Biochemical Actions of Hormones that Regulates Fuel Metabolism - Feb 21 (9-10am) - Dr K

___ is synthesized by using rate limiting enzyme Tyrosine hydroxylase from Tyrosine.

L-DOPA

List stimulatory factors that regulate insulin secretion

-↑serum glucose -↑levels of proteins (AAs), keto acids, fatty acids, and TAGs -Incretins, GI polypeptide ("GIP") and glucagon-like polypeptide (GLP) -Activity of parasymp NS (Ach)

List inhibitory factors that regulate insulin secretion

-↓serum glucose -↓levels of proteins (AAs), keto acids, fatty acids, and TAGs -Somatostatin -Activity of symp NS (adrenergic effect of epi and norepi)

A dietary deficiency of iodine will lead to which one of the following? A. A direct effect on the synthesis of thyroglobulin on ribosomes B. An increased secretion of TSH C. Decreased production of TRH D. Increased heat production E. Weight loss

An increased secretion of TSH Explanation : When iodine is deficient in the diet, the thyroid does not make normal amounts of T3 and T4. Consequently, there is less feedback inhibition of TSH production and release; hence, an increased secretion of TSH would be observed. There is no direct effect on thyroglobulin synthesis (thus, A is incorrect). TRH is released by the hypothalamus to release TSH from the pituitary; a lack of thyroid hormone would increase production of TRH, not decrease it (thus, C is incorrect). An overproduction of thyroid hormone leads to increased heat production and weight loss; lack of thyroid hormone does not lead to these symptoms (thus, D and E are incorrect).

Match the following hormones with their structural origin 1st choice Calcitriol 2nd choice Norepinephrine 3rd choice Somatostatin 4th choice FSH A - Peptides of various sizes B - Tyrosine derivatives C - Glycoprotein D - Cholesterol derivatives

Cholesterol derivatives - Calcitriol Tyrosine derivatives - Norepinephrine Peptides of various sizes - Somatostatin Glycoprotein - FSH

Name some examples of hormones derives from cholesterol, tyrosine, and peptides?

Cholesterol: Estradiol, testoserone, cortisol, and progesterone Tyrosine: Epi, Norepi, T3 & T4 Peptides: Somatostatin, Insulin, Glucagon, TRH, and ACTH

When glucose deficiency occurs, the pancreas releases the peptide hormone glucagon. Glucagon then elevates blood glucose levels by promoting the breakdown of glycogen in the liver and inhibiting glycogen synthesis. Similarly, epinephrine stimulates the breakdown of glycogen by promoting glucagon secretion. If the glycogen stores have been depleted, thern the steroidal hormone called ___ stimulates gluconeogenesis by inducing the transcription of enzymes involved in this glucose-producing pathway. Conversely, under fed conditions, insulin serves to lower blood glucose levels by promoting the synthesis of glycogen (to store glucose), stimulating glycolysis (to catabolize glucose), and inhibiting the activity or synthesis of enzymes involved in gluconeogenesis.

Cortisol

Which one of the insulin counterregulatory hormones stimulates both amino acid release from the muscle and glycogenesis? A. Glucagon B. Epinephrine C. Cortisol D. Growth hormone E. Thyroid hormone

Cortisol Explanation : Glucagon, epinephrine, and norepinephrine decrease glycogenesis (the synthesis of glycogen). Growth and thyroid hormones have no effect on glycogenesis. The only counterregulatory hormone to increase glycogenesis is cortisol, which is preparing the body for future needs by storing amino acid carbons (obtained from protein degradation in the muscle) as glycogen in the liver.

Secretion of ___ and ___ from the adrenal medulla is stimulated by a variety of stresses, including pain, hemorrhage, exercise, hypoglycemia, and hypoxia. They both synthesized from L-tyrosine. The rate-limiting enzyme tyrosine hydroxylase makes Dopa which eventually converted to dopamine, norepi, and epi. Epi stimulates glycogen breakdown in muscle and liver, gluconeogenesis in the liver, and lipolysis in adipose tissue.

Epi and Norepi

Thyroidal hormone release mainly stimulates the biosynthesis which of the following type of biomolecules? A. Sugars B. Fats C. Proteins D. Vitamins E. Glycoproteins

Fats

The hormone ___ that stimulates growth, lipolysis, AA uptake, gluconeogenesis and secretion increases during exercise, deep sleep, hypoglycemia and secretion inhibited by glucose and somatostatin release.

GH

Combination of which of the following counter-regulatory hormones increases the blood-glucose levels very high while working synergistically to maintain glucose homeostasis? A. Cortisol B. Glucagon C. Epinephrine D. Glucagon + Epinephrine E. Glucagon + Epinephrine + Cortisol

Glucagon + Epinephrine + Cortisol

Which of the following hormones inhibits the secretion of insulin, glucagon, gastrin, cholecystokinin, growth hormone and pancreatic polypeptide? A. Cortisol B. Epinephrine C. Growth hormone D. Thyroxine E. Somatostatin

Somatostatin

In the liver ___ hormone increases the glycolysis and synthesis all fats (cholesterol, fatty acids, bile salts and triglycerides). This enzyme will be regulated by thyroid stimulating hormone and synthesized from tyrosine and molecular iodide.

Thyroid

A patient has been diagnosed with acromegaly caused by a GH-secreting tumor in the anterior pituitary. The patient is prescribed an analog of somatostatin to suppress GH secretion from the tumor in order to treat the condition. This treatment will also lead to the suppression of which one of the following hormones? A. Epinephrine B. Norepinephrine C. Glucocorticoid D. Thyroid hormone E. Erythropoietin

Thyroid hormone Explanation : Somatostatin leads to the inactivation of adenylate cyclase, thereby reducing cAMP levels. This reduces the secretion of GH, TSH, insulin, glucagon, serotonin, and TRH. The reduction of TRH and TSH would reduce thyroid hormone production. Somatostatin will not reduce the secretion of GCs, catecholamines (such as epinephrine and norepinephrine), and erythropoietin.

The reaction between diiodotyrosine and monoiodotyrosine produces which of the following molecules? A. Tetraiodothyronine B. Triiodothyronine C. Diiodothyronine D. Pentaiodothyronine E. Hexaiodothyronine

Triiodothyronine

The rate-limiting enzyme in epinephrine biosynthesis pathway is: A. Phenylalanine hydroxylase B. Tyrosine hydroxylase C. dopa decarboxylase D. dopamine beta-hydroxylase

Tyrosine hydroxylase

Cortisol is essential for survival during fasting states because of its proteolytic effects. During fasting, liver glycogen stores are used for glucose production but quickly become depleted. Gluconeogenesis is initiated using amino acids (from protein catabolism) in the presence of cortisol. However, if cortisol is deficient, death from hypoglycemia occurs. Plasma levels of cortisol during fasting are only slightly to moderately elevated (usually relative to the degree of initial hypoglycemia), but this elevation of cortisol is sufficient because cortisol has a permissive effect on key metabolic enzymes. The permissive effect may be seen as analogous to "priming." Corticosteroids prime metabolic pathways to respond to other hormones. For example, the effects of epinephrine on glycogen degradation and synthesis are greatly facilitated (potentiated) by cortisol. During fasting, the body also breaks down stored ___ in adipose tissue into glycerol and fatty acids. Glycerol can then be converted to glucose in the liver. Cortisol enhances this lipolysis.

fat

Epinephrine diminishes insulin secretion by a cAMP-coupled regulatory path. In addition, epinephrine counters the effect of nsulin in liver and peripheral tissue, where it binds to B-adrenergic receptors, induces adenylate cycles activity, incr CAMP, and activates PKA similarly to that of glucagon. The latter events induce ___ and ___, both of which are hyperglycemic and which thus counter insulin's effect on blood glucose levels.

glycogenolysis & gluconeogenesis

Acromegaly is characterized by protruding jaw; enlargement of the nose, hands, feet, and skull; and a thickening of the skin. This disorder is the result of excessive production of which of the following hormones? A. corticotropin-releasing hormone B. gonadotropin-releasing hormone C. growth hormone D. insulin-like growth factor II E. thyroid-stimulating hormone

growth hormone Acromegaly results when there is an excess production of growth hormone after epiphysial closure and cessation of long bone growth.

The release of several GI hormones is triggered by the components of food, the distension of the stomach upon food intake, and neural stimulation. These hormones, in turn, regulate the secretion of digestive enzymes. In the stomach, pepsin digests dietary proteins into peptides. Another peptide (14 AAs) hormone, ___, produced by D cells of the antral mucosa, acts to inhibit gastrin and acid release. This hormone inhibits the secretion of pancreatic polypeptide, vaso intestinal peptide, and 5-HT.

somatostatin

The pancreas play an important role in the control of blood glucose by its secretion of insulin and glucagon. The release of insulin and glucagon is inhibited by somatostatin, which is also secreted by the pancreas. Which of the following cells of the pancreas secrete somatostatin? A. acinar cells B. α-cells C. β-cells D. δ-cells E. F cells

δ-cells Delta cells of the islet of Langerhans in the pancreas secrete somatostatin-14, a 14-amino-acid peptide, that inhibits the release of insulin and glucagon.