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What are the building blocks (monomers) of polysaccharides (carbs), polypeptides (proteins), lipids, and nucleic acids?
Monosaccharides, amino acids, fatty acid+glycerol, and nucleotides; respectively.
What are the brush border enzymes found in the small intestine responsible for carb digestion?
Dextrinase and glucoamylase: act on oligosaccharides.
Disaccharidases are enzymes responsible for breaking down disaccharides, which are double sugar molecules, into monosaccharides, which are single sugar molecules. Examples: maltase, sucrase, lactase.
What is bile? What is the primary component of bile?
Bile is a digestive fluid produced by the liver and stored in the gallbladder. The main component of bile is bile salts.
Where is bile produced? From which molecule?
In the liver, from cholesterol.
What are chylomicron?
Large lipoprotein particles that transport dietary lipids, such as triglycerides and cholesterol, from the intestine to the liver.
What is metabolism? Define the different reactions involved.
Metabolism: The sum of all biochemical reactions in the body.
Catabolism: involves the breakdown of complex molecules into simpler ones, releasing energy in the process.
Anabolism: is the synthesis of complex molecules from simpler ones, requiring an input of energy.
What does 1 calorie signify?
The definition of 1 calorie (abbreviated as "c") is the amount of heat energy needed to raise the temperature of 1 gram of water by 1 degree Celsius.
What is ferritin?
It is a protein found in cells (mostly in liver and macrophages) that serves as the primary intracellular storage form of iron in the body
What is the only way for the body to get rid of cholesterol?
Through fecal excretion, with the help of bile
What function does lipid emulsification serve?
To break down large fat globules into smaller droplets, increasing the surface area of the fats. This process facilitates the action of digestive enzymes making them more accessible for digestion and absorption.
Why does carb digestion not continue in the stomach even though the bolus from your mouth contains some salivary amylase (the enzyme found in saliva responsible for breaking down polysaccharides)?
Because salivary amylase, the enzyme responsible for breaking down carbohydrates, is deactivated by the acidic environment of the stomach.
What role does transferrin serve in the body? Where in particular does transferrin go (which two parts of the body)?
Transferrin is a protein responsible for transporting iron in the bloodstream. It binds to iron and carries it throughout the body, delivering it to cells that need it for various functions, including hemoglobin synthesis (red blood cell production) in the bone marrow and myoglobin synthesis in the muscle.
Classify the following vitamins as water-soluble or lipid-soluble: A,B,C,D,E,K.
Which of the two vitamin groups higher risk of accumulating in your body intil reaching toxic? Why?
Water soluble: B, C.
Lipid-soluble: A, D, E, K.
Lipid-soluble. They are stored in the fatty tissues and liver. Because they dissolve in fat, they can accumulate in these tissues over time.(Exception: Vitamin K)
Water soluble: any excess amounts are readily excreted through urine. Since these vitamins dissolve in water, they are easily transported to the kidneys where they can be filtered from the blood and excreted in the urine.
What occurs to the fatty acids and monoglycerides upon entering the enterocyte? What lipoprotein is synthesize inside the enterocyte?
(a) Once inside the enterocyte, fatty acids and monoglycerides are reassembled into triglycerides. (b) Inside the enterocyte, these triglycerides are incorporated into chylomicrons,
What is a lipoprotein?
Tiny droplets with a core of cholesterol and TGs and a coating of proteins (apolipoproteins) and phospholipids.It serves as a vehicle for transporting lipids in the body.
What happens to the iron released by macrophage degradation of senescent red blood cells? Is it recycled?
Yes it is recycled. Macrophages can release iron into the bloodstream for transport to other tissues and organs via the protein transferrin.
What role does ferroportin serve in the body? Where is it located?
Ferroportin is a protein involved in the transport of iron out of cells to the bloodstream. It is primarily found on the surface of enterocytes in the small intestine and macrophages in the reticuloendothelial system.
What are the 3 steps that occur in the intestine with fats before they are transported to the enterocytes?
1-Emulsification: large fat globules are broken down into smaller droplets by bile salts, increasing the surface area of the fats for digestion.
2-Lipid digestion by lipases.
3-Micelle Formation (to facilitate their transport to the enterocyte membrane)
What is the function of lipoprotein lipase? And where is it found?
To hydrolyze triglycerides present in circulating lipoproteins, such as chylomicrons and VLDL, into free fatty acids and glycerol, which facilitates their uptake by various tissues for energy production or storage.
Bound to the endothelial cells lining the capillaries
Among HDL, LDL, and VLDL,, which lipoprotein harbors the highest concentration of cholesterol? and triglycerides?
(a) LDL. (b) VLDL.
What is hepicidin and what is its primary objective: to increase or decrease levels of iron? How does it accomplish this?
Hepcidin is a peptide hormone produced by the liver that plays a central role in regulating iron levels in the body. Its main objective is to decrease blood levels of iron.
By inhibiting iron absorption from the intestine, iron released from macrophages, and iron recycling from senescent red blood cells. Hepcidin achieves this goal by binding to ferroportin which triggers internalization and degradation of ferroportin, reducing the export of iron from cells into the bloodstream.
Which form of iron, ferrous (Fe2+) or ferric (Fe3+) is more readily absorbed by the body? How is this form achieved in the duodenum? Which transporters does iron use to enter inside the enterocyte?
Ferrous (Fe2+) iron.
By the presence of gastric acid (coming from the stomach) that weakens iron bonds with other food molecules and the enzyme ferric reductase.
Divalent Metal cation Transporter 1 (DMT 1)
They are remnants of chylomicrons that have undergone partial lipid digestion. They are smaller particles that contain mostly cholesterol and some remaining triglycerides. To deliver dietary cholesterol and fat-soluble vitamins to the liver for further processing and metabolism.
What leads to the conversion of VLDL into LDL? What is the role of LDL?
VLDL is converted into LDL primarily through the removal of triglycerides from VLDL particles during their circulation in the bloodstream (previous conversion to IDL). It transports and delivers cholesterol to the cells.
What leads to the formation of ketone bodies, and from which molecule do they originate?
Ketone bodies form as a result of the breakdown of fatty acids. They originate from acetyl-CoA. When there is an insufficient supply of glucose for energy production, such as during fasting or low-carbohydrate diets, fatty acids are oxidized to acetyl-CoA, which can then undergo ketogenesis to form ketone bodies.