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Sexual Reproduction in Humans - Coggle Diagram
Sexual Reproduction in Humans
Sex Hormones
Secondary sex characteristic are brought about by it
male sex hormones
Testosterone (produced in testes)
Chemical substances which act as messengers , which are released into the blood stream
female sex hormones
Estrogen (produced in ovaries)
Produced by ductless glands in body
Puberty
Boys
Hairs grows on the face, chest, armpits and pubic area
Voice box enlarges so voice 'breaks' and deepens
Shoulders become wider
Reproductive organs grow larger in size
Body becomes more muscular
Testes produces more male sex hormones and sperm
Height increases rapidly
Appetite increases
Start at the age of 12-14
production of sperm may lead to nocturnal emission (released of sperm at night)
Girls
Hair may grow in the armpit and in pubic region
Hips become rounder and wider
Breast grow bigger
Ovaries produces female sex hormones and releases mature ova
Height increases rapidly
Menstruation starts
Starts at the age of 10-12
Sex Cells
The nuclei contains half the number of chromosomes of a normal cell
instead of 23 pairs of chromosomes, they have 23 single chromosomes
Each cell has a nucleus and some cytoplasm
Sperm
consists of a head ,middle piece and a tail
middle piece contains mitochondria to release energy fir swimming
starts from puberty (12yrs) to 70yr
produced in the testes
about 2 billion sperms are produced each day
male sex cells
Ova
A new born baby has several hundred thousand partly developed ova in her ovaries
After birth, no new ova are produced and majority of them disintegrate
Developed in the ovaries while female is still a foetus
Remaining ova mature at different times from puberty onwards
female sex cells
Ova cannot move on their own
They are round and surrounded by a jelly coat
Ovulation
Ovaries would stop releasing ova after a woman undergoes menopause ( around age 45-50)
Between puberty and menopause , a woman releases around 500 ova
The ova are released 1 at a time from the ovaries during ovulation
Menstrual Cycle
Ovulation will start 11-16 days after the first day of menstruation
If fertilisation does not occur in 2 days ,the ovum will die
The uterus lining would then slowly disintegrate and be passed out along with the dead ovum and blood through the vagina
this is know as menstruation/period
This usually occurs 14 days after ovulation and lasts 3-5 days
The ovaries stop releasing ova until the baby is born
If the ovum is fertilised ,it would develop in the uterus
1 mature ovum is released from 1 ovary , once every 28 days during ovulation
during this the uterus forms a lining of soft tissue rich with blood vessels to prepare for receiving the fertilised ovum