Midterm Exam Flashcards
Amylopectin
a form of starch found in plants; polysaccharide; a branched-chain polymer, with branch points occuring through alpha (1-6) bonds
Amylose
a linear, unbranched chain in which the glucose residues are attached solely through alpha (1-4) glycosidic bonds
β-glucan
- water soluble, highly fermentable by colonic bacteria, and form viscous gels within the digestive tract
- consists of a chain of glucoses joined mostly in beta (1-4) linkages but also some beta (1-3) linkages
β-oxidation
the catabolic process by which fatty acids are broken down to generate acetyl-CoA; MORE?
Bilirubin
A waste end product of hemoglobin degradation
BMR
Basal Metabolic Rate- the amount of energy needed to sustain basic life processes such as respiration, heartbeat, renal function, brain and nerve function, blood circulation, active transport, and synthesis of proteins and other complex molecules
Cellulose
a dietary and functional fiber; long, linear polymer; mainly beta (1-4) linked glucose units
Cholecystokinin
secreted into the blood by I cells of the proximal small intestine and by enteric nerves in the distal ileum and colon, principally stimulates pancreatic acinar secretory cells to release digestive enzymes into the duodenum. It also has trophic actions on the pancreas and stimulates gallbladder contraction and the relaxation of the sphincter of Oddi to facilitate the release of bile into the duodenum.
Cholesterol ester
Delivered to the liver as a component of chylomicron remnants, LDL and HDL; some cholesterol present in food is esterified with a fatty acid; cholesterol esters cannot be absorbed and must be hydrolyzed to free cholesterol and free fatty acids
Cholesterols
The most common sterol in humans; serves as the precursor for many important steroids in the body
Cis fatty acid
Cis configureation results in folding and bending of the molecule; more?
Crypts of Lieberkuhn
Tubular glands that lie between the finger-like projections of the inner surface of the small intestine.
De novo fatty acid synthesis
a pathway for phosphatidylcholine syntheisis; this increases when a deficiency of the essential amino acid methionine exists.
DRI (including RDA, AI, and UL)
- DRI = Dietary Reference Intakes
- RDA = Recommended Dietary Allowances
- AI = Adequate Intakes
- UL = Tolerable Upper Intake Levels
Fructose
Ketonic monosaccharide found in plants
Galactose
a monosaccharide sugar; requires energy as ATP and SGLT1
Gastrin
Produced in the stomach and small intestine and stimulates gastric acid secretion and pepsinogen secretion.
Ghrelin
a hormone that stimulates hunger and food intake; promotes digestion. Produced predominately in the stomach
Gluconeogenesis
The formation of glucose by th liver or kidney from noncarbohydrate precursors
Glucose
a simple sugar important as an energy source
Glycemic index (what makes a food have a lower/higher GI?)
Increase in blood glucose during 2-hour period after consumption of a certain amount of CHO compared with equal CHO from reference food
Glycogen
more branched than amylopectin, a polysaccharide which forms glucose on hydrolysis
Glycogenesis
the pathway by which glucose is converted to glycogen
Glycogenolysis
the pathway by which glycogen is enzymatically broken down to glucose
Glycolysis
oxidation of glucose to pyruvate
Gums
secreted at the site of plant injury by specialized secretory cells and can be exuded from plants; highly branched and composed of sugars and derivatives; main galactose backbone joined by beta (1-3) linkages and beta (1-6) linkages with side chains
Inulin
naturally occuring polysaccharides; consists of a beta (2-1) liked fructose chain; chicory, asparagus, leeks, onions, garlic, artichoke
Ketosis
a condition resulting in elevated ketone body concentration in the blood
Km (Michaelis constant)
- Concentration of substrate in a reaction when the reaction is ½ max velocity (Vmax)
- •High Km enzyme
- high [substrate] high Km
- Tends to be a low affinity of enzyme for substrate
- Reaction rate response to [substrate]
- Low Km enzyme
- low [substrate] low Km
- Enzyme is likely to be saturated with substrate
- Tends to be a high affinity of enzyme for substrate
- Reaction rate is not responsive to [substrate]
- 2 enzymes responsible for phosphorylation/activation of glucose
- Hexokinase (HK)
- Low Km enzyme (high affinity for substrate)
- Glucokinase (GK)
- High Km enzyme
- Hexokinase (HK)
Lactose
Disaccharide, major energy supply. It is composed of galactose linked by a beta (1-4) glycosidic bond to glucose
Leptin
Appetite suppressant; decreases the urge to eat and increases physical activity to produce a negative energy balance; secreted by white adipose tissue, interacts with hypothalamus to reduce hunger
Linoleic acid
Must be obtained from diet (plant sources), more?
Linolenic acid
Alpha lenolenic acid serves as a precursor for the highly unsaturated n-3 fatty acids
Lipolysis
the breakdown of fats and other lipids by hydrolysis to release fatty acids
Pancreatic exocrine cells
cells in the pancreas that produce enzymes that are secreted into the small intestine. These enzymes help digest food by releasing enzymes as it passes through the gastrointestinal tract
Pectin
a dietary and functional fiber, found in plant cell walls. Promotes gelling. In the digestive tract, pectins form viscous gels and are almost completely fermented by bacteria in the colon
Pentose phosphate shunt
a pathway that is available to glucose in the cytosol; generates intermediates not produced in other pathways –> pentose phosphates and the reduced cosubstrate NADPH
Peptide YY
Produced in the small and large intestine, while diminishing gastric acid secretion and gastric emptying; supresses hunger in the long term
Phospholipid
phosphate containing lipids that form the structural basis of all cell membranes
Resistant starch
starch that cannot be easily enzymatically digested
Secretin
secreted into the blood by S cells in the proximal small intestine in response to the presence of unneutralized acidic chyme and the products of protein digestion in the duodenum. Secretin acts primarily on pancreatic duct cells, stimulating the release of pancreatic juice rich in bicarbonate. The presence of this bicarbonate in the duodenum in turn neutralizes the acidic chyme and serves as feedback control. Secretin also exhibits trophic action on the pancreas and decreases gastric acid secretion and gastric emptying.
Sphingolipid
found in the plasma membrane of all cells, built on the amino alcohol sphingosine
Sucrose
the most widely distributed disaccharide, composed of glucose and fructose
TCA cycle
pyruvate from glycolysis is sent to the mitochondria, decarboxylated to acetyl-CoA, and oxidized via TCA cycle to produce ATP through oxidative phosphorylation
TEF
Thermic Effect of Food
- an estimation of kcal reqt. to process food (digest, absorb, transport, metabolize, store, etc.)
- ~10% of energy intake
Trans fatty acid
an unsaturated fatty acid of a type occurring in margarines and manufactured cooking oils as a result of the hydrogenation process, having a trans arrangement of the carbon atoms adjacent to its double bonds.
Triglyceride
an ester formed from glycerol and three fatty acid groups. Triglycerides are the main constituents of natural fats and oils
Describe the fed state
- The fed state lasts 3 hours after meal ingestion.
- The liver uses some glucose at first (⅔ passes into systemic circulation), delivered to body tissues.
- There is retained glucose, and excess glucose exceeding the liver’s glycogen storage capacity is converted to fatty acids and triactylglycerols, delivered to adipocytes by circulating lipoproteins.
Describe the post absorptive state.
- The post absorptive state is from 3-18 hours following meal.
- hepatic glycogenolysis is the major provider of glucose to the blood
- lactate constant carbon source
- Gluconeogenesis occurs through glucose-alanine cycle and muscle glycogenolysis
- In an overnight fast, almost all reserves of liver glycogen are depleted
- Fatty acids are another valuable source of energy for cardiac and skeletal muscle. The liver may also use these.
Describe the fasting state.
- The fasting state from 18 hours to 2 days without additional food intake.
- Amino acids (primarily), glycerol, and lactate used for gluconeogenesis
- Ketone formation
- Nitrogen losses due to breakdown of muscle protein and synthesis of glucose through hepatic gluconeogeneis
- Glutamine increase
Describe the starvation state.
- Fully adaptive state of deprivation lasting longer than 2 days.
- Protein sparing actions
- shift from gluconeogenesis to LIPOLYSIS
- fatty acids used to greater extent
- glycerol major glucose source (thorugh gluconeogenesis)
- increased ketone body synthesis and utilization
- ketosis after oxaloacetate depletion
- survival time depends on fat stores
What is the effect of anabolic hormones on metabolic responses to macronutrients?
- Insulin- critical in fed state, promotes glucose uptake; stimulates glycogen synthesis (liver and skeletal muscle, glycogenesis); inhibits gluconeogenesis in liver, lipolysis in adipose tissue and proteolysis in muscle
- What is the effect of catabolic hormones on metabolic responses to macronutrients?
a. Glucagon- metabolic responses opposite of insulin; prominent in non-fed state
b. Epinephrine- neurotransmitter in nervous system, stress hormone in circulation; inhibits insulin secretion, increases glucagon secretion
c. Cortisol- considered stress hormone, released in response to low BG levels; stimulates gluconeogenesis and glycogenolysis in liver