Ch 16.5 -- Pancreatic and Biliary Secretions -- VTPP 435

Ch 16.5 -- Pancreatic and Biliary Secretions -- VTPP 435

Pancreas

-behind and below stomach above first duodenum loop
-has Acini sacs that empty contents into duodenum

Exocrine Pancreas

-secretes pancreatic juice
-pancreatic enzymes secreted by acinar cells that form acini
-aqueous alkaline solution secreted by duct cells that line pancreatic duct

Acinar Cells secrete 3 types of pancreatic enzymes

-work best in a neutral or little alkaline environment
1) Proteolytic Enzymes -- protein digestion
2) Pancreatic Amylase -- carb digestion
3) Pancreatic Lipase -- fat digestion

3 Proteolytic Enzymes

1) Trypsinogen --> Trypsin
2) Chymotrypsinogen --> Chymotrypsin
3) Procarboxypeptidase --> Carboxypeptidase

Trypsinogen

-secreted into duodenal lumen
-activated by enteropeptidase
-inhibited by Trypsin inhibitor

Pancreatic Amylase

-converts dietary staches to disaccharide maltose and alpha-limit dextrin
-secreted in pancreatic juice in an active form

Pancreatic Lipase

-hydrolyzes dietary triglycerides into monoglycerides and free fatty acids
-secreted in active form

Steatorrhea

-main pancreatic exocrine insufficiency

Liver Functions

-secretes bile salts
-metabolic processing of major nutrients after absorption
-detoxifies or degrades body wastes
-synthesizes plasma proteins
-store glycogen, fats, Fe2+, Cu2+, and vitamins
-activate Vitamin D
-secrete 3 hormones
-produces acute phase proteins for inflammation
-excretes cholesterol and bilirubin
-removes bacteria and worn-out blood cells

Hepatocyte

-liver cell
-do all liver functiosn except phagocytic activity

Kupffer Cells

-liver macrophages

Hepatic Portal System

blood goes from digestive tract to liver to filter, then to heart

Lobules

-functional units of liver
-have vascular and bile channels
-have artery, portal vein, and bile duct connected to it

Sinusoids

-expanded capillary spaces in lobule where blood from artery
-lined with Kupffer cells

Common Bile Duct

transports bile from lobules to gall bladder

Gall Bladder

-small saclike structure beneath liver
-stores bile between meals
-contracts during a meal

Bile Constituents

-bile salts
-cholesterol
-lecithin (phospholipid)
-bilirubin
-in an aqueous alkaline fluid

Enterohepatic Circulation

-recycles old reabsorbed bile salts between small intestine and liver
-bile salts reabsorbed into blood by active transport at terminal ileum

Micelle

-hydrophobic inner and hydrophilic outer shell
-can dissolve water-soluble and insoluble substances
-carry fat products to sites fo absorption

Bile Salts

-actively secreted into bile
-help with digesting & absorbing fats

Jaundice

-excess bilirubin that is not excreted
-appear yellowish
-3 causes of Jaundice: Prehepatic, Hepatic, & Post hepatic

Prehepatic Jaundice

-excessive breakdown of RBCs
-results in liver having more bilirubin than normal

Hepatic Jaundice

liver diseased and cannot deal with even normal load of bilirubin

Post Hepatic Jaundice

-bile duct is obstructed so bilirubin cannot be removed in feces
-usually by a gallstone

Hepatitis

-inflammation of liver
-causes: viral infection, obesity, exposure to toxins

Cirrhosis

-damaged hepatocytes replaced by connective tissue
-eventually leads to chronic liver failure