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Test Review

Test Review. Chapters 27 and 17. Mammary Glands. Modified sweat glands consisting of 15–25 lobes Areola: pigmented skin surrounding the nipple Suspensory ligaments: attach the breast to underlying muscle Lobules within lobes contain glandular alveoli that produce milk .

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Test Review

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  1. Test Review Chapters 27 and 17

  2. Mammary Glands • Modified sweat glands consisting of 15–25 lobes • Areola: pigmented skin surrounding the nipple • Suspensory ligaments: attach the breast to underlying muscle • Lobules within lobes contain glandular alveoli that produce milk

  3. Breast Cancer: Detection and Treatment • 70% of women with breast cancer have no known risk factors • Early detection via self-examination and mammography • Treatment depends upon the characteristics of the lesion: • Radiation, chemotherapy, and surgery followed by irradiation and chemotherapy

  4. Breast Cancer • Usually arises from the epithelial cells of small ducts • Risk factors include: • Early onset of menstruation and late menopause • No pregnancies or first pregnancy late in life • Family history of breast cancer • 10% are due to hereditary defects, including mutations to the genes BRCA1 and BRCA2

  5. Oogenesis • Production of female gametes • Begins in the fetal period • Oogonia (2n ovarian stem cells) multiply by mitosis and store nutrients • Primary oocytes develop in primordial follicles • Primary oocytes begin meiosis but stall in prophase I

  6. Ovaries (oogenesis) • Follicle • Immature egg (oocyte) surrounded by • Follicle cells (one cell layer thick) • Granulosa cells (when more than one layer is present)

  7. Follicles • Several stages of development • Primordial follicle: squamous-like follicle cells + oocyte • Primary follicle: cuboidal or columnar follicle cells + oocyte • Secondary follicle: two or more layers of granulosa cells + oocyte • Late secondary follicle: contains fluid-filled space between granulosa cells; coalesces to form a central antrum

  8. Ovaries • Vesicular (Graafian) follicle • Fluid-filled antrum forms; follicle bulges from ovary surface • Ovulation • Ejection of the oocyte from the ripening follicle • Corpus luteum develops from ruptured follicle after ovulation

  9. Tunica albuginea Oocyte Granulosa cells Late secondary follicle Cortex Degenerating corpus luteum (corpus albicans) Mesovarium and blood vessels Germinal epithelium Vesicular (Graafian) follicle Primary follicles Antrum Oocyte Ovarian ligament Zona pellucida Theca folliculi Medulla Ovulated oocyte Corpus luteum Corona radiata Developing corpus luteum (a) Diagrammatic view of an ovary sectioned to reveal the follicles in its interior Figure 27.11a

  10. Oogenesis • Each month after puberty, a few primary oocytes are activated • One is selected each month to resume meiosis I • Result is two haploid cells • Secondary oocyte • First polar body

  11. Oogenesis • The secondary oocyte arrests in metaphase II and is ovulated • If penetrated by sperm the second oocyte completes meiosis II, yielding • Ovum (the functional gamete) • Second polar body

  12. Meiotic events Follicle development in ovary Before birth Oogonium (stem cell) Follicle cells Mitosis Oocyte Primary oocyte Primordial follicle Growth Infancy and childhood (ovary inactive) Primary oocyte (arrested in prophase I; present at birth) Primordial follicle Each month from puberty to menopause Primary follicle Primary oocyte (still arrested in prophase I) Secondary follicle Spindle Vesicular (Graafian) follicle Meiosis I (completed by one primary oocyte each month in response to LH surge) Secondary oocyte (arrested in metaphase II) First polar body Ovulation Sperm Meiosis II of polar body (may or may not occur) Ovulated secondary oocyte Meiosis II completed (only if sperm penetration occurs) In absence of fertilization, ruptured follicle becomes a corpus luteum and ultimately degenerates. Polar bodies (all polar bodies degenerate) Second polar body Ovum Degenating corpus luteum Figure 27.17

  13. Ovarian Cycle • Monthly series of events associated with the maturation of an egg • Two consecutive phases (in a 28-day cycle) • Follicular phase: period of follicle growth (days 1–14) • Ovulation occurs midcycle • Luteal phase: period of corpus luteum activity (days 14–28)

  14. Ovulation • Ovary wall ruptures and expels the secondary oocyte with its corona radiata • Mittelschmerz: twinge of pain sometimes felt at ovulation • 1–2% of ovulations release more than one secondary oocyte, which, if fertilized, results in fraternal twins

  15. Luteal Phase • Ruptured follicle collapses • Granulosa cells and internal thecal cells form corpus luteum • Corpus luteum secretes progesterone and estrogen

  16. Luteal Phase • If no pregnancy, the corpus luteum degenerates into a corpus albicans in 10 days • If pregnancy occurs, corpus luteum produces hormones until the placenta takes over at about 3 months

  17. Establishing the Ovarian Cycle • During childhood, ovaries grow and secrete small amounts of estrogens that inhibit the hypothalamic release of GnRH • As puberty nears, GnRH is released; FSH and LH are released by the pituitary, and act on the ovaries • These events continue until an adult cyclic pattern is achieved and menarche occurs

  18. Establishing the Ovarian Cycle • During childhood, until puberty • Ovaries secrete small amounts of estrogens • Estrogen inhibits release of GnRH

  19. Establishing the Ovarian Cycle • At puberty • Leptin from adipose tissue decreases the estrogen inhibition • GnRH, FSH, and LH are released • In about four years, an adult cyclic pattern is achieved and menarche occurs

  20. Hormonal Interactions During a 28-Day Ovarian Cycle • Day 1: GnRH  release of FSH and LH • FSH and LH  growth of several follicles, and estrogen release •  estrogen levels • Inhibit the release of FSH and LH • Stimulate synthesis and storage of FSH and LH • Enhance further estrogen output

  21. Hormonal Interactions During a 28-Day Ovarian Cycle • Estrogen output by the vesicular follicle increases • High estrogen levels have a positive feedback effect on the pituitary at midcycle • Sudden LH surge at day 14

  22. Hormonal Interactions During a 28-Day Ovarian Cycle • Effects of LH surge • Completion of meiosis I (secondary oocyte continues on to metaphase II) • Triggers ovulation • Transforms ruptured follicle into corpus luteum

  23. Hormonal Interactions During a 28-Day Ovarian Cycle • Functions of corpus luteum • Produces inhibin, progesterone, and estrogen • These hormones inhibit FSH and LH release • Declining LH and FSH ends luteal activity and inhibits follicle development

  24. Hormonal Interactions During a 28-Day Ovarian Cycle • Days 26–28: corpus luteum degenerates and ovarian hormone levels drop sharply • Ends the blockade of FSH and LH • The cycle starts anew

  25. Hypothalamus Hypothalamus 5 GnRH 4 Positive feedback exerted by large in estrogen output. 8 Travels via portal blood 1 Anterior pituitary 5 1 Progesterone Estrogen Inhibin LH surge FSH LH Ruptured follicle 6 8 2 2 3 Slightly elevated estrogen and rising inhibin levels. 7 Thecal cells Granulosa cells Corpus luteum Androgens Mature follicle Ovulated secondary oocyte Convert androgens to estrogens Inhibin 2 Late follicular and luteal phases Early and midfollicular phases Figure 27.19

  26. LH FSH (a) Fluctuation of gonadotropin levels: Fluctuating levels of pituitary gonadotropins (follicle-stimulating hormone and luteinizing hormone) in the blood regulate the events of the ovarian cycle. Figure 27.20a

  27. Primary follicle Vesicular follicle Corpus luteum Degenerating corpus luteum Secondary follicle Ovulation Luteal phase Follicular phase Ovulation (Day 14) (b) Ovarian cycle: Structural changes in the ovarian follicles during the ovarian cycle are correlated with (d) changes in the endometrium of the uterus during the uterine cycle. Figure 27.20b

  28. Uterine (Menstrual) Cycle • Cyclic changes in endometrium in response to ovarian hormones • Three phases • Days 1–5: menstrual phase • Days 6–14: proliferative (preovulatory) phase • Days 15–28: secretory (postovulatory) phase (constant 14-day length)

  29. Uterine Cycle • Menstrual phase • Ovarian hormones are at their lowest levels • Gonadotropins are beginning to rise • Stratum functionalis is shed and the menstrual flow occurs

  30. Uterine Cycle • Proliferative phase • Estrogen levels prompt generation of new functional layer and increased synthesis of progesterone receptors in endometrium • Glands enlarge and spiral arteries increase in number

  31. Uterine Cycle • Secretory phase • Progesterone levels prompt • Further development of endometrium • Glandular secretion of glycogen • Formation of the cervical mucus plug

  32. Estrogens Progesterone (c) Fluctuation of ovarian hormone levels: Fluctuating levels of ovarian hormones (estrogens and progesterone) cause the endometrial changes of the uterine cycle. The high estrogen levels are also responsible for the LH/FSH surge in (a). Figure 27.20c

  33. Endometrium • Stratum functionalis (functional layer) • Changes in response to ovarian hormone cycles • Is shed during menstruation • Stratum basalis (basal layer) • Forms new functionalis after menstruation • Unresponsive to ovarian hormones

  34. Blood vessels Endometrial glands Menstrual flow Functional layer Basal layer Days Menstrual phase Proliferative phase Secretory phase (d) The three phases of the uterine cycle: • Menstrual: Shedding of the functional layer of the endometrium. • Proliferative: Rebuilding of the functional layer of the endometrium. • Secretory: Begins immediately after ovulation. Enrichment of the blood supply and glandular secretion of nutrients prepare the endometrium to receive an embryo. Both the menstrual and proliferative phases occur before ovulation, and together they correspond to the follicular phase of the ovarian cycle. The secretory phase corresponds in time to the luteal phase of the ovarian cycle. Figure 27.20d

  35. Uterine Cycle • If fertilization does not occur • Corpus luteum degenerates • Progesterone levels fall • Spiral arteries kink and spasm • Endometrial cells begin to die • Spiral arteries constrict again, then relax and open wide • Rush of blood fragments weakened capillary beds and the functional layer sloughs

  36. Effects of Estrogens • Promote oogenesis and follicle growth in the ovary • Exert anabolic effects on the female reproductive tract • Support the rapid but short-lived growth spurt at puberty

  37. Effects of Estrogens • Induce secondary sex characteristics • Growth of the breasts • Increased deposit of subcutaneous fat (hips and breasts) • Widening and lightening of the pelvis

  38. Effects of Estrogens • Metabolic effects • Maintain low total blood cholesterol and high HDL levels • Facilitates calcium uptake

  39. Effects of Progesterone • Progesterone works with estrogen to establish and regulate the uterine cycle • Effects of placental progesterone during pregnancy • Inhibits uterine motility • Helps prepare the breasts for lactation

  40. Hormonal Regulation of Male Reproductive Function • A sequence of hormonal regulatory events involving the hypothalamus, anterior pituitary gland, and the testes • The hypothalamic-pituitary-gonadal (HPG) axis

  41. HPG Axis • Hypothalamus releases gonadotropin-releasing hormone (GnRH) • GnRH stimulates the anterior pituitary to secrete FSH and LH • FSH causes sustentacular cells to release androgen-binding protein (ABP), which makes spermatogenic cell receptive to testosterone • LH stimulates interstitial cells to release testosterone

  42. HPG Axis • Testosterone is the final trigger for spermatogenesis • Feedback inhibition on the hypothalamus and pituitary results from • Rising levels of testosterone • Inhibin (released when sperm count is high)

  43. 1 GnRH Anterior pituitary Via portal blood 8 7 2 Inhibin 2 LH FSH Interstitial cells 4 3 6 Testosterone Somatic and psychological effects at other body sites Sustentacular cell Spermatogenic cells 5 Seminiferous tubule Stimulates Inhibits Figure 27.9

  44. Mechanism and Effects of Testosterone Activity • Testosterone • Synthesized from cholesterol • Transformed to exert its effects on some target cells • Dihydrotestosterone (DHT) in the prostate • Estrogen in some neurons in the brain

  45. Mechanism and Effects of Testosterone Activity • Prompts spermatogenesis • Targets all accessory organs; deficiency leads to atrophy • Has multiple anabolic effects throughout the body • Is the basis of the sex drive (libido) in males

  46. Male Secondary Sex Characteristics • Features induced in the nonreproductive organs by male sex hormones (mainly testosterone) • Appearance of pubic, axillary, and facial hair • Enhanced growth of the chest and deepening of the voice • Skin thickens and becomes oily • Bones grow and increase in density • Skeletal muscles increase in size and mass

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