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83 Cards in this Set
- Front
- Back
What endocrine products does the pancreas synthesize and release?
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Hormones: glucagon, insulin, somatostatin
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What exocrine products does the pancreas synthesize and release?
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Enzymes
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Where does the pancreas release hormones such as insulin, glucagon, and somatostatin?
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Into the portal vein (circulation)
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Where does the pancreas release enzymes?
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Into the intestine
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What is the major stimulus for endocrine secretion?
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Glucose
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What is the major stimulus for exocrine secretion?
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Secretion depends on phases of digestion
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Secretion of islet hormones a)_________ and b)_________ is coordinated with the secretion of c)___________________
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a) insulin
b) glucagon c) exocrine pancreatic enzymes |
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What regulates insulin and glucagon secretion?
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The entry of nutrients into GI tract
and GI hormones |
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What cells of the pancreas secrete insulin?
What is the percentage of these cells? |
B (beta) cells of the Islets of Langerhans
65-70% |
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What cells of the pancreas secrete glucagon?
What is the percentage of these cells? |
A (alpha) cells of the Islets of Langerhans
about 20% |
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What cells of the pancreas secrete somatostatin?
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D (delta) cells of the Islets of Langerhans
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What inhibitory peptide of the pancreas inhibits islets cell secretion?
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Somatostatin
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Is insulin an anabolic hormone or a catabolic hormone?
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Anabolic
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Is glucagon an anabolic hormone or a catabolic hormone?
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Catabolic
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Levels of which pancreatic hormone rise when body has excess of nutrients?
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Insulin
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Which pancreatic hormone allows the body to use carbohydrates as an energy source and store nutrients?
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Insulin
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Levels of which hormone rise when the body is in a state of nutrient/food deprivation?
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Glucagon
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When glucagon levels are high, what nutrient reserves are mobilized as an energy source?
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Glycogen, fat, and protein
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Increased plasma glucose stimulates __________ secretion
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Insulin
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Decreased plasma glucose stimulates ___________ secretion
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Glucagon
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Insulin __________ glucagon secretion
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inhibits
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Glucagon _________ insulin secretion
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stimulates
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Insulin increases activity of which metabolic processes?
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Glucose oxidation
Glycogen synthesis Fat synthesis Protein synthesis |
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Glucagon increases activity of which metabolic processes?
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Glycogenolysis (glycogen degradation)
Gluconeogenesis (glucose from pyruvate, which comes from acetyl coa) Ketogenesis |
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The fasting plasma glucose level is about _____ mg/dl with a range of ________ mg/dl
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90 mg/dl
70-110 mg/dl |
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After a meal, plasma glucose _________ and stimulates __________ secretion
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increases
insulin |
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During overnight fasting, plasma glucose ___________, insulin secretion ___________, and glucagon secretion __________.
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Plasma glucose decreases
Insulin secretion decreases Glucagon secretion remains steady |
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What are the serum stimulators of insulin secretion?
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elevated glucose (>100 mg/dl)
elevated amino acids elevated free fatty acids elevated ketone bodies |
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What are the serum inhibitors of insulin secretion?
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low glucose
low amino acids low free fatty acids |
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What hormones stimulate insulin secretion?
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Gastroinhibitory peptide (GIP), Glucagon-like peptide-1(GLP-1)
gastrin cholescystokinin (CCK) secretin vasoactive peptide (VIP) Glucagon epinephrine (β2-AR) |
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What hormones inhibit insulin secretion?
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Somatostatin
Epi/Norepi (alpha2-AR) |
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Insulin secretion is caused by the ____________ nervous system.
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parasympathetic (Ach)
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Insulin inhibition is caused by the _______________ division of the autonomic nervous system.
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sympathetic (alpha2-AR)
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Steps of insulin secretion:
a) Glucose enters the _________ via ___________ transporter b) Glucose → _________ → → _______ production c) ATP binds to the _________________ → ↓K+ efflux → β cells ___________ d) "2nd answer to c" causes the _____________ channels to open → _______ influx → _____ stimulates insulin release by __________ |
a) β cells, GLUT2
b) glucose-P, ↑ATP c) ATP-sensitive K+ channels (KATP), depolarization d) voltage-gated Ca2+, ↑ Ca2+, Ca2+, exocytosis d) |
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Insulin secretion in beta-cells:
a) is _________ by ACETYLCHOLINE, GLUCAGON, beta-2-adrenergic stimulation b) is ___________ by alpha2-adrenergic stimulation (the predominant response to sympathetic stimulation is mediated via alpha2-AR), SOMATOSTATIN |
a) increased
b) decreased |
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What is a polypeptide containing two chains of amino acids (A and B chain)?
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Insulin
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What makes insulin antigenic?
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Minor species differences in the amino acid composition
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Insulin synthesis!
Initially, a)___________ is the inactive form that is secreted into the b) ____________. Post-translational processing clips the _____________ and forms the disulfide bridges (proinsulin). The polypeptide is clipped at d)____(#) positions to release the intervening chain C (C peptide is detached before secretion). e) __________ and f) __________ are secreted by g) ____________ |
a) preproinsulin
b) endoplasmic reticulum c) N-terminal signal sequence d) 2 e) active insulin f) C peptide g) exocytosis |
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T/F
Most of insulin and C-peptide are released in unequal molar amounts. |
False!
90 -97% of insulin and C-peptide are released in equimolar amounts |
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What can be measured in plasma and its level provides an index of the β cell function?
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C-peptide
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What reduces glomerular hyperfiltration and reduces urinary albumin excretion in patients with diabetes?
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C-peptide
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What reduces glomerular hyperfiltration functions in repair of the muscular layer of arteries?
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C-peptide
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T/F
C-peptide functions are not fully understood. |
True!
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Insulin receptors are ________________ receptors.
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tyrosine-kinase (Tk) linked
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Insulin receptors are activated by what?
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Binding of insulin to the receptor
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When insulin binds its own receptor, the activated insulin receptor phosphorylates insulin-receptor substrate and induces effects on cellular:
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metabolism
membrane transport activity of transcription factors |
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What hormone promotes cellular growth and survival (brain cells)?
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Insulin
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What hormone inhibits β–oxidation of fatty acids?
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Insulin
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What hormone promotes transmembrane transport of potassium, magnesium, and phosphate ions into cells?
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Insulin
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Insulin-dependent glucose transport is via:
This is located where? |
GLUT4
adipose or skeletal/cardiac muscle cell Activation of insulin receptors → activation of phosphoinositide-3-kinase → translocation of the GLUT4-containing endosomes into the cell membrane. GLUT4 has a high affinity for glucose. |
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Insulin-independent glucose transport is via:
This is located where? |
GLUT2
liver cell |
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Name the transporter:
Sodium-dependent transport. Cotransports molecule of glucose or galactose. Does not transport fructose. Major expression sites: Intestinal mucosa and kidney tubules |
SGLUT1 and SGLUT2
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Name the transporter:
Transports glucose (high affinity) and galactose, not fructose. Expressed in many cells. Major expression sites: Brain, erythrocyte, endothelial cells, fetal tissues, cardiac myocytes |
GLUT-1
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Name the transporter:
Transports glucose, galactose and fructose. A low affinity, high capacity glucose transporter; serves as a "glucose sensor" in pancreatic beta cells. Major expression sites: Liver, pancreatic beta cell, small intestine, kidney |
GLUT-2
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Name the transporter:
Transports glucose (high affinity) and galactose, not fructose. The primary glucose transporter for neurons. Major expression sites: Brain, placenta and testes |
GLUT-3
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Name the transporter:
Transports fructose, but not glucose or galactose. Present also in brain, kidney, adipocytes and muscle. Major expression sites: Small intestine and sperm |
GLUT-5
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What hormone is a single-chain peptide?
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Glucagon
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What is the second messenger for glucagon?
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cAMP
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What are possible stimuli for glucagon secretion?
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Decreased serum glucose
Increased serum amino acids (arginine, alanine) Sympathetic stimulation (via β2-AR) Stress Prolonged fasting Exercise |
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What are possible inhibitors of glucagon secretion?
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Somatostatin
Insulin ↑ Serum glucose |
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Glucagon stimulates glycogenolysis and gluconeogenesis in what organ?
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The liver
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What hormone increases plasma levels of free fatty acids and ketoacids while decreasing level of amino acids?
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Glucagon
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T/F
Glucagon and Insulin have anatagonistic effects at numerous steps in hepatic glucose and fatty acid metabolism. |
True!
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How does glucagon decrease plasma levels of amino acids?
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By increasing uptake of amino acids by the liver
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A supply of glucose is absolutely required to sustain function of which organ?
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The brain
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Does glucagon increase or decrease cortisol release?
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Increase
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Does glucagon increase or decrease epinephrine release?
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Increase
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What hormone stimulates expression of the Insulin gene?
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Growth Hormone
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What hormone induces resistance to the action of insulin?
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Growth Hormone
Glucose uptake by muscle and adipose cells is inhibited, and the plasma glucose concentration rises. Hyperinsulinemia results in compensation. |
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What hormone is considered a diabetogenic hormone?
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Growth Hormone
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Growth hormone __________ gluconeogenesis and __________ glucose absorption in the intestine.
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increases, increases
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Growth hormone __________ plasma glucose levels.
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increases
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Growth hormone, glucocorticoids and catecholamines all __________ the plasma glucose level.
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Increase
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What decreases glucose uptake by muscle tissue (by reducing sensitivity to insulin)?
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Glucocorticoids
They also stimulate gluconeogenesis and stimulate glycogen synthesis when plenty of glucose is available |
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What stimulates glycogenolysis in the liver and in the muscle, therefore increasing muscle glucose supply and glycolysis?
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Catecholamines
Also, released lactate serves as a substrate for hepatic gluconeogenesis |
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What stimulates gluconeogenesis directly through α1 receptors in the liver?
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Catecholamines
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T/F
Catecholamines stimulate insulin secretion and stimulate insulin-stimulated glucose uptake by muscle tissue. |
False!
Catecholamines actually inhibit insulin secretion and inhibit insulin-stimulated glucose uptake by muscle tissue. |
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Does exercise increase or decrease skeletal glucose?
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Increases
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What are the normal, impaired, and diabetic glucose concentration ranges during fasting?
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Normal - < 110mg/dl
Impaired glucose control – 100-126 mg/dl Diabetes – > 126 mg/dl |
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What are the normal and diabetic glucose concentration ranges after a meal?
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Normal: 200 mg/dl
Diabetes: >200mg/dl after 2 hours after a meal |
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For a glucose tolerance test:
a) When do you perform it? b) How much glucose do you take orally for the test? c) When do you measure the plasma glucose level? d) What are the normal and diabetic ranges at this time? |
a) after an overnight fast
b) 75g of glucose c) 2 hours after taking it d) N:< 200mg/dl; diabetes: >200 mg/dl |
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Hyperglycemia leads to elevated intracellular glucose in specific cell types and may contribute to pathological changes. What cell types are these?
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Endothelial cells in the retina, kidney, and capillaries associated with peripheral nerves
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What are some complications related to diabetes, due to glycosylation of target proteins and oxidative stress?
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Microvascular dysfunctions:
Retinopathies (microaneurisms, retinal hemorrhage) Neuropathies Nephropathies (renal failure) Macrovascular dysfunctions: atherosclerosis (endothelial damage + dyslipidemia) |