G Protein and Cyclic Nucleotide Signaling Quiz

• Molecular Endocrine system focuses on signals transduction and receptors.
• Gonadotropin Releasing Hormone (GnRH) is secreted by the hypothalamus, stimulating the synthesis and release of Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH) from the pituitary gland.
• The hypothalamus is part of the brain, acting as an integration and control center, connected to the pituitary gland.
• The pituitary gland consists of anterior pituitary hormones, including TSH, ACTH, LH, FSH, GH, and Prolactin, and posterior pituitary, which includes distal axons of hypothalamus magnocellular neurons producing oxytocin and vasopressin.
• Vasopressin regulates water balance, while oxytocin regulates reproductive behavior and stimulates milk ejection and uterine contractions.
• Anterior pituitary disorders, like pituitary dwarfism, acromegaly, and Gigantism, can result from a tumor causing a decrease in hormonal output, or hyperplasia of pituitary gland resulting in abnormally high levels of growth hormone.
• Diabetes Insipidus is a disorder where large volumes of hypotonic or dilute urine are produced due to the absence or inadequate response to vasopressin.
• The thyroid gland secretes thyroid hormones, which include Thyroxine (T4) and Triiodothyronine (T3), and requires iodine to produce them. Thyroid hormones bind to receptors in the nucleus and regulate enzymes controlling carbohydrate and lipid metabolism.
• The parathyroid gland produces parathyroid hormone (PTH), which raises calcium blood levels and stimulates the intestinal absorption of calcium.
• The adrenal glands have the medulla, which is stimulated by the sympathetic nervous system and secretes catecholamines (epinephrine and norepinephrine), and the cortex, which is stimulated by anterior pituitary hormone ACTH and secretes corticosteroids.
• The pancreas has exocrine and endocrine functions, with endocrine function governed by islets of Langerhans, which secrete insulin and glucagon to regulate blood glucose levels.
• Sexual differentiation occurs between the 1st and 6th week of development, and the 7th week marks the start of primary reproductive organ development, with hormones produced from the organs determining the sex of the embryo.
• The Y chromosome determines male sex, with the SRY gene directing the synthesis of testicular determine factor (TDF), which binds to DNA and causes the differentiation of cells from genital ridges into testes.
• Male hormonal regulation is controlled by the hypothalamus, with GnRH causing the release of FSH and LH, which stimulate sperm production in the testes and testosterone production in the interstitial cells.
• Androgens, like testosterone, maintain male secondary sex characteristics and stimulate inhibin production, which downregulates FSH synthesis and inhibits FSH secretion.

Test your knowledge of G protein and cyclic nucleotide signaling with this quiz. Explore the activation of Protein Kinase A, second messenger molecules, and the cellular responses triggered by G protein activation.