A&P Quiz 10 (Ch 28 pt 4)

Puberty in Females

associated with increased rate of estrogen and progesterone secretion by the ovaries

Before Puberty in Females

gnrh secretion from hypothalamus is very low

lh and fsh secretion from anterior pituitary is very low

estrogen and progesterone are secreted in very small amounts

estrogen and progesterone from ovaries have a strong negative feedback effect on the hypothalamus and pituitary gland

After Puberty in Females

larger amounts of gnrh, lh, and fsh are secreted

estrogen and progesterone have less of a negative feedback effect on hypothalamus and pituitary gland

sustained increase in estrogen concentration has a positive feedback effect

normal cyclic pattern of reproductive hormone secretion is established

Menstrual Cycle

refers to the cycling changes in sexually mature nonpregnant females, normally described as 28 days long

Variation in Menstrual Cycle Length

cab vary between 18-40 days, vary between females and from month to month in the same female depending on different factors (nutrition, stress, level of activity)

Menstrual Cycle is Divided Into

ovarian cycle

uterine cycle

Uterine Cycle (simple)

changes associated specifically with the uterus during menstruation

Ovarian Cycle

regular events that occur in the ovaries of sexually mature nonpregnant females during the menstrual cycle

2 Phases of Ovarian Cycle

follicular

luteal

Ovulation

release of secondary oocytes on day 14 of ovarian cycle

Follicular Phase

phase of ovarian cycle that occurs before ovulation (days 1-14), primordial follicle develops into mature follicle, primary oocyte undergoes first meiotic division

Luteal Phase

phase of ovarian cycle that occurs after ovulation, follicle form corpus luteum that secretes progesterone and small amount of estrogen

Ovarian Cycle Diagram

Steps 1-3 of Ovarian Cycle

lh stimulates theca interna cells to produce androgens

androgens diffuse into granulosa cells

fsh stimulates granulosa cells to convert androgens to estrogen and gradually increases lh receptors in granulosa cells

Steps 4-6 of Ovarian Cycle

estrogen increases lh receptors in the theca interna cells

lh stimulates granulosa cells to produce progesterone

progesterone diffused to theca interna cells and is converted to androgens

Steps 7-9 of Ovarian Cycle

androgens are converted into estrogen by granulosa cells

causes a gradual increase in estrogen secretion by granulosa cells throughout the follicular phase

inhibin secreted by the developing follicle inhibits fsh secretion

Early Hormones Secreted During Ovarian Cycle

hypothalamus increases gnrh, which increases secretion of fsh and lh from anterior pituitary

FSH and LH in Ovarian Cycle

stimulate growth and maturation of the ovarian follicles (follicular phase), fsh initiates development of primary follicles (up to 25 per cycle), typically only one is ovulated, can by ovulated during a later cycle, remaining follicles degenerate, both an LH surge and FSH surge occur

Role of Estrogen Secreted by Maturing Follicle

stimulated uterine endometrial proliferation, positive feedback on hypothalamic and anterior pituitary secretion, determination of which follicles degenerate (larger follicles appear to secrete estrogen and other substances that have an inhibitory effect on less mature follicles

LH Surge

occurs several hours earlier and to a greater degree than fsh surge in ovarian cycle, stimulates maturation of follicle and completion of meiosis i, triggers inflammation like events in the mature follicles that result in ovulation

Corpus Luteum in Ovulation

formed shortly after ovulation, secretes progesterone and estrogen

Progesterone and Estrogen in Ovarian Cycle

cause negative feedback on the hypothalamus and anterior pituitary to decrease fsh and lh secretion

Ovarian Cycle if Fertilization Occurs

developing embryo secretes hcg

hcg keeps corpus luteum from degenerating

keeps blood levels of estrogen and progesterone from decreasing

menses of the next uterine cycle does not occur

Ovarian Cycle if Fertilization Does Not Occur

hcg is not produced

cells of corpus luteum begin to atrophy after day 25 or 26

blood levels of estrogen and progesterone decrease rapidly

menses occurs

Uterine Cycle

changes that occur primarily in the functional layer of the endometrium during the menstrual cycle, more subtle changes take place in the vagina and other structures

3 Phases of Uterine Cycle

menses

proliferative phase

secretory phase

Menses

phase of uterine cycle, period of mild hemorrhage that occurs about once a month, functional layer of the endometrium is sloughed off and expelled from the uterus

Menstruation

discharge of the sloughed endometrial tissue and blood

Proliferative Phase

phase of uterine cycle, time between the ending of menses and ovulation, endometrium begins to regenerate

Endometrium Regeneration During Proliferative Phase

epithelial cells divide to produce low cuboidal epithelial cells that become columnar, spiral glands and spiral arteries reform

Spiral Glands

region of endometrium that regenerates during proliferative phase of uterine cycle, tubular folds of the cells of the functional layer

Spiral Arteries

region of endometrium that regenerates during proliferative phase of uterine cycle, blood vessels project through the delicate connective tissue that separates the individual spiral glands to supply endometrial cells

Secretory Phase

phase of uterine cycle, time after ovulation to the next menses, endometrium becomes thicker, spiral glands develop to greater extent and begin secreting small amounts of fluid rich in glycogen, around day 21 the endometrium is prepared to receive a developing embryonic mass

Uterine Cycle Diagram

What controls female sexual behavior and the female sex act?

female sex drive depends on hormones, psychological factors can affect sexual behavior, neural pathways controlling sexual responses are the same as in males

Hormones of Female Sex Act and Sexual Behavior

adrenal glands and other tissues convert steroids to androgens, androgens and possibly estrogen affect brain cells (hypothalamus) to influence sexual behavior but no not control sex drive alone

Neural Control of Female Sexual Behavior and Female Sex Act

sensory action potentials conducted from genitals to the sacral region, integrate reflexes regulating sexual responses, ascending pathways (spinothalamic tracts) carry sensory information to the brain, descending pathways carry information back to the sacral region to influence sacral reflexes

Motor AP of Female Sexual Behavior and Sex Act Carried By

parasympathetic and sympathetic nerve fibers from the spinal cord to the reproductive organs

somatic motor nerve fibers to the skeletal muscles

Parasympathetic Stimulation in Female Sexual Behavior Causes

erectile tissue in the clitoris and around vaginal opening to become engorged with blood, nipples often become erect, mucous glands in the vestibule secrete mucus, large amounts of mucus like fluid are extruded into the vagina through the vaginal wall

Function of Parasympathetic Vaginal Secretions

lubrication allows for easy entry and movement of the penis during intercourse

Orgasm

triggered by tactile stimulation of female’s genitals and psychological stimuli, vaginal/uterine/perineal muscles contract rhythmically, muscle tension increases throughout the body, not required for fertilization to occur

Resolution

characterized by sense of satisfaction and relaxation, successive orgasms are possible

Travel of Sperm for Fertilization

sperm are transported through the cervix, body of the uterus, and uterine tubes after ejaculation

What allows sperm to move?

sperm’s ability to swim

muscular contraction of the uterus and uterine tubes

Capacitation

removal of proteins and modification of glycoproteins of the sperm cell plasma membrane after which sperm cells can move

What causes muscular contractions of the uterus and uterine tubes?

oxytocin (posterior pituitary) and prostaglandins (semen) stimulate smooth muscle contractions

Fertilization in Uterine Tubes

one sperm cell enters the secondary oocyte, oocyte can be fertilized up to 24 hours after ovulation, some sperm cells remain viable in the female reproductive tract for up to six days (most degenerate after 24 hours), sexual intercourse must occur between five days before and one day after ovulation

Fertilization to Pregnancy

series of cell division occur for several days following fertilization, developing embryo passes through the uterine tube to the uterus, 7-8 days after ovulation (day 21-22 of the menstrual cycle) endometrium is prepared for implantation, implantation of trophoblast (developing embryo) begins

Implantation of Trophoblast

outer layer of trophoblast secretes proteolytic enzymes that digest cells of endometrium to form part of the placenta, placenta and ovary secrete several hormones throughout pregnancy (hcg, estrogen, progesterone)

Pregnancy Hormones

embryo and developing placenta secrete hcg

progesterone secretion increases during most of the pregnancy until end of third trimester

estrogen levels increase slowing throughout pregnancy (increase more rapidly near the time of birth)

hCG Functions in Pregnancy

causes the corpus luteum to remain functional

corpus luteum increases estrogen and progesterone levels

secretion increases rapidly and peaks around 8-9 weeks after fertilization

levels decline until around week 16 and then remain relatively constant through pregnancy

Pregnancy Hormones

corpus luteum secretes progesterone and estrogen that are essential for maintenance of pregnancy, placenta form and secretes progesterone and estrogen

3 Months Into Pregnancy

corpus luteum is no longer needed to maintain pregnancy

Perimenopause

menstrual cycles become less regular and ovulation often does not occur consistently around age 40-50 years, lasts 3-5 years

Menopause

cessation of the menstrual cycles, associated with changes in the ovaries, treated with hormone replacement therapy (hrt)

Changes in Ovaries During Menopause

few follicles remain, remaining follicles are less sensitive to stimulation by lh and fsh

Symptoms of Menopause

uncomfortable sweating (hot flashes), fatigue, anxiety, temporary decrease in sex drive, occasionally severe emotional disturbances