Topic H: Human Reproduction Flashcards
Define Sexual reproduction?
Always involves the fusion of two cells called gametes.
Define a-sexual reproduction?
offspring genetically same because they have the same DNA as parents.
Define hermaphrodite?
Organism that can produce both types of gamete.
Define Ovary?
Produces eggs, attached to back wall of the abdominal cavity blow the kidney.
define Vagina?
Muscular tube that opens to the outside.
Define Prostate gland?
opens into the urethra and produces an alkaline fluid which neutralizes urine.
Define Sperm duct?
from the testis, opens into urethra
Define Urethra?
passes down penis, both sperm and urine pass through it.
Define Epididymis?
leads to sperm duct
define testis?
bundle of sperm producing tubules which join and lead to the epidermis.
When is the Ova released?
An Ova is released each month form an overy in the menstrual cycle.
Two ways in which the Ova is moved?
-Muscles expanding and contracting -Wafted along by the Cilia.
When does fertilization occur?
fertilization occurs when an ova meets with a sperm during its journey along the oviduct and then fuse together.
What happens during fertilization?
Fertilization occurs when the nucleus from the sperm fuses with the nucleus from the ova
A fertilized egg is called an…
Zygote
What then happens after fertilization?
The zygote will travel towards the uterus. This journey will take approx 3 days, in that time the zygote will divide and grow by MITOSIS into a ball of 64 cells known as a BLASTOCYST.
what is the ball of 64 cells known as?
a Blastocyst
What happens on implantation?
The blastocyst will then embed itself in the endometrium or the lining of the uterus wall.
What happens after implantation?
after implantation the blastocyst will develop into a embryo and then on to a foetus.
What is the period of development in the uterus will known as?
Gestation
How long does does gestation last in humans?
40 weeks
What is the Placenta?
The Placenta is the organ that allows a consistent exchange of materials between the mother and the foetus. The placenta develops from the foetal tissues
the structure of the Placenta?
The Placenta contains blood vessels of the foetus and blood vessels of the foetus and blood vessels of the mother.the blood vessels run very close to each other but do not touch. this means that the foetus’s blood and the mothers blood are kept separate and do never mix.
How are substances moved from the mothers blood to the foetus blood and vice versa?
This in in the Placenta and is done by diffusion.
What are the essential substances the foetus needs for its development from its mother blood?
Glucose, oxygen(respiration) and amino acids. waste produced will pass back into the mothers blood and she will excrete these substances such a carbon dioxide.
What is amniotic fluid used for?
-It protects and cushions the foetus from bumps -It helps with development of the lungs -It helps provide a constant temperature -It helps the development of the muscles
What area does the foetus develop?
The foutes develops inside a sac known as the amniotic sac.
Where is Testosterone made?
Testes (under the influence of another hormone)
What is the role of Testosterone?
To trigger puberty in males which leads to sexual maturity.
Effects of testosterone?
Chest broadens, voice becomes deeper, muscles get larger. Facial hair develops, hair under armpits, Teste begin to produce sperm, Penis becomes larger.
What is the Oviduct (Fallopian tube)
leads from Overy to uterus
What is the cervix?
neck of uterus
When does the menstrual cycle start and end?
Starts at puberty, ends at the menopause
What is the menstrual cycle?
The 28 day cycle is controlled by hormones. one egg is produced each eycle from alternative overies. the egg lives for only about one day and fertillisation is possible then. the uterus lining (endometrium) thickens up in preperation for a possible pregnancy. if fertilization does not occur, this is shed from the body in the monthly period.
What does FSH do?
Causes development of the follicle containing the ovum.
What does LH do?
causes ovulation and the formation of the corpus luteum
What do high levels of Oestrogen lead to?
They lead to ovulation, oestrogen is therefore found in fertility drungs to help woman becasome pregnant. if an ovum is present, fertilization and pregnacy may follow.
What does Oestrogen do?
Development of sexual characteristics.
It repairs uterus lining and high levels stimulate the release of LH, casueing ovulation.
Where are oestrogen and progesterone produced?
these are produced in the ovaries from puberty to the menopause. These cause the secondary sexual chracteristics, which change a girl into a woman, including the menstrual cycle.
What does Progesterone do?
Maintains uterus lining and prepares the body for pregnancy.
In what order do the hormones peak in the 28 day cycle?
FSH - Oestrogen - LH - Progesterone
What is the role of testosterone?
To trigger puberty in males which leads to sexual maturity.
Where is testosterone made?
Testes (under the influance of another pituitory hormones)
What are the effects of testosterone?
Chest broadens, muscles get larger and voice becomes deeper.
How does the ova get down the oviduct?
It is wafted along by the cilia.
When does fertilisation occur?
This occurs when an ova meets with a sperm during its jeorney along the oviduct and they fuse together.
What is fertilisation?
This is when the nucleous from the sperm fuses with the nucleaus from the ova.
A fertilized ova is called a…
Zygote
After fertilization in the oviduct, the zygote will travel towards the..
uterus
How long does the jeorney take from the oviduct to the uterus?
takes, approx 3 days during which time the zygote will divide and grow by mitosis into a ball of 64 cells known as a blastocyst.
how many cells are in a blastocyst?
64
What is implantation?
This is when the blastocyst will inbed itself in the endometrium or linign of the uterus wall.
The period of development in the uterus is known as…
gestation
The blastocyst will develop into a ……….. and then into a ………..
Embryo and then into a foetus
Fertilization must include…
the fusion of a male and female gamete to produce a zygote that undergoes cell division and develps into a embryo.
Where is the normal site of fertalistation?
The Filopian tube
State two ways in which the egg and sperm cell are similar?
- Both have a nucleus
- Both have a cell membrane
Why are the testis situated outside of the body cavity?
There is a lower temperature outside of the body which is better suited to them.
What happens to the lining of the uterus during menstruation?
in shed/ broken down
What is the relationship between the level of oestrogen and ovulation?
- Ovulation occurs when oestrogen is high.
What happens during fussion?
egg and sperm fuse to form a fertalized zygote with a full set of DNA
Where does the formation of Gametes occur?
Overys and Testis
What is Mitosis and what does it do?
Mitosis is the type of cell division that leads to growth or repair. When a cell divides by mitosis:
two new cells form
each cell is identical to the other one, and the cell they were formed from
Diagram for Mitosis
What is meosis and what does it do?
The cells that are formed by meiosis have half as many chromosomes as the cell that formed them. Human body cells contain 23 pairs of chromosomes, while human gametes contain 23 single chromosomes.
The main features of meiosis are:
the chromosomes are copied
the cell divides twice, forming four gametes
days of menstution?
1-4
days that ovem is developing into a follicle and peak of oestrogen?
Day 14
follicle develop day 1-10
Fertile period and ovulation?
11-17
ovulation day 14
Progesterone peaks and formation of Corpus Leutenm
Corpus luteum 21 onwards
progesterone day 21.
What is the young Follicle?
One begins to develop about every 28 days in one of the ovaries - stimulated to do so by a hormone FSH from the piputary gland
mature follicle?
Fluid filled - secretes the female sex horemones oestrogen and progesterone and is stimulated by the pitutary hormone LH
Ovulation
Follicle burts open to release the ovum - remaining follicle forms corpus luteum
Corpus luteum
forms from ruptered follicle and secretes progesterone in lage quantites - degenerates after 14 days - menstruation and the restarting of the cycle.
