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menstrual cycle physiology follicular ovulation luteal phase hormonal regulation overview

menstrual cycle physiology

menstrual cycle ovarian and endometrial phases hormonal changes diagram

https://www.ncbi.nlm.nih.gov/books/NBK500020

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mkdir -p "/tmp/workspace/reproductive-physiology-menstrual-cycle/src" "/tmp/workspace/reproductive-physiology-menstrual-cycle/output" && python - <<'PY' from pathlib import Path p=Path('/tmp/workspace/reproductive-physiology-menstrual-cycle/src/build_menstrual_cycle_pdf.py') p.write_text(r'''from reportlab.lib.pagesizes import A4 from reportlab.lib import colors from reportlab.lib.styles import getSampleStyleSheet, ParagraphStyle from reportlab.lib.enums import TA_CENTER, TA_LEFT from reportlab.lib.units import cm from reportlab.platypus import SimpleDocTemplate, Paragraph, Spacer, PageBreak, Table, TableStyle, KeepTogether from reportlab.pdfbase.ttfonts import TTFont from reportlab.pdfbase import pdfmetrics from reportlab.lib.colors import HexColor from reportlab.pdfbase.pdfmetrics import stringWidth from reportlab.pdfgen import canvas from reportlab.platypus import Flowable from reportlab.lib.colors import Color OUT='/tmp/workspace/reproductive-physiology-menstrual-cycle/output/Menstrual_Cycle_LAQ_and_Cheat_Sheet.pdf' navy=HexColor('#183B56'); teal=HexColor('#087E8B'); blue=HexColor('#EAF5F7'); pale=HexColor('#F7FAFC'); gold=HexColor('#F6C85F'); red=HexColor('#A83A3A'); grey=HexColor('#4A5568') styles=getSampleStyleSheet() styles.add(ParagraphStyle(name='TitleX', parent=styles['Title'], fontName='Helvetica-Bold', fontSize=22, leading=27, textColor=navy, alignment=TA_CENTER, spaceAfter=10)) styles.add(ParagraphStyle(name='SubTitle', parent=styles['Normal'], fontName='Helvetica', fontSize=10.5, leading=14, textColor=grey, alignment=TA_CENTER, spaceAfter=14)) styles.add(ParagraphStyle(name='H1X', parent=styles['Heading1'], fontName='Helvetica-Bold', fontSize=16, leading=20, textColor=navy, spaceBefore=11, spaceAfter=7)) styles.add(ParagraphStyle(name='H2X', parent=styles['Heading2'], fontName='Helvetica-Bold', fontSize=12.4, leading=15, textColor=teal, spaceBefore=8, spaceAfter=4)) styles.add(ParagraphStyle(name='BodyX', parent=styles['BodyText'], fontName='Helvetica', fontSize=9.6, leading=13.1, textColor=HexColor('#202B36'), spaceAfter=5)) styles.add(ParagraphStyle(name='SmallX', parent=styles['BodyText'], fontName='Helvetica', fontSize=8.25, leading=10.2, textColor=HexColor('#202B36'), spaceAfter=2)) styles.add(ParagraphStyle(name='BoxX', parent=styles['BodyText'], fontName='Helvetica-Bold', fontSize=9.5, leading=13, textColor=navy, spaceAfter=0)) styles.add(ParagraphStyle(name='CheatH', parent=styles['Heading2'], fontName='Helvetica-Bold', fontSize=11.3, leading=13, textColor=navy, spaceBefore=4, spaceAfter=3)) class FooterCanvas(canvas.Canvas): def __init__(self,*args,**kwargs): canvas.Canvas.__init__(self,*args,**kwargs); self.pages=[] def showPage(self): self.pages.append(dict(self.__dict__)); self._startPage() def save(self): n=len(self.pages) for state in self.pages: self.__dict__.update(state) self.setStrokeColor(HexColor('#B5C5D1')); self.line(1.6*cm,1.38*cm,19.4*cm,1.38*cm) self.setFont('Helvetica',8); self.setFillColor(grey) self.drawString(1.6*cm,0.88*cm,'MBBS First Year Physiology | Reproductive Physiology') self.drawRightString(19.4*cm,0.88*cm,f'Page {self._pageNumber} of {n}') canvas.Canvas.showPage(self) canvas.Canvas.save(self) def P(text, style='BodyX'): return Paragraph(text, styles[style]) def bullet(text): return P('&bull; '+text) def box(title,text): t=Table([[P('<b>'+title+'</b><br/>'+text,'BoxX')]],colWidths=[17.6*cm]) t.setStyle(TableStyle([('BACKGROUND',(0,0),(-1,-1),blue),('BOX',(0,0),(-1,-1),0.55,teal),('LEFTPADDING',(0,0),(-1,-1),9),('RIGHTPADDING',(0,0),(-1,-1),9),('TOPPADDING',(0,0),(-1,-1),7),('BOTTOMPADDING',(0,0),(-1,-1),7)])); return t def table(headers, rows, widths, small=False): st='SmallX' if small else 'BodyX' dat=[[P('<b>'+h+'</b>',st) for h in headers]]+[[P(x,st) for x in r] for r in rows] t=Table(dat,colWidths=widths,repeatRows=1) t.setStyle(TableStyle([('BACKGROUND',(0,0),(-1,0),navy),('TEXTCOLOR',(0,0),(-1,0),colors.white),('VALIGN',(0,0),(-1,-1),'TOP'),('GRID',(0,0),(-1,-1),0.35,HexColor('#B9CED8')),('ROWBACKGROUNDS',(0,1),(-1,-1),[colors.white,pale]),('LEFTPADDING',(0,0),(-1,-1),5),('RIGHTPADDING',(0,0),(-1,-1),5),('TOPPADDING',(0,0),(-1,-1),4),('BOTTOMPADDING',(0,0),(-1,-1),4)]));return t story=[] story += [P('MENSTRUAL CYCLE','TitleX'), P('Detailed Long-Answer Question (LAQ) with one-page revision cheat sheet','SubTitle'), box('How to use this answer','For a 10-15 mark question: write the definition, draw the integrated cycle diagram, explain ovarian and uterine phases with hormones, then finish with menstruation and a short conclusion.'), Spacer(1,8)] story += [P('1. Definition and normal pattern','H1X'), P('<b>Menstrual cycle</b> is the series of regular, cyclic changes in the ovaries and female reproductive tract, especially the endometrium, occurring from menarche to menopause. Its purpose is to mature and release an oocyte and prepare the uterus for implantation. If fertilization does not occur, the prepared superficial endometrium is shed as menstrual bleeding.'), P('Day 1 is the <b>first day of menstrual bleeding</b>. The often-quoted cycle is 28 days, but cycle length normally varies mainly because the follicular phase varies. The luteal phase is relatively constant at about 14 days. Menstrual blood loss is usually about 30-40 mL; loss above 80 mL is considered excessive.'), box('Core idea','<b>One cycle, two linked cycles:</b> ovarian cycle (follicular phase -> ovulation -> luteal phase) and uterine/endometrial cycle (menstrual -> proliferative -> secretory phase).')] story += [P('2. Hormonal control: hypothalamus -> pituitary -> ovary -> uterus','H1X'), P('The cycle is controlled by the hypothalamo-pituitary-ovarian axis. Pulsatile hypothalamic <b>GnRH</b> stimulates the anterior pituitary to release <b>FSH</b> and <b>LH</b>. These act on the ovary, which produces <b>estradiol</b>, <b>progesterone</b>, and <b>inhibin</b>. Ovarian steroids act on the uterus and also feed back to the brain and pituitary.'), table(['Hormone','Main source','Key action in the cycle'], [('GnRH','Hypothalamus','Pulsatile release drives pituitary FSH and LH secretion.'),('FSH','Anterior pituitary','Recruits and supports growing follicles; stimulates granulosa-cell aromatase, so estrogen is formed.'),('LH','Anterior pituitary','Stimulates theca cells to make androgens; LH surge triggers ovulation and luteinization.'),('Estradiol','Growing follicle, especially granulosa cells','Causes proliferative growth of endometrium. Usually inhibits FSH/LH, but sustained high preovulatory level causes positive feedback and LH surge.'),('Progesterone','Corpus luteum after ovulation','Converts proliferative endometrium to secretory endometrium; inhibits GnRH, FSH and LH; slightly raises basal body temperature.'),('Inhibin','Granulosa cells/corpus luteum','Selectively suppresses FSH, helping prevent recruitment of further follicles.')],[2.2*cm,4.0*cm,11.4*cm],True), Spacer(1,5), P('<b>Two-cell, two-gonadotropin concept:</b> LH acts mainly on <b>theca interna</b> cells, producing androgens. These androgens diffuse into <b>granulosa</b> cells, where FSH stimulates aromatase to convert them into estradiol.')] story += [P('3. Ovarian cycle','H1X'), P('The ovarian cycle has three parts: follicular phase, ovulation, and luteal phase.'), P('A. Follicular phase (day 1 to ovulation)','H2X'), P('At the end of the preceding cycle, the corpus luteum regresses. Therefore progesterone, estrogen, and inhibin fall. Their negative feedback is removed, so FSH rises slightly. FSH recruits a group of antral follicles. Usually, one follicle becomes the <b>dominant follicle</b>; the remaining follicles undergo atresia.'), P('The dominant follicle produces progressively more estradiol and inhibin B. Rising estradiol supports follicular growth and makes the endometrium proliferate. It also lowers FSH, which helps ensure that only the best-supported dominant follicle survives. For most of this phase, estrogen exerts negative feedback on LH and FSH.'), P('B. Ovulation (approximately day 14 in a 28-day cycle)','H2X'), P('When estradiol remains high for about 2 days near the end of the follicular phase, feedback switches from negative to <b>positive</b>. This produces a large <b>LH surge</b> and a smaller FSH surge. Ovulation occurs about 36 hours after onset of the LH surge. The LH surge completes final oocyte maturation, weakens the follicular wall through local enzymes and prostaglandins, and ruptures the mature Graafian follicle to release the secondary oocyte.'), P('C. Luteal phase (ovulation to next menses)','H2X'), P('After ovulation, the ruptured follicle becomes the <b>corpus luteum</b>. Under LH influence, granulosa and theca cells luteinize and secrete large amounts of progesterone, moderate estrogen, and inhibin A. This produces strong negative feedback, keeping FSH and LH low and preventing another ovulation in the same cycle.'), P('If fertilization and implantation do not occur, the corpus luteum survives only about 14 days and regresses to corpus albicans. Progesterone and estrogen then fall sharply. This steroid withdrawal causes menstruation and allows FSH to rise, starting the next cycle. If pregnancy occurs, hCG maintains the corpus luteum until the placenta takes over steroid production.')] story += [P('4. Uterine (endometrial) cycle','H1X'), P('The endometrium has a deep <b>stratum basalis</b>, which remains after menstruation, and a superficial <b>stratum functionalis</b>, which grows and is shed each month. Uterine changes mirror ovarian hormone changes.'), table(['Phase and usual days','Dominant hormone','Endometrial events and appearance'], [('Menstrual phase, days 1-4/5','Fall in progesterone and estrogen','Functional layer breaks down and is shed with blood and tissue. Basal layer remains, permitting regeneration.'),('Proliferative phase, days 5-14','Estrogen','Endometrium regenerates from basal layer and thickens. Glands are straight, narrow and tubular; stroma proliferates; spiral arteries lengthen. Cervical mucus becomes thin, watery and sperm-friendly.'),('Secretory phase, days 15-28','Progesterone, with estrogen','Endometrium becomes thick, edematous, vascular and receptive to implantation. Glands become coiled/tortuous and secrete glycogen-rich material. Spiral arteries become highly coiled. Cervical mucus becomes thick and less permeable.')],[3.0*cm,3.6*cm,11.0*cm],True), Spacer(1,5), P('<b>Menstruation:</b> Without pregnancy, luteal regression produces progesterone withdrawal. Spiral arteries constrict intermittently, causing ischemia and local tissue injury. Prostaglandins and inflammatory mediators contribute to vasoconstriction and uterine contractions. The functionalis breaks down and is expelled. The basalis is not shed, so repair begins quickly.')] story += [P('5. Integrated hormonal changes: write this diagram in the exam','H1X'), box('Simple sequence','<b>Luteolysis</b> -> estrogen and progesterone fall -> FSH rises -> follicle grows -> estradiol rises -> <b>sustained high estradiol</b> -> positive feedback -> <b>LH surge</b> -> ovulation -> corpus luteum -> progesterone rises -> secretory endometrium -> if no pregnancy: luteolysis and menstruation.'), Spacer(1,5), table(['Time','FSH/LH','Estrogen','Progesterone','Ovary / uterus'], [('Early follicular','FSH modestly rises; LH low','Low then rising','Low','Follicles recruited; menses begins, then proliferation.'),('Late follicular','FSH falls; LH rises modestly','High and rising','Low','Dominant follicle; proliferative endometrium.'),('Mid-cycle','Large LH surge; small FSH surge','Brief peak then fall','Starts rising','Ovulation.'),('Mid-luteal','FSH and LH suppressed','Moderately high','Highest','Corpus luteum; secretory endometrium.'),('Late luteal','FSH begins to rise again as feedback is lost','Falls','Falls sharply','Corpus luteum regresses; menstruation follows.')],[2.4*cm,4.1*cm,3.2*cm,3.0*cm,4.9*cm],True)] story += [P('6. Other cyclic changes and clinical correlations','H1X'), bullet('<b>Basal body temperature:</b> progesterone has a thermogenic action. After ovulation, basal temperature rises by about 0.3-0.5 degrees C and remains elevated through the luteal phase. This supports, but does not precisely predict, ovulation.'), bullet('<b>Cervical mucus:</b> estrogen makes it abundant, thin, clear, stretchable and shows ferning, helping sperm passage near ovulation. Progesterone makes it scant, thick and viscid after ovulation.'), bullet('<b>Vagina:</b> estrogen promotes epithelial proliferation and cornification; progesterone causes secretory change and more leukocytes.'), bullet('<b>Anovulatory cycle:</b> ovulation and corpus luteum formation do not occur. Thus progesterone is absent, and endometrium experiences unopposed estrogen stimulation, often producing irregular bleeding.'), P('A regular cycle does not prove ovulation. Evidence of ovulation includes a mid-luteal rise in serum progesterone, biphasic basal body temperature, luteal changes in endometrium, follicle rupture on ultrasound, and detection of the urinary LH surge before ovulation.')] story += [P('7. Model conclusion for an LAQ','H1X'), P('Thus, the menstrual cycle is a precisely coordinated interaction between pulsatile GnRH, pituitary FSH and LH, ovarian estrogen and progesterone, and the endometrium. Estrogen predominates before ovulation and causes proliferative growth. The LH surge causes ovulation. Progesterone from the corpus luteum dominates after ovulation and produces secretory transformation. Withdrawal of progesterone and estrogen causes menstruation if pregnancy does not occur.')] story.append(PageBreak()) story += [P('ONE-PAGE CHEAT SHEET: MENSTRUAL CYCLE','TitleX'), P('Read this the night before or immediately before the paper.','SubTitle')] story += [box('Definition','Cyclic ovarian and uterine changes that mature an oocyte, permit ovulation, and prepare the endometrium for implantation. <b>Day 1 = first day of bleeding.</b>'), Spacer(1,5)] story += [P('The two cycles','CheatH'), table(['Ovarian','Uterine / endometrial','Main hormone'], [('Follicular phase','Menstrual + proliferative phase','Estrogen'),('Ovulation','Mid-cycle','LH surge'),('Luteal phase','Secretory phase','Progesterone')],[5.7*cm,6.2*cm,5.7*cm],True)] story += [P('28-day timeline','CheatH'), table(['Days','What happens','Hormonal key'], [('1-4/5','Menstruation','Estrogen and progesterone fall; FSH begins to rise.'),('5-13','Follicle becomes dominant; endometrium proliferates','Estradiol rising; FSH gradually falls.'),('~14','Ovulation','Sustained high estradiol -> positive feedback -> LH surge. Ovulation ~36 h after LH-surge onset.'),('15-28','Corpus luteum; secretory endometrium','Progesterone high. If no pregnancy: corpus luteum regresses, progesterone falls, menses begins.')],[2.0*cm,9.0*cm,6.6*cm],True)] story += [P('High-yield mechanism lines','CheatH'), bullet('<b>FSH:</b> follicular growth + granulosa-cell aromatase -> estrogen.'), bullet('<b>LH:</b> theca androgen production; LH surge -> ovulation + luteinization.'), bullet('<b>Estrogen:</b> proliferative endometrium. Low/moderate = negative feedback. Sustained high level = positive feedback -> LH surge.'), bullet('<b>Progesterone:</b> secretory endometrium, thick cervical mucus, raised basal temperature, negative feedback on FSH/LH.'), bullet('<b>Inhibin:</b> inhibits FSH.'), bullet('<b>Two-cell, two-gonadotropin:</b> LH-theca-androgens; FSH-granulosa-aromatase-estrogen.') story += [P('Endometrium: write these keywords','CheatH'), table(['Menstrual','Proliferative','Secretory'], [('Progesterone withdrawal; spiral-artery constriction; shedding of functionalis; basalis remains.','Estrogen: thickening, straight tubular glands, stromal mitosis, spiral arteries lengthen.','Progesterone: tortuous glands with glycogen secretion, edema, coiled spiral arteries, implantation-ready.')],[5.8*cm,5.8*cm,5.8*cm],True)] story += [P('One-line flowchart','CheatH'), box('Flowchart','Corpus luteum regresses -> E/P fall -> FSH rises -> follicles grow -> E rises -> LH surge -> ovulation -> corpus luteum -> P rises -> secretory endometrium -> no pregnancy -> E/P fall -> menstruation.')] story += [P('Last-minute exam checklist','CheatH'), bullet('Draw ovarian and uterine phases on one timeline.'), bullet('Underline: <b>positive feedback, LH surge, ovulation, corpus luteum, progesterone withdrawal</b>.'), bullet('State that follicular phase is variable; luteal phase is about 14 days.'), bullet('End with a conclusion linking hormone withdrawal to menstruation.')] story += [Spacer(1,6), P('<b>Sources used for study preparation:</b> Costanzo Physiology, 7th ed., menstrual-cycle section; Ganong’s Review of Medical Physiology, 26th ed., “The Menstrual Cycle”; Berek & Novak’s Gynecology, “Menstrual Cycle Physiology”; and the NIH [<link href="https://www.ncbi.nlm.nih.gov/books/NBK500020">menstrual-cycle overview</link>].', 'SmallX')] doc=SimpleDocTemplate(OUT,pagesize=A4,rightMargin=1.6*cm,leftMargin=1.6*cm,topMargin=1.5*cm,bottomMargin=1.8*cm,title='Menstrual Cycle LAQ and Cheat Sheet',author='Orris') doc.build(story,canvasmaker=FooterCanvas) print(OUT) ''') PY python "/tmp/workspace/reproductive-physiology-menstrual-cycle/src/build_menstrual_cycle_pdf.py"

.../src/build_menstrual_cycle_pdf.py

python "/tmp/workspace/reproductive-physiology-menstrual-cycle/src/build_menstrual_cycle_pdf.py"

python - <<'PY' from pypdf import PdfReader p='/tmp/workspace/reproductive-physiology-menstrual-cycle/output/Menstrual_Cycle_LAQ_and_Cheat_Sheet.pdf' r=PdfReader(p) print('pages=',len(r.pages)) for i,page in enumerate(r.pages,1): t=page.extract_text() or '' print(i, 'chars=',len(t), 'starts=',repr(t[:80])) PY

.../src/build_menstrual_cycle_pdf.py

.../src/build_menstrual_cycle_pdf.py

.../src/build_menstrual_cycle_pdf.py

.../src/build_menstrual_cycle_pdf.py

python "/tmp/workspace/reproductive-physiology-menstrual-cycle/src/build_menstrual_cycle_pdf.py" && python - <<'PY' from pypdf import PdfReader p='/tmp/workspace/reproductive-physiology-menstrual-cycle/output/Menstrual_Cycle_LAQ_and_Cheat_Sheet.pdf' r=PdfReader(p) print('pages=',len(r.pages)) for i,page in enumerate(r.pages,1): t=page.extract_text() or '' print(i,len(t),repr(t[:45])) PY