Chapter 17- Part 3Digestive functions of:• Liver• Gallbladder• Pancreas

The LiverLesson Outline:1. Location and structure (ANATOMY)2. Blood supply with all the “stuff” in the

blood that is needed to function (PHYSIOLOGY-organ-level function)

3. See the micro-structure of the liver (HISTOLOGY)

4. Marvel at the wonder of hepatocytes, or liver cells—are they perhaps the most ‘intelligent” entities on the planet? (CYTOLOGY)

Liver Brainstorm• Perhaps least

understood, both popularly and scientifically?

• Brainstorm: 30 seconds and three adjectives or phrases.

Liver Brainstorm—take 30 seconds to write your first thoughts about the liver:Adjective/phrase 1:

Adjective/phrase 2:

Adjective/phrase 3:

Locate Your Liver

• Upper right quadrant deep to inferior ribs

• Dome of liver lies against inferior diaphragm surface

• Left/right lobes• Gall bladder is thin

muscular sac on inferior surface where bile collects (#1 above)

Easy to percuss because it is solid and large.

Lobes

--Two principal lobes (R & L) separated by falciform ligament

-Two accessory lobes ( caudate & quadrate lobes are not true “lobes”)

What does it do?• Secretes bile- emulsifies fat, makes them water soluble.

• Carbohydrate metabolism-glucose/glycogen

• Stores glycogen,vitamins A, D, E, K, B12 cholesterol, iron

• Makes clotting proteins• Detoxifies blood• Destroys damaged RBC by

phagocytosis• Makes lipoproteins,

phospholipids, adipose for storage, and cholesterol

• Detoxifies drugs and alcohol• Makes urea from aa

Multi-function, blood-processing “factory”

• Regulates nutrient levels in blood—keep constant supply of sugars, fats, amino acids, nucleotides (including cholesterol)

What is bile???• Yellow-green, alkaline (pH 7.6-8.6)• Composed of water, ions, bile acids,

organic molecules (including cholesterol, phospholipids, bilirubin)

• Bile Salts: Acids and salts that emulsify (break up) fats for absorption across wall of small intestines. Ions to buffer chyme from stomach.

• Bile pigments: Contains waste products from RBC breakdown and other metabolic processing (color of feces from bilirubin in bile)

ruby

Bili Lights

Performed on newborn or premature infants to reduce elevated levels of bilirubin. If blood levels of bilirubin become too high, the bilirubin begins to dissolve in the body tissues, producing the characteristic yellow eyes and skin of jaundice. 

Regulation of bile Release• fatty chyme entering duodenum stimulates gallbladder to release bile

• 95% of the bile produced by the liver is “recycled”…often 2 or 3 times during the digestion of a single meal

Cholesterol & the Liver• Our body needs cholesterol for:

– Cell membranes– Vitamin D– Hormones—progesterone and testosterone– Myelin (neuron axonal “wrapping”)– Component of bile salts

• 85% of cholesterol in our blood is made by our own cells (mostly liver)

• 15% comes from the food we eat

So, is zero-cholesterol good…or even healthy?

Hepatocytes (liver cells) Many organelles

Rough ER – manufactures blood proteins Smooth ER – help produce bile salts and detoxifies

blood-borne poisons Peroxisomes – detoxify other poisons, including

alcohol Golgi apparatus – packages Mitochondria – a lot of energy needed for all this Glycosomes - role in storing sugar and regulation of

blood glucose (sugar) levels Produce 500-1000 mL bile each day

Secrete into bile ducts Regeneration capacity through liver stem cells

CV

lobu

le

sinusoid

triad

Triads: Branches of three vessels: hepatic portal vein, hepatic artery, along with bile drainage ducts all run together to infiltrate all parts of liver. Sinusoids: where blood flows and bile is removed.

Functional Unit

Triad

Kupffer cells Liver macrophages Old blood cells and microorganisms

removed

Cirrhosis of the Liver

Alcohol or drug abuseHepatitisBiliary diseaseMetabolic disease (iron or copper)Vascular outflow obstruction (ascites)

Vascular obstruction N = liver cells, F =

fibrous scar tissue

Normal

Ascites

Hepatitis

Lots of WBC

Cancer

Alcohol/Drug Abuse

Gallbladder Bile is stored in the gallbladder Concentrates bile by removing water Bile is excreted into the duodenum when

needed (fatty meal) Bile helps dissolve fat and cholesterol

Gall Stones Normally, cholesterol is in bile

solution, but it can precipitate with the bile salts Intermittent pain: ball valve

effect causing intermittent obstruction

Or infection and a lot of pain, fever, vomiting, etc.

Pancreas – Exocrine function• LUQ behind

stomach• releases

juice/enzymes into duodenum

Acinar cells make 22 kinds of enzymes

Enzymes released to duodenum, where activated

Pancreatic Juice

1. Pancreatic amylase – polysaccharide into disaccharides

2. Pancreatic lipase – breaks triglycerides into fatty acids

3. Proteases: Example-trypsin. All secreted in inactive forms and then converted with other enzymes to prevent digesting proteins in the cells that secrete them.

4. Nucleases – break nucleic acids into nucleotides

5. Alkaline (bicarbonate ions) to neutralize chyme and provide optimal pH for enzymes.