ANAPHY: U13.2 Digestive System (Biliary Tract)

Liver & Pancreas

Large accessory glands that produce secretions and empty into the duodenum

Liver

Largest internal organ of the body, located at R upper quadrant of abdomen

R Lobe, L Lobe, Caudate Lobe, Quadrate Lobe

4 Lobes of the Liver

Falciform Ligament (Connective Septum)

What separates the R & L lobes of the liver?

Hepatic Artery

What delivers O2 to the liver?

Hepatic Portal Vein

What delivers nutrient-rich blood from the digestive tract to the liver?

Inferior Vena Cava

Where do the hepatic veins empty into?

Hepatic Lobules

Subdivisions of the liver with portal triad (hepatic portal vein, hepatic artery & hepatic duct) & central vein (collecting blood)

Hepatic Portal Vein, Hepatic Artery, Hepatic Duct

What is part of the portal triad of the liver (component of hepatic lobules)?

Central Vein

What component of hepatic lobules collects blood?

Hepatic Cords

String of cells from the hepatic vein, composed of hepatocytes (functional cells of liver)

Hepatocytes

What are the functional cells of the liver?

Portal Blood

Where do hepatocytes get nutrients from?

Hepatic Sinusoids or Bile Canaliculi

Nutrients are stored, detoxified, used to synthesize new compounds before being sent to where?

Bile

What do hepatocytes produce?

Common Hepatic Duct

Hepatic ducts converge & empty to R & L hepatic ducts, which join to form what?

Gallbladder

What stores concentrated bile?

Cystic Duct

What initially carries bile?

Common Bile Duct

The Cystic duct joins with the common hepatic duct to form what?

Pancreatic Duct

What does the common bile duct join with in the duodenum?

Duodenal Papilla

Where do the common bile duct and pancreatic duct open into?

Sphincter

What controls the emptying of Bile?

1. Digestion

2. Excretion

3. Nutrient Storage

4. Nutrient Conversion

5. Detoxification of Harmful Substances

6. Synthesis of New Molecules

6 Functions of the Liver

Digestion

One of the functions of the liver

Bile neutralizes stomach acid, bile salts emulsify fats that helps fat digestion by lipase

Stomach Acid

What does bile help neutralize?

Lipase

By what enzyme are fats digested by, which are initially emulsified by bile salts?

Excretion

One of the functions of the liver

Bile contains excretory products such as: cholesterol, fats, bile pigments (bilirubin)

Cholesterol, fats, bile pigments (bilirubin)

What are excretory products contained in bile?

Nutrient Storage

One of the functions of the liver

Liver cells remove sugar from blood, store as glycogen, also store fat, Vitamin (ABDEK), copper and iron

Vitamins ABDEK

What Vitamins are produced by the liver?

Nutrient Conversion

One of the functions of the liver

Converts amino acids to lipids; glucose & fats converted to phospholipids; Vit D into active form

Detoxification of Harmful Chemicals

One of the functions of the liver

Remove ammonia from blood and convert it to urea & excreted in the urine; other substances are secreted in the bile

Ammonia

What does liver remove from the blood?

Urea

What does the liver convert ammonia into?

Synthesis of New Molecules

One of the functions of the liver

Liver synthesizes blood proteins such as albumin, fibrinogen, globulins and clotting factors

Albumin, Fibrinogen, Globulins, Clotting Factors

What blood proteins are synthesized by the liver?

1. Parasympathetic Division of Vagus Nerve

2. Secretin

3. Cholecystokinin

4. Bile Salts

4 Stimulants of Bile Secretion of the Liver

Parasympathetic Division of Vagus Nerve

One of the stimulants of Bile Secretion

Stimulate bile secretion by the liver and contract GB, release into duodenum

Secretin

One of the stimulants of Bile Secretion

From duodenum; stimulate bile secretion and release

Cholecystokinin

One of the stimulants of Bile Secretion

Produced by duodenum acts on GB, GB contracts, sphincter relaxes, release bile into the duodenum

Bile Salts

One of the stimulants of Bile Secretion

Increase bile secretion by positive-feedback mechanism

Pancreas

Retroperitoneal organ consisting of head, body and tail; Both endocrine and exocrine

Head, Body, Tail

What are the components of the pancreas?

Pancreatic Islets (Islets of Langerhans)

What is the endocrine part of the pancreas consisted of?

Insulin, Glucagon, Somatostatin

What 3 hormones does the endocrine part of the pancreas produce?

Blood levels of glucose and amino acids

What does insulin and glucagon control?

Regulates insulin and glucagon secretion & inhibits growth hormone secretion

What does somatostatin control?

Acinar Cells

What is the exocrine part of the pancreas consisted of?

Digestive/Pancreatic Enzymes & HCO3 Ions

What do acinar cells of exocrine part of the pancreas produce?

Trypsin, Chymotrypsin, Carboxypeptidase

What 3 enzymes continue digestion of protein in the small intestines started in the stomach?

Pancreatic Amylase

What enzyme from the pancreas continues polysaccharide digestion that started in the mouth?

Lipase

What enzyme produced by the pancreas digests lipids?

Nuclease

What enzyme produced by the pancreas degrade DNA and RNA into nucleotides?

1. Parasympathetic Division of Vagus Nerve

2. Secretin

3. Cholecystokinin

3 Controls of Pancreatic Secretion

Parasympathetic Division of Vagus Nerve

One of the controls of pancreatic secretion

Causes release of digestive enzymes from pancreas to blood

Secretin

One of the controls of pancreatic secretion

Stimulated by acidic chyme in duodenum; stimulates pancreas to release HCO3 into duodenum

Cholecystokinin

One of the controls of pancreatic secretion

Stimulated by fatty acids and amino acids in the duodenum; Stimulate pancreas to release enzyme-rich solution that digest fatty acids and amino acids

Digestion

Breakdown of food to small molecules to be absorbed into blood

Mechanical & Chemical Digestion

2 Types of Digestion

Mechanical Digestion

Type of digestion

Breaks large molecules into smaller ones.

Chemical Digestion

Type of digestion

Uses enzymes to break organic molecules

Polysaccharides & Disaccharides into Monosaccharides

In digestion of carbohydrates, what is broken down into what?

Triglycerides into Fatty Acids & Monoglycerides

In digestion of lipids, what is broken down into what?

Polypeptides to Peptides & Amino Acids

In digestion of proteins, what is broken down into what?

Absorption

Begins in the stomach, especially lipid-soluble molecules (alcohol and aspirin) which diffuse through stomach epithelium into the blood

Mostly done in duodenum, jejunum, some in ileum; some diffuse into intestinal wall.

Stomach

Where does Absorption begin?

Lipid-Soluble Molecules (like Alcohol & Aspirin)

What begins to be absorbed in the stomach which diffuse through the stomach epithelium and into the blood?

Duodenum & Jejunum (some in Ileum)

Where does most absorption occur?

Cotransport with Na

Absorption of Carbohydrate (Glucose): How is glucose absorbed into the intestinal epithelium?

Facilitated Diffusion

Absorption of Carbohydrate (Glucose): How does glucose move out of intestinal epithelial cells?

Intestinal Epithelium —> Intestinal Villi —> Hepatic Portal Vein —> Liver

Absorption of Carbohydrate (Glucose): What is the flow of glucose?

Hepatic Portal Vein

Absorption of Carbohydrate (Glucose): What carries glucose to the liver?

Insulin

Absorption of Carbohydrate (Glucose): What molecule does the rate of transport of glucose greatly depend on?

Triglycerides, phospholipids, steroids and fat-soluble vitamins

What 4 types of lipids?

Saturated & Unsaturated Fats

2 Types of Triglycerides/Fats

Saturated Fats

Type of triglyceride/fat; from meat, dairy products, eggs, nuts, coconut oil & palm oil

Unsaturated Fats

Type of triglyceride/fat; from fish and most plant-based oil

Simple Diffusion

How do lipids, fatty acids and monoglycerides molecules pass into intestinal epithelial cells?

Lipoproteins

Inside the epithelial cells, fatty acids & monoglycerides regroup into triglycerides, packed with protein-coat called what?

Pancreatic Lipase

Digest lipid molecules

Low-Density Lipoproteins (LDL) & High-Density Lipoproteins (HDL)

2 Types of Lipoproteins

Cholesterol

What do lipoproteins bring or carry?

Low-Density Lipoproteins (LDL)

One type of lipoprotein

Carries cholesterol to the tissues for use by cells

High-Density Lipoproteins (HDL)

One type of lipoprotein

Bring cholesterol from tissues to the liver

Adipose Tissues

What are some fats stored as, which can be used as energy?

Proteins

Chains of amino acids found in plant and animal products

Pepsin

Digest protein into polypeptides

Cotransport

How are amino acids absorbed by the epithelial cells then move to the liver?

Glycogen or Lipids

What does the liver modify amino acids into, which are then released into the blood for distribution?

Transport

Needs carrier molecules

Facilitated Diffusion, Cotransport, Active Transport

What are 3 examples of transport?

Energy

What do cotransport and active transport need?

9L

What total volume of water enters the digestive tract as intake, food, and digestive secretions?

Osmotic Gradient

How does water move in the digestive tract?

1%

What percent of water is excreted through feces?

Na, K, Ca, Mg, & Phosphate Ions

What 5 minerals are actively transported from the small intestines?