Endocrine system - Quiz

Insulin is a hormone produced by the pancreas that helps regulate the body's metabolism of carbohydrates, fats, and proteins. Insulin promotes the uptake and storage of glucose in cells and inhibits the breakdown of stored glucose, called glycogenolysis. It also stimulates the conversion of glucose to glycogen, known as glycogenesis, and the synthesis of fats from glucose, called lipogenesis. However, insulin does not promote the production of glucose from non-carbohydrate sources such as amino acids and fats, which is known as gluconeogenesis. This is because insulin signals the body to use glucose as a primary source of energy and to conserve glucose for use in the brain and other essential organs.

Endocrine glands are ductless glands, which means that they do not have ducts. Instead, they secrete their products directly into the bloodstream, which carries the hormones to the target organs and tissues. This allows for a more rapid and specific response than if the hormones had to travel through a duct to reach their destination. Therefore, option B) is the correct answer.

Steroid hormones are a type of lipid-soluble hormone that are synthesized from cholesterol. Cholesterol is converted into various steroid hormones by a series of enzymatic reactions. For example, the precursor of estrogen and testosterone is cholesterol.
Dehydroepiandrosterone (DHEA) is also a steroid hormone that is synthesized from cholesterol. Therefore, option B is the correct answer.

Gonadotropin Releasing Hormone (GnRH) is a hormone released by the hypothalamus, which stimulates the anterior pituitary gland to release follicle stimulating hormone (FSH) and luteinizing hormone (LH). These hormones are essential for reproductive function in both males and females. GnRH is secreted in a pulsatile manner, with each pulse stimulating the release of FSH and LH. The frequency and amplitude of these pulses can vary depending on factors such as age, sex, and stage of the menstrual cycle. GnRH is regulated by various neurotransmitters and hormones, such as estrogen and progesterone, and disruptions in its release can lead to infertility or other reproductive disorders.

Iodine is an essential mineral that plays a crucial role in the functioning of the thyroid gland, which regulates the body's metabolism. Iodine deficiency can lead to thyroid disorders, including goiter, cretinism, and hypothyroidism. Iodized salt contains a small amount of iodine, which helps to maintain adequate levels of iodine in the body and prevent iodine deficiency. By consuming iodized salt, individuals can prevent the development of thyroid disorders and maintain optimal thyroid function.

Endocrine glands are the type of glands that secrete hormones into the bloodstream or surrounding tissues. These hormones regulate various physiological functions in the body, such as metabolism, growth and development, and reproduction. Exocrine glands, on the other hand, secrete their products through ducts into a body cavity or onto a body surface. Heterocrine glands produce both exocrine and endocrine secretions, while partially endocrine glands have both endocrine and non-endocrine functions. Therefore, the correct answer is option A, endocrine glands, as they are solely responsible for secreting hormones.

Hormones are chemical messengers that are secreted by endocrine glands and transported through the bloodstream to target cells or organs, where they produce specific physiological responses. Hormones can affect a wide range of physiological processes, including growth and development, metabolism, reproduction, and behavior. Examples of hormones include insulin, which regulates glucose metabolism, and testosterone, which is involved in the development of male secondary sexual characteristics. Hormones are typically produced in response to specific stimuli, such as changes in blood glucose levels or the presence of a particular chemical or hormone in the body.

Peptide hormones are made up of amino acids and are typically water-soluble. Oxytocin, vasopressin, and melanocyte stimulating hormone are examples of peptide hormones. Oxytocin is produced in the hypothalamus and released from the posterior pituitary gland. It plays a role in social bonding, sexual reproduction, and childbirth. Vasopressin, also known as antidiuretic hormone, is also produced in the hypothalamus and released from the posterior pituitary gland. It helps regulate water balance in the body. Melanocyte stimulating hormone is produced in the anterior pituitary gland and plays a role in skin pigmentation.

Adenylate cyclase is an enzyme that plays a crucial role in the formation of the hormone receptor complex. When a hormone binds to its receptor on the cell surface, it activates the G-protein which in turn stimulates the adenylate cyclase enzyme to produce cyclic AMP (cAMP). This cAMP molecule acts as a second messenger and activates protein kinase A (PKA) which ultimately leads to the formation of the hormone receptor complex. The hormone receptor complex is responsible for carrying out various cellular functions, including gene transcription and protein synthesis.

Insulin is a peptide hormone that regulates glucose metabolism in the body. It is composed of two peptide chains, called the A and B chains, that are linked by disulfide bonds. The A chain has 21 amino acids, while the B chain has 30 amino acids. The insulin molecule is formed from a single chain precursor called proinsulin, which is cleaved by specific proteases to release the mature insulin molecule.
The mature insulin molecule is a dimer composed of two polypeptide chains, A and B, that are held together by disulfide bonds. The A chain contains two cysteine residues that form a disulfide bond with one of the cysteine residues in the B chain. The other two cysteine residues in the A chain form a disulfide bond with each other. The resulting structure is a dimer composed of two chains, each with an A and a B subunit, held together by two disulfide bonds.