Glycogen Formation and Breakdown

Liver glycogen can release glucose into other organs.

Muscle glycogen is used only by the muscle itself; it cannot be shared.

Glucose-6-Phosphate (G6P) is the form of glucose found in muscle cells.

An enzyme that breaks down glycogen into glucose.

The remaining 4 units of glucose after glycogen phosphorylase acts on the glycogen chain.

Byproducts formed from the beta-oxidation of fatty acids during fasting.

The process of synthesizing ketone bodies from acetyl CoA.

The first ketone body produced in ketogenesis.

A ketone body produced from the reduction of acetoacetate.

A ketone body produced in the bloodstream.

The breakdown of fatty acids to produce acetyl CoA.

A molecule important in both carbohydrate and fat metabolism.

A period without food intake.

A duct that carries bile from the liver and gallbladder to the small intestine.

Enzymes produced by the pancreas that aid in fat digestion.

Part of the digestive system where most nutrient absorption takes place.

Specialized lymphatic vessels that absorb lipids in the small intestine.

Packages that transport lipids from the small intestine to the bloodstream.

Location where ketogenesis occurs.

Liver cells.

The process of removing an amine group (NH2) from an amino acid, converting it to a keto acid and releasing ammonium ions (NH4+).

Oxidative deamination of glutamate, a common amino acid, produces alpha-ketoglutarate and ammonium ions. This process is essential for nitrogen removal in the body.

Oxidative deamination mainly takes place within the mitochondria of liver cells.

The enzyme responsible for catalyzing oxidative deamination of glutamate. It can utilize either NAD or NADP as cofactors.

Ammonium ions released from oxidative deamination are converted to urea through a series of reactions. Fumarate, a product of the Krebs cycle, interacts with aspartate, leading to the formation of arginine, which eventually breaks down to urea.

Some amino acids are broken down into intermediates that can re-enter the Krebs cycle, aiding in the removal of urea and maintaining metabolic balance.

Examples include arginine and aspartate entering through oxaloacetate, isoleucine, methionine, and valine entering through succinyl CoA, and isoleucine, leucine, and tryptophan entering through acetyl CoA.

Oxidative deamination is a critical process in nitrogen removal, as it removes ammonia from the body. This is vital for preventing toxicity and maintaining proper cell function.

The breakdown of hemoglobin, the protein responsible for carrying oxygen in red blood cells.

The protein component of hemoglobin, which is broken down into amino acids.

The non-protein part of hemoglobin containing iron, which is converted into bilirubin.

A yellow pigment produced from the breakdown of heme, transported to the liver for processing.

The liver conjugates bilirubin with glucuronic acid, making it water-soluble and easier to excrete in bile.

A molecule produced in the Krebs cycle that can be used in other biochemical processes.

A chemical reaction that transfers an amino group from one molecule to another.

A metabolic pathway that converts ammonia, a toxic waste product, into urea for excretion.

The continuous process of protein breakdown and synthesis within the body, crucial for maintaining a balance of amino acids for various functions.

There are two main stages: removal of the amino group (deamination) and degradation of the carbon skeleton.

Amino acids are not stored in the body, unlike carbohydrates and fats. They are either used for protein synthesis or broken down for energy.

Individual amino acids are transported into cells using specific transporters, with one transporter for each type of amino acid.

Amino acids can be reused for protein synthesis within the body, meaning they're not always broken down.

Excess amino acids, not used for protein synthesis, are catabolized (broken down) for energy production in the liver.

Protein digestion begins in the stomach with the action of hydrochloric acid (HCl) and pepsin.

HCl is crucial for protein digestion, breaking down proteins and creating a very acidic environment (pH 1.5 to 2).

Pepsin, a protease enzyme, helps break down peptide bonds within proteins in the stomach.

By the time digested proteins reach the small intestine, they are in the form of large polypeptides.

The presence of large polypeptides in the small intestine triggers the release of inactive enzymes called zymogens from the pancreas.

Ferritin is the primary storage form of iron within the body.

When red blood cells break down, macrophages release the heme group, which is further processed to produce bilirubin.

Heme is converted to bilirubin by heme oxygenase and bilirubin reductase.

In the liver, bilirubin is conjugated with glucuronic acid, making it water-soluble.

Conjugated bilirubin is processed by intestinal bacteria to form stercobilin, which is excreted in feces.

Conjugated bilirubin is also processed into urobilinogen, which is excreted in urine.

Damaged red blood cells are broken down by macrophages, releasing heme and other components.

When heme is broken down, iron is released and stored in ferritin.