Sexual reproduction in humans Flashcards
Gametes are produced when…
Cells divide by meiosis
Sperm is produced in the…
Testes
Ova (eggs) are produced in the…
Ovaries
Meiosis produces cells that are not…
Genetically identical
Sperm and egg cells are not…
Clones to the organism they come from
Sperm tail is called
Flagellum
Purpose of flagellum
To move sperm through water
Egg cells are released…
Monthly
Women are born with…
All of their eggs
Males produce sperm…
In puberty
Sex cells are called…
Gametes
Ovary is where…
Egg cells are formed by meiosis
The ovary produces…
Hormones oestrogen and progesterone
What happens in the oviduct
Egg cells travel down this to the uterus
Lined with cilia which move the cell
What happens in the uterus
The foetus develops here
Thick muscular walls which contract during labour
Embryos implant…
In the uterus lining
What is the cervix
Narrow opening to the uterus. This dilates during labour
What is the vagina
Muscular tube that leads from the cervix to the outside of the woman’s body
What are the testes
Where sperm cells are formed by meiosis and produces the hormone testosterone
What is the sperm duct
Tube transporting mature sperm
What do the seminal vesicles and prostate gland do
Release liquids into the sperm duct which mixes with sperm to form semen.
What does semen do
Provides nutrients to the sperm
What is the urethra
Tube inside the penis which can transport either urine or semen
External fertilisation e.g in fish
Takes place outside the body
Females release ova into the water. Sperm swim through water.
Internal fertilisation
Male animals ejaculate their sperm into the females. Fertilisation is much more likely due to environment.
A normal human body cell will have…
46 chromosomes (23 pairs of homologous chromosomes) 23 from male and 23 from female
Homologous chromosomes contain
The same genes
The cell has two sets of chromosomes
Diploid cell
Fertilisation is…
The fusion of haploid male and female gametes restoring the diploid number of chromosomes in the zygote
First cell formed at fertilisation
Zygote
Fertilisation is said to be…
Random
Randomness causes…
Variation in the genetics of the new offspring
Zygote goes to
Embryo goes to foetus
What does the placenta do?
Secretes the hormone progesterone to keep the lining of the uterus thick and prevents the embryo from aborting.
Anchors the embryo in the uterus
Allows nutrients and oxygen to move from the mother to the embryo
Allows metabolic wastes (CO2 and urea) to move from the embryo to the mother.
The mother’s blood does not mix with the embryo’s blood because…
There is no physical connection between the circulatory systems
Problems that would occur if the mother’s circulatory system connected with the embryo.
Mother’s blood is much higher pressure
Mother’s blood has white blood cells that would see the foetal blood as foreign and attack it.
Function of the menstrual cycle
To control the development of the lining of the uterus so that it will be thick and ready to receive a fertilised egg.
If the egg is not fertilised, the lining of the uterus is shed. This is called a period.
FSH
Secreted from pituitary gland
Maturing follicle releases…
Oestrogen
Oestrogen secreted from…
The ovary
LH secreted from…
Pituitary gland and stimulates ovulation
Progesterone secreted from…
The ovary
Timing of events in menstrual cycle is controlled by…
Four hormones
Corpus luteum is…
What is left of the follicle after ovulation
Secondary sexual characteristics in boys
Armpit hair growth Voice break Shoulders broaden Sperm production begins Greater muscle development Growth and development of genitalia Possible mood swings and acne
Secondary sexual characteristics in girls
Voice deepens but doesn’t break
Men
