Lecture Part 3 Flashcards
(22 cards)
Why is it important to keep nitrogen in balance?
Positive nitrogen balance: (more nitrogen intake than excretion) essential for tissue repair, growth, recovery, etc.
Negative nitrogen balance: (more nitrogen excretion than intake) can lead to muscle loss and catabolic processes.
What contains nitrogen?
Dietary protein is our main source of absorbed nitrogen.
After an amino acid is absorbed, describe all of the different things it can be used for:
- Used to make proteins (protein synthesis)
- Converted to other AAs (transamination)
- Can be converted to FAs from acetyl-CoA
- Used for lipogenesis
- Can be used to make glucose (gluconeogenesis)
After fats are absorbed, describe all of the different things it can be used for:
Pass through the lymph system and then throughout the body via your bloodstream to be used for energy, cell repair, and growth.
End products = fatty acids and glycerol
What are some of the functions of fats?
Primary energy substrates for hepatocytes, adipocytes, and muscle cells.
- Energy storage
- Insulation
- Absorption of fat- soluble vitamins
How can fats be broken down for energy?
Lipolysis (in cytoplasm): Triglycerides broken down into fatty acids and glycerol. Fatty acids oxidized into acetyl CoA (used in Krebs cycle)
Does the breakdown of fats or glucose release more energy?
Fats
What is lipogenesis?
The metabolic process when the body converts excess glucose or other substrates into fatty acids, and then they are stored as triglycerides in adipose tissue.
When does lipogenesis occur?
When the body has excess glucose and energy needs are low.
Why does lipogenesis occur?
To store excess energy.
What kinds of molecules can be converted to fats?
Carbohydrates and proteins, which turn into Acetyl-CoA —> fats
What molecule must be present in order for fats to be broken down?
lipase enzymes (pancreatic), and bile enhances the enzymes.
Describe the special ways lipids can be transported in the blood stream. Why do they need to be transported in special ways?
Due to their hydrophobic nature, lipids are packaged into lipoproteins to be transported through blood.
- Chylomicrons (lowest density) transport dietary lipids
- Very-Low-Density lipoproteins (VLDL produced in liver) delivers triglycerides to the tissues
- Low-Density lipoproteins (LDL) deliver cholesterol to cells
- High-Density lipoprotein transport cholesterol from tissues back to liver
What are proteins used for?
Structural support, enzyme activity, hormone production, and transportation of molecules.
Describe the general processes that take place in order for amino acids to be catabolized:
Deamination, produces a keto acid that might participate in gluconeogenesis, while amino group must be dealt with as a waste product, keto acid is converted to pyruvate, acetyl-CoA, or a citric acid intermediate.
Compare the breakdown of glucose, fat, and proteins for energy. Which one gives the most energy? Which one is quickest? Which is the worst source of energy? Why?
Most energy: Fat (more energy-dense chemical bonds)
Quickest: Glucose (derived from carbohydrates so it is quick)
Worst source of energy: Proteins (structure over energy production)
What are essential amino acids?
Isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine
What does the liver do in metabolism?
Converts nutrients in our diets into substances that the body can use, stores these substances, and supplies cells with them as needed.
What does the adipose tissue do in metabolism?
Stores energy, secreting hormones like adipokines, and regulating lipid and glucose metabolism.
What does the skeletal muscle do in metabolism?
Primary site for glucose uptake and storage, a reservoir of amino acids, and a major consumer of energy during physical activity.
What does the nervous tissue do in metabolism?
Regulating and coordinating various metabolic processes throughout the body.
What does the kidney do in metabolism?
Filtering waste products from the blood, reabsorbing nutrients, and regulating various metabolic processes.
