Sunday, 25 September 2011
Sunday, 18 September 2011
3.2 Fertalisation
The adult male and female gametes are formed by meiosis.
When we have sufficient cells this will then be called an embryo.
The cells that are formed by meiosis have half as many chromosomes as the cell that formed them.
Fertilisation occurs when a male and female gamete join.
The zygote divides into a ball of cells, called the blastula which then grows to form the embryo.
When we have sufficient cells this will then be called an embryo.
The cells that are formed by meiosis have half as many chromosomes as the cell that formed them.
Fertilisation occurs when a male and female gamete join.
The zygote divides into a ball of cells, called the blastula which then grows to form the embryo.
Sunday, 11 September 2011
3.9b - Female Reproductive System
- Vagina - collects the sperm cells and allows them to pass throw the cervix into the uterus
- Ovary - meiosis occurs and production of female gamete(eggs)
- Oviducts - carry the eggs to the uterus and where fertilization takes place. where sperm cells meet the egg cells.
- Uterus - wall of the uterus is made of muscle. stretches to accommodate pregnancy and contracts during birth.
- Lining of the uterus - develops the fertilized egg into the embryo and then the child. can see the development here of the placenta
- Cervix - entrance to the uterus - where sperm cells enter.
- Uterus space - where the sperm and egg cells move. Embryo develops into the unborn child
- Ovary - meiosis occurs and production of female gamete(eggs)
- Oviducts - carry the eggs to the uterus and where fertilization takes place. where sperm cells meet the egg cells.
- Uterus - wall of the uterus is made of muscle. stretches to accommodate pregnancy and contracts during birth.
- Lining of the uterus - develops the fertilized egg into the embryo and then the child. can see the development here of the placenta
- Cervix - entrance to the uterus - where sperm cells enter.
- Uterus space - where the sperm and egg cells move. Embryo develops into the unborn child
3.9a - Male Reproductive System
- Urethra - common tube that joins the left and right testis. takes semen/urine down the penis
- Penis - carries sperm cells into the vagina during sexual intercourse
- Bladder - Store urine
- Testis - 2 of them - carry out meiosis - produces the gamete, sperm
- epididymis - stored sperm cells
- vas deferens - carry sperm cells to the penis during sexual stimulation. the tube pulses making the walls contract and push the sperm from the testis to the penis
- prostate - adds about 20/30% of the volume of the semen. contains sugars and is alkali.
- Seminal Vesicles - 70& of the volume of the semen. contains sugars and is alkali
- Penis - carries sperm cells into the vagina during sexual intercourse
- Bladder - Store urine
- Testis - 2 of them - carry out meiosis - produces the gamete, sperm
- epididymis - stored sperm cells
- vas deferens - carry sperm cells to the penis during sexual stimulation. the tube pulses making the walls contract and push the sperm from the testis to the penis
- prostate - adds about 20/30% of the volume of the semen. contains sugars and is alkali.
- Seminal Vesicles - 70& of the volume of the semen. contains sugars and is alkali
Thursday, 8 September 2011
3.12 Amniotic fluid
In the uterus space there is the amniotic fluid
functions:
- can protect the developing embryo - comes from the fluid (largely water) not being able to be compressed.
- When you try to squeeze the fluid it absorbs the pressure.
- This means any blows or force applied to the uterus wall - the amniotic fluid will absorb this pressure and will prevent damage to the unborn child.
functions:
- can protect the developing embryo - comes from the fluid (largely water) not being able to be compressed.
- When you try to squeeze the fluid it absorbs the pressure.
- This means any blows or force applied to the uterus wall - the amniotic fluid will absorb this pressure and will prevent damage to the unborn child.
3.11 Placenta
when the child is in the uterus - water filled environment (amniotic fluids) - child cannot digest or breath or excrete
- baby obtains food - blood vessels lead from the embryo down the umbilical cord and then spread out to form placenta.
- placenta biologically grows out of the developing embryo. not out of the mother.
- blood vessels inside the placenta are the child's (veins and arteries)
- placenta grows into the lining of the uterus (wall)
- mother continues to eat and so in the blood vessel we have things like glucose, amino acids and fats. these travel through blood stream and into the wall of the uterus. they then cross into the childs blood at the placenta.
- to make this efficient the placenta has a large surface area and the barrier between the mother and childs blood is very thin.
- child produces CO2 and Urea which then goes back into the mothers blood.
- baby obtains food - blood vessels lead from the embryo down the umbilical cord and then spread out to form placenta.
- placenta biologically grows out of the developing embryo. not out of the mother.
- blood vessels inside the placenta are the child's (veins and arteries)
- placenta grows into the lining of the uterus (wall)
- mother continues to eat and so in the blood vessel we have things like glucose, amino acids and fats. these travel through blood stream and into the wall of the uterus. they then cross into the childs blood at the placenta.
- to make this efficient the placenta has a large surface area and the barrier between the mother and childs blood is very thin.
- child produces CO2 and Urea which then goes back into the mothers blood.
Sunday, 4 September 2011
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