energy release from food and forms of storage in the human body Flashcards
(21 cards)
what compounds are lipids
Tripalmitoylglycerol, Phosphatidylcholine, Cholesterol
what are some purposes of metabolism
to generate heat in some specialised cells (in human babies and hibernating mammals)
to process waste products, to facilitate excretion in urine
to convert food molecules to new cellular material and essential components
to oxidise food to provide energy in the form ATP
what is correct about digestion of dietry triacylglycerols
Dietary TAG are digested by pancreatic lipase
It breaks down TAG into monoglycerides and fatty acids. These products are then absorbed by the intestinal cells.
what is a carbohydrate
Carbohydrates are organic molecules composed of carbon, hydrogen, and oxygen, typically with the formula (CH₂O)n. They include sugars, starches, and structural polysaccharides.
e.g glycogen and cellulose
What happens to fatty acids released from adipose tissue during fasting?
Fatty acids released from adipose tissue are bound to serum albumin in the bloodstream. This transport allows them to be delivered to muscle and other tissues, where they are used as an energy source. This process occurs during fasting or energy demand, and the binding to albumin helps solubilize the otherwise hydrophobic fatty acids.
What is the most efficient form of energy storage in the human body, and why?
Fat (triacylglycerols) is the most efficient energy storage form in the human body. It has a high energy density (~9 kcal/g), is stored without water (anhydrously), and provides a compact, long-term energy reserve. This makes it more efficient than glycogen, which is heavier due to water content and has limited storage capacity.
Where does protein digestion begin and what enzyme is involved?
Protein digestion begins in the stomach, where pepsinogen (the inactive form of the enzyme pepsin) is activated by hydrochloric acid (HCl). Pepsin then starts breaking down proteins into smaller peptides.
Are proteins, carbohydrates, and lipids absorbed by the body as macromolecules?
False. Proteins, carbohydrates, and lipids are broken down into smaller molecules (amino acids, monosaccharides, and fatty acids) during digestion before they are absorbed by the body’s cells.
are collagen and hexokinase proteins?
yes
Collagen is a structural protein in connective tissues.
Hexokinase is an enzyme involved in the phosphorylation of glucose.
As food is digested, which smaller molecules are absorbed by the cells of the intestinal epithelium (enterocytes)?
Amino acids, small peptides, monosaccharides, fatty acids, monoacylglycerols, cholesterol
what are all the main forms of nutrient storage in humans
Glycogen in liver and skeletal muscle cells and triacylglycerides in adipose tissue cells
What do chylomicrons primarily contain in their hydrophobic core?
Chylomicrons primarily contain dietary triacylglycerols in their hydrophobic core. They transport fats, cholesterol, and fat-soluble vitamins from the intestines to various tissues in the body.
What happens during the absorptive phase in terms of glucose uptake in skeletal muscle cells?
During the absorptive phase, high insulin levels mediate glucose uptake in skeletal muscle cells. Insulin promotes the movement of glucose transporters (such as GLUT4) to the cell membrane, allowing glucose to enter the cells for energy storage or utilization.
What type of chemical bond links the smaller molecules that make up the complex carbohydrates?
Glycosidic bond
Where is glucose-6-phosphatase found, and what is its role?
Glucose-6-phosphatase is found in liver cells but not in muscle cells. It plays a key role in the final step of glycogenolysis and gluconeogenesis, converting glucose-6-phosphate to free glucose for release into the bloodstream, a process that does not occur in muscle cells.
Which smaller molecules are complex carbohydrates made of?
monosaccharides
What nutrients circulate in the blood after digestion and absorption?
After digestion and absorption, the nutrients that circulate in the blood include amino acids, small peptides, monosaccharides, fatty acids, monoacylglycerols, and cholesterol. These are absorbed from the small intestine and enter the bloodstream, where they are transported to various tissues for use or storage.
what are the sugar monomers in lactose
Galactose and fructose
When does glycogen synthesis occur?
Glycogen synthesis occurs when there is a high insulin to glucagon ratio. This typically happens after meals when insulin is released in response to high blood glucose levels, signaling the body to store excess glucose as glycogen in the liver and muscles.
What structures in the small intestine contribute to its large surface area for nutrient absorption?
The small intestine’s large surface area for absorption is due to circular folds in the lining, villi on each fold, and microvilli on the brush-border membrane of the enterocytes lining the villi.
What type of chemical bonds link the smaller molecules that make up the triacylglycerides to the glycerol ‘backbone’ of the triacylglycerides?
esteric bonds
ester bonds form between the hydroxyl groups of the glycerol molecule and the fatty acid chains. These bonds are a type of covalent bond where the hydroxyl group (-OH) of glycerol reacts with the carboxyl group (-COOH) of fatty acids, releasing water and forming an ester linkage.
