Liver and bile secretionBile is a complex fluid formed by the liver cells Bile is a complex fluid formed by the liver cells and pass through bile ducts into the duodenum and pass through bile ducts into the duodenum

it may be considered as secretionit may be considered as secretion because it because it contain specific substance very important for contain specific substance very important for

body function, bile salts .body function, bile salts .

It may considered as excretionIt may considered as excretion due to presence due to presence of substance which are not of substance which are not needed by the

body ,bile pigments.

Characters of bile:Volume : 1-2 liter per day : 1-2 liter per day PH: Liver bile : alkaline : Liver bile : alkaline Gall bladder bile : acidic. : acidic.Constituents; inorganic substance ,all inorganic substance ,all composition of plasma proteincomposition of plasma proteinOrganic : mainly bile salts & bile : mainly bile salts & bile pigmentspigments

Small amount of cholesterol ,fat, fatty Small amount of cholesterol ,fat, fatty acids, lecithin, and phospholipids.acids, lecithin, and phospholipids.

Functions of bile salts:► 1- Digestion: bile salts are able to decrease the surface tension of fat : bile salts are able to decrease the surface tension of fat

globules and breaks them into fine particles. This is called emulsifying or globules and breaks them into fine particles. This is called emulsifying or detergent action of bile salts. this helps in exposing a large surface areas for detergent action of bile salts. this helps in exposing a large surface areas for the action of lipase enzyme.the action of lipase enzyme.

► 2- 2- Absorption: Bile salts are important for the absorption of Bile salts are important for the absorption of ► Fatty acidsFatty acids ► Fat soluble vitaminsFat soluble vitamins D,E and K. D,E and K.► Help the absorption of Help the absorption of iron and calciumiron and calcium..► 3-Choleretric:Bile salts are the best stimulant of bile secretion by the Bile salts are the best stimulant of bile secretion by the

liver.liver.► 4- Solvents: Bile salts help to keep cholesterol in solution .so they prevent : Bile salts help to keep cholesterol in solution .so they prevent

their precipitation in the gall bladder and formation of gall stones.their precipitation in the gall bladder and formation of gall stones.► 5- 5- Stimulation of peristalsis; Bile Bile salts stimulate the movements of small salts stimulate the movements of small

& large intestine and prevent constipation.& large intestine and prevent constipation.► 6- 6- Anti-putrefactive: This effect is secondary to stimulation of fat effect is secondary to stimulation of fat

absorption , in the absence of bile salts, the unabsorbed fat form a layer absorption , in the absence of bile salts, the unabsorbed fat form a layer around the protein particles that prevent their digestion and absorption ,the around the protein particles that prevent their digestion and absorption ,the unabsorbed proteins act as a good medium for growth of bacteria in the unabsorbed proteins act as a good medium for growth of bacteria in the colon.colon.

► 7-7-Neutrilization of gastric HCL. of gastric HCL.► 8- Excretion of certain drugs, as toxins, copper. of certain drugs, as toxins, copper.

Regulation of bile secretion:► 1- Neural regulation.1- Neural regulation.► 2- hormonal regulation.2- hormonal regulation.► 3- Choleretric agents.3- Choleretric agents.► 1- Neural ► Vagal stimulation increases the rate of bile secretion markedlyVagal stimulation increases the rate of bile secretion markedly► 2- Hormonal regulation:► Secretin; can stimulate rate of bile secretion up to 80% above basal levels Secretin; can stimulate rate of bile secretion up to 80% above basal levels

,secretin does not increase rate of bile synthesis.,secretin does not increase rate of bile synthesis.► 3- Regulation by choleretric agentsalts ► Bile salts themselves stimulate bile secretion.Bile salts themselves stimulate bile secretion.► Histamine ,secertin, salicylates and bilocarpine.Histamine ,secertin, salicylates and bilocarpine.► Bile salts are reabsorbed via enterohepatic circulation rather than loss in Bile salts are reabsorbed via enterohepatic circulation rather than loss in

faeces and recycle over and provide a strong stimulus for bile flow by the faeces and recycle over and provide a strong stimulus for bile flow by the liver.liver.

► Hepatic blood flow: within limits regulate bile secretion.Hepatic blood flow: within limits regulate bile secretion.

Function of gall bladderFunction of gall bladder1-Storage of bile: which needed for fat digestion.which needed for fat digestion.2-Concentration of bile:: It concentrate bile from 600 cc to 60 cc (10 times by absorption of H2O , NAHCO3 from It concentrate bile from 600 cc to 60 cc (10 times by absorption of H2O , NAHCO3 from

bile secreted by the liver.bile secreted by the liver.

3- 3- Acidification of liver bile :So prevent ca+ stone formation. because ca dissolve in acidic mediaSo prevent ca+ stone formation. because ca dissolve in acidic media4-Equalization of pressure; The gall bladder help in preventing increase pressure in biliary passage.The gall bladder help in preventing increase pressure in biliary passage.

5- Secretion of mucus;So protect mucosa of gall bladder from highly concentrated bileSo protect mucosa of gall bladder from highly concentrated bile

► Mechanism of gall bladder evacuation:► 1- Nervous mechanism::The conditioned & unconditioned reflexes causes weak contraction of gall bladder wall. The conditioned & unconditioned reflexes causes weak contraction of gall bladder wall.

It is responsible for 10% of gall bladder evacuationIt is responsible for 10% of gall bladder evacuation..► 2-Hormonal mechanism:The contact of fat and the lesser extent protein with the duodenal mucosa stimulate The contact of fat and the lesser extent protein with the duodenal mucosa stimulate

the secretion of cholecystokinin hormone.it cause strong contraction of gall bladder the secretion of cholecystokinin hormone.it cause strong contraction of gall bladder wall and relax the sphincter of oddi. It is responsible for evacuation of 90% of gall wall and relax the sphincter of oddi. It is responsible for evacuation of 90% of gall bladder content.bladder content.

► Cholagogue: stimulate gall bladder evacuation. stimulate gall bladder evacuation.Example: cholecystokinin.Magnesium sulphate. Example: cholecystokinin.Magnesium sulphate. ► Choleretric: Stimulate bile secretion as bile salts.: Stimulate bile secretion as bile salts.

► Mechanism of gall bladder evacuation:► 1- Nervous mechanism::

The conditioned & unconditioned reflexes causes weak contraction of The conditioned & unconditioned reflexes causes weak contraction of gall bladder wall. It is responsible for 10% of gall bladder gall bladder wall. It is responsible for 10% of gall bladder

evacuationevacuation..► 2-Hormonal mechanism:The contact of fat and the lesser extent protein with the duodenal The contact of fat and the lesser extent protein with the duodenal

mucosa stimulate the secretion of cholecystokinin hormone.it mucosa stimulate the secretion of cholecystokinin hormone.it cause strong contraction of gall bladder wall and relax the cause strong contraction of gall bladder wall and relax the sphincter of oddi. It is responsible for evacuation of 90% of gall sphincter of oddi. It is responsible for evacuation of 90% of gall bladder content.bladder content.

► Cholagogue: stimulate gall bladder evacuation. stimulate gall bladder evacuation.Example: cholecystokinin.Magnesium sulphate. Example: cholecystokinin.Magnesium sulphate. ► Choleretric: Stimulate bile secretion as bile salts.: Stimulate bile secretion as bile salts.

JaundiceDefinition:

Yellowish coloration of all tissues caused by Yellowish coloration of all tissues caused by hyper bilirubinaemiahyper bilirubinaemia

Bilirubin level above 2mg% or20 Bilirubin level above 2mg% or20 micromole/litermicromole/liter

Normal level .0.2-0.8 mg%Normal level .0.2-0.8 mg%Types of jaundice:

1-Haemolytic jaundice;;Due to excessive destruction of RBC, the rate Due to excessive destruction of RBC, the rate of formation and excretion of bilirubin is of formation and excretion of bilirubin is increasedincreased..

22 - -Obstructive jaundice:Due to obstruction of biliary passage .the Due to obstruction of biliary passage .the obstruction may be intra hepatic or extra obstruction may be intra hepatic or extra hepatic .Gall stones & cancerhepatic .Gall stones & cancer. .

3-Hepatogenic jaundice:Caused by damage of the liver as a resultCaused by damage of the liver as a result of viral hepatitis, or phosphorus poisoningof viral hepatitis, or phosphorus poisoning..The liver function are impairedThe liver function are impaired . .

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