 Consists of glands that secrete substances called hormones into the blood stream.  Hormones stimulate growth and other kinds of reactions such as changes in activity levels and moods.  Hormones are produced by several different glands.  Glands include the Pituitary, thyroid, adrenal, ovaries and testes.

 Called the master gland  Size of a pea.  It lies just below the hypothalamus  Examples of the many hormones it secretes are Growth hormone, prolactin, oxytocin

 Too much growth hormone…  Tanya Angus Tanya Angus

 Thyroxin-affects body’s metabolism  Hypothyroidism-too little can cause a person to be overweight  Hyperthyroidism-too much can make a person be excitable, have difficulty sleeping or lose too much weight.

 Located right above kidneys  Produce adrenaline and noradrenaline.  These hormones enable a person to cope with a stressful situation.  Adrenaline plays a role in the emotions people experience. (fear and anxiety)  Noradrenaline is also a neurotransmitter.

 Produce hormones testosterone, estrogen, progesterone.  Testosterone is secreted during the prenatal period and adolescence. It influences the development of the sex organs.

 Estrogen aids in primary and secondary sex development. Progesterone stimulates female growth hormones, and prepares the body for pregnancy.  They both vary greatly during female cycle and are linked to Premenstrual syndrome. This can lead to depression, fatigue and irritability.

 Psychologists study the sex hormones to learn about the differences in males and females, physically and mentally.

 Neurotransmitters belong to the nervous system, whereas hormones belong to the endocrine system.  Transmission of neurotransmitters is across the synaptic cleft, whereas that of hormones is by blood.  Hormones are produced by endocrine glands while neurotransmitters are produced by neurons.  Action of neurotransmitters is extremely fast, which could be up to few milliseconds. In contrast, effect of hormones could be last for a long period which could be in the range of few seconds to few days.