinase
what would happen if proteolytic enzymes in the pancreas were secreted in active forms
auto degradation of the pancreas may occur
is pancreatic amylase secreted in active or inactive form
active
example of lipolytic enzyme in pancreas
lipase
is lipase secreted in active or inactive form
inactive
what and where is lipase activated in the pancreas
activated by trypsin in the duodenum
what controls pancreatic secretions
nervous and hormonal control
what happens in the cephalic phase (pancreatic secretions)
nervous reflex involves medulla and vagal innervation
what happens in the gastric phase (pancreatic secretions)
gastrin released in response to stomach distension
what happens in the intestinal phase (pancreatic secretions)
secretin and CCK is secreted by mucosa in response to presence of chyme in duodenum
what is secretin
bicarbonate rich aqueous juice
what is CCK
enzymatic juice
what is pancreatitis
pancreatic enzymes are activated within the pancreas, causing them to attack the pancreas itself
what are the two forms of pancreatitis
acute and chronic
when does acute pancreatitis become chronic
when pancreatic tissue is destroyed and scarring develops
what causes pancreatitis
gallstones
alcohol abuse
unknown causes
how to treat pancreatitis
pain and infection management
electrolyte therapy
surgical intervention (in severe cases)
where is the liver
lies in abdomen under diaphragm
what % of the total blood supply does the liver hold
13%
what are some functions of the liver
- processing digested food from intestine
- manufacture of bile
- storage
- metabolism
how does the liver help in storage
it converts excess monosaccharides to glycogen
stores iron, vitamins and other essential chemicals
how does the liver work for metabolism
breaks down stored glycogen, fat or protein to glucose (hormone control)
metabolises drugs and breaks down poisons
bactericidal activity
how are hepatic (liver) cells arranged
in radial pattern around central vein
what do hepatocytes make up
functional units called lobules
what do lobules form
lobes of liver (two main lobes)
how does the liver receive blood
receives oxygenated blood from hepatic artery
receives deoxygenated, nutrient rich blood from portal vein
what do hepatic cells do
- extract oxygen and most nutrients
- detoxify or store poisons and drugs
- secrete products (not bile) into hepatic vein
what are the characteristics of bile
excretory product of liver metabolism
a digestive secretion
what do bile salts do
emulsify fat into small droplets
what makes bile cholesterol soluble
bile salts
what does bile pigments do
give urine and faeces their colour
absorbed from blood
what do the epithelial cells lining the bile ducts secrete
bicarbonate ions which neutralise acid chyme
what increases secretion from the liver
vagal stimulation and secretin
what does the gallbladder do
stores and concentrates bile by extracting water and ions
can lead to increased insoluble cholesterol levels
how does bile enter the gall bladder
by the cystic duct when the small intestine is empty
when does ejection of bile into the duodenum occur
when protein or fat-rich chyme enters the duodenum, causes CCK release
what does the CCK cause the gallbladder to do
contract and the sphincter of Oddi to relax, allowing bile to enter the duodenum
what are gallstones
crystalline deposits that accumulate when there is too much cholesterol and not enough bile salts
how to treat gallstones
they can be dissolved
if they are severe the gall bladder can be removed
why is jaundice a symptom of gallstones
- stones can block the common bile duct
- increased levels of bilirubin in blood plasma
- discolouration of skin
