What technology allows for the production of human insulin?
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Recombinant DNA technology.
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What technology allows for the production of human insulin?
Recombinant DNA technology.
What is the significance of insulin analogs?
They are modified forms of insulin with altered amino acid sequences for specific effects.
What is the brand name of insulin lispro?
Humalog.
What effect does increased β1 receptor have on renal juxtaglomerular cells?
Stimulates increased renin release.
What is proglucagon processed into by Prohormone Convertase 2 in the pancreas?
Glicentin Related Pancreatic Polypeptide (GCPP), Glucagon, Intervening Peptide 1 (IP1), and Major Proglucagon Fragment (MPGF).
Which substances also stimulate insulin secretion besides glucose?
Fatty acids (FFA) and amino acids (AA).
What role do neural inputs and incretin hormones play in insulin secretion?
They modulate insulin secretion.
What percentage of post-glucose insulin secretion is attributed to incretin effects?
50-70%.
How do thyroid hormones affect basal metabolic rate (BMR)?
They increase Na+-K+ ATPase activity, O2 consumption, heat production, and overall BMR.
What protective effect does GLP-1 have on beta cells?
It induces beta cell proliferation and reduces beta cell apoptosis.
What is a common cause of hypothyroidism related to iodine?
Iodine deficiency.
What is a goiter?
Any enlargement of the thyroid gland, which can occur in both hyperthyroid and hypothyroid conditions.
How does insulin aspart differ from regular insulin?
Proline is changed to aspartic acid, making it more acidic and fast-acting.
What are the products of proglucagon processing in the intestines?
Glucagon-like Peptide 1 (GLP1), Glucagon-like Peptide 2 (GLP2), Oxyntomodulin, Glucagon, IP1, and Intervening Peptide 2.
What enzyme rapidly degrades GIP and GLP-1?
Di-peptidyl peptidase-4.
What is the half-life of GIP and GLP-1?
GIP = 4-5 minutes; GLP-1 = 2-3 minutes.
What is cretinism?
A devastating form of hypothyroidism in infants and children characterized by short stature and blunted affect.
What effect does glucagon have on adipose tissues?
Stimulates fat breakdown, increasing free fatty acid levels for tissue use and sparing glucose.
What is the first step in the molecular mechanism of incretin action?
Binding of incretin hormones to incretin receptors.
What does the activation of adenylyl cyclase lead to in pancreatic beta cells?
An increase in intracellular cAMP.
How does somatostatin affect the secretion of growth hormone?
It inhibits the secretion of growth hormone.
What autoimmune condition is a common cause of primary thyroid disease?
Hashimoto’s thyroiditis.
What effect do GIP and GLP-1 have on food intake?
They have an anorexigenic effect, leading to a loss of appetite.
What happens to glucagon levels in response to GIP?
Glucagon levels increase.
How do incretin hormones respond to glucose levels?
They potentiate insulin secretion at high sugar levels (hyperglycemia) and do not potentiate at low sugar levels (hypoglycemia).
What effect does insulin have on lipid metabolism?
It inhibits lipolysis in liver and adipose tissue.
What happens to intracellular glucose levels during hypoglycemia?
They decrease.
How do thyroid hormones influence the central nervous system?
Both high and low concentrations of thyroid hormones can lead to alterations in mental state.
What is the effect of thyroid hormones on the cardiovascular system?
They increase heart rate, contractility, cardiac output, and promote vasodilation, decreasing peripheral resistance.
What causes Grave's disease?
Autoantibodies bind to and activate the thyroid-stimulating hormone receptor, leading to overproduction of thyroid hormones.
What are common symptoms of hyperthyroidism?
Nervousness, insomnia, high heart rate, exophthalmos, and anxiety.
What effect do catecholamines have on the pupils?
Dilation of pupils to deal with stressful situations.
What are the products formed during the coupling process in thyroid hormone synthesis?
T4 is formed by binding two DIT, and T3 is formed by binding MIT and DIT.
How does TSH influence thyroid hormone synthesis?
TSH binds to its receptor on follicular cells, inducing cAMP production and opening the Na-Iodine symporter for iodine influx.
What type of receptors does insulin bind to?
Tyrosine kinase receptors.
What is myxedema?
A clinical condition with severe signs of hypothyroidism, sometimes leading to coma.
What is the term used to describe the increased insulin secretion from oral glucose intake?
Incretin effect.
What amino acid is the precursor for catecholamines?
Tyrosine.
What are common symptoms of hypothyroidism?
Lethargy, fatigue, cold intolerance, weakness, hair loss, reproductive failure.
What triggers glucagon secretion from α-cells?
Hypoglycemia.
How does GLP-1 affect glucagon secretion?
It inhibits glucagon secretion.
What is the effect of GLP-1 on gastric emptying and body weight?
It inhibits gastric emptying and reduces food intake and body weight.
What is the most common form of hyperthyroidism?
Grave's disease.
What reproductive issues are associated with hypothyroidism?
Hypothyroidism is commonly associated with infertility and affects normal reproductive physiology.
What do follicular cells in the thyroid gland produce?
Iodine-rich T4 and T3, mostly T4.
How do GLP-1 and GIP affect the pancreas?
They increase insulin secretion.
What type of feedback mechanism regulates TRH and TSH release?
Negative feedback inhibition.
What is glucagon synthesized from?
Glucagon is synthesized from proglucagon in alpha cells of the islets of Langerhans.
What is the purpose of the isoglycemic test?
To ensure that oral and intravenous glucose cause similar increases in blood sugar.
What primarily modulates insulin secretion?
Glucose.
Which cells in the intestines process proglucagon?
L-cells.
What do greater C-peptide levels after oral glucose indicate?
They indicate a greater insulin secretion due to the incretin effect.
Where are catecholamines synthesized and secreted?
In the adrenal medulla and sympathetic neurons.
What thyroid function test results indicate hypothyroidism?
↑ TSH & ↓ fT3 & fT4.
What is the prototype condition for a lack of insulin or insulin resistance?
Diabetes Mellitus.
What is the role of ATP-sensitive K channels in glucagon secretion?
Closure of these channels leads to depolarization of the cell membrane.
What is somatostatin and where is it synthesized?
A cyclic peptide synthesized in the delta cells of the pancreas.
What are the two forms of somatostatin?
Somatostatin (SS) - 14 and SS - 28, referring to their amino acid chain lengths.
What second messenger is involved in glucagon signaling?
cAMP.
What triggers the release of insulin from pancreatic beta cells?
An increase in intracellular calcium.
Where does the majority of T3 come from?
Peripheral conversion from T4.
What percentage of T4 and T3 are protein-bound?
More than 99%.
What is the problem with incretin hormones?
They are rapidly degraded by the DPP-4 enzyme.
What are the pharmacologic effects of low doses of DPP-4 inhibitors?
They increase insulin, decrease glucagon, and lower plasma glucose.
What are the elevated hormone levels indicative of hyperthyroidism?
Elevated T3 and T4 with suppressed TSH.
What is the role of T4 in protein synthesis?
T4 binds to nuclear receptors, leading to transcription of DNA, translation of mRNA, and synthesis of new proteins.
How does insulin affect carbohydrate metabolism?
It stimulates most aspects of carbohydrate metabolism, including insulin-dependent entry of glucose into cells, gluconeogenesis, and glycogenolysis.
How is insulin cleared from the body?
Through the liver and kidney.
What is the role of K cells and L cells in incretin hormone production?
K cells produce GIP and L cells produce GLP-1 after food intake.
What are the primary effects of glucagon in the liver?
Stimulates glycogenolysis and gluconeogenesis, while inhibiting glycolysis and glycogenesis.
What is the first step in the synthesis of catecholamines?
Conversion of tyrosine into DOPA by tyrosine hydroxylase.
What stimulates the secretion of catecholamines?
Release of Ach from preganglionic sympathetic fibers and stressors like exercise and trauma.
What happens to excess glucose in the kidneys?
It is excreted, leading to glycosuria.
What is the effect of incretin hormones on β-cell apoptosis and proliferation?
They decrease β-cell apoptosis and increase β-cell proliferation.
What is the effect of insulin on glucose uptake?
Insulin triggers increased glucose uptake by muscles, improving glycemic control.
What are the principal raw materials required for the synthesis of thyroid hormones?
Thyroglobulin and iodine.
What is the major role of glucagon?
To maintain normal glucose concentrations in blood in response to hypoglycemia.
What hormones stimulate protein synthesis, including beta 1 receptors in the heart?
T3 and T4.
What are incretin hormones?
Substances from the gut that regulate insulin secretion after eating.
What are the two major incretin hormones?
GIP (Glucose-dependent Insulinotropic Polypeptide) and GLP-1 (Glucagon-like Peptide 1).
What is the role of GIP and GLP-1 in insulin release?
They stimulate insulin release from β-cells of the pancreas.
What stimulates the alpha cells of the pancreas to increase glucagon levels?
Any decrease in plasma concentration.
What is the therapeutic significance of GLP-1?
It has cardioprotective effects and helps lower blood sugar.
What modifications are made in insulin glargine?
Two arginine are added at the end of the β-chain, and alanine is replaced with glycine at the end of the α-chain.
What effect does GLP-1 have on glucagon secretion?
It inhibits glucagon secretion in a glucose-dependent manner.
What enzyme rapidly degrades incretin hormones?
Dipeptidyl peptidase-4 (DPP-4).
What effect do catecholamines have on the heart?
Increase the rate and force of contraction of heart muscles.
How do incretin hormones affect calcium channels in pancreatic beta cells?
They promote closure of Ca2+ channels and facilitate membrane depolarization.
What does cAMP activate in glucagon signaling?
Protein Kinase A (PKA).
What is a notable symptom of hypothyroidism in infants?
Inaudible shock and a shrill cry.
What happens to GLP-1 and GIP levels after food intake?
There is an increase in GLP-1 and GIP levels.
What is the role of TSH in the thyroid axis?
Stimulates the thyroid to release T4 and T3.
What is the function of the Na-Iodine symporter (NIS)?
It opens to allow iodine influx into the follicular cells.
What is the effect of T4 binding to intranuclear receptors?
It induces gene expression by initiating transcription of target genes.
What is observed regarding insulin secretion when glucose is given orally compared to intravenously?
There is greater insulin secretion when glucose is given orally.
What condition is indicated by exophthalmos?
Grave's disease.
What causes exophthalmos in patients with Graves' disease?
Autoimmune binding of antibodies to receptors in the retrobulbar area.
What is cretinism?
The most severe form of hypothyroidism in young children, leading to irreversible growth and mental retardation.
What metabolic processes are increased by thyroid hormones?
Thyroid hormones increase glucose absorption, glycogenolysis, gluconeogenesis, lipolysis, and protein synthesis and degradation.
What is a common sign of hypothyroidism?
Non-pitting edema in the lower extremities and a puffy face.
What are the consequences of untreated cretinism?
Height may normalize with treatment, but mental retardation may be permanent.
What is the effect of depolarization on voltage-gated Ca2+ channels?
It causes them to open, allowing an influx of Ca2+.
What type of receptors do glucagon bind to?
G-protein coupled receptors.
What metabolic changes do catecholamines induce?
Increase metabolic rate, oxygen consumption, and heat production.
What are the two main thyroid hormones derived from?
Tyrosine.
What are DPP-4 inhibitors and their purpose?
DPP-4 inhibitors, known as Gliptins, decrease the degradation of GLP-1 for diabetes treatment.
What happens to the thyroid hormone receptor (TR) in the absence of thyroid hormones?
TR binds to a co-repressor (CoR), inhibiting or silencing gene expression.
What is the relationship between thyroid hormones and cholesterol levels?
Decreased thyroid hormones are associated with increased blood cholesterol concentration, indicating hypothyroidism.
What is the half-life of GIP and GLP-1?
GIP: 7.3 ± 1.0 min; GLP-1: 2.0-4.0 min.
What is the anabolic effect of insulin on protein metabolism?
It enhances protein synthesis and retards degradation.
What is the importance of thyroid hormones for growth?
They are necessary for normal growth in children and young animals, including fetal and neonatal brain development.
What is a characteristic of active/mature insulin?
It increases glycolysis by stimulating glucokinase.
What is the difference between Type 1 and Type 2 diabetes?
Type 1 is insulin-dependent, while Type 2 is non-insulin dependent and may be insulin-resistant.
What is the incretin effect?
The potentiation of insulin response by incretin hormones.
How do catecholamines affect blood vessels?
They cause constriction, increasing peripheral resistance and arterial blood pressure.
What role does calcium play in insulin secretion?
Calcium promotes transcription of the proinsulin gene, increasing insulin content in beta cells.
What is the effect of EPAC2 activation on insulin secretion?
It increases the density of insulin-containing granules in the plasma membrane, potentiating insulin secretion from beta cells.
What stimulates the release of TSH from the anterior pituitary?
TRH from the hypothalamus.
What happens when TSH binds to its receptor on follicular cells?
cAMP production is induced, leading to iodine influx.
What occurs when T3 binds to the thyroid hormone receptor?
The receptor dimer undergoes a conformational change, causing co-repressor to dissociate and allowing co-activators to bind.
What triggers the release of insulin from beta cells?
Hyperglycemia.
Which statement is NOT true about active/mature insulin?
It binds to a hormone-response element (HRE).
What is the effect of catecholamines on fat cells?
They increase lipolysis, releasing fatty acids for energy production.
What is a key difference between hyperthyroidism and hypothyroidism?
Hyperthyroidism results from over-secretion of thyroid hormones, while hypothyroidism results from under-secretion.
What is the effect of PKA activation on metabolic enzymes?
It phosphorylates various enzymes, which can increase or decrease their activity.
Which thyroid hormone is biologically more active?
T3 is more biologically active than T4.
What is organification in the context of thyroid hormone synthesis?
The binding of iodine with thyroglobulin to form monoiodotyrosine (MIT) or diiodotyrosine (DIT).
What role does thyroid peroxidase play in thyroid hormone synthesis?
It transports iodine into the lumen of the follicle along with thyroglobulin.
How do thyroid hormones T3 and T4 enter target cells?
They can freely pass through the cell membrane.
What is the primary action of somatostatin in the pancreas?
Inhibits the secretion of both insulin and glucagon.
What gastrointestinal hormones does somatostatin inhibit?
Gastrin, cholecystokinin, secretin, and vasoactive intestinal peptide.
What role does somatostatin play in the nervous system?
It has neuromodulatory activity and complex effects on neural transmission.
What is the role of GLP-1 and GIP in glucagon production?
They suppress the production of glucagon.
What is the effect of GLP-1 receptor agonists on blood sugar?
They normalize blood sugar by potentiating insulin secretion and inhibiting glucagon secretion.
What is the half-life of glucagon?
Approximately 5 minutes.
