If life were a bowl of cherries...

OK... so whoever designed the human reproductive system was HIGH! Seriously.... let me give you a brief lesson. Hormones are in bold, other scientific words that I need to learn to spell (and that you might not know) are in italics.

Spermatogenisis (the male side)

The hypothalamus (in the brain) releases GnRH (Gonadatrophic Releasing Hormone - Gonads being the sex organs). This travels the short distance south to the Anterior Pituitary Gland. The Anterior Lobe of the Pituitary Gland is stimulated to produce FSH (Follicle Stimulating Hormone) and ISCH (Intersticial Cell Stimulating Hormone - female equivilent is LH). These hormones then travel the long distances through many blood vessels to the testicles.

Now we need some anatomy. The testis is compised of seminiferous tubules (that make sperm) and then cells that make up the tissue between the tubules such as blood vessels and other intersticial cells. ISCH stimulates the intersticial cells to produce testosterone. Testosterone has several functions. The one you will all know is stiumlating the onset of secondary sexual characteristics in prepubescent males (poor things). Testosterone also stiumlate sertoli cells and inhibits the production of GnRH (more on that later).

Back to the seminiferous tubules. The walls of these tubules are comprised of highly specialised sertoli cells that govern the process of spermatogenisis. The outer cell layer of these tubules is a germinal epithelial layer - a source of unspecialised cells that can be transformed into sperm. These cells undergo meiosis, splitting twice to form 4 haploid cells - half the number of chromosomes. The first meiotic split halves the DNA content of the cell and create two haploid gametes (primary spermatocytes), the second split is just a staightforward cloning (as in mitosis) to produce the 4 haploid secondary spermatocytes.

The sertoli cell then governs the specification of these into spermatids and the sperm. This process involves the creation of a long flagellum (tail), production of many mitochondria in the middle piece to fuel the movement of the sperm, the digestion of the cell cytoplasm to reduce bulk and the production of an acrosome layer on the head of the spem which contains enzymes to break through the wall of the developed ovule (technically secondary oocyte).

The process of spermatogenis occurs from the external wall of the seminiferous tubule (the germinal epithelium) inwards towards the lumen (empty space of the tubule) in the centre. In effect average/normal cells go in on the outside and then fully fledged sperm are collected in seminiferous tubules as part of a continuous cycle.

This cycle is regulated by the inhibiting effects of testosterone and the inhibin produced as a by product of the action of sertoli cells. These two hormones stimulate the hypothalamus into *not* producing GnRH and therefore the Anterior Lobe of the Pituitary Gland is not stiumlated to produce ISCH and FSH. Consequently the rate of spermatogensis falls. Once the levels of inhibin and testosterone fall again then the is less (indirect) inhibition of ISCH and FSH and the rate of spermatogenisis rises. This is an example of the negative feedback of certain products (or by-products) of a reaction to maintain homeostasis.

Ok. So we have our sperm. The sperm produced and collected in the seminiferous tubules pass into small ducts called the vasa efferentia and then into the epididymis where they can be stored for up to 18 hours. Prior to ejaculation the sperm are moved the vas deferens (a muscular tube), the seminal vesicle releases mucus whilst the ejaculatory glands release an alkali solution to neutralise vaginal acids (Prostate Gland) and a solution of sugars to provide energy for the sperm on their travels (Coweper's Gland). This is mixture has now formed semen which will be released from the urethra by ejaculation.

Ejaculation is stimulated by increased supply of blood to the spongy tissue in the penis causing it to swell and harden and stiumlating the contaction of errectile tissue. Physical contact stimulates the glans penis which causes the muscles along the ejaculatory tract (the epididymis to the urethra) to contract moving the sperm/semen through the tract via peristalsis and finally the contraction of the urethra results in ejaculation.

Inside the femal the force of ejaculation propels *some* sperm into the uterus (/top of the vagina). In three days the sperm will have "swum" to the oviduct. Out of 500 million sperm only a few hundred reach the oocyte. Only one can ever fertilise.

It is interesting to note that there are also hormones in semen that stimulate muscular contraction of the uterus/oviducts to help the sperm reach the oocyte and improve the probability of fertilisation. There are only 5 million sperm in 5cm^3 of semen. The testies hang outside the body because the reactions involved occur at an optimum temperature of 35 degrees celcius.

WOW hasn't that taken the fun out of it!

And if you think that that might be a little complicated... sometime I might try to explain the female system which is approximately 4.7 times worse.

Anyone would think the intention of the entire process was failure... it certainally causes a significant stumbling block for most A Level students - And this really is the easy one.

I have decided this is a good way to revise. :P

xXx 

Woke up feeling really panicky this morning. Which is iritating. It is the second time this has happened in a week. This is also slightly odd as the one thing that I can think of warrenting panic (recital) is over and done with. I know it isn't the exams because I feel calmer (!) when I think of them (exams make sense, you just do the work and then sit the paper, then it is all over).

I have no idea what it is, but if it doesn't stop I will get more than slightly irritated.

xXx 

For those of you were concerned... the earlier depressing post (before the happy, crotchety one) was not about a recent occurance. The events being referred to happened about 3 or 4 months ago and it is simply that recent comments have sparked them off....

:P

xXx 

Just finished with the Ladies Baber-Shop choir and WE SOUND GOOD! lmao... we actually do. :D I love taking choirs, particularly when we are singing good music. I don't get the chance that often and though I suppose this choir is technically Sutcliff's baby, its great to have been so involved. 

In the space of 30 minutes we have gone from utterly fudging something to singing it pretty damn well. It didn't take the much either. Just a little bit of breaking things apart and working on lines in pairs. Saying difficult rhythms before we sang them. Working out how parts linked together and where things were either consonant or dissonant. Things I have learnt from countless choir directors over the last decade and a bit (from their successes and mistkaes). Elementary stuff.

Practise. 

The choir just needed a few corners ironing out. Just a few odd notes coorrected and rhythms reheased to precision. Just a little confidense and familiarity. OH and fun! Lots of laughs, lots of jokes... lots of arguments over who was more stunning: The Alto's or Sopranos (The Metzos decided they won hands down anyway). But it is truly wonderful to work with a choir who will be in hysterics and then you count them 4 in and they find their note and start singing! :D  Makes such a difference.

But I am good at it. It is one of the few things I'll admit I am good at. And I love it so much.  

xXx 

PS: Please excuse the appalling pun... it's my blog and I'll write what I like however much it insults the English language.

And for those of you who read my facebook status, it isn't much better at all really.

I don't think I'll ever really question what I did. By the end of it I had no choice in the matter. A series of mistakes (from all parties) had pushed things to a more than unpleasent conclusion and as far as I can see - even in hindsight - I had very few choices left.

Hurting someone out of necessity prompts enough guilt. But that isn't the hard bit. The hard bit is that you can never be sure of your reasons; never be sure how much of what drove you was necessity and how much was just final retaliation at being pushed too far. Who can day how much was a desperate attempt to sort out the conequences of a mistake and how much was just hitting out and hitting hard.

It may have been necessity, but the necessity might well only have been an excuse in your mind.

And that bugs me somewhat.

Ignorance is no excuse, giving up is no excuse... necessity is a poor one.... cruelty and revenge is heartless.

I suppose the solution is:

• Would I now (in calmer and rational hindsight) do things differetly?            No.
  
• Did I hate them then or now?                                                            No.

And that, regretfully, must be my answer. The past haas been and gone and I hope this time around I learnt my lessons. It seems regrettably that some level of cruelty is part of life. And maybe the more significant part of it is how much it hurts us when we are forced to choose the lesser of two evils. Maybe what defines us is not what we do but the ultimate reasons behind it.

More importantly, maybe we are defined by how we react and respond to our own acts of cruelty - necessary or unnecessary. Do we feel guilt? Do we try to learn, to study where things became inevitable and strive to avoid a repetition. Do we deal with the fall out responsibly and rationally.

In a world where too often it seems that our choices aren't between black and white, but varying shades of grey and greyer... Maybe what we have to hold on to is our own integrity: our intentions, our compassion... and ultimately our strength and determination that by the end of it we will try to do right by those around us. 

And if the end result hurts us as much as it hurt them, and still you would not change what you chose... then it may well have been right, and you may well find the strength to live with yourself someday, and it may well work out for the better in the end (Only God could tell you that) ... But you will have learnt something.

And that is what life seems to be about for the most part. 

xXx