Biology - Human Reproduction 🙎🏽♂️ Flashcards
What are primary sexual characteristics?
They are sexual characteristics present at birth. They are exclusive to the sex of the individual. They comprise of external and internal genitalia.
What are some examples of primary sexual characteristics in men?
- The penis
- The testes
What are some examples of primary sexual characteristics in women?
- The vagina
- The ovary/ovaries.
What are secondary sexual characteristics?
They are sexual characteristics that develop during puberty for humans, or sexual maturity for animals. They are mostly exclusive to the sex of the individual.
What are some examples of secondary sexual characteristics found mostly in men?
- More body hair
- More developed muscles
- More facial hair
- A deeper voice than most women
What are some examples of secondary sexual characteristics found mostly in women?
- Breasts
- Wider hips
- A higher voice than most men
- Little facial/body hair
What is the purpose of primary sexual characteristics?
They enable humans to reproduce.
What is the purpose of secondary sexual characteristics?
They differentiate men and woman.
What are the hormones responsible for secondary sexual characteristics in men?
Testosterone, made by testes.
What are the hormones responsible for secondary sexual characteristics in women?
Oestrogen, made by ovaries.
When does puberty occur?
At age 11-14 for females.
At age 13-15 for males.
What makes puberty occur?
It starts when the pituitary gland sends hormones to the genital organs.
What changes occur during puberty in women?
- Female secondary sexual characteristics develop
- Ovaries start releasing egg cells, and menstruation starts.
What changes occur during puberty in men?
- Male secondary sexual characteristics develop
- Testes start producing sperm cells.
What secondary sexual characteristics commonly occur in all genders?
- Pubic hair develops
- Underarm hair develops
- Sexual organs mature
Do emotional changes occur during puberty?
Yes!
What is the penis?
The male organ inserted into the female vagina during sexual intercourse.
What are the testes?
The two male organs that make sperm cells and testosterone.
How are the two testes contained?
They are contained in a bag-like structure called the scrotum, which is outside the body.
Why are the testes contained out of the body?
Inside the body it is too warm, and sperm die. Outside the body, they are kept at the right temperature.
What are the two functions of the penis?
- Passing out urine
- Passing semen
What is the epididymis?
There are two of them. They are a mass of coils that connects the testicles to the vas deferens / sperm duct.
What is the vas deferens / sperm duct?
The sperm pass through this from the epididymis.
Where do the sperm ducts lead to?
They are lead to the ejaculatory ducts. Here the sperms are mixed with fluids.
Why are sperm mixed with fluids in the ejaculatory ducts?
The sperm need nourishment to survive, and need to be protected from acidic conditions coming their way.
What are the two parts that help produce fluids for the sperm to be mixed with in the ejaculatory ducts?
The prostate gland and the seminal vesicles.
What is the function of the seminal vesicles?
It secretes a fluid that helps nourish the sperms.
What is the function of the prostate glands?
It secretes the prostate fluid.
What is the Cooper’s gland / Bulbourethral gland?
It is the gland that provides the final secretion of fluid that forms semen.
What is the mixture of sperm and fluids called?
Semen.
What is the urethra?
The tube were the semen leaves the penis, and enters the female. It can also carry urine.
Why does sperm not mix with urine?
There is a ring of muscle that prevents this.
Are sperm unicellular or multicellular?
They are unicellular. They contain a nucleus, mitochondria to provide energy, and a tail to propel it. The tail lets it move on its own, which means sperm are motile.
What processes take place / things happen in the female reproductive system?
Ovum production, Fertilization, and The uterus - which is where a foetus grows.
What are the ovaries? Why are there two of them?
The two female organs that holds hundreds of undeveloped female sex cells called egg cells. There are two because each ovulation, a different one releases an egg.
Around how many egg cells do women have in their ovaries?
2 Million!
What are fimbriae?
They are finger-like projections that receive ovum when released from the ovaries, and connect them to the fallopian tubes / oviducts. They hold the ovum, and also help sweep the ovum to the fallopian tubes.
Are egg cells motile or non-motile?
Unlike sperm, egg cells are non-motile. This means they cannot move on their own
What two structures do the fallopian tubes connect?
The fallopian tubes connect the ovaries to the uterus.
What process takes place in the fallopian tubes?
Fertillisation. It is in the fallopian tubes that the sperm are able to swim to and fertilise the ovum. A zygote is formed.
What is the uterus?
The uterus is the “womb”, and is the site of development of a baby. It has strong muscular walls and a soft lining.
What is the cervix?
The cervix is a ring of muscle that holds a baby in place during a woman’s pregnancy. It opens into the vagina.
Where does a fully grown baby leave the parent’s body naturally?
A fully grown baby leaves through the vagina.
What is the vagina?
The vagina is a small muscular tube that opens to the exterior from the cervix.
What are the functions of the vagina?
- It is the site where sperms are received.
- It is the passage where the baby is passed out of the body during childbirth
What does the middle piece of a sperm cell contain?
A middle piece of a sperm cell contains lots of mitochondria to provide energy for the sperm.
What’s the acrosome in a sperm cell?
The acrosome is in the head of a sperm, and contains enzymes which break through an ovum’s jelly coating.
How many chromosomes do both the egg cell and the sperm cell have?
They both have 23 chromosomes as gametes. A zygote has 46 chromosomes.
Around how large is an egg cell?
Around 130 micrometers in diameter.
What is the function of the yolk of an egg cell?
It has nutrients to provide to the embryo.
What is the jelly coat of an egg cell?
The jelly coat of an egg cell only lets sperm in.
Why do many sperm die when they enter the vagina?
Many flow out of the vagina or die in it’s acidic environment.
How do sperm get through the cervix?
They are able to get through the cervix because although it is normally closed, when the person ovulates it opens for a few days. Many die trying to get through the “cervical mucus”
What assists the sperm to get to the egg in the uterus?
Muscular uterine contractions assist the sperm.
Why do resident immune system cells in the woman kill sperm?
They mistake the sperm for foreign invaders.
Why do half the sperm not reach the egg when they get to the fallopian tubes?
There are two fallopian tubes, and in one of them the ovaries do not release an egg cell, so half the sperm head to the wrong tube.
In the fallopian tubes, what push the egg cell forward? Why are these “pushers” a challenge for the sperm?
Many cilia push the egg cell towards the uterus. This is a challenge as the sperm have to surge against the motion to reach the egg.
What do chemicals in the fallopian tubes do to the sperm?
They cause the sperm heads to change, and put them in a hyperactive state that helps them swim faster.
What is the corona radiata?
A layer of cells that cover the egg. The sperm have to push through this to reach the surface of the egg.
Which sperm fertilize the egg?
The first sperm to make contact fertilise the egg. Then, the other sperms are pushed away by chemicals.
Zygote -> _____ -> ______
Zygote -> Embryo -> Fetus
What is the scientific name for embryo development?
Embryogenesis.
What happens to a fertilised egg cell as it is traveling to the uterus?
It keeps on dividing: From one cell to two, and from two to four, an from four to… This results in the formation of a ball-like structure.
When there are 16 cells in an egg, what is the stage called?
A morula.
What is the stage after a morula?
A blastula. This is the stage where the cells align themselves to form a hollow mass structure.
What is a blastocyst?
The stage of an egg after a blastula where the cells differentiate themselves.
What is the process of differentiation?
When one cell gets differentiated from the other cells in its vicinity. As a result, it creates a variety of cells.
What is implantation?
The sinking of the embryo into the uterus lining. (While a blastocyst). Now it is at one fixed position.
Why does the embryo implant itself in the uterus?
To derive nutrition from the wall, Give away waste, and exchange gases.
What is the placenta?
An organ that grows into the uterus which connects the baby with the parent.
What is the umbilical cord?
It’s what attaches the fetus to the placenta.
What is the amnion?
A fluid filled sac that surrounds the fetus. It is filled with amniotic fluid and protects the baby.
What is the stage when a baby’s organs can be identified?
The foetal stage.
When do major organs in a baby begin to grow?
At 6 weeks old. It is about 4mm long.
When does an embryo begin to move?
At 8 weeks old.. It is about 13mm long.
When is an embryo a foetus?
At 11 weeks old. It is about 50mm long and moves vigorously.
When is a foetus normally fully developed?
About 38 to 39 weeks after fertilisation.
What orientation is a baby in before birth?
It lies with its head downwards.
How does a baby fit out of a woman’s body naturally?
The muscles in the wall of the uterus contract, and make the opening of the uterus wider. Then the muscles contract in a different way to push the baby out of the opening of the uterus and through the vagina.
What is ovulation?
When an egg is released from an ovary.
What is the menstural cycle?
The process of ovulation and menstruation (having a period) in girls.
What are the 4 stages of the menstrual cycle?
Menstruation, the lining regrowing, ovulation, and the lining thickening.
How long is the menstrual cycle?
28 days.
What is menstruation?
When an egg is not fertilised, the uterus lining is not needed so it is shed. The bleeding usually lasts 2-5 days.
When in the 28 days does menstruation usually happen?
Day 1 to 5
Why does the uterus lining regrow?
To be ready in case the woman becomes pregnant. The lining is made of spongy tissues.
When in the 28 days does the uterus lining begin to regrow?
Days 6 to 10
When in the 28 days does ovulation usually occur?
Days 10 to 14
What is the “fertile period”? When is it?
It is a few days after the woman releases their egg, and they can become pregnant. It normally is around day 14.
Why does the uterus lining continue to thicken?
To be ready for a potential pregnancy.
When in the 28 days does the uterus lining continue to thicken?
Days 15 to 28
