Reproduction in humans Flashcards
Testis
- Produces sperms
- Produces male sex hormones, testosterone
Sperm duct
- Pathway travelled by sperm after they are released from the testis to the urethra
Urethra
- Urine and semen exit the body through this tube
Scrotum
- Maintains a lower temperature for the development of sperms outside the body
Penis
- Becomes erect and hard during sexual intercourse to enter and deposit semen in the vagina of female
Prostate gland
- Activates sperms by secreting a fluid that contains nutrients and enzymes
Ovary
- Produces egg
- Produces female sex hormone, progesterone and oestrogen
Oviduct
- Fertilization occur here
- Mature egg is released from the ovary into the oviduct
Uterus
- Location where the fetus develops
- Has elastic muscular wall that enables contraction during birth to expel the fetus
Cervix
- It is the circular ring of muscle and the lower end of the uterus
- It dilates during birth to allow the fetus to pass
Vagina
- Location where semen is deposited during sexual intercourse
Structure of sperm
- Contains a flagellum
- enables the sperm to swim towards the egg - Contains many mitochondria
- To provide more energy for the sperm to swim towards the egg
Menstrual cycle
Day 1 - 5:
- Menstruation
- Uterine lining breaks down
- Uterine lining, blood and unfertilized egg is discharged out of the body through the vagina
Day 6 - 10:
- Repair of uterine lining
- Ovary produces oestrogen to stimulate the uterine lining to repair and grow
Day 11 - 16:
- Fertile period
- Sexual intercourse during fertile period is likely to result in pregnancy
- High levels of oestrogen in blood causes ovulation on day 14
Day 17 - 28:
- Thickening of uterine lining
- Ovary produces progesterone while decreasing production of oestrogen
- Progesterone stimulates the uterine lining to thicken and vascularize to prepare for fertilized egg
- Progesterone prevents ovulation from taking place
Ovulation
It is the release of mature egg from the ovary into the oviduct
Fertilisation
Occurs when haploid nucleus in sperm fuses with haploid nucleus in egg to form a diploid zygote
Early development of embryo
- Cilia lining in the oviduct sweeps zygote to the uterus
- As the zygote travels along the oviduct, it undergoes mitosis to form an embryo
- When the embryo gets imbedded in the uterine lining, implantation has occurred
Function of placenta
- It allows oxygen and dissolved food substances to diffuse from the maternal blood into the fetal blood
- It allows metabolic waste products and excretory products such as urea and carbon dioxide to diffuse from the fetal blood into the maternal blood
- it allows antibodies to diffuse from the maternal blood into the fetal blood to protect the fetus
- It produces oestrogen and progesterone to maintain the uterine lining
Function of umbilical cord
- Umbilical artery transports deoxygenated and excretory products from the fetus to the placenta
- Umbilical vein transports oxygenated blood and dissolved food substances from the placenta to the fetus
Function of amniotic sac
- Protects the fetus from injury by absorbing shock
- Supports and cushions the fetus
