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Chapter 5

Human Sexuality Ch.5.docx

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Western University
Psychology 2075

Chapter 5: sex hormones, sexual differentiation, and menstruation 10/16/2012 8:38:00 PM Sex Hormones:  Prenatal period: the time from conception to birth  Hormones: chemical substances secreted by the endocrine glands into the bloodstream o Effects are rapid  Testosterone: a hormone secreted by the testes in the male (and also present at lower levels in the female  Androgens: the group of male sex hormones, one of which is testosterone  Estrogens: the group of female sex hormones  Progesterone: a female sex hormone secreted by the ovaries  Pituitary gland: a small endocrine gland located on the lower side of the brain below the hypothalamus; the pituitary is important in regulating levels of sex hormones  Hypothalamus: a small region of the brain that is important in regulating many body functions , including the functions of the sex hormones o Below the pituitary Sex hormones in males  Testosterone is released by the testes and maintains secondary sec characteristics like beard growth  Follicle stimulating hormone: a hormone secreted by the pituitary, it stimulates follicle development in females and sperm production in males  Luteinizing hormone: a hormone secreted by the pituitary, it regulates estrogen secretion and ovum development in the female and testosterone production in the male  Gonadotropin releasing hormone: a hormone secreted by the hypothalamus that regulates the pituitary secretion of gonad- stimulating hormones  HPG axis: hypothalamus-pituitary-gonad axis, the negative feedback loop that regulates sex hormone production o When the testosterone hormone falls, the loop turns on and increases the amount of testosterone production  Inhibin: a substance secreted by the testes and ovaries that regulates FSH levels o Uses a negative feedback loop Sex hormone systems in females  The ovaries produce estrogen and progesterone o Also responsible for maintain the mucous in the vaginal wall o Also responsible for stopping the production of bone, this is why women are generally smaller than men  The increase of estrogen inhibits the production of GnRH and LH  Pituitary also produces oxytocin and prolactin o Oxytocin is responsible for the ejaculation of milk  Endocrine disrupters: chemicals found in the environment that affect the endocrine system as well as the biological functioning and behaviour of animals, including humans The menstrual cycle  Phases of the menstrual cycle: o Follicular phase: day 5-13  The first phase of the menstrual cycle, beginning just after menstruation, during which an egg matures in preparation for ovulation o Ovulation phase: day 14  Release of an egg from the ovaries; the second phase of the menstrual cycle o The luteal phase: day 15-28  the third phase of the menstrual cycle, following ovulation  corpus luteum: the mass of cells of the follicle remaining after ovulation it secretes progesterone o menstruation phase: day 1-5  the fourth phase of the menstruation cycle, during which the endometrium of the uterus is sloughed off in the menstrual discharge  if the egg is fertilized about 6 days later in arrives in the uterus where it is nourished and grows  the corpus luteum produces progesterone for about 10 - 12 days if pregnancy doesn’t occur the amount of hormones rapidly decreases o length and timing of the cycle  generally about 20-36 days  average: 28 days  all women are different, there are many factors that effect how long a women’s cycle is  Other cyclic changes o Two other changes are the cervical mucus cycle and the basal temp cycle  One function of the mucus is to protect the entrance of the cervix  As estrogen increases the mucus gets thicker  When the LH production begins the mucus becomes more watery making it easier for sperm to move through  Basal temperature drop at the ovulation phase  Menstrual problems o Dysmenorrhea: painful menstruation o Prostaglandins: chemicals secreted by the uterus that cause the uterine muscles to contract; they are a likely cause of painful menstruation  The best way to get rid of these symptoms is to masturbate- takes away the congestion o Endometriosis: a condition in which the endometrium grows abnormally outside of the uterus; the symptom is unusually painful periods with excessive bleeding o Amenorrhea: the absence of menstruation Prenatal sexual differentiation  Sex chromosomes o XX-female o XY-male o Abnormalities are a male with an extra X chromosome, making them infertile, and produce less testosterone  Gonads: th o Developed in the 7 week after conception o The ovaries will develop around the 11 thand 12 thweek o Sex-determining region-Y chromosome (SRY): a gene on the Y chromosome that causes testes to differentiate prenatally  If not present- female development occurs  Prenatal hormones and the genitals: o Mullerian ducts: duct found in both the male and female fetuses; in males they degenerate and in females they develop into the fallopian tubes, the uterus and the upper part of the vagina o Wolffain ducts: ducts found in both the male and females fetuses; in females they degenerate and i
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