Endocrine system - Quiz

Thyroid hormone is a type of hormone that is synthesized from tyrosine, an amino acid, and is classified as a fat-soluble hormone. Unlike water-soluble hormones such as amine, peptide, and protein hormones, which dissolve in water and are transported through the bloodstream, fat-soluble hormones are transported through the bloodstream bound to carrier proteins.
The lipid-soluble nature of thyroid hormones allows them to easily pass through the cell membrane and bind to intracellular receptors, which are located in the nucleus or cytoplasm of target cells. This binding activates the transcription of specific genes, leading to changes in cellular metabolism and growth.
In contrast, water-soluble hormones cannot pass through the cell membrane and therefore bind to receptors located on the cell surface. This binding triggers a series of intracellular signaling events that ultimately lead to changes in cellular function.

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.

The gall bladder is a small, pear-shaped organ located under the liver. Its primary function is to store and concentrate bile, a greenish-yellow fluid that is produced by the liver and helps in the digestion of fats. Bile is secreted into the small intestine when food enters from the stomach, and the gall bladder contracts to release the stored bile. If the gall bladder is removed, bile is still produced by the liver, but it is not stored, leading to more frequent and less concentrated release of bile into the small intestine.

Adrenaline, also known as epinephrine, is a hormone that is produced by the adrenal glands. It is released into the bloodstream in response to stress, fear, or excitement. Adrenaline acts on various organs in the body, including the heart, by increasing the heartbeat and the force of contractions. This results in an increase in blood pressure and blood flow to the muscles, preparing the body for physical activity. Adrenaline also produces a feeling of excitement or arousal, which is why it is often referred to as the "fight or flight" hormone.

Estrogen is a female sex hormone that plays an important role in the development and maintenance of female reproductive system and secondary sex characteristics. It is mainly produced by the ovarian follicles, which are small sacs within the ovaries that contain the immature eggs. During each menstrual cycle, a follicle grows and develops under the influence of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) produced by the pituitary gland. As the follicle matures, it produces increasing amounts of estrogen until it reaches a peak level, which triggers ovulation. After ovulation, the remaining cells of the follicle form a structure called the corpus luteum, which produces both estrogen and progesterone. However, estrogen is primarily produced by the follicles.

Protein hormones, also known as polypeptide hormones, are hormones made up of chains of amino acids. They are water-soluble and are synthesized in the endoplasmic reticulum and Golgi apparatus of the cell before being secreted. Gonadotropic hormones, such as follicle-stimulating hormone (FSH) and luteinizing hormone (LH), somatotrophic hormone (STH), and thyrotropic hormone (TSH) are all protein derivatives hormones. Gonadotropic hormones are released by the anterior pituitary gland and are involved in the regulation of the reproductive system, while STH, also known as growth hormone, is involved in the regulation of growth and metabolism. TSH is released by the pituitary gland and regulates the thyroid gland's hormone secretion.

The liver is the largest gland in the human body and is also the largest exocrine gland. It secretes bile, a digestive fluid that is stored in the gallbladder and released into the small intestine to help with the digestion of fats. The liver is located in the upper right portion of the abdomen, under the diaphragm, and is responsible for performing many vital functions, including detoxification, metabolism, and the production of certain proteins.

Catecholamines are a class of hormones that are produced by the adrenal medulla, which is located in the center of the adrenal gland. The two primary catecholamines are epinephrine (also known as adrenaline) and norepinephrine (also known as noradrenaline). These hormones play a critical role in the body's "fight or flight" response to stress, as they increase heart rate, blood pressure, and respiration, while decreasing digestion and other non-essential functions. Additionally, catecholamines are involved in a variety of other physiological processes, including metabolism, mood regulation, and the immune response.

cAMP, or cyclic adenosine monophosphate, is a molecule that activates adenylate cyclase, an enzyme that catalyzes the conversion of ATP to cyclic AMP. This cyclic AMP then activates protein kinase A, which triggers a cascade of events leading to the release of hormones. Adenylate cyclase is an important component of many hormone signaling pathways and is found in a variety of tissues throughout the body. Thus, the correct option is A) cAMP.

IP3 and DG (diacylglycerol) act as second messengers to amplify signals initiated by hormones or neurotransmitters binding to cell surface receptors. IP3 binds to receptors on the endoplasmic reticulum, leading to the release of calcium ions into the cytoplasm, which in turn activates various enzymes and other proteins. DG, on the other hand, activates protein kinase C, which phosphorylates target proteins and amplifies the signal. This amplification of signals is crucial for the body to achieve appropriate physiological responses.