Metabolism and Glucose Catabolism Quiz

Metabolism encompasses all chemical processes within an organism to sustain life, involving converting food to energy and the life-sustaining chemical reactions.
It involves two main processes: catabolism and anabolism.
- Catabolism breaks down complex organic compounds to release energy.
- Anabolism uses energy to synthesize complex molecules from simpler ones.
ATP (adenosine triphosphate) plays a central role in energy exchange.
Cells have billions of ATP molecules to quickly produce energy.
Half the energy released is lost as heat.
Energy is found in bonds between atoms. Oxidation is a decrease in a molecule's energy content (electron loss and H+). Reduction is an increase (electron gain and H+).
- Oxidation-reduction (redox) reactions are always coupled in the body.

Direct calorimetry measures heat production, while indirect calorimetry measures O₂ consumption and CO₂ production.

A series of membrane proteins in the inner mitochondrial membrane.
The ETC facilitates oxidation-reduction reactions, transferring electrons to make an H+ gradient.
The H+ gradient is used to produce ATP through chemiosmosis.

Metabolism and storage of carbohydrates, proteins, and fats
Detoxifies blood by removing or altering drugs and hormones (including thyroid and estrogen).
Removes bilirubin from the breakdown of red blood cells.
Releases bile salts for digestion.
Stores fat-soluble vitamins (A, D3, E, and K).
Stores iron and vitamin B12.
Removes worn-out blood cells and bacteria (phagocytosis).
Plays a role in vitamin D activation.

Glycolysis: Breakdown of glucose to pyruvate or lactate.
Glycogenolysis: Breakdown of glycogen to glucose.
Glycogenesis: Formation of glycogen from glucose.
Gluconeogenesis: Formation of new glucose from other substances (e.g., amino acids, glycerol).

Glycogenesis (stimulated by insulin): glucose to glycogen synthesis
Glycogenolysis (stimulated by glucagon and epinephrine): glycogen to glucose breakdown

Glycolysis is the breakdown of glucose, while gluconeogenesis is the formation of glucose from other metabolites.
Glycolysis uses glucose to produce pyruvate, while gluconeogenesis creates glucose from pyruvate and other sources.

Lipids are transported in the blood as lipoproteins, which combine with proteins.
Lipoproteins are categorized by density.
Lipoproteins include chylomicrons, VLDLs, LDLs, and HDLs.

Oxidation for ATP production.
Storage in adipose tissue or the liver.
Synthesis of structural molecules (phospholipids, lipoproteins, thromboplastin, myelin sheaths).
Synthesis of bile salts and steroid hormones .

Lipolysis: breakdown of triglycerides into glycerol and fatty acids.
Beta Oxidation: Fatty acids are broken down into acetyl-CoA.
Lipogenesis: synthesis of triglycerides from fatty acids and glycerol, amino acids.

Lipids undergo beta oxidation, breaking them down to produce acetyl-CoA.
Ketogenesis: occurs in liver cells and produces ketone bodies, which are used by heart muscle and the kidney cortex for energy production.

Proteins are broken down into amino acids.
Amino acids can be deaminated to enter the Krebs cycle.
Amino acids can be used to synthesize new proteins throughout the body.
Excess amino acids may be converted to glucose or triglycerides.
Absorption of amino acids into body cells is stimulated by insulin-like growth factors (IGFs) and insulin.

Carbohydrate Metabolism:
- Converts amino acids to glucose (gluconeogenesis).
- Converts triglycerides to glucose (gluconeogenesis).
- Stores excess glucose as glycogen (glycogenesis).
- Converts glycogen back to glucose (glycogenolysis) as needed.
Lipid Metabolism:
- Synthesizes cholesterol.
- Synthesizes lipoproteins (e.g., HDL and LDL) to transport fatty acids and cholesterol.
- Stores fat (lipogenesis).
- Breaks down fatty acids (beta-oxidation).

Protein Metabolism:
- Deamination: Removes an amino group from amino acids to create urea for excretion.
- Transamination: Transfer of an amino group from one amino acid to another.
- Synthesizes plasma proteins needed for clotting and the immune system.

The time after a meal when nutrients enter the bloodstream and need to be stored.
The hepatic portal system is used for the absorption of glucose and amino acids.
Lacteals are used for the absorption of dietary fats.

The state after a few hours after absorbing nutrients.
The body relies on stored fuels to maintain blood glucose levels.
Liver's role is crucial as it converts glycogen back into glucose.
Glucose is also produced through gluconeogenesis from glycerol, amino acids and lactic acid.
Fatty acids and ketone bodies become important sources of energy.

Glucose enters the bloodstream from the liver via glycogenolysis and gluconeogenesis.
Amino acids and lactic acid from muscle are also used for glucose production.
Alternative fuel source: fatty acids fed into Krebs cycle and ketone body oxidation.