Reproduction In Humans Flashcards
2 advantages of asexual reproduction
1) animals which don’t move around or live in isolation don’t need to search for a mate in order to produce offspring
2) a parent plant with beneficial traits will be able to pass them on to the offspring
2 advantages of sexual reproduction
Genetic variability of the species is increased
Species is more likely to be able to adapt to the environment
2 disadvantages of asexual reproduction
If the environment is changing, the offspring might struggle to survive
If the parent is of poor quality, the offspring will also be of that poor quality
2 disadvantages of sexual reproduction
A lot of time and energy is spent seeking a mate
Few offspring may be produced
In males the gametes are called
Sperms or spermatozoa
In females the gametes are called
Ova or eggs
Function of the acrosome
contains enzymes that break down the outer membrane of an egg cell, allowing the sperm to fertilize the egg.
Function of the middle piece of sperm cell
Provides energy for the sperm to move
The fluids from the Cowper’s gland mix with sperm to form
Semen
During puberty, what is released because of the pituitary gland?
Testosterone and oestrogen
Another name for the uterine lining
Endometrium
What sex hormones do the ovaries secrete
Oestrogen
Progesterone
What part of the female reproductive system is richly supplied with blood vessels
Endometrium (uterine lining)
What are the tiny hairs lining the walls of the oviduct called?
Cilia
Functions of the vagina
Acts as a passage for menstruation to occur
Receives sperm deposited by the penis
Pathway for childbirth
The average length of a menstrual cycle
28 days
The first menstrual cycle is called
The menarche
Describe the menstrual cycle
Before ovulation, the lining of the uterus wall thickens in readiness to receive an egg from the ovary
After ovulation the lining gets very thick. If fertilisation doesn’t take place, the lining breaks down and blood flows from the vagina
What days do oestrogen levels rise then drop
Rise on day 4
Drop between day 12 and 14
What days do progesterone levels rise then drop
Rise on day 14
Drop on day 24
Events of the menstrual cycle
Day 1-5: menstruation
Day 6-10: the immature follicles in the ovary are stimulated by the FSH from the pituitary gland to grow. The follicles secrete oestrogen.
Day 11-17: ovulation occurs on day 14.
Day 18-28: if no fertilization occurs, the egg breaks down. When this happens, progesterone production stops
The sperm swims through what to get to the oviduct?
From the top of the vagina through the cervix and uterus
Sperm swims through the uterus into the…
Fallopian tube
Describe fertilization
Only 1 sperm is able to fertilize an egg. As soon as one sperm has penetrated the ovum a special skin forms around it to keep out other sperm. Inside the ovum the sperm’s nucleus fuses with the ovum’s nucleus.
Development of the embryo
During the growth of an embryo, amnion develops around it. The membrane secretes amniotic fluid.
After 8 weeks, the embryo undergoes significant tissue and organ formation, making the embryo appear human.
Functions of the amniotic fluid
Supports and cushions the foetus before birth
Acts as shock absorber
Protects foetus from mechanical injury
Placenta functions
Prevent the passage of drugs and chemicals from maternal blood to foetal blood
Protect progesterone to maintain the thickness of the uterine lining
Functions of the umbilical cord
Carries deoxygenated blood containing waste products from the foetus to the mother
Carries oxygenated blood containing nutrients from the mother to the foetus
When it’s time for labour, what hormone is released?what does it cause?
Oxytocin
Causes powerful rhythmic contractions in the uterus
