THE ENDOCRINE SYSTEM AND HEREDITY
ENDOCRINE SYSTEM
The endocrine system consists of glands that secrete substances called hormones into the blood stream.Hormones stimulate growth and many kinds of reactions, such as changes in activity level or mood.Since hormones affect behavior and emotional reactions, psychologists are interested in the endocrine system.
It secretes many different hormones that affect various aspects of behavior including the regulation of growth of muscles, bones, and glands.
PITUITARY GLAND
It produces thyroxin which affects the body’s metabolism; its rate of converting food to energy. Too much thyroxin leads to weight gain. Too little causes excitability, insomnia, and weight loss.
THYROID GLAND
ADRENAL GLANDS
They produce cortical steroids which promote resistance to stress and promote muscle development. They also produce adrenaline and noradrenaline which help us cope with stress and intensify emotions of fear and anxiety.
TESTICLES AND OVARIES
Testicles in males and ovaries in females produce the hormones testosterone, estrogen, and progesterone. Testosterone is a male sex hormone, although females have small amounts as well. It influences development of sex organs, aids in the growth of muscle and bone as well as development of sex characteristics.
Estrogen and progesterone are female sex hormones, although males have a small amount as well. They foster development of sex characteristics, regulate menstrual cycle, and prepare the body for pregnancy.
Heredity is the transmission of characteristics from parent to offspring. It plays a key role in the traits we inherit which help shape our behavior. It is vital in the transmission of physical traits such as appearance, height, hair color, and eye color.
HEREDITY
Some psychological traits such as shyness, intelligence, leadership, and interest in arts are influenced by heredity but environment also shapes these traits. Heredity is one factor in psychological disorders too.
Genes- basic building blocks of heredity.
Chromosomes- microscopic threadlike structure in the nucleus of every living cell; it contains genes. They are composed of DNA. Most human cells have 46 chromosomes organized into 23 pairs.
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