51 - Pancreatic juice – composition and functions. Regulation of pancreatic secretion. Formation and secretion of bile. Composition and function of bile. Regulation of bile secretion. Functions of the liver.

section

composition of pancreatic juice

bicarbonate and water roles in pancreatic juice

function of pancreas

regulation of pancreatic secretion

phases of pancreatic secretion

bile formation

composition of bile

function of bile

regulation of bile secretion

humoral effects on bile formation

function of liver

composition of pancreatic juice

• Pancreatic juice 700ml in 24 hrs, ph 7-8

• water, multiple enzymes for digesting of the three major types of food:

• proteins, carbohydrates, lipids, and fats

• The main types of pancreatic enzymes are:

  • Lipase: Breaks down fats. 

  • Protease: Breaks down proteins. 

  • Amylase: Breaks down carbohydrates. 

• The protein-digesting enzymes are secreted in inactive form to prevent them from digesting the pancreas itself.

  • Pancreatic juice is secreted most abundantly in response to the presence of chyme in the upper portions of the small intestine

bicarbonate and water roles in pancreatic juice

The 2 important components of pancreatic juice, :bicarbonate ions and water

• Bicarbonate ions play an important role in neutralizing the acidity of the chyme that enter duodenum from stomach

function of pancreas

– produce enzymes that break down carbohydrates, fats, and proteins

regulation of pancreatic secretion

• Nervous and humoral control initiated by three main stimuli:

• Three basic stimuli are important in causing pancreatic secretion:

  • Acetylcholine – released from the parasympathetic vagus nerve endings and from other cholinergic nerves in the enteric nervous system.

  • Cholecystokinin – released by the duodenum , increase secretion of digestive eenzymes

  • Secretin –secreted by the duodenum when acidic chyme enters small intestine. stimulates pancreas increase in secretion of bicarbonate ions and water

  • All cause increase in digestive enzymes

phases of pancreatic secretion

1. Cephalic phase

2. Gastric phase

3. Intestinal phase:

bile formation

• Bile is made in the Liver hepatocytes makes bile, 0.8-1L.--> GALL BLADDER Ph- 7.5-8.5

• Bile is secreted in two stages by the liver:

  • bile is from hepatocytes, contains large amounts of bile acids, cholesterol → gall bladder.

  • Secreted in duodenum

composition of bile

water, bile salts.

function of bile

• Emulsifies lipids,

• increases surface area so easier to break down by enzymes

• they aid in absorption of the digested fat, end products through the intestinal mucosa.

• Bile serves as a means for excretion of several important waste products from the blood. These include especially bilirubin and excesses of cholesterol

regulation of bile secretion

• Nervous:

  • Parasympathetic stimulation increase production of bile

• Humoral:

  • Secretin stimulates the secretion of bile

  • Cholecystokinin stimulates release of bile from the gall bladder- cause gall bladder contraction and relaxation of sphincter of oddi

function of liver

1. Maintains a normal blood glucose level.

2. Stores some triglycerides and breaks down fatty acids.

3. Synthesizes most plasma proteins

4. Detoxifies substances, such as alcohol, drugs

5. Excretes the bile.

6. Bile salts synthesis.

7. Stores vitamins (A, D, E, K, B12) and minerals.

8. Phagocytosis.

9. Activation of vitamin D.

10. Filtration and storage of blood