2.3 Reproduction Flashcards
1
Q
What are the 3 functions of the reproductive system and its specialised organs ?
A
1) To make sex cells or gametes (eggs and sperm). Ovaries produce eggs and testes produce sperm
2) To allow eggs and sperm to join together in the process of fertilization
3) To protect and nourish the embryo in the uterus
2
Q
What is sexual reproduction?
A
- Sexual reproduction produces offspring that have a combination of genes inherited from 2 sex cells or gametes.
- Gametes are produced by cell division
3
Q
How are gametes (sex cells) produced ?
A
By cell division
4
Q
What are the functions of the male reproductive organs ?
A
1) To make and support sperm (male sex cells or gametes) and semen ( a fluid needed for transporting sperm)
2) To transfer sperm into the female reproductive system, during sexual intercourse
3) To produce and secrete male sex hormones, responsible for maintaining the male reproductive system
5
Q
What are the male sex cells (gametes)
A
Sperm
6
Q
Where is most of the male reproductive system located ?
A
Outside the body
7
Q
What is the function of the penis ?
A
- The male organ used in sexual intercourse
- consists of chambers made of special, sponge-like tissue filled with thousands of large spaces that fill with blood allowing the penis to become stiff, this is called an erection and in this state the penis is able to enter the vagina during sexual intercourse
8
Q
At what state does the penis enter the vagina during sexual intercourse?
A
- When the penis is erect
- The penis consists of chambers made of special, sponge-like tissue filled with thousands of large spaces that fill with blood allowing the penis to become stiff, this is called an erection and in this state the penis is able to enter the vagina during sexual intercourse
9
Q
What is at the tip of the penis ?
A
At the tip of the penis is the opening of the urethra, the tube that transports semen and urine.
10
Q
What is the function of the urethra in the male reproductive system?
A
It is the tube that transports urine and semen out of the penis
11
Q
What is semen ?
A
- Semen is the liquid that contains sperm
- Semen also contains chemicals and nutrients which are added to provide the sperm with food to help them swim to the egg so that fertilisation can take place, the chemicals and nutrients are produced from specialised glands like the prostate gland
12
Q
What is the function of the scrotum ?
A
- helps to keep the testes cool
- for maximum sperm development, the testes must be slightly cooler than normal body temperature
- muscles in the wall of the scrotum sac can move the testes closer to the body for warmth or farther away from the body to cool down
13
Q
What are the testes ?
A
- two oval organs found in the scrotum
- produce sperm cells which pass from the testes along the sperm duct during sexual intercourse
- also responsible for making testosterone (male sex hormone)
14
Q
What are the functions of the female reproductive system?
A
1) produces the female egg cells (ova) needed for reproduction and transports them to the site of fertilisation, normally the oviducts
2) Allows the fertilised egg to implant into the walls of the uterus, beginning pregnancy
3) The reproductive system produces female sex hormones that maintain the reproductive system
15
Q
What makes up the female reproductive system ?
A
- Vagina
- Cervix
- Uterus
- Ovaries
-Oviducts - Also many glands which produce secretions like mucus to prevent infections from microbes
16
Q
What is the function of the vagina?
A
- the vagina is a canal that joins the cervix (neck of the uterus) to the outside if the body
- The baby passes along the vagina during birth
- Where the penis is placed during sexual intercourse
17
Q
What is the function of the cervix?
A
- The area between the vagina and the uterus
- Allows sperm to enter and menstrual blood to exit
- Dilates (widens) during birth to allow the baby to move from the uterus, through the vagina and out of the mothers body
18
Q
What is the function of the uterus?
A
- Hollow, pear shaped organ where the foetus develops
- After ovulation, the egg moves into the uterus and implants into the uterine wall. If the egg is fertilised, it will develop into an embryo and then into a foetus.
- Made of muscle and can expand to hold a developing baby
19
Q
What is the function of the ovaries ?
A
- Two small oval shaped glands, located on either side of the uterus
- Produce eggs and hormones like oestrogen
20
Q
What is the function of the oviducts ?
A
- Narrow tubes attached to the upper part of the uterus and serve as tunnels for the ova (egg cells) to travel from the ovaries to the uterus
- Fertilisation takes place here
21
Q
What must cells used in sexual reproduction undergo ?
A
Cells used in sexual reproduction must undergo a special type of cell division to make the diploid cells haploid
22
Q
How many chromosomes do human gametes (sex cells) contain ?
A
23 chromosomes
23
Q
What hormone controls sperm production?
A
Testosterone
24
Q
What hormone controls egg (ovum) production ?
A
Oestrogen
25
What type of cells are produced by meiosis?
Haploid cells (gametes) that contain half of the normal number of chromosomes
26
What are haploid cells?
They are cells that contain half of the normal amount of chromosomes. This means they contain half the normal amount of DNA
27
What does the term diploid mean?
Cells are usually diploid and this means they contain two copies of each chromosome
28
What three sections does the sperm cell have ?
1. The head - which contains the nucleus and the fathers DNA, the nucleus is haploid and contains 23 chromosomes
2. The body/ middle - contains many mitochondria to supply energy to move
3. Flagellum/ tail - used to swim and find the egg
29
What is the function of the head of the sperm ?
- It contains the nucleus which is haploid and contains 23 chromosomes
- Contains the fathers DNA
30
What is the function of the body/ middle of the sperm cell ?
- contains many mitochondria to supply energy to move
31
What is the function of the flagellum ?
The flagellum is used to swim and find the egg
32
Sperm cells are produced by what type of cell division ?
Sperm cells are produced by meiosis, a type of cell division which produces haploid cells ( this means they contain half the normal amount of DNA; usually cells are diploid)
33
What is the structure of the Egg cell ( ovum)
- The egg cell is much larger than the sperm cell
- It is circular and surrounded by a layer of jelly
- The haploid nucleus, containing the mothers DNA is at the centre of the ovum
- Eggs or ova can't move themselves but are moved along by cilia which line the oviducts
34
How are eggs or ova moved along the oviducts ?
They were moved along by cilia which line the oviducts
35
By what type of cells division are egg cells produced ?
- Egg cells are produced by meiosis, a type of cell division which produces haploid cells ( meaning they contain half the normal amount of DNA; usually cells are diploid)
- only one sperm cell is required to fertilise the egg cell
36
How many sperm cells are needed to fertilise the egg cell ?
Only one sperm cell is needed to fertilise the egg cell
37
Where does fertilisation take place ?
Fertilisation takes place in the oviducts when the haploid sperm and egg cell nuclei fuse to give a diploid zygote
38
Where and how does fertilisation take place?
Fertilisation takes place in the oviducts when the haploid sperm and egg cell nuclei fuse to give a diploid zygote
39
What happens when sperm are released into the vagina during sexual intercourse ?
They swim through the cervix and uterus and into the oviducts and if an egg is released at ovulation and sperm is present they will meet and fuse. When the sperm and egg cell nuclei fuse this is fertilisation. The cell is now diploid and called a zygote
40
What happens to the zygote cell after it is formed ?
- The zygote cell divides by a form of cell division called mitosis and develops into balls of cells that travel down the oviduct into the uterus.
- It can then sink into the thickened lining of the uterus and this is called implantation
41
What happens after the zygote has implanted into the uterus lining ?
- after implantation it is then able to receive nutrients from the mothers body as it continues to develop and produces a variety of tissues and organs, becoming an embryo and then a foetus.
- After implantation in the uterus lining, the embryo then differentiates to produce a variety of tissues and organs.
42
After implantation, how long does the embryo continue to change until it is more human-like and is called a foetus?
After about 8 weeks it is more human like and is called a foetus
43
What is the function of the amniotic sac/membrane
- it is filled with amniotic fluid, which cushions and supports the foetus as it develops
44
How is the embryo connected to the placenta?
By an umbilical cord
45
What happens in the placenta?
The exchange of materials between the fortal and maternal circulatory systems
46
How do materials pass from the one blood system to the other in the placenta
-Materials pass from one blood system to the other by diffusion.
- There is no physical connection between the 2 circulatory systems which means the mum and baby's blood never mix !
47
How is the placenta adapted to allow maximum diffusion of materials such as dissolved nutrients,oxygen, carbon dioxide and urea?
- Villi develop in the placenta and these Villi form the border between maternal and Foetal blood systems but also increase the surface area so that more molecules can diffuse.
- The materials are carried along the umbilical cord in blood vessels to and from the mother and foetus
48
What do the branches of the umbilical arteries carry to the Villi ?
Branches of the umbilical cord carry embryonic blood to the Villi and after circulating through the capillaries of the Villi, blood returns to the embryo through the umbilical vein
49
What do the Villi do ?
The vili form a border between maternal and Foetal blood systems
50
What materials move from mother to the foetus ?
Nutrients ( glucose, amino acids, iron and calcium) and oxygen move from the mother to the embryo
51
What materials move from the embryo to the mother ?
Waste materials like urea and carbon dioxide move from the embryo to the mother
52
What is the order of the foetus, zygote and embryo
Zygote (1 week)
Embryo (4 weeks)
Foetus (8 weeks)
53
At how many weeks does the zygote become an embryo
Around 4 weeks
54
At how many weeks does the embryo become a foetus?
At around 8 weeks
55
What five pieces of advice may be given to pregnant women?
Take folic acid in the first trimester
- avoid excess vitamin A
- Do not eat for 2
- Exercise gently
- avoid drugs and alcohol
56
What happens if there is an egg present in the oviducts and no sperm to fertilise it ?
- Eggs only live for about 24 hours after ovulation.
- If no sperm are present, the egg dies but still continues it's journey to the uterus
- It still implants itself into the lining of the womb but after about a week, the lining breaks down and passes out of the body along with the dead ovum, through the vagina. This is called a period
57
How long can sperm live up to in the uterus ?
Sperm can live for up to 3 days in the uterus
58
What happens if there are sperm present in the oviducts and no egg to fertilise it ?
- Sperm can live up to 3 days In the uterus but if there is no egg, then fertilisation cannot occur and the sperm dies.
- However, if ovulation occurs while sperm are present, fertilisation will occur, meaning that pregnancy may not occur on the day of sexual intercourse but it may happen up to 3 days later.
59
What happens during the process of childbirth ?
- The process starts when the mother's hormone levels begin to change and one of the first signs is when the amniotic sac breaks and the amniotic fluid flows out of the uterus and the vagina. This is known as the waters breaking
- After the water breaks the uterus begins to contract and causes the cervix to dilate (begin to open)
- The contractions get stronger and stronger as it prepares to push the baby out of the womb.
60
What happens if the cervix doesn't dilate enough, the baby is too big for a natural delivery or there are difficulties experienced during birth ?
The baby is delivered via caesarean section
61
What is a caesarean section?
A caesarean section is an operation that means the abdomen and the uterus are cut open to remove the baby through this route and not through the normal birthing process through the vagina.
62
What is done to the baby once the baby is born ?
Once the baby is born the baby's umbilical cord is cut detaching from the placenta. The stump of the umbilical cord withers and falls off after a few weeks leaving behind a scar on the abdomen ( navel or belly button)
63
What also needs to be delivered after the baby is delivered?
After the baby is born the placenta also needs to be delivered.
This usually happens quickly as the strong contractions of the uterus easily force the soft placenta out of the body
64
Why is it important that both sperm and egg cells are haploid?
It is important that the sperm and cells are haploid and contain only half the chromosomes because when the fuse together the cell will have 46 chromosomes which is the healthy human amount
65
How is the process of reproduction controlled ?
Hormones
66
Where is testosterone produced?
In the testes
67
Where is oestrogen produced?
In the ovaries
68
What are the male and female sex hormones ?
Testosterone and oestrogen
69
What changes is testosterone responsible for as boys bodies go through during puberty?
-Body and pubic hair grows
- Voice deepens (breaks)
- Sex organs get larger
- The body gets more muscular
- Sexual awareness and drive increase
70
What changes is oestrogen responsible for as girls bodies mature during puberty?
- Body and pubic hair grows
- Breasts develop
- Periods start (menstruation)
- Pelvis and hips widen
- Sexual awareness and drive increases
71
How long does a normal menstrual cycle last ?
Between 28 - 35 days
72
How long does menstruation typically last ?
5- 7 days
73
When does menstruation begin and what is it ?
- Menstruation begins on day 1
- It is the breakdown of the uterus lining and it's removal from the system in preparation for a newly fertilised egg to implant
74
When does ovulation occur?
Usually happens on day 14 but can range from day 13 - 15
75
What happens during ovulation?
During ovulation an egg is released from an ovary and the most fertile time for a woman is when ovulation is just about to take place.
76
What two hormones are present in the menstrual cycle?
Oestrogen and progesterone
77
What is the role of oestrogen in the menstrual cycle?
- To ensure that only one egg matures at a time. If this wasn't controlled multiple births would be very common.
- Oestrogen is also responsible for repairing, thickening and maintaining the lining of the uterus prior to implantation.
- It also triggers the pituitary gland to start the ovulation process
78
What is the role of progesterone in the menstrual cycle?
- Also produced by the ovaries
- To maintain the lining of the uterus after implantation and during any future pregnancy
- If the woman becomes pregnant the placenta produces progesterone and this maintains the lining of the uterus during pregnancy and means that menstruation doesn't happen as this would result in the developing zygote/embryo/foetus being removed and this is called a miscarriage
79
What hormone is responsible for making sure only one egg matures at a time as well as repairing and thickening the lining before implantation and triggering the pituitary gland to start ovulation?
Oestrogen
80
What is the hormone responsible for maintaining the lining of the uterus during pregnancy and means menstruation won't happen?
Progesterone
81
What are the 3 main types of contraceptive methods ?
- mechanical
- chemical
- surgical
82
What do mechanical/ barrier contraceptives do ?
They are used as a barrier method to prevent the passage of sperm but also prevent the spread of STIs some of which can lead to infertility.
83
How do chemical contraceptives work and
-Chemical contraceptives stop eggs being produced
- The contraceptive pill and implants change hormone levels and stop the development of the ovum
84
What is surgical contraception and how
These are permanent forms of contraception like male and female sterilisation and they prevent the passage of sperm and ova respectively
85
What are the 2 permanent methods of contraception and what do they involve ?
Female and male sterilisation which is the cutting or blocking the oviducts to prevent the passage of eggs or cutting or blocking the sperm ducts to prevent passage of sperm
86
What are the mechanical methods of contraception?
Male and female condom
87
What are the chemical methods of contraception?
Contraceptive pill and contraceptive implants
88
What are the surgical methods of contraception
Male and female sterilisation
89
How does the contraceptive pill work ?
It prevents the egg from being produced using huge doses of hormones
90
What advantages do mechanical methods of contraception have for the individual?
- Doesn't have a permanent effect on hormones
- Fairly good efficiency
91
Which method increases the risk of thrombosis and blood clotting ?
The contraceptive pill
92
What is a serious consequence of some STI infections like Chlamydia ?
They can cause infertility
93
How many couples face difficulties conceiving
1 in 6
94
After how long is a couple considered infertile
If the couple have had unprotected sex for more than 12 months and are still not pregnant there may be problems with fertility and they may be infertile
95
What percentage of infertility are female causes ?
35 - 40 %
96
What percentage of infertility are male causes ?
35 - 40 %
97
What percentage of infertility unexplained and combined causes ?
20 - 35%
98
What are the 5 female causes of infertility?
- Endometriosis
- Ovulation problems
- Poor egg quality
- Polycystic Ovary Syndrome
- Female tube blockages
99
What is endometriosis, its treatment and success ?
- Endometriosis is a medical condition when the lining of the uterus grows outside the uterus and when it breaks down causes painful menstrual periods, irregular heavy bleed and possible miscarriage
- Surgery can remove abnormal tissue and treatment with IVF has high success rates
100
What causes ovulation problems, what is it and how can they be treated?
- Usually caused by a hormonal condition that prevents the release of a mature egg from an ovary
- Usually absent or infrequent periods are common
- Can be corrected by ovulation drugs and hormone treatments
101
What causes poor egg quality and what are possible treatments ?
- Damaged eggs or those that have chromosome abnormalities cannot sustain a pregnancy
- Usually problems are age related as egg quality declines In the late 30s and early 40s
- Egg donation or surrogacy can be successful
102
When does egg quality decline
Late 30s to early 40s
103
What is Polycystic Ovary Syndrome and what are treatments and success rates?
- Causes the ovaries to develop small cysts, hormonal levels are out of balance and ovulation and periods are irregular
- Excessive hair growth, acne and weight gain are also symptoms
- Treatments with ovulation drugs and hormone treatment can work but risk of miscarriage is high even after fertilisation
104
What are the causes, treatment and success of female tube blockages ?
- Blocked or damaged oviducts prevent eggs from passing to the uterus and from sperm getting to the egg
- Causes include Pelvic Inflammatory disease, STIs such as Chlamydia
- Surgery is needed to open the tubes but scar tissue may still cause problems
105
What are male causes of infertility?
- Male tube blockages
- Sperm problems
- Sperm allergy
106
What are the causes, treatments and success of male tube blockages?
- STIs like Chlamydia are linked to the blockage problems.
- Surgery may correct the problem
- Success rates are quite high
107
What causes sperm problems and what are treatment options?
- Low or no sperm count, poor sperm mobility and abnormally shaped sperm can all cause infertility
- Fertility drugs can boost sperm production or donor sperm can be used.
- injection of the sperm nucleus directly into the egg ( intercytoplasmic sperm injection) can increase success
108
What are some of the causes of unexplained infertility?
- over or under weight
- excessively exercising
- environmental toxins may all be factors but no direct links have been confirmed and there is no specific treatment but fertility drugs, IVF and other assisted conception methods may be successful
109
What is combination infertility?
The term used to describe couples who have both male and female infertility problems or when one partner has more than one fertility problem
