pp 1031-1042 ENDOCRINE SYSTEM

Homeostasis FEEDBACK MECHANISMS How is this done? Homeostasis: maintaining stable internal environment How is this done? FEEDBACK MECHANISMS

FEEDBACK MECHANISMS Last step of the series controls the first

POSITIVE FEEDBACK A secondary substance increases production of the initial substance Ex. Earth’s Temperature and ice caps Ex. Oxytocin and contractions

NEGATIVE FEEDBACK A secondary substance inhibits production of the initial stimulating substance A = Insulin B = glucagon (sugar)

Endocrine FUNCTION Communication system that controls metabolism, growth, development Uses chemical messengers (hormones)

PARTS Glands: organs that secrete hormones Hormones: chemical messengers that act on target cells

Relies on circulatory system to send chemical message.

PITUITARY GLAND Size of a pea Produces hormones that affects other glands (thyroid, gonads, adrenal glands) controls growth, metabolism, sexual development, and reproduction Known as “master gland”

Growth hormone or GH - GH stimulates growth in childhood and is important for maintaining a healthy body composition. In adults it is also important for maintaining muscle mass and bone mass. It can affect fat distribution in the body. Adrenocorticotropin or ACTH - ACTH stimulates production of cortisol by the adrenal glands. Cortisol, a so-called "stress hormone," is vital to survival. It helps maintain blood pressure and blood glucose levels. Thyroid-stimulating hormone or TSH - TSH stimulates the thyroid gland to make thyroid hormones, which, in turn, control (regulate) the body's metabolism, energy, growth and development, and nervous system activity. Luteinizing hormone or LH - LH regulates testosterone in men and estrogen in women. (gonadotropin) Follicle-stimulating hormone or FSH - FSH promotes sperm production in men and stimulates the ovaries to release eggs (ovulate) in women. LH and FSH work together to allow normal function of the ovaries or testes. (gonadotropin) Oxytocin - Oxytocin causes milk letdown in nursing mothers and contractions during childbirth. Antidiuretic hormone or ADH - ADH, also called vasopressin, is stored in the back part of the pituitary gland and regulates water balance. If this hormone is not secreted properly, this can lead to problems of sodium (salt) and water balance, and could also affect the kidneys so that they do not work as well.

Gigantism: over production of growth hormone Pituitary Disorder Gigantism: over production of growth hormone Tallest man recorded: 8 ft 11 in

THYROID Butterfly-shaped that surrounds trachea Produces thyroxin and calcitonin Regulates heart rate, blood pressure, body temperature, and metabolism

ADRENAL GLANDS Triangle shaped and located on top of kidneys Produces adrenaline Responds to stress

PANCREAS Produces insulin and glucagons to regulate blood sugar levels

Thymus Thymus: stimulates formation of white blood cells (T-cells)

Gonads Gonads: sex hormones

Create and fill in this chart on the back Feature Endocrine Nervous System Organs involved Type of Signal (electrical or chemical) Rate of Transfer (fast or slow?) Voluntary or Involuntary? Examples of Processes Controlled

Endocrine vs. Nervous System