IB Biology6 Human Health and Physiology

6.6 Reproduction

Jason de Nys

All syllabus statements ©IBO 2007All images CC or public domain or link to original material.

Censored

6.6.1 Draw and label diagrams of the adult male and female reproductive systems

Fallopian tubes (also known as oviducts)

are named after Gabriel Fallopio

They say that he was the discoverer, but really, most of us have been there

Think! Which people have not been

there?

http://commons.wikimedia.org/wiki/File:Scheme_female_reproductive_system-en.svg

Urethra

Penis

EpididymisTestis

pl. Testes

Vas deferenspl. Vasa deferentia

Anus

Cowper’s gland

Prostate

Seminal Vesicle

Bladder

http://commons.wikimedia.org/wiki/File:Male_anatomy_blank.svg

6.6.2 Outline the role of hormones in the menstrual cycle including FSH (follicle stimulating hormone), LH (luteinising hormone), oestrogen and progesterone.

FSHProduced by: Pituitary GlandStimulates :• follicle growth (well duh!)• oestrogen* secretion• progesterone secretion

And a burst of FSH leads to ovulation

http://commons.wikimedia.org/wiki/File:Follitropine.gif

http://commons.wikimedia.org/wiki/File:Wartburg-Laute_001.jpg

LH*Produced by: Pituitary GlandStimulates : Formation of corpus luteum

(lutenising….luteum)

A burst of LH leads to ovulation(along with FSH)

*Lutenising hormone has nothing to do with lutes

*Oestrogen, Estrogen…Tomayto, tomahto

Oestrogen*Produced by: Ovary (follicle)Stimulates : • Thickening of endometrium• Secondary sexual characteristics• Inhibits secretion of FSH• Stimulates secretion of LH

Oestrogens are actually a group of hormones. The one most commonly referred to when someone mentions “Oestrogen” is estradiol, pictured here

http://commons.wikimedia.org/wiki/File:Progesterone-3D-balls.png

ProgesteroneProduced by: • Corpus luteum• Placenta when pregnantMaintains:The endometriumInhibits : • Ovulation• FSH• LH

Because hopefully you are, or soon will be:

6.6.3 Annotate a graph showing hormone levels in the menstrual cycle, illustrating the relationship between changes in hormone levels and ovulation, menstruation and thickening of the endometrium.

Get the poster!

What is happening with the endometrium down here?

Can you fill the blanks with the correct

hormones?

http://commons.wikimedia.org/wiki/File:MenstrualCycle.png

Excellent animation

http://commons.wikimedia.org/wiki/File:Order_of_changes_in_ovary.svg

1 - Menstruation 2 - Maturing follicle 3 - Mature follicle4 - Ovulation 5 - Corpus luteum 6 - Deterioration of corpus luteum

Producing Oestrogen to prepare the endometrium

Producing Progeterone to inhibit LH, FSH and more ovulation

The action of progesterone on the hypothalamus to prevent the release of LH and FSH is a classic example of negative feedback

Gonadotropin-releasing hormone (GnRH) (also known as Luteinizing-hormone-releasing hormone!) is mentioned in the McGraw Hill animation below.

You are not required to know about this hormone for the course, but it would add another dimension to your understanding of what is going on.

6.6.5 Outline the process of in vitro fertilisation (IVF)

IVF

Anim

ation

1) The woman is treated with hormones so that multiple ova mature at the same time. This might be the woman planning on having the baby, or a donor donating the eggs

2) Ova are harvested by a needle passed through the wall of the vagina and into the ovary to suck the ova out of the follicles.

3) Ova are combined with sperm (washed to remove semen) and left to incubate until the zygote has divided into 6-8 cells, or in some cases, until it is a blastocyst

4) The embryo is placed into the uterus via a fine tube inserted through the cervix. Typically multiple embryos are inserted at the same time to increase the chance of success.

http://commons.wikimedia.org/wiki/File:Icsi.JPG

Intracytoplasmic Sperm Injection (ICSI)

may be used if the sperm are

poor swimmers

IVF is often used to overcome infertility caused by blocked Fallopian tubes.

On the right is a special x-ray called a hydrosalpingogram.

A dye is infused through the cervix into the uterus and from there it flows through the fallopian tubes and into the pelvic cavity.

This woman is all clear, you can see the swirls of dye coming out the ends of her tubes

Uterus

Tube administering dye via vagina

Fallopian tube filled with dye

Dye in the pelvic cavity

http://commons.wikimedia.org/wiki/File:Hysterosalpingogram.jpg

Other causes of infertility:Female:• Ova not maturing or being released• Abnormality in uterus prevents

implantation• Antibodies in cervical mucus impair

sperm

Male• Unable to achieve an erection or normal

ejaculation• Low sperm count or sperm are

abnormal with low motility• Blocked vas deferens

Two tailed sperm, unable to swim

http://goo.gl/XqAOk

6.6.6 Discuss the ethical issues associated with IVF

http://goo.gl/O1xgc

1) Multiple blastocysts are usually implanted in an attempt to ensure success. If too many develop into viable embryos, some may be aborted to improve the chance of success of the others

Is that murder?

http://goo.gl/O1xgc

1) All of the cells in a blastocyst are totipotent until the embryo is about three weeks oldSo technically, each of those cells could become an individual

2) Children born as a multiple are often of lower birth weight, with the attending health risks

3) Parents face more stress coping with multiple births, this can impact on their relationship and on other children

http://www.flickr.com/photos/hundreds/129975159/

2) Multiple births do happen naturally as well and since parents with an IVF pregnancy are usually more closely monitored, multiples are usually discovered earlier

3) As long as parents are informed of the risks inherent in their choice, they can prepare, and after all, they are prepared to go through the difficulty of IVF to have a child

4) In some countries IVF is at great financial cost to the patient, putting stress on their family, and leaving them less money to spend elsewhere in the community.

5) Any health issues as a result of being an IVF child will also have to be borne by the parents

6) People are profiting from administering the procedure and this may blur their medical judgement

7) Donors can make a lot of money in some countries, are they being exploited?

http://www.flickr.com/photos/epsos/8463683689/

4) And 5) Parents have the right to spend their money as they see fit

6) Medical professionals in the field may be doing it for altruistic reasons and not all are compensated beyond a fair amount

7) Donors have the right to do as they wish with their bodies, the money can help poor women to get an education or start a business. In many countries donors are not offered money beyond a small amount of compensation for their time and discomfort

Further information:

Three of the best sites for IB-specific Biology information. The top link takes you to the PPT by Stephen Taylor

There are a whole series of videos in this channel