Some things are scary when we don't understand them. Like blood coming out of the vagina? Especially when it's brown chunks. That surely isn't poop, what is it? Also scary and unknown: this chart. And phrasing like, 
    "During the follicular phase, estradiol suppresses production of luteinizing hormone from the anterior pituitary gland."
    What does this even mean?
     I could give up. But I'd rather help us get the picture.

[Intro]

    Menstruation is a cycle. Maybe not a consistent one but still enough of one that we call it a menstrual CYCLE. It's a set of actions or patterns that happen again and again in the same order... ish.
    Bleed, lay egg, cramp, bleed, lay egg, cramp. Sometimes bleed, lay egg, get pregnant, bleed, but usually the former, and usually every month. Menses: monthly.
    Before I got my period, I thought that menstruation happened once a year. I thought, "I can handle that", and then  found out that it was once a month. 
    For 450-480 months, beginning, day one, with the bleeding. About this much to this much comes out brown, bright red, goopy, liquidy for 3, 4, 5 days, sometimes longer. Why?
    Well, the uterus, which is above the vagina, spends most of the month building a mattress for a fertilized egg to grow. But when that doesn't happen, the surface of the endometrium sloughs off. This is called menstruation, or a period.
    My friend Jamie calls it shark week.
    I knows it seems weird that we start the cycle when this feels like the end, but it's a very practical marker because, blood, and it IS a beginning for the ovaries. There's the whole menstrual cycle; then there's the uterine cycle, which is what the uterus is doing; and the ovarian cycle, which is what is happening in the ovaries. 
    There are 2 ovaries. Each of them started with .5 to 1 million eggs. By puberty there's a quarter of them left. Every menstrual cycle, some are shuffled to the top, called follicles. These 20 or so vie for dominance until 1, or 2 in the case of twins, take the lead, growing 3 times the original size. The big, big one is called the graafian follicle. The follicle growing? Follicular phase.
   Meanwhile, the uterus is back to building a mattress in its next phase, the proliferative phase. Proliferative? Prol- meaning offspring, fer meaning bearing. Preparing for the baby phase!
   What are those squiggles and gaps? Blood vessels! Veins and spiral arteries loading up the endometrium with blood and nutrients, because if impregnation happens, this becomes the placenta.
    An incredible amount of communication is happening between the brain, the ovaries, and the follicles to coordinate all of this. And right in the middle of this cycle, day 12, 13, 14, there is a surge in those chemical messengers. A hormone called luteinizing hormone or LH. It spikes, causing the egg to bust out of the follicle and the ovary.  Ovulation!
    Yup, squeezed out. 
    Ouch.
    Yeah, it can hurt. The egg, now called an ovum, is swept up by the finger-like ends of the Fallopian tube -- "come hither!"--, leaving behind a crust that looks kind of like this dried pineapple. This marks the final phases of both the uterine and ovarian cycles, so the menstrual cycle too. This is about day 14 to 28. The ovum is coasting through the Fallopian tube, where it may or may not meet a sperm and get fertilized.
    Fertilization happens in the Fallopian tubes!
    Either way, the ovum travels to the uterus, where a furnished apartment waits. 
    The corpus luteum (corpus = body, luteum = yellow) is still hanging out in the ovary. The luteal phase.
    While it may appear like leftovers, it's really more like a satellite control center passing along messages.
    "Hey! There's an egg en route, stop producing eggs. And you, yeah those breasts. Bigger. The areolas, darker. Whoops, looks like acne. Hey! Let's hold on to some water over here."
    It's also responsible for the final touches on the endometrium. During this time the endometrium is enhancing itself to receive and deliver secretions.
     There's much more secretion-friendly surface area here than here. So in the uterine cycle this is called the secretory phase.
     If a fertilized ovum embeds successfully in the endometrium, this is a pregnancy and the secretions will support it. If an ovum goes unfertilized, it will disintegrate and expel with the mattress, starting the cycle again.
      This is not everyone's experience of the menstrual cycle. The average is 28 days, but the range is 21 to 40. Some experience spotting, or lighter bleeding throughout the month, others experience overgrowth of the endometrium, or anovulation, where an ovum isn't even released. No egg!
      If something seems wildly wrong, talk to a doctor. All bodies are different. Stay curious.