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
- About _______ of all American adults have one or more preventable, diet-related chronic diseases, including cardiovascular disease, type 2 diabetes, and overweight and obesity.
half
- Why is the statement “you are what you eat” inaccurate?
- Yes, and what we absorb is important, beyond just what we ingest.
- According to the DGA’s 2015-2020, a health eating pattern includes limited added sugars to less than ____% of calories per day.
- 10
- Define thermogenesis.
- Thermogenesis is the production of heat from the body.
- Indicate whether the following INCREASE or DECREASE a person’s % body water.
- Male gender = increase
- Stage of life-older adulthood = decrease
- Increased lean body mass = increase
- Stage of life- childhood = increase
- Obesity = decrease
- The Dietary Guidelines for Americans are designed for those age ____ and older.
2
- List 3 factors that affect nutrient requirements.
- Age, growth, gender
- Match the dietary recommendation with the correct definition.
- DRI- the general term for a set of reference values used to plan and access nutrient intakes of healthy people
- RDA- the intake that meets the nutrient need of almost all healthy individuals in a specific age, gender group
- AI- established in instances when evidence is insufficient to establish an RDA (no estimate of the average requirement is available). Set at a level assumed to ensure nutritional adequacy
- UL- the maximum intake that is unlikely to pose adverse health effects in almost all healthy adults
- Define TEF.
- TEF is the thermic effect of food. Basically this is the amount of energy above the basal metabolic rate due to the cost of processing food for use and storage.
- Calculate the fat free mass (FFM) for a person who weighs 220 pounds and has 18% body fat.
- 180
- Match the following their location/function in the GI tract:
- Lower esophageal sphincter- distal end of the esophagus; above the juncture with the stomach
- Folds of Kerckring- large, circular bends of mucosa
- Crypts of Lieberkuhn- small pits between the vill of the small intestine; cells migrate and differentiate from these pits
- Spincter of Oddi- controls the flow of secretions from the common bile duct into the duodenum
- Pyloric Sphincter- controls the flow of chime from the stomach to the duodenum
- Ileocecal valve- distal end of the ileum; protects against bacterial translocation
- Match the corresponding action to the hormone. Each choice is used only once.
- Stimulates insulin secretion- glucagon-like peptides
- Stimulates pancreas juice secretion- secretin
- Inhibits gallbladder contraction- somatostatin
- Stimulates pepsinogen secretion- gastrin
- Decreases gastric emptying- pancreatic polypeptide
- Why is it important that the proteases released from the pancreas be in their inactive state?
- It is important that proteases released are in their inactive state because if they were secreted in their active form, they could digest the proteins within the pancreatic cells in which they were formed.
- What purpose does unabsorbed material serve in the large intestine?
- Unabsorbed materials also promote fecal bulk to aid in regularity (avoiding constipation and diarrhea).
- List 3 of the benefits provided by short-chain fatty acids in the large intestine.
- Exhibit trophic effects on mucosal cells
- Acidify lumen of the colon
- Stimulate the immune system
- Nutrient deficiencies (such as vitamin B12 or protein deficiency) can cause atrophy of villi and microvilli.
- True
- When the pH of the stomach is increased to avoid GERD, over time, the stomach may not be acidic enough. What is the most likely outcome?
- Decreased protein digestion
- The pancreas is a digestive system accessory organ with two types of active tissue—the ductless endocrine cells that secrete insulin and glucagon and the ____.
- Acinar exocrine cells that produce digestive enzymes
- The surface coat of microvilli is known as:
- Glycocalyx
- The total bile acid pool in the human body is 2.5 to 5g. What percentage of bile is reabsorbed in the distal ileum?
- 90%
- In which organelle do the TCA cycle and fatty acid oxidation occur?
- mitochondrion
- The organelle that serves as the digestive system for the cell is the:
- lysosome
- Peripheral proteins are involved in cell-cell recognition, whereas integral proteins function primarily as receptors/transporters.
- true
- In the human, most triacylglycerols are synthesized by the:
- Liver
- A protein-sparing shift in metabolism from gluconeogenesis to lipolysis occurs during the:
- Starvation state
- Which hormone has the primary responsibility for directing energy metabolism in the fed state?
- insulin
- What is the preferred source of energy used by muscles to spare protein during prolonged starvation?
- Ketones
- A fasted state is characterized by protein synthesis.
- false
- Match the regulatory hormones with their primary functions in integrative metabolism.
- Glucagon- stimulates liver glycogenolysis and gluconeogenesis
- Growth Hormone- stimulates lipolysis and increases triacylglycerol uptake from VLDL
- Cortisol- stimulates gluconeogenesis and glycogenolysis in the liver
- Insulin- stimulates removal of glucose from the blood and anabolic reactions
- Epinephrine- produced from phenylalanine and tyrosine; functions as a neurotransmitter and a stress hormone
- Which of the following hormones or molecules increases the urge to eat?
- Ghrelin
- What is the most common digestible polysaccharide existing as both amylose and amylopectin?
- Starch
- The glucose transporter that is sensitive to insulin is ____.
- GLUT4
- Which hormonal changes occur in response to a fall in blood glucose concentration?
- Decreased insulin, increased glucagon
- Due to a lack of the enzyme glucose-6-phosphatase, which tissue capable of glycogenesis cannot contribute to blood glucose levels between meals?
- Muscle
- Fructose transport into the enterocyte relies on the facilitative transporter GLUT5.
- True
- According to USDA food availability data, calories available from ____ increased the most since 1970.
- Fat
- Which tissue has the least activity of the pentose phosphate pathway?
- Skeletal muscle
- ____ are the hydrocolloids that are secreted at a site of injury on a plant or surround the endosperm of some seeds and are used as thickening agents.
- Gums
- Common food sources of fructans include:
- chicory, onions, and Jerusalem artichokes
- The predominant source of chitin is:
- Shells of crab, lobster, and shrimp
- The characteristics of fiber on which health benefits are based include______ and _______.
- Viscosity
- Fermentability
- Which scenario is NOT a typical gastrointestinal response to ingestion of dietary fiber?
- Increased glucose absorption
- Health Benefits of Fiber: Match the condition with the benefit provided by the fiber. Each answer is used only once.
- Cardiovascular disease- viscous, gel-forming fibers lowers total and LDL cholesterol
- Diabetes mellitus- viscous, gel-forming fibers improve glycemic control
- Satiety- fiber-rich foods and hormones, such as ghrelin, peptide YY, and CCK modulate appetite
- Constipation- non or less fermentable fibers increase fecal bulk
- Colon cancer- fiber reduces bile concentration, dilutes intestinal contents, and reduces colonic transit time
- Explain how exercise increases insulin sensitivity
- Exercise increases GLUT4 content and activation of proteins involved in skeletal muscle insulin signal transduction (AMPK), which increases insulin stimulated GLUT4.
- Based on the research article presented in class, diets high in vegetable protein instead of animal protein do not help with chronic diseases such as Cardiovascular disease and Type 2 Diabetes.
- False
- Which of the following is NOT required for pancreatic lipase to be active?
- Lipoprotein
- We digest and absorb fat efficiently under normal conditions (95% or more).
- True
- Exogenous lipid transport begins with secretion of:
- Chylomicrons from the small intestine
- One of the primary functions of this type of lipid, ____________, is possible because of its structure, which allows it to be both hydrophobic and hydrophilic.
- phospholipid
- Unlike long-chain fatty acids, short-chain fatty acids from the diet leave the enterocyte via the portal vein and go directly to the liver.
- true
- Where does pancreatic lipase begin to work?
- The duodenum
- What is the most common lipid found in animals that is characterized by a four-ring core structure?
- cholesterol
- Cholesterol serves as a precursor for all of the following EXCEPT:
- phospholipids
- What is the carrier for medium-chain fatty acids in portal circulation?
- albumin
- Which of the following is the major site for lipoprotein formation from exogenously derived lipids?
- intestine
- The three main components of energy expenditure
- BMR, PA, and TEF
- Which hormone inhibits gastric motility and stimulates gallbladder contraction?
- CCK
- The lipoprotein synthesized and secreted by the liver (endogenous lipid transport) to transport triacylglycerols
- VLDL
- This type of indigestible CHO is physically inaccessible to our digestive enzymes, tightly packed inside granules within foods, or retrograde starch from cooking and cooling foods
- Resistant starch
- This protein is important for fructose transport, but not glucose
- GLUT-5
- This is the concentration of substrate when reaction is at half of maximum velocity
- Km (Michaelis Constant)
- The general term for a set of reference values for healthy people
- DRI
- The term for an energetically favored reaction
- Exothermic
- This hormone decreases the urge to eat and has been found in high amounts in obese patients
- Leptin
- The three things that impact fluid composition in the body
- Age, gender, tissue type
- The life stage groups separated in dietary reference intake values
- Infancy, childhood, adolescence, pregnancy, lactation
- This hormone is critical in the fed state
- Insulin
- The key enzyme in lipoprotein metabolism which assists in breaking down the TAGs from chylomicrons in non-hepatic tissues
- Lipoprotein lipase
- What enzymes are present in the mouth
- Salivary amylase and lingual lipase
- The maximum intake of nutrients that is unlikely to pose health risks
- Tolerable upper intake levels (ULs)
- The cells found here will migrate up to eventually become absorptive cells on th tips of the villus
- Crypts of lieberkuhn
- The main site of aerobic energy metabolism in the cell
- Mitochondrea
- This disaccharide poses significant digestive issues for a large percent of the global pop
- Lactose
- The cyclical pathway that cleaves two carbons at a time
- Beta oxidation
- This hormone stimulates gastric acid and pepsinogen secretion
- Gastrin
- The starter for fatty acid synthesis
- Acetyl CoA
- These bonds are important characteristics of amylopectin and glycogen
- Alpha 1-6 glycosidic bond
- Which sphincter controls the flow of pancreatic juices and bile in the small intestine
- Sphincter of Oddi
- This process (synthesis of glucose from non-CHO sources) is upregulated when there are high levels of ATP compared to ADP
- Gluconeogenesis
- The lipid that most tissues in the body can synthesize, is a component of cell membranes, and is only consumed in our diet through animal foods
- Cholesterol
- The process related to lipid metabolism that is stimulated by excess carbohydrate intake
- Fatty acid synthesis
