Functions:
1. Production of bile- (breaks down lipids) and stores bile in the
gall bladder.
2. Removes extra nutrients from the blood and stores them
(glucose is stored as glycogen)
3. Stores iron and some vitamins
4. Breaks down “poisons” and detoxifies them to be excreted in
urine.
5. Removes and breaks down bacteria and old RBC’s.
Gross anatomy:
•Largest visceral organ
•Has 4 lobes; divided into lobules.
•Lesser omentum anchors the liver to the stomach.
•Gets its blood supply from the hepatic artery; blood drains away
from the liver by the hepatic portal vein.
Gross anatomy:
•Bile is produced by the liver and collects in
ducts which lead to the hepatic duct.
•This fuses with the cystic duct from the
gall bladder and together form the
common bile duct which empties into
the duodenum.
•On the way, if it’s not needed, bile can
back up into the cystic duct and on into
the gall bladder to be stored.
Gross anatomy:
•Bile is 97% water and 3% salts. It’s made from cholesterol and is
the main way we excrete extra cholesterol. Too much fat in the diet
will sometimes cause cholesterol to come out of solution and
deposit as crystals in the gall bladder, causing gall stones.
•Function: to emulsify fat globules- that is to break them apart into
smaller globules that can be suspended in the watery intestinal
juices. This also greatly increases the surface area so the lipid (fat)
molecules can be broken down by the pancreatic enzyme, lipase.
•Lipase digests lipids
Three types of Lipids:
•Neutral fats (fats and oils)
•Phospholipids
•Steroids
Their 4 main properties include:
•Non-polar
•Insoluble in water (can’t dissolve)
•Soluble in alcohol
•Made of C,H, and O (phospholipids also include P)
NEUTRAL FATS:
•Also called fats and oils; Make up adipose tissue
Fatty acid
Fatty acid
Fatty acid
FUNCTIONS:
Neutral fats are used for:
1. Fuel: can be converted to sugars; It’s main function is to store
energy (stores 2X the energy as carbohydrates)
2. Padding: for organs, ex.-kidneys
3. Insulation: which helps maintain body temp.
4. Transport: helps the body dissolve and transport fat-soluable
vitamins that are insoluble in water. Oil droplets can be pushed
along in the blood stream by blood pressure and vitamins “ride”
the oil droplet.
Neutral Lipids come in two forms: Saturated and Unsaturated
Saturated Lipids: absorbed by LDL
•TYPES OF BONDS: Contain fatty acids with all carbons attached
by single bonds. (the max. number of hydrogens are bonded to each
carbon)
•PROPERTIES: solid at room temperature; ex-fats.
•HEALTH RELATIONSHIP: Have been linked to buildup of fatty
plaque in arteries and contribute to hardening of the arteries
(athroschlerosis) and the development of type II diabetes.
Unsaturated Fats: absorbed by HDL
•TYPE OF BONDS: Contain fatty acids with one or more than one
carbon to carbon double bond so they don’t have as many
hydrogens.
•One double bond = monounsaturated
•More than one double bond= polyunsaturated
• PROPERTIES: Are liquid at room temperature ex-oils (plant fat)
•Release energy when the carbon to hydrogen bonds are broken
•HEALTH RELATIONSHIP: Are less likely to cause plaque
buildup, some research suggests it reduces arterial plaque
Phospholipids:
•Function: Make up cell membranes.
Steroids: (not anabolic steroids)
•Health effects: Too much in the blood stream can lead to
arthrosclerosis
•Example: cholesterol
•Makes vitamin D, steroid hormones and bile salts
•Found in and gives structure to the cell membrane
Microscopically, they have no capillary network. Instead it is made
up of microscopic lobules which contain the cells that produce bile
and within them are sinusoids (tiny spaces)
Sinusoids are lined with Kupffer cells which phagocytize and
break down old RBC’s and bacteria.
Bilirubin is a breakdown product of hemoglobin from RBC
disassembly. It gives bile its yellowish color as seen in feces. If
too many RBC’s are being destroyed, or the liver malfunctions
(as with cirrhosis or hepatitis), bilirubin build up in the system
causes us to turn yellow = jaundice.
•The body’s major producer of
digestive enzymes.
•Is located below the stomach,
nestled in the curve of the
duodenum.
•Is an exocrine gland (produces
enzymes) and also a endocrine
gland produces hormones.
• Exocrine part has digestive
functions. Units are acini
(clusters of cells that make
pancreatic juices)
• Ducts leading from acini secrete
sodium bicarbonate to help
neutralize pH of liquid coming
from the stomach.
• All small ducts throughout the
pancreas merge into 1 big ductthe pancreatic duct.
• This combines with the common
bile duct just before both empty
into the duodenum close to the
pyloric valve.
The pancreas participates in digestion of all 3 major biochemical
nutrients and nucleic acids (DNA/RNA). This takes place where
the pancreatic duct dumps pancreatic juices into the duodenum
(upper small intestine).
Carbohydrates- Amylase
Proteins- Protease
Lipids- Lipase
Nucleic Acids (RNA/DNA)- Nuclease
The pancreatic enzymes are activated in the duodenum by the
enzyme enteropeptidase. This is so the pancreas doesn’t digest
itself!
Hepatic duct
Cystic duct
duodenum