Disclaimer: Due to unforeseen difficulties, we have had to take down the images on this notes page. They will be replaced shortly. We apologise for the inconvenience, but hope that the new images will provide you with an even better learning experience.

 

  1. Identify and name on diagrams of the male reproductive system: the testes, scrotum, sperm ducts, prostate gland, urethra and penis

The vas deferens is the sperm duct. Also, testis is singular, while testes is plural.

 

  1. State the function of the parts of the male reproductive system limited to:
    • Testes – production of male gametes (sperm)

The testes are the glands in which sperm are produced. Sperm are male sex gametes.

  • Scrotum – sac that holds the testes outside the body

The scrotum is the sac that holds the testes outside the body. It protects the testes, and by holding them outside the body, allows the testes to be kept several degrees cooler than the normal body temperature. This is important to produce sperm.

  • Sperm ducts – transfer sperm to the urethra

Sperm ducts are the ducts through which the sperm pass in order to move from the testes to the urethra.

  • Prostate gland – secrete fluids for sperm to swim in forming semen

The prostate gland secretes prostate fluid for sperm to swim in. The mixture of prostate fluid and sperm is called semen.

  • Urethra – carries urine and semen to vagina during sexual intercourse

The urethra carries urine to the outside of the body during urination.

It also carries semen to the vagina during sexual intercourse.

  • Penis – transfers semen to vagina during sexual intercourse

The penis transfers semen to the vagina during sexual intercourse, mostly through ejaculation. Ejaculation is when semen is ejected from the body.

The penis is the primary male sex organ. When a male is aroused, the blood vessels in the penis expand, allowing more blood to flow into the penis. Blood flow out of the penis is restricted, and thus the penis becomes hard. This is important for sexual intercourse to happen, or else the penis cannot penetrate the vaginal opening.

 

  1. Identify and name on diagrams of the female reproductive system: the ovaries, oviducts, uterus, cervix and vagina

 

  1. State the function of the parts of the female reproductive system limited to:
    • Ovaries – release of female gametes (eggs)

Oocytes (undeveloped ovums/ eggs) are produced in the ovaries. Once a month, about half-way through the female menstrual cycle, one egg is released from one of the ovaries into the connecting oviduct. This process is called ovulation.

  • Oviducts – transfers egg to uterus and the site of fertilisation

Oviducts (also known as fallopian, uterine or ovarian tubes) allow the transmission of the ovulated oocyte from an ovary to the uterus. Oviducts are also the site of fertilisation and maturation of the oocyte into an ovum.

  • Uterus – where the fetus develops

The uterus nurtures the fertilised ovum that develops into a foetus and holds the baby until it is mature enough for birth. The fertilized ovum is implanted into the endometrium and it receives nourishment from the blood vessels developed for this purpose.

  • Cervix – ring of muscle at the opening of the uterus

The cervix is a ring of muscle at the opening of the uterus. It allows the flow of menstrual blood from uterus into the vagina, and directs the sperm into the uterus during sexual intercourse. The opening of the cervix is usually very narrow but widens to about 10 cm during labour. A loose cervical opening can often lead to miscarriages.

  • Vagina – receives penis during sexual intercourse

The vagina receives the penis during sexual intercourse, allowing ejaculated semen to travel from the vagina, through the cervix and into the uterus, where sperm have the opportunity to swim towards the oviducts to fertilise an egg.

 

  1. Describe fertilisation as the fusion of the nuclei from a male gamete (sperm) and a female gamete (egg cell/ ovum)

Fertilisation is the fusion of nuclei from a male gamete (sperm) and a female gamete (egg cell/ ovum)

During sexual intercourse, an erect penis is inserted into the vagina.

Semen is then ejaculated, and millions of sperm are released into the neck of the vagina. Out of these millions, numerous sperm will find the egg – as shown in the animated picture above the sperm vs. ovum table – but only one will penetrate.

A fertilisation membrane is secreted around the egg once one sperm penetrates, preventing the penetration of numerous sperm.

 

Finally, the sperm nucleus and egg nucleus fuse to form a zygote. This is fertilisation.

 

 

 

  1. Compare male and female gametes in terms of size, structure, motility and numbers

sperm vs egg table

 

  1. State the adaptive features of sperm, limited to flagellum and the presence of enzymes

Sperm cells possess a flagellum – this is the tail of the sperm. The flagellum makes a whipping motion, propelling the sperm forwards, helping it swim. This helps the sperm swim towards and fertilise an egg.

Egg cells possess a jelly coat called the zona pellucida. They are also surrounded by cushioning cells which make up the corona radiata. To help the sperm make its way through these layers, it possesses digestive enzymes in a sac in its head. The sac is called the ‘acrosome’. When the sperm comes into contact with its layers, the acrosome releases its enzymes, helping the sperm digest its way through these layers.

 

  1. State the adaptive features of egg cells, limited to energy stores and a jelly coating that changes after fertilisation

Egg cells contain large energy stores – these provide nutrients for the embryo during early development.

Egg cells are also surrounded by a jelly coating called the zona pellucida. After one sperm manages to penetrate the zona pellucida, its changes to become impenetrable to more sperm. This stops polyspermy – where more than one sperm nucleus interacts with an ovum nucleus.

 

  1. Describe the menstrual cycle in terms of changes in the uterus and ovaries (knowledge of sex hormones are not required)

The menstrual cycle is a hormone regulated cycle.  On average, it lasts 28 – 35 days.

It should also be noted that each ovary contains numerous follicles.

A follicle is a fluid filled sac that contains an oocyte (an immature egg).

There are two main phases in each menstrual cycle: The follicular phase – which lasts approximately 2 weeks, and the luteal phase, which lasts another two weeks.

Menstruation marks the beginning of each cycle, and thus, the first part of the follicular phase. This is when the endometrium lining sheds. If you’re a girl who’s hit puberty, you’ll know that this is the messiest part.

Washing out blood stains is absolute torture, and don’t even get me started on the cramps.

You don’t need to know this, but those cramps are caused by muscle contractions – similar to the ones you experience during labour, but usually much less intense.

How long the menstrual phase lasts varies from girl to girl – it spans 3 to 9 days, depending on the person.

During menstruation, follicles start to develop, and along with them, the oocytes they carry. The Endometrium lining starts getting repaired. The dominant follicle – i.e. the one that will release the egg in ovulation, will only finish developing after the end of menstruation.

Next is Ovulation. This marks the transition from the follicular phase to the luteal phase. In ovulation, the dominant follicle bursts and turns into a corpus luteum, and the oocyte is released into the oviduct. The luteal phase has begun.

The hormones produced by the corpus luteum ensure that the thickness of the endometrium is maintained.

The egg is moved slowly down the oviduct by fluids and the muscles in the oviduct walls.

If the egg is fertilised while in the oviduct, it will form a zygote, which then forms an embryo, a foetus, and finally, a baby. The uterus wall (endometrium) thickness will be maintained until birth.

If the egg is not fertilised, it will die in the fallopian tube and dissolve. The hormones maintaining the endometrium stop being produced and the endometrium starts to break down.

This causes menstruation and marks the start of the next cycle.

 

  1. State that in early development, the zygote forms an embryo which is a ball of cells that implants into the wall of the uterus

In early development, the zygote forms an embryo. An embryo is a ball of cells that implants into the wall of the uterus.

 

  1. State the functions of the umbilical cord, placenta, amniotic sac and amniotic fluid

The umbilical takes blood from the foetus to the placenta, through the umbilical artery. Foetal blood returns from the placenta returns to the foetus through the umbilical vein through the umbilical cord.

The placenta (which carries the mother’s blood) and the foetal blood vessels that branch out into capillaries close to the villi walls bring the foetal blood and maternal blood very close, but don’t allow them to mix.

This is very important because the foetus may have a different blood group to the mother, and mixing blood groups will cause blood clotting. Also, the mother’s blood pressure is much higher, and this could damage the foetal organs.

The proximity of the maternal and foetal blood allow substances from one’s blood to diffuse across into the other’s blood.

embryo in amniotic sac
Embryo at approximately 8-10 weeks EGA from conception.” by lunar caustic is licensed under CC BY 2.0

This is a picture of the amniotic sac and fluid. The amniotic sac is the thin membrane (which is formed from cells of the embryo). You can also see the foetus, almost developed into a baby.

The white cord extending from approximately the baby’s belly button is the umbilical cord. The fluid that the foetus is suspended in is called the amniotic fluid.

Just to give you guys an idea of the positioning of the amniotic sac, I’ve included this diagram. Note that in normal pregnancy, foetus’ and babies will change position several times but should always be upside down for the last stages and during birth.

The function of the amniotic sac is enclosing the amniotic fluid and preventing the entry of bacteria.

The function of amniotic fluid is supporting the foetus and protecting it from physical damage. It also absorbs excretory materials (urine) release by the foetus.

 

  1. Describe the function of the placenta and umbilical cord in relation to exchange of dissolved nutrients, gases and excretory products and providing a barrier to toxins (structural details are not required)

The umbilical cord brings foetal blood to and from the placenta, in the umbilical artery and vein. The placenta provides a surface in which the mother’s blood and foetus’s blood can be brought very close together without mixing. This allows nutrients and gases such as oxygen to diffuse across the placenta to the foetus, and for waste products like carbon dioxide and excretory products to diffuse to the mother. The placenta provides a barrier to most toxins, protecting the foetus from most things that the mother may be exposed to.

 

  1. State that human immunodeficiency virus (HIV) infection may lead to acquired immune deficiency syndrome (AIDS)

HIV may lead to AIDs.

Note: HIV is the name of the virus. It attacks cells of your immune system and weakens your defence against everyday infections.

AIDs is the name used to describe a number of potentially life-threatening infections and illnesses that happen when your immune system has been severely damaged by HIV.

 

  1. Describe the methods of transmission of HIV

HIV is primarily spread through the transfer of body fluids.

It can be transmitted in the following ways:

  • From infected mother to foetus across placenta
  • Feeding a baby milk from an infected mother
  • Unprotected sexual intercourse with an infected person
  • Transfusion with unscreened blood
  • Use of unsterilized surgical instruments
  • Sharing hypodermic needles when taking drugs

 

  1. Explain how the spread of sexually transmitted infections (STIs) is controlled

There are many ways to minimise the risk of contracting an STI. The following is taken from the mayo clinic website:

  • Abstinence: abstaining from sex will prevent the transmission of STIs
  • Having only one sexual partner: if you and your partner are uninfected, and have sex with no one else, the chances of you contracting an STI are extremely low. If your partner has an STI, you have a relatively high risk of contracting the infection if your partner is not treated. However, maintaining only one sexual partner means the infection will not be spread to other people.
  • Wait and test: avoid vaginal and anal intercourse with new partners until you both have been tested for STIs. Oral sex is less risky, but use a latex condom or dental dam to prevent direct skin-to-skin contact between the oral and genital mucous membranes.
  • Get vaccinated: getting vaccinated early, before sexual exposure, is effective in preventing certain types of STIs. Vaccines are available for HPV (human papillomavirus), hepatitis A and hepatitis B.
  • Use condoms and dental dams consistently and correctly: use a new latex condom or dental dam for each sex act. Never use an oil-based lubricant, such as petroleum jelly, with a latex condom or dental dam.
  • Avoid drinking alcohol excessively or using drugs: if you’re not sober, you’re more likely to take sexual risks.
  • Communicate: before any serious sexual contact, communicate with your partner about practising safe sex. Be sure you specifically agree on what activities will and won’t be OK.

I’m not sure you’ll need to know the following point for your exams, but I’ll put it here just in case:

  • Consider male circumcision: There’s evidence that male circumcision can help reduce a man’s risk of contracting HIV from an infected woman by as much as 60%. Male circumcision may also prevent the transmission of genital HPV and genital herpes.

 

 

 

Notes submitted by Sarah

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