The Endocrine System

Question 1

Glucagon

Answer 1

Polar, water soluble peptide hormone released by the alpha cells of the pancreas when blood glucose levels drop. Stimulates glycogenolysis and gluconeogenesis in the liver.

Question 2

Insulin

Answer 2

Polar, water soluble peptide hormone released by the beta cells of the pancreas when blood levels of carbohydrates or proteins are high. Promotes glycolysis in all tissues, glycogenesis in liver and muscle, fatty acid synthesis in liver and fatty acid storage in adipocytes. In late starvation, absence of insulin promotes ketogenesis.

Question 3

Antidiuretic hormone (ADH)

Answer 3

Also called Vasopressin. Small, polar, water soluble peptide hormone produced in the neural cell bodies of the hypothalamus, and transported down axons to the posterior pituitary, where it is released into the blood and causes the collecting ducts of the kidney to become permeable to water, reducing the volume of urine and concentrating the urine. When water is reabsorbed from the collecting tubule, the osmolarity of the blood plasma decreases. Also secondarily increases blood pressure. Primary stimulus for the release of ADH is high plasma osmolarity. Increases free water absorption, thereby increasing blood volume but decreasing plasma osmolarity.

Question 4

Aldosterone

Answer 4

Non polar, lipid soluble steroid hormone (mineral corticoid) secreted by the adrenal cortex. Acts in the distal convoluted tubule and the collecting duct to increase Na+ and Cl- reabsorption and K+ and H+ secretion. Each NaCl is reabsorbed with a corresponding water molecule, so while the total amount of salt in the body increases, the concentration of salt in the bloodstream remains the same. This reabsorption results in an eventual increase in blood pressure. Main effect of aldosterone is to increase plasma volume without affecting plasma osmolarity. Primary stimulus for release is low blood volume.

Question 5

Oxytocin

Answer 5

Small, polar, water soluble peptide hormone produced in the neural cell bodies of the hypothalamus, and transported down axons to the posterior pituitary, where it is released into the blood and increases uterine contractions during pregnancy and causes milk to be ejected from the breasts.

Question 6

Hormones released by the anterior pituitary

Answer 6

HALF PiT- Human growth hormone (HGH, somatotropin), Adrenocorticotropin (ACTH), Luteinizing hormone (LH), Follicle-stimulating hormone (FSH), Prolactin, Thyroid stimulating hormone (TSH, thyrotropin)
All of these are peptide hormones.

Question 7

Human growth hormone (HGH, somatotropin)

Answer 7

Polar, water soluble peptide released by the anterior pituitary that stimulates growth in almost all cells of the body. Stimulates growth by increasing episodes of mitosis, increasing cell size, increasing rate of protein synthesis, mobilizing fat stores, increasing the use of fatty acids for energy, and decreasing the use of glucose. Effect of HGH on proteins is accomplished by increasing amino acid transport across the cell membrane, increasing translation and transcription, and decreasing the breakdown of protein and amino acids.

Question 8

Adrenocorticotropin (ACTH)

Answer 8

Polar, water soluble peptide released by the anterior pituitary that stimulates the adrenal cortex to release glucocorticoids via the second messenger system using cAMP. Stimulated by many types of stress.

Question 9

Thyroid-stimulating hormone (TSH, thyrotropin)

Answer 9

Polar, water soluble peptide released by the anterior pituitary that stimulates the thyroid to release T3 and T4 via the second messenger system using cAMP. TSH increases thyroid cell size, number, and the rate of secretion of T3 and T4. T3 and T4 concentrations have a negative feedback effect on TSH release.

Question 10

Prolactin

Answer 10

Polar, water soluble peptide released by the anterior pituitary that promotes lactation (milk production) by the breasts. Hypothalamus mainly inhibits the release of prolactin.