ch4-adolescence - Puberty and Menstruation Adolescence a...

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Puberty and Menstruation Adolescence: a transition phase between childhood and adulthood. Puberty: the age at which a young person becomes physically capable of sexual reproduction Menarche: the beginning of menstruation Most girls enter puberty between the ages of 10 and 15; the average is 12 In general, African American and Latina girls get their periods earlier than white people, and Asians get their periods later. o Body weight is an important factor in this. Secondary sex characteristics: features of the body related to reproduction but not directly involved in it. Start forming at about 10 or 11 years old. These characteristics include breast development and pubic hair. The average woman menstruates approximately 450 times during her life The hypothalamus monitors the body’s level of estrogen during the monthly cycle When estrogen levels are low, the hypothalamus signals the pituitary gland, which produces follicle-stimulating hormone and luteinizing hormone. Four hormones contribute to the menstrual cycle: o Follicle-stimulating hormone acts on the follicles within the ovaries, making them produce estrogen and progesterone o Luteinizing hormone is necessary for the development of an ovum o Estrogen, primarily produced by the ovaries, stimulates the development of the uterine lining. o Progesterone, also produced by the ovaries, regulates the system; when the level of luteinizing hormone is high enough, progesterone stops the release of that hormone. Uterus: the organ in which a fetus develops Endometrium: the lining of the uterus Feedback loop: when the level of a particular hormone is too low, a structure in the brain is signaled, and the chain of events that follows produces more of that hormone. Later, when the level of a hormone is too
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high, a signal to a structure in the brain begins a chain of events that decreases that hormone. Menstrual cycle:
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ch4-adolescence - Puberty and Menstruation Adolescence a...

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