Basics of Hormonal Regulation Flashcards
What are the differences between water-soluble and fat-soluble hormones with regard to their interactions and effects?
Water-soluble hormones are relatively short-lived and interact with receptors on the cell surface. Fat-soluble hormones are longer-lasting and interact with intracellular receptors.
Insulin and glucagon are this type of hormone produced by the pancreas.
Endocrine hormone
What is the function of exocrine hormones produced by the pancreas?
Synthesize precursors of digestive enzymes
What pancreatic cells produce insulin?
Beta cells
What pancreatic cells produce glucagon?
Alpha cells
Describe the synthesis of insulin.
Preproinsulin is synthesized from mRNA. Preproinsulin is cleaved by enzymes in the ER to produce proinsulin. Proinsulin is converted to insulin and packaged for release in the Golgi.
Describe the secretion process of insulin.
Insulin is stored in granules in the pancreas and liver. GLUT-2 senses rising glucose levels and mediates transportation of glucose into beta cells. Glucose is metabolized to produce ATP. Na+ channels are closed and Ca2+ channels opened. This causes an influx of Ca2+ into the cell that stimulates insulin secretion and synthesis.
What transporter on liver and pancreas cells is responsible for glucose absorption into the cell?
GLUT-2
What is the effect of insulin receptor binding on muscle and adipose cells?
Glycogen synthesis in muscle cells and fat synthesis in adipose cells
What transporter is responsible for glucose absorption in cells following insulin binding to the insulin receptor?
GLUT4
What tissues are primarily affected by insulin?
Liver, muscle, adipose
What effects does insulin have on cellular mechanisms?
Increases the number and activity of enzymes
What is the relationship between insulin and glucagon?
Insulin and glucagon are inversely related
Describe the process of glucagon signal transduction.
Glucagon binds a GPCR. This stimulates the adenylyl cyclase to produce cAMP. cAMP production activates the PKA, which goes on to phosphorylate substrates.
What are the effects of glucagon on target cells?
Decrease glycolysis, increase gluconeogenesis, glycogenolysis, and fatty acid oxidation
What is the relationship between feeding and insulin and glycogen secretion.
Feeding stimulates insulin secretion and inhibits glycogen secretion. Fasting stimulates glycogen secretion and inhibits insulin secretion.
What are the catecholamines?
DOPA, Dopamine, Norepinephrine, Epinephrine
Where are catecholamines produced?
Adrenal medulla
What is the function of catecholamines?
Bind GPCR to stimulate the adenylyl cyclase and activate PKA. Catecholamines facilitate the fight or flight response.
How does the effect of epinephrine differ between the liver and heart?
Epinephrine has an opposing effect on the liver and heart. In the liver, glycolysis is inhibited, while in the heart, the rate of glycolysis is greatly increased.
Where is cortisol produced?
Adrenal cortex
Describe the process of cortisol secretion.
Corticotropic releasing hormone (CRH) secreted by the hypothalamus stimulates the pituitary gland to release ACTH. ACTH stimulates the release of cortisol from the adrenal cortex.
CRH (hypothalamus) –> ACTH (anterior pituitary) –> cortisol (adrenal cortex)
How is cortisol transported in the blood?
Bound to corticosteroid-binding globulin (transcortin)
What is the effect of cortisol on blood glucose levels?
Works with other hormones to increase blood glucose levels, but takes longer to take affect
What disease is associated with hypercortisolism? What are the symptoms?
Cushing’s Syndrome - increases lipolysis, protein degradation, glycogen synthesis, and gluconeogenesis results in thin arms and legs with central obesity
Describe the synthesis of thyroid hormone.
Thyrotropin-releasing hormone (TRH) is released from the hypothalamus to stimulate the release of thyroid stimulating hormone (TSH) from the pituitary gland. TSH binds the TSH receptor on the thyroid. TSHR binding stimulates synthesis of thyroglobulin. Thyroglobulin is digested in a lysosome to produce T3 & T4.
How is thyroid hormone transferred in the blood?
Bound to thyroxine binding globulin (TBG)
What is the function of thyroid hormone?
Stimulates the Na+/K+ pump, increases metabolism, generates heat
What disease results from hyperthyroidism? What are the symptoms?
Grave’s Disease - excessive sweating, weight loss, anxiety, fast heart rate, increased metabolism
What disease results from hypothyroidism? What are the symptoms?
Hashimoto’s Thyroiditis - cold intolerance, slow weight gain, fatigue, slow heart rate, decreased metabolism
What stimulates secretion of parathyroid hormone?
Low blood Ca2+
What is the function of PTH?
Increases blood calcium by increasing intestinal absorption, renal re-absorption, and osteoclast activity
