endocrine system

• Hormones are chemical signals that instruct internal organs to perform various tasks
• These chemical signals are produced by endocrine glands that make up the endocrine system
• The endocrine system comprises ductless glands that manufacture and secrete hormones necessary for the functioning of specific organs and tissues
• The term "endocrine" is derived from the Greek words "endo" meaning inside, and "crinis" meaning to secrete
• Hormonal secretions of endocrine glands are essential for maintaining and regulating the body's internal environment
• Endocrine glands create hormones by extracting and processing specific elements and nutrients in the blood, then releasing them as molecular substances back into the bloodstream
• The hypothalamus serves as the link between the nervous and endocrine systems
• The hypothalamus manufactures hormones produced by the pituitary gland and releases hormones necessary for regulating the amount of hormones released by other endocrine glands
• The pituitary gland is located below the hypothalamus
• The pituitary gland is divided into anterior and posterior parts, each producing different hormones
• Anterior pituitary gland produces growth and metabolic hormones
• Posterior pituitary gland produces oxytocin and a diuretic hormone that controls water levels in the body
• The pineal gland, located near a ventricle in the midbrain, releases melatonin, regulating sleep-wake patterns
• Parathyroid gland produces parathyroid hormones (PTH) to control calcium levels in the body for bone integrity
• The pineal gland, located near a ventricle in the midbrain, releases melatonin, regulating sleep-wake patterns
• Thyroid gland, butterfly-shaped and in the lower front of the neck, produces hormones like thyroxine and triiodothyronine affecting metabolism, heart functions, and digestion
• Thymus, between the lower neck and upper chest, produces thymosin enhancing the immune system during puberty
• Adrenal glands atop the kidney produce hormones like adrenaline and cortisol for body actions during stress
• Adrenal glands also regulate blood sugar levels, manage gastrointestinal functions, and maintain cardiovascular condition
• Pancreas, an accessory gland in the digestive system, produces enzymes for digestion
• Pancreas secretes insulin and glucagon, regulating blood sugar levels to prevent diabetes
• Ovaries in the female reproductive system produce estrogen and progesterone
• Estrogen develops the female body and regulates the menstrual cycle
• Progesterone prepares the uterus for the development of a fertilized egg
• Ovaries communicate with the hypothalamus and pituitary gland to receive luteinizing hormone and follicle-stimulating hormone for estrogen and progesterone production
• Testes, male reproductive parts, produce testosterone for maintaining healthy sperm count and developing male characteristics
• Testes use luteinizing hormone and follicle-stimulating hormone for testosterone production
• Just like the nervous system, the endocrine system regulates the functions of organ systems to maintain a well-balanced internal environment. The nervous system achieves this by sending nerve impulses along neurons, setting the target organs in action. The endocrine system reinforces these actions by releasing necessary hormones to limit the production up to the appropriate amount. The main gland that adjusts hormone secretion is the hypothalamus, a small organ at the center of the brain that enables interaction between nervous and endocrine systems. 
• Homeostasis is the tendency of the body to resist change and restore itself.