chapter 23 bio 142 part 4

Right Lobe of liver

Largest lobe; located on the right side of the liver, separated from the left lobe by the falciform ligament (anteriorly).

Contains most of the liver's mass.

Left Lobe liver

Smaller lobe; located on the left side of the liver.

Extends across the upper abdomen toward the spleen.

Caudate lobe

Small lobe on the posterior (back) surface of the liver, between the inferior vena cava and the ligamentum venosum.

Functionally independent; has its own blood supply and venous drainage.

Quadrate Lobe

Small lobe on the inferior (underside) surface of the liver, between the gallbladder fossa and the ligamentum teres.

Anatomically separate but functionally considered part of the left lobe.

1. What do you call the “ligament” that separates the right and left lobes of the liver?

falciform ligament.

Hepatic Portal Vein

carries:

Nutrient-rich, oxygen-poor blood from the digestive organs, spleen, pancreas, and gallbladder to the liver

nutrient in

Proper Hepatic Artery

carries

Oxygen-rich blood from the heart to supply the liver tissue

oxygen in

Bile Duct

carries

Bile produced by liver cells, carrying it away from the liver toward the gallbladder and small intestine

bile out

Describe the eight major function of the liver.

Easy mnemonic: "B-GM DSS BI"

• Bile production

• Glucose regulation

• Metabolism of nutrients

• Detoxification

• Synthesis of proteins

• Storage of vitamins/minerals

• Bilirubin processing

• Immune filtration

What do you call the microscopic hexagon-shaped functional units of the liver?

Hepatic lobules

What is found in the outer corner of each hepatic lobule?

The portal triads

What is found at the center of each hepatic lobule?

The central vein

What do you call liver cells?

Hepatocytes

Hepatocytes function

They perform most liver functions, including bile production, nutrient metabolism, detoxification, protein synthesis, and storage of vitamins and glycogen

What do you call the special capillaries within the liver that the blood flows through?

Hepatic sinusoids

What do you call the macrophages within the liver?

Kupffer cells

Trace a drop of blood from the hepatic portal vein or hepatic artery through the lobules and out of the liver.

Hepatic Portal Vein or Hepatic Artery → Sinusoids → Central Vein → Hepatic Vein → Inferior Vena Cava → Heart.

Trace a drop of bile from production to the duodenum.

Hepatocytes → Bile Canaliculi → Bile Ducts → Hepatic Ducts → Common Hepatic Duct → Gallbladder (optional storage) → Common Bile Duct → Duodenum

What is the function of bile?  Where is it made?

Function: Emulsifies fats and aids fat absorption.
Made by: Hepatocytes in the liver.

Name the components of bile

Water, bile salts, bile pigments (bilirubin), cholesterol, phospholipids, and electrolytes.

How are bile pigments formed?

Bile pigments, mainly bilirubin, are formed when old or damaged red blood cells are broken down.

What is the function of the gallbladder?

• Stores bile

• Concentrates bile

• Releases bile into the duodenum

Gallbladder location:

• On the underside of the liver in the upper right abdomen.

What hormone stimulates contraction of the gallbladder?  What stimulates the release of this hormone?

• Hormone: Cholecystokinin (CCK)

• Stimulus for release: Presence of fats (and proteins) in the duodenum.

CCK effect on stomach:

Slows gastric emptying.

CCK effect on pancreas:

Stimulates release of digestive enzymes

Pancreas function:

Produces digestive enzymes and bicarbonate; secretes insulin and glucagon.

Elastase

digest

Proteins, especially elastin fibers

Ribonuclease (RNase)

Deoxyribonuclease

digest dna and rna into nucleotides

Secretin → stimulates release of

bicarbonate-rich pancreatic juice

Which cells secrete pancreatic juice?

acinar cells

duct cells

What chemical in pancreatic juice causes it to be alkaline?

Bicarbonate ions (HCO₃⁻)

What two hormones stimulate pancreatic secretion?

Secretin + Cholecystokinin (CCK)

Oral cavity

Chewing + begins carbohydrate digestion.

Stomach

Churning + begins protein digestion.

Small intestine:

Completes digestion + absorbs most nutrients.

Large intestine:

• Absorbs water and electrolytes + forms feces.

Describe the changes that occur to the digestive system during the aging process.

slower digestion,

decreased secretions,

reduced nutrient absorption,

increased risk of constipation and digestive diseases.

Describe the process of carbohydrate digestion. Be sure to include the enzymes that are used.

1. Mouth

   • Salivary amylase begins breaking starch into smaller polysaccharides and maltose.

2. Stomach

   • Little carbohydrate digestion occurs because stomach acid inactivates salivary amylase.

3. Small Intestine

   • Pancreatic amylase continues digestion of starch into disaccharides.

   • Brush-border enzymes of the small intestine:

     • Maltase → maltose → glucose

     • Sucrase → sucrose → glucose + fructose

     • Lactase → lactose → glucose + galactose

4. Absorption

   • Monosaccharides (glucose, fructose, galactose) are absorbed into blood capillaries of the villi.

2. Describe the process of protein digestion. Be sure to include the enzymes that are used.

• Stomach

  • Pepsin begins protein digestion by breaking proteins into smaller peptides.

• Small Intestine

  • Pancreatic enzymes:

    • Trypsin

    • Chymotrypsin

    • Carboxypeptidase

  • These break peptides into smaller peptide fragments.

• Brush Border of Small Intestine

  • Peptidases break peptides into amino acids.

• Absorption

  • Amino acids are absorbed into blood capillaries in the villi.

3. Describe the process of lipid digestion. Be sure to include the enzymes that are used.

• Mouth and Stomach

  • Minor digestion by lingual and gastric lipases.

• Small Intestine

  • Bile salts from the liver/gallbladder emulsify fats into tiny droplets.

  • Pancreatic lipase breaks triglycerides into fatty acids and monoglycerides.

• Absorption

  • Fatty acids and monoglycerides enter intestinal cells.

  • They are packaged into chylomicrons.

  • Chylomicrons enter lacteals (lymphatic vessels) and eventually enter the bloodstream.

4. Describe the process of nucleic acid digestion. Be sure to include the enzymes that are used.

1. Small Intestine

   • Pancreatic enzymes:

     • DNase digests DNA.

     • RNase digests RNA.

2. Brush Border Enzymes

   • Nucleotidases and phosphatases break nucleotides into nitrogenous bases, sugars, and phosphate groups.

3. Absorption

   • These components are absorbed through the intestinal lining into the blood.

Simple Diffusion-absorbition

Fatty acids, glycerol, some vitamins, water

Facilitated Diffusion-absorbition

Fructose and some ions

Active Transport-absorbition

Glucose, amino acids, many vitamins and minerals

Osmosis-absorbition

Water