Fat Structure and Digestion

Study Notes

Fat Structure & Absorption

Fats, primarily triglycerides, are composed of glycerol and three fatty acid chains.
Fatty acids can be saturated (no double bonds) or unsaturated (one or more double bonds).
Unsaturated fats are further categorized as monounsaturated or polyunsaturated, depending on the number of double bonds.
The structure of fatty acids influences their physical properties like melting point and solubility.
Fats are hydrophobic and insoluble in water.
Emulsification is crucial for fat digestion, breaking large fat globules into smaller droplets.
Bile salts, produced in the liver and stored in the gallbladder, aid in emulsification.

Fat Digestion

Digestion begins in the small intestine.
Pancreatic lipase is the primary enzyme responsible for breaking down triglycerides into monoglycerides and free fatty acids.
Bile salts help to emulsify fats, increasing the surface area for lipase action.
Monoglycerides and free fatty acids, along with other lipids, are absorbed into intestinal cells.
Within the intestinal cells, these products are reassembled into triglycerides.
Chylomicrons, lipoprotein complexes, transport absorbed triglycerides to the rest of the body.
Chylomicrons are transported into the lymphatic system, then enter the bloodstream.

Fat Catabolism

Fat catabolism is the process of breaking down stored triglycerides for energy.
This process occurs when blood glucose levels are low or during prolonged fasting.
Triglycerides are hydrolyzed into glycerol and fatty acids.
Glycerol can be converted to glucose via gluconeogenesis (under specific circumstances).
Fatty acids undergo beta-oxidation in the mitochondria.

Beta-Oxidation

Beta-oxidation is the metabolic pathway for breaking down fatty acids into acetyl-CoA.
Fatty acids are transported into the mitochondria for beta-oxidation.
Each cycle of beta-oxidation shortens the fatty acid chain by two carbons.
Acetyl-CoA enters the citric acid cycle (Krebs cycle) to generate ATP.
NADH and FADH2, produced during beta-oxidation, contribute significantly to ATP production via the electron transport chain.

Fat Anabolism

Fat anabolism is the synthesis of fatty acids from other molecules.
Excess carbohydrates and proteins can be converted to fatty acids.
Acetyl-CoA is the key precursor for fatty acid synthesis.
Fatty acids are assembled into triglycerides for storage in adipose tissue.
Adipose tissue stores triglycerides as a primary energy reserve.
Insulin promotes fatty acid synthesis and storage.
Hormones like glucagon and epinephrine regulate fat breakdown and mobilization.
Fatty acid synthesis is primarily localized in the cytoplasm.

Description

This quiz covers the essential aspects of fat structure and digestion, focusing specifically on triglycerides, fatty acids, and the role of bile salts in emulsification. Understand how different types of fats are categorized and how they are broken down in the digestive system.