Hormone

Physiologie FK Hormone

• Hormone: Chemical messengers that act slowly and long-term. They are produced in endocrine glands and travel through the circulatory system to target cells, where they exert their effects via receptors.

Hormonal Regulation in the Hypothalamic-Pituitary System

• Hypothalamic-Pituitary Axis: A neural signal triggers the release of releasing hormones (RH) in the hypothalamus. These hormones stimulate the pituitary gland, which then releases tropic hormones. These tropic hormones impact peripheral endocrine glands, which release the "actual" hormones into the bloodstream. Once sufficient hormone levels are reached, a negative feedback loop stops further production.

Hypothalamus and Pituitary Gland Hormone Production

• Hypothalamus: Produces releasing hormones (RH) and inhibiting hormones (IH) that regulate the pituitary. Also produces antidiuretic hormone (ADH) for water reabsorption in the kidneys and oxytocin for uterine contractions and milk ejection.

• Anterior Pituitary: Produces hormones such as follicle-stimulating hormone (FSH), luteinizing hormone (LH), thyroid-stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), growth hormone (GH), and prolactin.

• Posterior Pituitary: Stores and releases ADH and oxytocin, although both are produced in the hypothalamus.

Peripheral Hormone Actions

• Gonads: FSH and LH stimulate estrogen, progesterone, and testosterone production, impacting sexual development and bone metabolism.

• Thyroid: TSH stimulates thyroxine (T4) and triiodothyronine (T3) production, affecting growth and metabolism.

• Adrenal Cortex: ACTH stimulates the production of glucocorticoids (e.g., cortisol), regulating metabolism and electrolyte balance.

Endocrine vs. Exocrine Glands and Cells

• Endocrine Glands: Release hormones directly into the bloodstream (e.g., thyroid, adrenal glands).

• Exocrine Glands: Release substances through ducts to exterior surfaces (e.g., sweat glands).

• Endocrine Cells: Scattered throughout organs, they influence distant target organs via hormones released into the bloodstream.

Other Hormones

• Paracrine Action: Hormones that have local effects, influencing only adjacent cells, rather than distant targets via the bloodstream.

• Hypothalamic-independent Hormones: These are hormones produced by organs outside of the hypothalamic-pituitary axis. Examples include adrenaline from the adrenal medulla and erythropoietin from the kidney.

Diabetes Mellitus

• Type 1 Diabetes: Characterized by a lack of insulin due to autoimmune destruction of insulin-producing cells.

• Type 2 Diabetes: Insulin resistance, which can result in a reduction in insulin production.

Calcium Metabolism

• Parathyroid Hormone (PTH): Released by the parathyroid glands when blood calcium levels are low, increasing calcium levels in the blood through bone resorption, increased renal reabsorption, and Vitamin D activation.

• Calcitonin: Released from the thyroid gland when calcium levels are high, decreasing calcium levels in the blood through inhibiting bone resorption.

Vitamin D

• Vitamin D3 (Cholecalciferol): Produced in the skin via UV light, or obtained through diet; it is converted in the liver to calcidiol, and then to calcitriol in the kidneys.
• Calcitriol: The active form of vitamin D; increases calcium absorption in intestines and calcium reabsorption in the kidneys. Also influences bone metabolism.

In diesem Quiz geht es um die physiologische Rolle von Hormonen, einschließlich ihrer Produktion und Funktion im hypothalamisch-hypophysären System. Erfahren Sie, wie Hormone als chemische Botenstoffe wirken und welche Rolle negative Rückkopplungsmechanismen dabei spielen.