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Endocrine System. Chapter 8. Overview of Hormones. The endocrine and nervous systems often work together to bring about homeostasis. The blood stream transports hormones throughout the body. Each hormone acts on a certain type of tissue called its target tissue.
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Endocrine System Chapter 8
Overview of Hormones The endocrine and nervous systems often work together to bring about homeostasis. The blood stream transports hormones throughout the body.
Each hormone acts on a certain type of tissue called its target tissue. Organs, tissues, or cells lacking the specific receptor do not respond to its stimulating effects. Overview of Hormones
Negative Feedback Loop • A decrease in function in response to a stimulus • The system controls how much product it makes by shutting down manufacturing when levels of output or the amount of accumulated product gets too high • Example # 1: the regulation of the blood glucose level in the body • Example # 2: regulation of body temperature
Positive Feedback Loop • An increase in function in response to a stimulus • “A” produces more of “B” which in turn produces more of “A” • Only a few positive feedback loops occur in the human endocrine system. • Example: the process of birthing a child
Glands • Exocrine glands – secretions released into ducts opening onto an epithelial surface • Endocrine glands – ductless organs that secrete their molecules directly into the bloodstream
Hypothalamus • Controls the pituitary gland • Receives information from the nervous system
Pituitary • Location: Inferior to the hypothalamus • Known as the master gland
1. Growth hormone (GH) General metabolic hormone Major effects are directed to growth of skeletal muscles and long bones I. Anterior Pituitary
2. Prolactin (PRL) Stimulates and maintains milk production following childbirth Function in males is unknown I. Anterior Pituitary
I. Anterior Pituitary • 3. Adrenocorticotropic hormone (ACTH) • Regulates endocrine activity of the adrenal cortex which makes a hormone called cortisol (helps the body manage stress)
I. Anterior Pituitary • 4. Thyroid-stimulating hormone (TSH) • Produces the hormone thyroxine • Regulates the rate of metabolism
I. Anterior Pituitary • Gonadotropic hormones – Regulate hormonal activity of the gonads • 5. Follicle-stimulating hormone (FSH) • Stimulates follicle development in ovaries • Stimulates sperm development in testes
I. Anterior Pituitary • Gonadotropic hormones – Regulate hormonal activity of the gonads • 6. Luteinizing hormone (LH) • Triggers ovulation • Prepares uterus for fertilized egg • Stimulates testosterone production in males
II. Posterior Pituitary • 1. Oxytocin • Stimulates contractions of the uterus during labor • Causes milk ejection
2. Antidiuretic hormone (ADH) Can inhibit urine production In large amounts, causes vasoconstriction leading to increased blood pressure II. Posterior Pituitary
Posterior Pituitary Anterior Pituitary
Mnemonic Device for anterior and posterior pituitary gland • Anterior pituitary • FLAT PIG • 1. FSH • 2. LH • 3. ACTH • 4. TSH • 5. Prolactin • (Ignore) • 6. Growth Hormone • Posterior pituitary • Audio Osmosis = AO • 1. ADH • 2. Oxytocin