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Regulation of Carbohydrate, Fat, and Protein Metabolism, Exams of Nursing

A comprehensive overview of the interconversions and regulation of carbohydrate, fat, and protein metabolism in the human body. It covers key topics such as the fasted state metabolism, the role of the endocrine pancreas and hormones like insulin and glucagon, the mechanisms of insulin action, the effects of epinephrine and cortisol, and the pathologies related to thyroid, growth hormone, and adrenal hormones. The document also delves into the regulation of calcium homeostasis and the role of parathyroid hormone. This in-depth exploration of metabolic pathways and their hormonal control would be highly relevant for students studying human physiology, biochemistry, or endocrinology at the university level.

Typology: Exams

2023/2024

Available from 09/19/2024

Toperthetop
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Download Regulation of Carbohydrate, Fat, and Protein Metabolism and more Exams Nursing in PDF only on Docsity! biol 373- unit 7 what is metabolism - correct answer ✔✔"set of life-sustaining chemical transformations within the cells of living organisms" whether transformations of energy substrates (carbs, fats, proteins) are biased toward storage/ anabolism or breakdown/ catabolism how is metabolism regulated - correct answer ✔✔• endocrine - primary role- products of endocrine pancreas• insulin/glucagon ratio • neural - regulation of food intake- endocrine pancreas also innervated (autonomic) ingested biomolecules have what three fates - correct answer ✔✔fuel - metabolized to provide energy build - synthesis reactions for growth and maintenance of tissues store - as glycogen (liver, skeletal muscles) or fat metabolism is divided into what two states - correct answer ✔✔fed / absorptive state - anabolic, products of digestion being absorbedand used for synthesis or stored; building phase fasted / postabsorptive state - catabolic, body taps into stores; keeping up glucose or using alternate fuel nutrient pools for immediate use - correct answer ✔✔mostly circulating in plasma): • glucose • free fatty acids • amino acids what do enzymes do in fed-state metabolism - correct answer ✔✔In fed-state metabolism under influence of insulin, enzymeactivity for forward reaction increases.Enzymes for glycogen breakdown are inhibited net glycogen synthesis favouring the glucose to glycogen pathway what do enzymes do in fasted-state metabolism - correct answer ✔✔In fasted-state metabolism under influence of glucagon et al,enzymes that break down glycogen are more active, and enzymesfor glycogen synthesis are inhibited. net glucose synthesis favouring breakdown of glycogen interconversions of carbohydrate, fat and protein - correct answer ✔✔slide 5 unit 7 always running these cycles to keep ourselves alive fasted state we are breaking down glycogen and glycerol into the gluconeogenesis pathway and burn fatty acids to use as fuel and maek acetylcoA what are three characteristics of fasted (postabsorptive) state metabolism - correct answer ✔✔• under the control of hormones • goal is to maintain plasma glucose levels- achieved through pathways that yield glucose or provide ATP via alternate fuels • brain is acutely dependent on glucose(can also use ketones) carbs storage centres for fasted state - correct answer ✔✔liver and muscle how is glucose stored in liver - correct answer ✔✔glycogen in liver - can be broken down and exported as free glucose how is glucose stored and exported in muscle - correct answer ✔✔glycogen in muscle - can NOT be exported as free glucose- use within muscle, OR- export as pyruvate or lactate liver gluconeogenesis- glycogen is main source of glucose for fasted state» liver keeps ~4 h supply of glycogen fats are stored in - correct answer ✔✔liver and adipose tissue? Endocrine Pancreas: Islets of Langerhans - correct answer ✔✔islets of langerhaans minority of pancreas cells insulin in fed state how are blood glucose levels monitored how does pancreatic beta cells detect glucose - correct answer ✔✔beta cells sensor and integrating center features of pancreatic beta cells involved in glucose monitoring and insulin release - correct answer ✔✔• GLUT2 transporters - move glucose into beta cells by facilitated diffusion • K+ leak channels - usually open, close when ATP binds to them"ATP-gated K+ channel" • voltage-gated Ca2+ channels • secretory vesicles of insulin waiting for release signal pancreatic beta cell at rest when glucose is low vs releasing insulin - correct answer ✔✔low: default open leak channels open and positives are leaving high: atp channels are close cell becomes depolarized Insulin:Glucagon in Fed versus Fasted States and Glucose, Insulin and Glucagon before and after a meal - correct answer ✔✔90 mg/dL is a fasting level of blood glucose insluin rises after a meal and glucagon dips factors affecting insulin release - correct answer ✔✔increase plasma glucose (> 100 mg/dL), increase plasma AAs • increase GLP-1, increase GIP • increase parasympathetic (also amplifies other effects)(inhibited by sympathetic activity) insluin targets - correct answer ✔✔• (striated) muscle, adipose (express Glut4 transporter) • liver actions of insulin - correct answer ✔✔- increase glucose transport into Glut4-expressing target cells - increase glucose metabolism - increase glycogenesis - increase fat synthesis, increase protein synthesis insulin mechanism of action generalized - correct answer ✔✔ insulin effects in muscle and adipose and in hepatocytes fasted vs fed state - correct answer ✔✔ insulin is anabolic in that it activates enzymes which enhance - correct answer ✔✔• glycolysis (glucose oxidation) • glycogenesis (storage) • AA utilization / protein synthesis • lipogenesis (conversion of excessglucose or AAs into triglycerides) insulin is anabolic in that it inhibits enzymes that enhance - correct answer ✔✔inhibits enzymes that enhance: • gluconeogenesis • glycogenolysis • proteolysis • lipolysis • β oxidation of fatty acids when insulin is low which pathways predominate - correct answer ✔✔catabolic how does glucagon antagonize the effects of insulin - correct answer ✔✔• produced by alpha cells of pancreas • member of secretin family of peptides (incl secretin, GIP, GLP-1, et al.) • main trigger is low blood glucose• main target is liver • main function is to prevent hypoglycemia- during overnight fast, ~75% of the glucose from the liver comes from glycogenolysis, ~25% from gluconeogenesis increases glycogenolysis, gluconeogenesis, and ketogenesis endocrine response to hypoglycemia - correct answer ✔✔low blood glucose inhibits beta cells decrease in insulin allows catabolic effects to occur diabetes mellitus - correct answer ✔✔just means glucose in pee • group of diseases characterized by elevated blood glucose (hyperglycemia) resulting from:- inadequate insulin secretion Type 1- abnormal target cell responsiveness Type 2 • or both how does a normal vs diabetic person respond to ingested glucose - correct answer ✔✔normal: blood glucose starts around 90 at fasted and then rises to a bout 125 and lowers back down in diabtetic: fasting is high around 120/125 and just keeps rising when given the sugar acute pathophysiology of type 1 diabetes - correct answer ✔✔dont have to be able to reproduce this excess fat break down no glucose uptake and losing fat and muscle mass polyphagia-extreme hunger and losing glucose in urine and disrupt osmolarity metabolic acidosis type 2 diabetes - correct answer ✔✔• accounts for ~90% of diabetes- was once called "mature onset" diabetes (versus "juvenile") • typically there is "insulin resistance", with delayed response to an oral glucose challenge (oral glucose tolerance test)- can be coupled with low, normal or high insulin secretion • acute symptoms not as severe as Type 1, but metabolism is not normal • Type 2 diabetes, atherosclerosis and hypertension often occur together, typically in association with obesity'Metabolic Syndrome' • at least three of: central obesity hypertension fasting blood glucose > 110 mg/dL elevated fasting triglycerides low plasma HDL-cholesterol hypercortisolism - correct answer ✔✔Cushing's syndrome• primary - cortisol-secreting adrenal tumors (not regulated by ACTH)• secondary - pituitary tumor that over-secretes ACTH• iatrogenic - secondary to cortisol therapy for other conditions hypocortisolism - correct answer ✔✔• primary adrenal insufficiency (Addison's disease)• adrenal gland does not develop normally• mutations in key steroidogenic enzymes• adrenal gland damaged / destroyed (autoimmune)• secondary - lack of ACTH thyroid gland - correct answer ✔✔ thyroid hormone - correct answer ✔✔• amino acid derivative (from tyrosine), containing iodine - only known use of iodine in body • mechanism of action more like steroids - binds to nuclear receptor • lipophilic, travels in circulation bound to thyroid-binding globulin T4 - main circulating form T3 - most active form, converted within target cell by deiodinases (removing iodine) actions of thyroid hormone - correct answer ✔✔• essential for normal growth / development, esp nervous system- thyroid hormone levels checked in all newborns in Canada• in adults, not essential, but affects quality of life• main function is to provide substrates for oxidative metabolism- increase oxygen consumption and generation of heat (thermogenesis) in most tissues 'basal metabolic rate'• increase activity of Na+/K+-ATPase- interact with other hormones to modulate carbohydrate, protein and lipidmetabolism growth hormone - correct answer ✔✔GH, Somatotropin)Fig 23.8control of growth complex, many factors!• GH released throughout life but much more important during childhood• effects can be direct -- target cells express GH receptor• or indirect -- mediated by insulin-like growth factors(IGFs = somatomedins) produced by liver ortarget cells themselves• growth effects and metabolic effects growth hormone diagram - correct answer ✔✔ actions of growth hormone metabolic and growth - correct answer ✔✔metabolic • carbohydrate - indirect effects lead to increase plasma glucose • fat -increase lipolysis, increase oxidation • catabolic with respect to CHOs and fat, 'anti-insulin' • protein - increase AA uptake, increase protein synthesis, decrease oxidation for energy • anabolic with respect to proteins, 'pro-insulin' growth • increase proliferation and differentiation of chondrocytes cartilage and bone growth • increase muscle growth (see metabolic effects) • increase growth of other soft tissues growth hormone pathologies - correct answer ✔✔deficiency - due to GH hyposecretion, GH-receptor mutations ...dwarfism (though GH issues are not a common cause)• deficiency syndromes were difficult to treat when the only source of human GH was cadavers• availability of recombinant human GH (since 1980s) has raised ethical issues- how tall is tall enough?- how to predict which children will be 'too short'?- used as performance enhancing drug excess - depends on whether excess secretion is before or afterclosure of growth plates of long bones- before - giantism- after - acromegaly congenital adrenal hyperplasia - correct answer ✔✔genetic disease in which the adrenal gland is overdeveloped, resulting in a deficiency of certain hormones and an overproduction of others most common cause of hypocortisolism intracellular calcium - correct answer ✔✔intracellular calcium (0.9%)• in SR, cytosol, mitochondria• involved in muscle contraction, signalling pathways extrcellular fluid calcium - correct answer ✔✔extracellular fluid calcium (0.1%)• secretion / exocytosis (neurotransmitters, secretory products)• contraction of cardiac and smooth muscle• clotting cascade extrcaellular matrix calcium - correct answer ✔✔extracellular matrix calcium (99%)• component of ECM of bones and teeth• bone is largest reservoir of calcium but very little of it available for exchange- continually being remodelled by cells that lay down and remove mineral matrix• osteoblasts lay down Ca-PO4• osteoclasts secrete enzymes/H+ that dissolve mineral matrix resorption where does calcium come from - correct answer ✔✔Ca intake: only about 1/3 ingested calcium is absorbed- by paracellular and transcellular routes- absorption via transcellular route is hormonally regulated calcium output - correct answer ✔✔- primarily via kidneys - freely filtered, most reabsorbed• hormonally controlled reabsorption at distal nephron only calcium homeostasis regukated by what three hormones - correct answer ✔✔parathyroid hormone• released in response to hypocalcemia• raises plasma Ca2+ in three ways:- increases absorption from intestine (indirectly, via Vit D3)- increases reabsorption in distal nephron- increases resorption from bone Vitamin D3 (aka calcitriol, aka 1,25-dihydroxy cholecalciferol)• production regulated by PTH• enhances everything that PTH does (intestine, kidney, bone) calcitonin• released in response to hypercalcemia• lowers plasma calcium via actions on kidney, bone parathyroid gland - correct answer ✔✔slide 64 PTH released in response to ↓ plasma Ca2+ small intestine:↑ Ca2+ absorption by transcellular route(via vit D3) kidney:↑ Ca2+ reabsorption bone:↑ osteoclast activity ↑ bone resorption bumps on thyroid gland in the pharynx homeostatic response to hypocalcemia - correct answer ✔✔slide 65 in the diet take the vitamin d precursor or synthesized from energy from sun in the liver we have first hdyroxilation and then in kidney os the second hydroxylation vitamin d3 is a hormone kind of because it goes through blood