Processes in paper 1
Spermatogenesis
Under influence of testosterone
Germinal epithelium in the seminiferous tubules in the testes undergo meiosis
Each cell that undergoes meiosis produce four haploid spermatids
Each spermatid matures to form a spermatozoon
Oogenesis
Under the influence of FSH
The germinal epithelium of the ovary undergoes mitosis
To form numerous follicles
One cell inside a follicle enlarges and undergoes meiosis
Of the four cells that are formed, only one survives to form a mature ovum
Ovarian cycle
Under the influence of the follicle stimulating hormone produced by pituitary gland
The follicles in the ovary becomes a Graafian follicle containing a mature ovum
The Graafian follicle produces a hormone oestrogen which starts the preparation of
the uterus for the attachment of fertilised ovum
Approximately every 4 weeks the Graafian follicle raptures to release an ovum, this is
called ovulation
The ovum is collected by the funnels of the fallopian tube
The luteinising hormone also produced by the pituitary gland, helps convert empty
Graafian follicle into a structure called corpus luteum
The corpus luteum secretes hormone progesterone which maintains pregnancy
If fertilisation does not take place, the corpus luteum degenerates and progesterone
production drops
The unfertilised ovum passes down the fallopian tube into the uterus and leaves the
body.
, Uterine cycle
The Graafian follicle produces a hormone oestrogen which starts the preparation of
the uterus for the attachment of the fertilised ovum making the endometrium thicker,
more vascular and more glandular
This happens because the uterus is preparing itself for attachment of the fertilised
ovum just in case fertilisation takes place.
After the ovum is released, the corpus luteum continues secreting progesterone, which
continues the preparation of the uterus just in case fertilisation takes place
If the ovum is fertilised by a sperm cell, the corpus luteum continues secreting
progesterone which makes certain that the embryo remains attached to the uterine
wall
If the ovum is not fertilised, the corpus luteum is destroyed. Progesterone level drops
and menstruation occurs.
Fertilisation
In the fallopian tube
Haploid sperm cell makes contact with a haploid ovum
Enzymes of the acrosome penetrate the egg cell membrane
Only the nucleus of the sperm cell enters the ovum
To fuse with the nucleus of the egg cell
To form a diploid zygote
Development of the zygote until the foetus is formed
The zygote devides by mitosis
To form a ball of cells
Called the morula
More mitotic divisions of the morula occurs to form a hollow ball of cells
Called blastocyst
The blastocyst attaches to the endometrial lining
The outer wall of the blastocyst called the chorion
Develops projections called villi which
Embeds/implants to the in to the uterine wall
The cells of the embryo continues to divide
Spermatogenesis
Under influence of testosterone
Germinal epithelium in the seminiferous tubules in the testes undergo meiosis
Each cell that undergoes meiosis produce four haploid spermatids
Each spermatid matures to form a spermatozoon
Oogenesis
Under the influence of FSH
The germinal epithelium of the ovary undergoes mitosis
To form numerous follicles
One cell inside a follicle enlarges and undergoes meiosis
Of the four cells that are formed, only one survives to form a mature ovum
Ovarian cycle
Under the influence of the follicle stimulating hormone produced by pituitary gland
The follicles in the ovary becomes a Graafian follicle containing a mature ovum
The Graafian follicle produces a hormone oestrogen which starts the preparation of
the uterus for the attachment of fertilised ovum
Approximately every 4 weeks the Graafian follicle raptures to release an ovum, this is
called ovulation
The ovum is collected by the funnels of the fallopian tube
The luteinising hormone also produced by the pituitary gland, helps convert empty
Graafian follicle into a structure called corpus luteum
The corpus luteum secretes hormone progesterone which maintains pregnancy
If fertilisation does not take place, the corpus luteum degenerates and progesterone
production drops
The unfertilised ovum passes down the fallopian tube into the uterus and leaves the
body.
, Uterine cycle
The Graafian follicle produces a hormone oestrogen which starts the preparation of
the uterus for the attachment of the fertilised ovum making the endometrium thicker,
more vascular and more glandular
This happens because the uterus is preparing itself for attachment of the fertilised
ovum just in case fertilisation takes place.
After the ovum is released, the corpus luteum continues secreting progesterone, which
continues the preparation of the uterus just in case fertilisation takes place
If the ovum is fertilised by a sperm cell, the corpus luteum continues secreting
progesterone which makes certain that the embryo remains attached to the uterine
wall
If the ovum is not fertilised, the corpus luteum is destroyed. Progesterone level drops
and menstruation occurs.
Fertilisation
In the fallopian tube
Haploid sperm cell makes contact with a haploid ovum
Enzymes of the acrosome penetrate the egg cell membrane
Only the nucleus of the sperm cell enters the ovum
To fuse with the nucleus of the egg cell
To form a diploid zygote
Development of the zygote until the foetus is formed
The zygote devides by mitosis
To form a ball of cells
Called the morula
More mitotic divisions of the morula occurs to form a hollow ball of cells
Called blastocyst
The blastocyst attaches to the endometrial lining
The outer wall of the blastocyst called the chorion
Develops projections called villi which
Embeds/implants to the in to the uterine wall
The cells of the embryo continues to divide
