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.

Overview of Hormones 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.

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

Negative Feedback Loop

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

Positive Feedback Loop

Glands

Exocrine glands – secretions released into ducts opening onto an epithelial surface Endocrine glands – ductless organs that secrete their molecules directly into the bloodstream

Glands Endocrine glands are activated by other hormones

Hypothalamus Controls the pituitary gland Receives information from the nervous system

Pituitary Location: Inferior to the hypothalamus Known as the master gland

I. Anterior Pituitary 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 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

II. Posterior Pituitary 2. Antidiuretic hormone (ADH)  Can inhibit urine production  In large amounts, causes vasoconstriction leading to increased blood pressure

Posterior PituitaryAnterior Pituitary

Mnemonic Device for anterior and posterior pituitary gland  Anterior pituitary FLAT PIG  FSH  LH  ACTH  TSH  Prolactin  (Ignore)  Growth Hormone  Posterior pituitary Audio Osmosis = AO = ADH and Oxytocin

Mnemonic Device HormoneTargeted AreaProduces FFSHOvaries and Testes Sperm and egg LLHOvaries and Testes Ovulation and testosterone AATCHAdrenal GlandCortisol TTSHThyroidThryoxine PProlactinBreastMilk IIgnore-- GGHGHMuscles and bones Growth of muscles and bones Anterior Pituitary Gland Chart

Mnemonic Device HormoneTargeted AreaProduces AADHKidneysInhibit urine production OOxytocinUterus and breastUterine contraction and milk letdown Posterior Pituitary Gland Chart