consists of glands that secrete substances called hormones into the blood stream. hormones...
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Endocrine System
Endocrine System
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.
Pituitary Gland 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
Thyroid
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.
Adrenal glands
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.
Testes and Ovaries 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.
Why Study hormones?
Psychologists study the sex hormones to learn about the differences in males and females, physically and mentally.
Neurotransmitters vs. Hormones
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.