PSY 333 Exam 3 | Verified with 100% Correct Answers

PSY 333 Exam 3 | Verified with 100% Correct Answers What is the primary link between obesity and type 2 diabetes? Insulin resistance caused by obesity leads to B-cell dysfunction, which results in the inability to regulate blood glucose levels properly How do non-esterified fatty acids (NEFAs) contribute to insulin resistance? NEFAs impair insulin signaling and B-cell function, contributing to insulin resistance What role do pro-inflammatory cytokines play in insulin resistance? They activate pathways like JNK and IKK-B/NF-kB, which impair insulin signaling What is the role of β-cells in preventing hyperglycemia in insulin-resistant individuals β-cells increase insulin secretion to compensate for reduced insulin sensitivity What hormone released by adipose tissue acts as an insulin sensitizer? Adiponectin What is the primary function of glucagon-like peptide-1 (GLP-1)? GLP-1 stimulates insulin secretion, inhibits glucagon release, and slows gastric emptying How does GLP-1 influence appetite and food intake? It reduces appetite and food intake by acting on the brain and gastrointestinal tract What is the significance of GLP-1 receptor agonists in medicine? They are used as treatments for type 2 diabetes and obesity Where is GLP-1 primarily produced? In the L-cells of the intestine How does GLP-1 affect cardiovascular health? It has cardio-protective effects, reducing inflammation and promoting heart function. What are the two main forms of diabetes? Type 1: Body is unable to produce insulin Type 2: Body is resistant to insulin How does insulin regulate glucose metabolism? It facilitates glucose uptake into muscle and adipose tissue and promotes glycogen storage in the liver What role does GLP-1 play in insulin secretion? It enhances glucose-stimulation secretion from pancreatic β-cells How does GLP-1 influence gastric emptying? It slows gastric emptying ,which helps control postprandial glucose levels What is leptin, and what is its primary function? Leptin is an anorexigenic hormone that regulates energy balance by suppressing appetite How does serum leptin concentration correlate with body fat percentage? Leptin levels are strongly correlated with body fat percentage and can be used as an adiposity indicator How do BMI and leptin together estimate body fat percentage? They provide a better estimate of total body far than either measure alone Why is leptin an important hormone for energy balance? It signals the brain to regulate appetite and metabolism based on fat stores How does obesity affect leptin levels? Obese individuals have higher circulating leptin levels but may develop leptin resistance What is the significant of the Health ABC Study in leptin research? It provided evidence that BMI and leptin are independent predictors of body fat percentage in adults Why do most insulin-resistant individuals not develop type 2 diabetes? Because pancreatic β-cells compensate by increasing insulin secretion to maintain normal glucose tolerance What role does retinol-binding protein-4 (RBP4) play in insulin resistance? RBP4 contribute to insulin resistance by reducing PI93)K signaling in muscle and increasing gluconeogenesis in the liver How does tumor necrosis factor-a (TNF-α) contribute to insulin resistance? TNF-α stimulates inflammatory pathways that interfere with insulin signaling What is the relationship between obesity, B-cell dysfunction, and type 2 diabetes? Obesity leads to insulin resistance; if β-cells fail to compensate with increased insulin secretion, type 2 diabetes develops Why is B-cell dysfunction considered a critical factor in the development of type 2 diabetes? Because without sufficient insulin secretion, glucose levels cannot be properly regulated How does GLP-1 regulate glucose metabolism beyond insulin secretion? It suppresses glucagon secretion, slows gastric emptying, and promote satiety What are the two main forms of GLP-1 found in circulation? GLP-1 (7-36 amide) GLP-1 (7-37) How does GLP-1 interaction with the brain to influence appetite? It acts on the hypothalamus and vagus nerve to reduce food intake What is the primary enzyme responsible for degrading GLP-1? Dipeptidyl peptidase-4 (DPP-4) How do GLP-1 receptor agonists help in treating obesity? They enhance insulin secretion, suppress appetite, and slow gastric emptying How does insulin signaling affect food intake? Insulin acts as an anorexigenic signal, reducing food intake and preventing excessive weight gain What is the relationship between insulin and glucose tolerance? Insulin helps clear glucose from the blood stream Impaired insulin signaling leads to glucose intolerance How does the glucose tolerance test assess insulin function? It measures how quickly glucose is cleared from the blood after ingestion What happens when insulin receptors (IRS-1 and IRS-2) are deleted in mice? It leads to increased food intake and body weight gain How does high-fat diet consumption contribute to insulin resistance? It disrupts glucose metabolism and decreases insulin sensitivity What is leptin's primary function in energy homeostasis? It signals the brain to regulate appetite and metabolism based on fat store How does leptin resistance develop in obesity? Despite high leptin levels, the brain fails to respond to its appetite-suppressing effects Why might serum leptin be a better indicator of body fat than BMI? Leptin directly reflect adipocyte activity, while BMI does not distinguish between fat and lean mass What is the relationship between leptin levels and gender? Women typically have higher leptin levels than men due to higher body fat percentages How does aging affect leptin levels and fat distribution? Older adults may experience changes in fat distribution and altered leptin signaling How do GLP-1 and leptin interact in regulating energy balance? Both hormones reduce food intake, but GLP-1 acts acutely on meal size while leptin regulate long-term energy balance What is the effect of GLP-1 on insulin resistance? GLP-1 improves insulin sensitivity by enhancing glucose-dependent insulin secretion How does obesity lead to chronic low-grade inflammation? Adipose tissue releases pro-inflammatory cytokines like TNF-α and IL-6, which impair insulin signaling How do dietary choices influence insulin and leptin signaling? High-fat diets can impair insulin sensitivity and contribute to leptin resistance How does an increase in ATP/ADP ration influence insulin secretion? It triggers the closure of ATP-sensitive K+ (KATP) channels, leading to membrane depolarization and opening of voltage-gated Ca2+ channels, which induces insulin exocytosis What happens when KATP channels close in pancreatic β-cells? The cell membrane depolarizes, leading to Ca2+ influx through voltage-gated Ca2+ channels and subsequent insulin secretion What role do voltage-gated Ca2+ channels play in insulin secretion? They open in response to membrane depolarization, allowing Ca2+ influx, which triggers insulin granule exocytosis How does GLP-1 enhance insulin secretion at the cellar level? GLP-1 increases cAMP, which enhances PKA and Epac2 signaling, leading to increased Ca2+ release from intracellular stores and potentiation of insulin secretion What effect does cAMP have on KATP channels in β-cells? CAMP, via PKA, increases KATP channel sensitivity to ATP, leading to their closure and subsequent insulin release What is the relationship between intracellular Ca2+ levels and insulin granule release? Increased intracellular Ca2+ levels promote exocytosis of insulin granules, facilitating glucose-stimulated insulin secretion What is the function of Epac2 in insulin secretion? Epac2 enhances Ca2+ release from the endoplasmic reticulum and amplifies insulin exocytosis in response to GLP-1 How does GLP-1 regulate voltage-gated Ca2+ channels? GLP-1 inhibits voltage-gated K+ channels, prolonging Ca2+ influx and sustaining insulin secretion What effect does GLP-1 have on insulin secretion at low glucose levels? GLP-1 fails to stimulate insulin secretion at glucose concentrations below 2.8 mM but amplifies it at concentrations above 6.6 Mm Why is ATP generation crucial for insulin release? ATP is required to close KATP channels, depolarize the membrane, and initiate Ca2+ influx, which triggers insulin granule exocytosis What happens if KATP channels remain open due to a lack of ATP? The membrane remains hyperpolarized, preventing Ca2+ influx and reducing insulin secretion How do sulfonylureas, like glibenclamide, affect insulin secretion? They block KATP channels mimicking the effect of ATP, leading to B-cell depolarization and insulin secretion What happens to β-cells when intracellular Ca2+ stores are depleted? Insulin secretion is impaired because Ca2+ release is necessary for vesicle fusion and insulin exocytosis How does anaplerosis contribute to B-cell function? Anaplerosis replenishes TCA cycle intermediates, ensuring continuous ATP production for insulin secretion What role does protein kinase A (PKA) play in insulin secretion? PKA phosphorylation proteins involved in Ca2+ signaling and insulin granule priming, enhancing secretion How does B-adrenergic signaling influence insulin secretion? B-adrenergic agonists stimulate cAMP production, enhancing insulin release, whereas a2-adrenergic agonists inhibit secretion What is the role of the M2 muscarinic receptor in insulin secretion? It activated PKC and DAG-dependent pathways to stimulate insulin release in response to acetylcholine How do long-chain acrylic-CoA molecules regular insulin release? They enhance insulin secretion via PKC activation and direct stimulation of insulin granule exocytosis What is calcium-induced calcium release (CICR) in β-cells? CICR amplifies Ca2+ signals by triggering further Ca2+ release from intracellular stores in response to initial influx What effect does ATP depletion have on B-cell function? ATP depletion prevents KATP channel closure, reduces Ca2+ influx, and suppresses insulin secretion ATP Adenosine Triphosphate: The main energy carrier in cells ADP Adenosine Diphosphate: A lower-energy form of ATP that can be converted back into ATP KATP Channel ATP-sensitive Potassium Channel: A channel in pancreatic β-cells that regulates insulin secretion by sensing ATP levels Ca2+ Calcium Ion: A key secondary messenger in insulin secretion cAMP Cyclic Adenosine Monophosphate: A signaling molecule that enhance insulin secretion PKA Protein Kinase A: An enzyme activated by cAMP that plays a role in insulin secretion Epac2 Exchange Protein Activated by cAMP 2: A protein that enhances Ca2+ release and insulin secretion DAG Diacylglycerol: A signaling lipid involved in activating protein Kinase C (PKC) PKC Protein Kinase C: A kinase that plays a role in insulin secretion and other cellular processes CIRC Calcium-Induced Calcium Release: A mechanism where initial Ca2+ influx triggers further Ca2+ release from intracellular stores GLP-1 Glucagon-Like Peptide-1: A hormone that enhance insulin secretion IRS-1 and IRS-2 Insulin Receptor Substrate-1 &2: Proteins that mediate insulin signaling GLP-1R Glucagon-Like Peptide-1 Receptor: The receptor for GLP-1, involved in glucose metabolism IL-6 Interleukin-6: A cytokine involved in inflammation and metabolism TNF-α Tumor Necrosis Factor-Alpha: A cytokine that can contribute to insulin resistance NEFAs Non-Esterified Fatty Acids: Fatty acids that contribute to insulin resistance RBP4 Retinol-Binding Protein-4: A protein that contributes to insulin resistance K+ Potassium Ion: Involved in maintaining membrane potential in β-cells Na+ Sodium Ion: Plays a role in cellular membrane potential Voltage-Gated Ca2+ Channels Channels that open in response to membrane depolarization to allow Ca2+ influx, crucial for insulin secretion TCA cycle Tricarboxylic Acid Cycle (Krebs Cycle): A central metabolic pathway for ATP production Anaplerosis A process that replenishes TCA cycle intermediates to sustain ATP production DPP-4 Dipeptidyl Peptidase-4: An enzyme that degrades GLP-1, reducing its effectiveness M2 Muscarinic Receptor A receptor that influences insulin secretion in response to neurotransmitters What is homeostasis? The active process of maintaining a physiological parameter in a relatively constant state Who first encapsulated the idea of homeostatic control? Claude Bernard in the mid-19th century Which brain region is critical for ingestive behavior regulation? The hypothalamus What is the function of the ventromedial hypothalamus (VMH)? It regulates ingestive behavior and acts as a satiety center What happens when the VMH is damaged? It leads to hyperphagia (excessive eating) and significant weight gain What is Frohlich's Syndrome? A condition associated with obesity due to abnormalities in the VMH What is the function of the lateral hypothalamic area (LHA)? It is involved in feeding motivation and food intake What happens when the LHA is damaged? It results in severe anorexia and hypophagia What effect does electrical stimulation of the LHA have? It leads to an escalation of food intake What neurotransmitter in the LHA suppresses fasting-induced feeding? Neurotensin What was Brobeck's key observation about obesity in animals with hypothalamic lesions? They gain weight rapidly due to increased food intake What are the two phases of obesity development that are described by Brobeck? Dynamic phase: Rapid weight gain Static phase: Weight stability What did Hetherington and Randon demonstrate in 1940? That obesity can result from lesions in the ventromedial hypothalamus What role does lipid metabolism play in hypothalamic obesity? Increased lipid turnover and storage in liver and fat depots What evidence suggests that the pituitary gland is not responsible for obesity in these cases? Obesity can develop even in animals with removed pituitary glands What behavioral changes were observed in animals with hypothalamic lesions? Increased irritability, hyperactivity, and in some cases, lethargy How do hypothalamic lesions affect the reproductive system? They cause hypoplasia (underdevelopment) of the gonads What did experiments with stereotaxic instruments reveal about hypothalamic function? That lesions in specific areas, such as the ventromedial nucleus, can induce obesity What is the gut microbiome? A collection of microbes, including bacteria and archaea, that inhabit the human digestive system How does the Firmicutes-to-Bacteroidetes ratio change in obesity? It increases in obese individuals and decreases with weight loss What role do methanogenic archaea play in metabolism? They enhance energy extraction by consuming hydrogen produced by other gut microbes What is Methanobrevibacter smithii, and why is it significant? It is a dominant methanogen in the gut that may contribute to obesity by increasing caloric harvest What evidence suggests that gut microbes influence weight gain? Germ-free mice gain less weight than conventionally raised mice, despite eating more How does Roux-en-Y gastric bypass affect the gut microbiome? It alters the composition, increasing Bacteroidetes and reducing Firmicutes How does lipopolysaccharide (LPS) contribute to obesity? It triggers inflammation, which can lead to insulin resistance and increased fat storage What is metabolic endotoxemia? A condition where elevated plasma LPS levels lead to chronic inflammation and metabolic disorders What did studies show about methane production in breath tests? Methane produces had higher BMI and increased visceral fat What potential treatment was suggest for obesity based on gut microbiome research? Antibiotic treatments targeting methane-producing bacteria to improve metabolism What is the gut-brain axis? It is the communication network between the gut and brain that regulates hunger and energy balance What are the two types of satiety signals? Short-term: CCK Long-term: Leptin How do hunger and satiety signals influence food intake? Hunger signals promote eating, while satiety signals suppress appetite What is the role of leptin in energy regulation? Leptin signals to the brain that energy stores are sufficient, reducing hunger How does insulin contribute to energy balance? Insulin helps regulate glucose uptake and signals satiety to the brain Why is glucose regulation important for the body? It maintains stable blood sugar levels, ensuring a constant energy supply What happens when glucose regulation is impaired? It can lead to metabolic disorders like diabetes What environmental and genetic factors contribute to diabetes? Diet, genetics, socioeconomic status, and chronic stress Why is insulin crucial in glucose metabolism? It facilitates glucose uptake into cells and prevents hyperglycemia How does glucose stimulate insulin release from β-cells? Glucose metabolism increases ATP, closing KATP channels, and triggering Ca2+ influx What is the role of mitochondria in insulin secretion? They generate ATP which helps regulate KATP channels What happens when KATP channels close? Membrane depolarization occurs, leading to Ca2+ influx and insulin release What is the role of voltage-dependents Ca2+ channels in β-cells? They open upon depolarization, allowing Ca2+ influx to trigger insulin exocytosis What effect does ATP have on KATP channels? ATP closes KATP channels, leading to depolarization and insulin secretion Where is GLP-1 produced? In the intestines, specifically in L-cells What is the function of GLP-1? It enhances insulin secretion, reduces appetite, and slows gastric emptying How does GLP-1 influence insulin secretion? It amplifies insulin release in response to glucose What effect does GLP-1 have on food intake? It reduces appetite by acting on the brain and gut How does GLP-1 affect gastric emptying? It slows down the emptying of food from the stomach What role does the vagus nerve play in GLP-1 signaling? It mediates the effects of GLP-1 on gastric emptying and satiety What happens when the vagus nerve is damaged? GLP-1 loses its ability to delay gastric emptying How does the brain respond to GLP-1 signaling? It reduces activity in regions associated with food motivation Which brain areas are affected by GLP-1? The insular cortex and amygdala, which regulate emotions and hunger How does GLP-1 affect glucose tolerance? It improves the body's ability to manage blood sugar levels What is the genetic cause of leptin deficiency? Mutations in the ob gene How was leptin discovered? Through studies on obese mice with genetic mutation What is their primary function of leptin? To signal satiety and regulate fat storage Where is leptin produce? In adipose (fat) tissue Why do obese individual often have high leptin levels? Due to leptin resistance, where the brain does not respond properly to the hormone How does a high-fat diet influence insulin resistance? It disrupts normal insulin signaling, leading to reduced glucose uptake What is the purpose of glucose tolerance tests? To assess how well the body manages blood sugar levels Why is GLP-1 used in diabetes treatments? It enhances insulin secretion and improves glucose control What are the benefits of GLP-1 agonists? They help with weight loss and improve glucose metabolism Why is glucose homeostasis crucial for survival? It ensures that cells have continuous energy supply What is the hypothalamus? A brain region that regulates numerous autonomic functions, including hunger, thirst, and body temperature What does "afferent" mean in neuroscience? It refers to incoming signals that carry sensory information toward a central structure, like the brain What does "efferent" mean in neuroscience? It refers to outgoing signals that carry motor commands from the brain to the body What is the amygdala? A brain structure involved in emotional and motivational processing What is the parabrachial nucleus? A brain stem structure involved in processing taste (gustatory) and other sensory information What is the ventral subiculum? A part of the hippocampal formation involved in spatial processing and memory What are electrolytic lesions? Brain lesions causes by applying an electrical current to destroy targeted tissue What does "gustatory" refer to? Related to the sense of taste What is the periaqueductal gray (PAG)? A brain stem region involved in pain modulation and motivated behaviors What is the bed nucleus of the stria terminalis (BNST)? A brain region involved in stress regulation and reward processing What is hyperphagia? Excessive eating due to increased appetite or lack of satiety signals What is hypophagia? Reduced food intake, often due to decreased appetite What is the dual-center hypothesis? A theory suggesting the lateral hypothalamus stimulates feeding, while the ventromedial hypothalamus suppresses it What is the dynamic phase of hypothalamic obesity? The initial rapid weight gain after hypothalamic damage What is the status phase of hypothalamic obesity? The later phase in which weight stabilizes at a higher level What is intracranial self-stimulation (ICSS)? A phenomenon where animals press a level to electrically stimulate rewarding brain regions What is neurotensin? A neuropeptide that can suppress feeding behavior? What is the nucleus of the solitary tract? A brainstem structure that progresses visceral sensory information, including taste What is the Firmicutes-to-Bacteroidetes ratio? A measure of the relative abundance of two major bacterial phyla in the gut, often associated with obesity What is Methanobrevibacter smithii? A type of archaea that enhance caloric extraction from food and may contribute to obesity What is short-chain fatty acid (SCFA) production? The process by which gut bacteria ferment dietary fiber to produce energy-rich molecules like acetate, butyrate, and propionate Why is gut dysbiosis? An imbalance in gut microbial population that may contribute to disease like obesity and diabetes What is metabolic endotoxemia? A condition where bacterial lipopolysaccharides (LPS) enter the bloodstream, triggering inflammation and insulin resistance What is a germ-free (GF) mouse? A laboratory mouse that has no gut microbes, often used in microbiome research What is a Roux-en-Y gastric bypass (RYGB)? A weight-loss surgery that alters the digestive system and changes gut microbiota composition What is Fiaf (Fasting-induced adipose factor)? A protein that regulates fat storage by inhibiting lipoprotein lipase, which is suppressed by gut microbes in obese individuals What is methane excretion on breath tests used for? It is an indicator of gut methanogen activity, which is linked to obesity and altered metabolism What is the endocannabinoid system's role in obesity? A system involved in regulating appetite, metabolism, and permeability What is a prebiotic? A dietary substance that promotes the growth of beneficial gut bacteria What type of diet-induced obesity alters AgRP neuron activity? High-fat diet (HFD) Which hypothalamic neurons are responsible for promoting hunger? AgRP neurons How does obesity affect AgRP neuron responses to sensory food cues? It attenuates their response to food cues What happens to AgRP neuron responses after weight loss? Responses to food cues recover, but sensitivity to gastrointestinal hormones remains impaired Which hormone is required for dietary fat to inhibit AgRP neurons? Cholecystokinin (CCK) Which neuropeptide is considers one of the most potent orexigenic factors? Neuropeptide Y (NPY) What role does leptin play in appetite regulation? Leptin inhibits appetite by acting on hypothalamic neurons Which brain region is the central feeding control center? The hypothalamus Which peripheral hormone is known to stimulate hunger? Ghrelin How does insulin affect food intake? Insulin inhibits appetite and promotes satiety Which nerve sends peripheral feeding signals to the brainstem? The vagus nerve What are the two primary orexigenic signals in the accurate nucleus? NPY and AgRP Which anorexigenic signals inhibit feeding in the accurate nucleus? POMC and CART How does prolonged exposure to a high-fat diet affect NPY neurons? It increases their firing rate What happens to POMC expression when rodents are exposed to a high-fat diet? POMC expression becomes unaffected by insulin treatment What is the primary role of AgRP neurons in energy regulation? They link the body's need for energy to the motivation to eat How does leptin influence AgRP neurons over the long term? Leptin inhibits AgRP neuron activity, reducing hunger Which two rapid signals inhibit AgRP neurons upon food consumption? Sensory detection of food and gastrointestinal signals What effect does high-fat diet induced obesity have on ghrelin's ability to activate AgRP neurons? It reduces the responsiveness if AgRP neurons to ghrelin Which circuit component remains impaired even after weight loss in formerly obese mice? AgRP neuron responses to gastrointestinal hormones Which behavioral change is observed in diet-induced obese mice after fasting? They consume fewer calories than lean controls when reintroduced to food What is one reason why maintaining weight loss is difficult after obesity? Obesity causes persistent changes in hunger neurons that are not fully reversed by weight loss How does diet-induced obesity affect AgRP neuron response to intragastric fat? It selectively desensitizes AgRP neurons to dietary fat but not to glucose or protein Which hormone's effects on AgRP neurons are blunted in diet-induced obese animals? Both Cholecystokinin (CCK) and Ghrelin What is the primary consequence of AgRP neuron dysregulation in obesity? Impaired hunger signaling, making it harder to regulate food intake effectively What is the role of the accurate nucleus in appetite regulation? It integrates hormonal signals related to energy balance and feeding What is the function of neuropeptide Y (NPY) in appetite regulation?