PSYC 3310 Lecture Notes - Lecture 2: Adrenocorticotropic Hormone, Luteinizing Hormone, Dehydroepiandrosterone
20 Jun 2018
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CHAPTER 2 PUBERTY AND PHYSICAL
DEVELOPMENT
The Endocrine System and the Beginning of
Puberty
• Hormonal changes that lead to physical, cognitive, behavioural changes
• Endocrine system: a system of glands that produce hormones, as well as
parts of the brain and nervous system that regulate hormone production
o Hormones and glands
• Hormones: chemical substances that circulate through the bloodstream and
regulate many bodily functions
The Hypothalamus and Pituitary
• Hypothalamus: a part of the brain that monitors and regulates many bodily
functions, including hormone production
o Regulates hormones and glands
o Send other hormones to glands
o Checking and responding to the levels of different hormones
circulating in the blood
• Each hormone has a set point, a particular level the system tries to maintain.
• Pituitary gland: an endocrine gland that is considered the master gland of
the endocrine system
o Controls other endocrine glands by sending out hormones that make
them change the way they operate
• Gonads: the sex glands; ovaries in females, testes in males
o Major source of estrogen and androgens
o During most of childhood, the levels of estrogen and androgens are
very similar in girls and boys.
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The HPG Axis
• A feedback loop that regulates the hormones involved in puberty and growth
o Hypothalamus, pituitary, and gonads
• Hypothalamus senses that the sex hormones, and produces gonadotropin-
releasing hormone (GnRH) to the pituitary.
• Triggers the pituitary glands to release gonadotropic hormones
o Follicle stimulating hormone (FSH)
o Luteinizing hormone (LH)
o These hormones also play an important role in reproduction by
speeding up development of egg cells in the ovaries and sperm cells
in the testes.
• Gonadotropic hormones stimulate the production of sex hormones from the
gonads – ovaries and testes
o Females – estrogen, progesterone
o Males – testosterone (LH) and growth of seminiferous tubules that
produce sperms (FSH)
• When the level reaches the set pint, the hypothalamus lowers production of
GnRH, which signals the pituitary to stop producing LH and FSH.
o This in turn causes the gonads to reduce production of sex hormones.
Sex Hormones
Androgens
• Produced by gonads and adrenal glans
• Adrenocorticotropic hormone produced by the pituitary gland which triggers
release of androgens from the adrenal gland
o Testosterone
o Dehydroepiandrosterone (DHEA)
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• Influence on other body systems
o Growth of larynx
o Growth of bones, kidney, muscles
o Secretions from the sebaceous glands in the skin
o Recession of the hair line
• DHEA
o Growth of body hair
o Responsible for sexual arousal and attraction
Estrogens
• Female sex hormones, secreted mainly by the ovaries
• Estradiol
o Breast development
• Other influences
o Affect the functioning of liver
o Production of plasma
o Bone density
o Development of new neural synapses
Progestins
• Progesterone
How Puberty Begins
• For most of childhood, the hypothalamus suppresses the production of sex
hormones by operating with a very low set point for these hormones.
• Adrenarche: beginning of adrenal involvement
• 6 to 9 years – adrenal glands begin to mature
o Produce more DHEA
Document Summary
Gnrh, which signals the pituitary to stop producing lh and fsh: this in turn causes the gonads to reduce production of sex hormones. Androgens: produced by gonads and adrenal glans, adrenocorticotropic hormone produced by the pituitary gland which triggers release of androgens from the adrenal gland, testosterone, dehydroepiandrosterone (dhea) Influence on other body systems: growth of larynx, growth of bones, kidney, muscles, secretions from the sebaceous glands in the skin, recession of the hair line, dhea, growth of body hair, responsible for sexual arousal and attraction. Estrogens: female sex hormones, secreted mainly by the ovaries, estradiol, breast development, other influences, affect the functioning of liver, production of plasma, bone density, development of new neural synapses. Insulin-like growth factor-i: a substance produced in the liver that may be linked to the onset of puberty: increases during puberty but goes back to normal levels after puberty.
