the endocrine glands and the hormones they secrete

-hypothalamus secretes releasing factors, which stimulate hormone secretion, -and inhibiting factors, which slow down hormone secretion -these factors travel through blood vessels to anterior lobe of pituitary gland, influencing its hormone production

The posterior lobe of the pituitary gland is connected to the hypothalamus by nerve fibres. The hypothalamus produces hormones that travel along these nerve fibres to the posterior lobe, where they are stored and then released into the bloodstream. Unlike the anterior lobe, the posterior lobe does not secrete hormones but simply stores and releases them.

gonadotropins FSH LH GH (growth hormone) TSH (thyroid stimulating hormone) ACTH (Adrenocorticotropic hormone) Prolactin (PRL)

<p>In females, FSH stimulates the development of ovarian follicles containing eggs, while LH, triggers ovulation and the formation of the corpus luteum.</p> <p>In males, FSH stimulates the production and maturation of sperm, and LH stimulates interstitial cells in the testes to secrete male sex hormones.</p> Signup and view all the answers

<p>Growth hormone (GH) stimulates body growth, particularly the growth of the skeleton. It also increases the rate at which amino acids are taken up by cells and built into proteins. GH continues to be secreted throughout life to help maintain the size of organs after maturity is reached.</p> Signup and view all the answers

<p>Thyroid-stimulating hormone (TSH) stimulates the production and release of hormones from the thyroid gland, which regulate metabolism and energy production in the body.</p> Signup and view all the answers

<p>Adrenocorticotropic hormone (ACTH) controls the production and release of hormones from the cortex of the adrenal glands, which are involved in stress responses, metabolism, and immune function.</p> Signup and view all the answers

<p>Prolactin (PRL) works with other hormones to initiate and maintain milk production in females after childbirth.</p> Signup and view all the answers

<p>A: Oxytocin and ADH are produced in specialized nerve cells in the hypothalamus, not the posterior pituitary itself. These hormones travel down the long extensions of the hypothalamic neurons, passing through the infundibulum and reaching the posterior pituitary, where they are stored. Their release into the bloodstream is triggered by nerve impulses initiated in the hypothalamus, which are conducted along these cell extensions to the posterior pituitary.</p> Signup and view all the answers

<p>A: Oxytocin primarily stimulates contractions of the uterus, especially during labor, facilitating childbirth. It also promotes the release of milk from the mammary glands by causing contraction of milk ducts during breastfeeding. ADH, or vasopressin, influences the kidneys by promoting the reabsorption of water from urine back into the bloodstream, helping to maintain fluid balance in the body. At higher concentrations, ADH causes the constriction of small arteries (arterioles), which is why it is also called vasopressin.</p> Signup and view all the answers

<p>A: The hypothalamus contains the cell bodies of nerve cells that produce oxytocin and ADH, which are transported down their long nerve extensions to the posterior pituitary through a stalk-like structure called the infundibulum. Once in the posterior pituitary, these hormones are stored until they are triggered for release. Blood vessels connected to the posterior pituitary allow the hormones to enter the bloodstream directly when released, thus reaching their target organs and exerting their physiological effects.</p> Signup and view all the answers

<p>thyroxine–most body cells– increase metabolic rate and hence oxygen consumption and heat production</p> <p>triiodothyronine Calcitonin–bones, kidney– decreases calcium and phosphate levels in blood</p> Signup and view all the answers

<p>parathyroid hormone–bones, kidney– increases level of calcium in blood</p> Signup and view all the answers

<p>thymosins–T-lymphocytes– stimulates development and maturation of T-lymphocytes</p> Signup and view all the answers

<p>corticosteroids, including Aldosterone–kidney– increases reabsorption of sodium ions and excretion of potassium ions</p> <p>cortisol–most body cells– promotes normal metabolism; helps body deal with stress; promotes repair of damaged tissues</p> Signup and view all the answers

<p>Adrenaline and non-adrenaline– most body tissues– prepares the body for fight-or-flight responses; reinforces the effects of the sympathetic nervous system</p> Signup and view all the answers

<p>insulin-most body cells- stimulates uptake of glucose; lowers blood glucose level</p> <p>glucagon-liver and fat storage tissues- stimulates breakdown of glycogen and fat; increases blood glucose level</p> Signup and view all the answers

<p>androgens e.g. testosterone– many tissues– stimulates sperm production, growth of skeleton and muscles, and development of male sexual characteristics</p> Signup and view all the answers

<p>oestrogen–many tissues- stimulate development of female sexual characeristics; regulate the menstrual cycle</p> <p>progesterone- uterus and mammary glands- regulates menstrual cycle and pregnancy; prepares mammary glands for milk secretion</p> Signup and view all the answers

<p>People with hyperthyroidism experience weight loss because the thyroid gland produces excessive amounts of thyroid hormones (like T3 and T4), which increase the body's metabolism. This heightened metabolic rate accelerates the breakdown of nutrients, causing the body to burn more calories at rest and during activity. As a result, even with normal or increased food intake, individuals may still lose weight.</p> Signup and view all the answers

<p>Insulin and glucagon work together to regulate blood glucose levels through a negative feedback system. When blood glucose levels rise, such as after eating, the pancreas releases insulin, which facilitates the uptake of glucose into cells for energy or storage as glycogen in the liver and muscles. When blood glucose levels drop, such as between meals or during fasting, the pancreas releases glucagon, which signals the liver to convert stored glycogen back into glucose and release it into the bloodstream, keeping blood glucose within a normal range.</p> Signup and view all the answers

<p>The body maintains consistent blood calcium levels through the actions of the parathyroid hormone (PTH), calcitonin, and vitamin D. When blood calcium levels are low, the parathyroid glands release PTH, which increases calcium levels by stimulating bone resorption (release of calcium from bones), enhancing calcium reabsorption in the kidneys, and activating vitamin D to increase calcium absorption from the intestine. When calcium levels are high, the thyroid gland releases calcitonin, which inhibits bone resorption and encourages calcium storage in bones, reducing blood calcium levels. These mechanisms keep calcium levels balanced.</p> Signup and view all the answers