NG-385

♀️ Reproductive anatomy & the menstrual cycle

What each structure does, the two cycles running underneath, and where a pregnancy starts — the whole of Reproductive System I and II on one page.

⭐ The one idea

Ovulation happens about 14 days before the next period — not 14 days after the last one. The second half of the cycle is the fixed part. In a 35-day cycle, ovulation is around day 21, not day 17.

🧿 The female structures

Structure	What it does	Why it comes up
Ovaries	Hold the eggs; make estrogen and progesterone	The whole cycle starts here
Fallopian tubes	Where fertilisation happens — usually the outer third	The usual site of an ectopic pregnancy
Fundus	The top of the uterus	What you assess after birth
Endometrium	The lining that thickens and sheds	Implantation, and the period
Myometrium	The muscle layer	Contractions and clamping down after birth
Cervix	The neck of the uterus	Dilates and effaces in labor
Vagina	The birth canal	Acidic, which protects against infection

🧠 Endometrium = the lining that goes. Myometrium = the muscle that squeezes. Myo means muscle everywhere in the body.

🧿 Female anatomy, part by part

📍 External — the vulva

Five structures, outside in. Exams ask them as a list, so learn them as a list.

Mons pubis — the fatty pad over the pubic bone
Labia majora and labia minora — the outer and inner folds
Clitoris
Vestibule — the space the folds enclose; the urethral and vaginal openings sit in it
Perineum — the tissue between the vaginal opening and the anus

🧠 The perineum is the one that carries into every other maternity topic — it is what tears or is cut in an episiotomy, and what you assess after a birth.

🌴 The uterus divides into four

A hollow pear sitting between the bladder in front and the rectum behind. Top to bottom:

Part	Where	Why it matters
Fundus	The dome at the top	What you palpate and massage after birth
Corpus	The body — the bulk of it	Where the pregnancy grows
Uterine isthmus	The narrow waist above the cervix	Becomes the lower uterine segment — the low transverse C-section site
Cervix	The neck, opening into the vagina	Dilates and effaces in labor

Where the cervix dips down into the vagina it forms arch-shaped pockets around itself — the fornices.

🥪 The fallopian tube has three segments

Muscular corridors running from the top of the uterus out toward each ovary. Outer end first:

Infundibulum — the funnel-shaped end whose finger-like fimbriae sweep the egg in
Ampulla — the wide middle. Fertilisation normally happens here
Isthmus — the narrow part that joins the uterus

🧠 The ampulla is both where fertilisation happens and the commonest site of an ectopic pregnancy — one fact, asked two ways.

♂️ The male structures

Structure	What it does	Why it comes up
Testes	Make sperm and testosterone	Sit outside the body because sperm need to be cooler
Epididymis	Where sperm mature and are stored	Epididymitis — painful, and relieved by elevation
Vas deferens	Carries sperm up to the urethra	The tube cut in a vasectomy
Prostate	Adds fluid to semen	Enlarges with age — a urinary problem
Seminal vesicles	Add most of the fluid and the sugar sperm run on	—
Urethra	Carries both urine and semen	Hypospadias — the opening is not at the tip

Sperm take roughly two to three months to make, which is why anything that damages production shows up months later, and why improvements take months too.

♂️ Male anatomy, part by part

📍 External and internal

External: the penis, which serves both reproduction and urinary elimination, and the scrotum, the sac that houses the testes.

The scrotum has two jobs: protect the testes from trauma and regulate their temperature — sperm need to sit cooler than core body temperature.

Internal: the testes, which make male sex hormone and sperm; the ductal system, beginning with the vas deferens; and the accessory glands.

💧 The accessory glands, and what their fluid is for

The seminal vesicles are a pair that empty an alkaline, fructose-rich fluid into the ejaculatory ducts. The prostate is a muscular gland wrapped around the first part of the urethra as it leaves the bladder, and adds alkaline fluid too.

That fluid does three things — a favourite exam list:

Motility — it helps sperm move
Nourishment — fructose is the fuel they run on
Protection — being alkaline, it shields sperm from the acidic vagina

🧠 Move, feed, protect. And the two facts explain each other: the vagina is acidic on purpose, to keep infection down — so semen has to be alkaline to survive it.

📅 The cycle on one line

Hormone	From	What it does
FSH	Pituitary	Grows the follicle
LH	Pituitary	The surge triggers ovulation
Estrogen	The growing follicle	Thickens the lining; thins the cervical mucus
Progesterone	The corpus luteum	Holds the lining ready; raises basal temperature

🧠 FSH grows it. LH releases it. Estrogen builds the lining. Progesterone keeps it.

Signs of ovulation she can notice: clear, stretchy cervical mucus like raw egg white, a small rise in basal temperature after it has happened, and sometimes one-sided pain mid-cycle.

🔄 Two cycles, running at once

“The menstrual cycle” is really two cycles happening together — one in the ovary, one in the lining of the uterus. The ovary answers to the pituitary; the lining answers to the ovary.

🧸 Ovarian cycle — driven by the pituitary

Two phases, each named for the hormone that runs it:

Phase	Days	In charge
Follicular	1–14	FSH — follicle-stimulating hormone
Luteal	15–28	LH — luteinizing hormone

🧠 F before L — alphabetically and on the calendar. FSH grows the follicle; LH surges, releases the egg, and leaves the corpus luteum behind.

🩸 Uterine cycle — driven by the ovary

What the endometrium does in response to estrogen and progesterone. Four phases, and the order is usually the answer:

Menstrual — the lining sheds
Proliferative — estrogen rebuilds it
Secretory — progesterone makes it rich and ready to implant
Ischemic — no pregnancy, so hormones fall, the blood supply fails, and it is about to shed again

🧠 Ovarian has 2 phases, uterine has 4. If the question names FSH or LH it wants the ovarian cycle; if it names the lining it wants the uterine one.

🧬 Cells, gametes and chromosomes

Cell	What it is
Somatic cells	Every ordinary body cell — what the organs and tissues are made of
Gametes	The sex cells, found only in the reproductive glands — egg and sperm

The nucleus holds 23 pairs of chromosomes — 46 in all.

22 pairs are autosomes — they carry ordinary inherited traits: eye colour, hair colour, even ear-wax consistency
1 pair is the sex chromosomes

Each parent contributes one member of every pair — 23 chromosomes each, which is why the two together make 46.

🧠 Your lecture’s hook: 46 chromosomes equals little Mikey. The 22 pairs decide what he looks like; the 23rd pair decides whether he is a Mikey.

🥐 Signs of pregnancy — three tiers

The tier is decided by who noticed it and how sure it makes you — not by how convincing it sounds.

Tier	Kind of data	Example
Presumptive	Subjective — what she reports	“My breasts hurt”
Probable	Objective — what you can observe	Cervical changes
Positive	Diagnostic — the fetus itself	Fetal heartbeat, ultrasound

🧠 She says it, you see it, the baby proves it. Only the third tier is positive — everything she feels, and even a positive home test, sits below it.

🌱 Fetal development — three stages

Stage	Gestation
Pre-embryonic	3–4 weeks
Embryonic	5–10 weeks
Fetal	11–40 weeks

These are the weeks on your NUR 234 handout, so these are the ones to answer with. Some textbooks count from conception rather than from the last menstrual period and print roughly two weeks earlier for each stage. For a question from your course, use the numbers above.

🧠 The embryonic stage is short, and it is when the organs form — which is exactly why it is the window where teratogens do the most damage.

BUILD→ RELEASE→ HOLD OR SHED

NG-385 · Maternal & Newborn unit · ADHD-friendly visual edition