B10.3 : Sexual reproduction in humans Flashcards
Part of the male human reproductive system
- Sperm duct
- Penis
- Urethra
- scrotum
- Prostate gland
- Testes
Testes
- produce male hormones and sperm
- protected by the scrotum
- connected to the urethra
scrotum
- regulates the temperature of the sperm
- holds the testes
- The temperature needs to be regulated because sperm production is sensitive to heat. If they get too hot, the cells will not develop into sperm
sperm duct
- The sperm duct moves sperm from the testes into the urethra.
Prostate gland
- The prostate gland produces substances that are added to the sperm to make semen.
- Produce hormones such as Testosterone.
Penis
- The penis contains erectile tissue which allows it to enter the female vagina and deposit semen out of the urethra.
- Releases urine.
- Releases sperm.
urethra
- semen travels down this tube and exits from the penis
2. Connects the bladder and testes to the penis.
Part of the female human reproductive system
- Ovary
- Cervix
- oviduct
- uterus
- Vagina
Pathway of the egg cell
Eggs are stored in the ovaries and travel down the oviducts to the uterus, which is where fertilised eggs implant and grow during pregnancy.
cervix
- The cervix is the opening at the bottom of the uterus, leading to the vagina.
- connects the uterus to the vagina
Ovaries
- store the eggs
2. matures and releases the eggs
Vagina
- The vagina is the external opening of the female reproductive system and where the penis enters during sex.
oviduct
- eggs travel down these tubes from the ovaries to the uterus
- Pathway for released eggs
- Where the sperm fuses with the egg to create a zygote
- Do not connect directly to the ovaries, but has a funnel-shaped opening just a short distance away
Uterus
- where fertilised eggs implant
- where the foetus grows during pregnancy
- Zygote is embedded into the lining.
- Supports the zygote through blood vessels.
- Contains very thick walls, made of muscle
- Can stretch a great deal when a woman is pregnant
Sperm cell
- Sperm cells are specialised to fertilise egg cells.
- To do this, they need to travel long distances relatively to their size.
- They then break through to the egg cell and fertilise it (combine the sperm DNA with the egg DNA).
Flagellum
- The flagellum acts as a tail for the sperm cell
- is used for the cell’s motion.
- This allows sperm cells to travel towards the egg cell.
- Sperm spin their flagella in a corkscrew motion to move themselves towards their target - the egg.
Head of a sperm cell
- The ‘head’ contains the sperm cell’s nucleus. The nucleus carries one half of an organism’s genetic material. (haploid cell)
- This combines with the egg cell’s half of genetic material to fertilise the egg cell.
- It also contains an enzyme needed to penetrate (break into) an egg cell.
acrosome
- The acrosome at the tip of the head of the sperm cell contains an enzyme needed to penetrate (break into) an egg cell.
- It is an organelle
Middle section of a sperm cell
The middle section is filled with mitochondria to provide the sperm with the energy it needs to travel a long distance to reach the egg cell.
Parts of a sperm cell
- Mitochondria
- head
- Nucleus
- acrosome
- flagellum
Egg cell
- The egg cell is fertilised by a sperm cell to become a zygote (which grows into an embryo).
- An egg cell is much larger than a sperm cell and it is specialised to support the zygote as it grows.
Specialisation of the egg cell
- haploid nucleus
- jelly coat
- Cytoplasm
Cytoplasm of an egg cell
The cell is large and contains lots of cytoplasm, which is packed full of nutrients that the zygote will need to grow.
Nucleus of an egg cell
- Haploid nucleus
- The nucleus contains half the genetic information needed for the new zygote.
- The sperm cell provides the other half.
Jelly coat of an egg cell
The jelly coating around the cell is adapted to change structure once the egg is fertilised so that no more sperm can get into the egg cell.
Difference between the size of an egg and a sperm cell
- Egg cells are the largest human cells, but sperm cells are the smallest of any human cell.
- Egg cells are much larger than sperm because eggs contain lots of nutrients to sustain the zygote, but sperm need to be small and mobile
Difference between the structure of an egg and a sperm cell
Egg cells are round but sperm cells are made of sections (head, middle and tail) and are tadpole-shaped.
Difference between the motility of an egg and a sperm cell
- Sperm cells have tails and can move over large distances relative to their size.
- Egg cells cannot move but are wafted through the oviducts.
- after ovulation, the egg is caught in the funnel of the oviduct which is lined with cilia which beat rhythmically. This wafts the egg into the entrance of the oviduct
Difference between the number of egg and sperm cells
- Sperm are produced constantly and are stored in the testes in the millions.
- Much fewer egg cells are made and females are born with a limited number. At birth, a female will already have thousands of partly developed eggs inside her ovaries .
- At around 10 to 14 years old some of the eggs will begin to mature (one at a time)
Uterus lining
- made up of blood vessels in order to protect the zygote
2. Sheds at the beginning of each cycle.
