Human reproduction

Male and female gametes Cells fuse to form a fertilised egg 23 chromosomes Egg Sperm The human life cycle Cells fuse to form a fertilised egg 46 chromosomes

VIRUS (0.05 to 0.1 microns) BACTERIA RED BLOOD CELL (5 microns) OVUM SIZE COMPARISONS 10 microns (0.01mm) VIRUS (0.05 to 0.1 microns) BACTERIA 100 microns OVUM (0.5 to 1.5 microns) RED BLOOD CELL (5 microns) WHITE BLOOD CELL (5 to 8 microns) SPERM (60 microns)

Gland for making seminal fluid Bladder Gland for making seminal fluid Prostate Gland Sperm duct Penis Scrotum Testis

Male Gamete – Sperm vesicle contains enzymes involved in penetration of ovum during fertilization head Nucleus containing DNA middle piece mitochondria which release energy during respiration tail brings about movement

Sperm Sperm carry a nucleus in the head 300 million produced during intercourse Released in a liquid called semen

Secondary Sexual Characters During puberty boy : hair in pubic and facial regions larynx growth, voice break muscular development girl : breast development hips widen more fat under skin menstruation

Menstrual Cycle Generally about every 28 days The uterus lining becomes thickened 14 days after menstruation to prepare for the fertilized ovum to implant in it Uterus : thickening of lining menstruation (discharge of lining if no fertilization)

Menstrual Cycle Day 1 - 5 Menstruation starts Uterus lining decreases in thickness to a minimum

Menstrual Cycle Day 6 - 14 Lining becomes thicker with increased blood supply Day 14 : ovulation

Menstrual Cycle Day 14 - 28 Lining remains thick to ready for implantation of fertilized ovum

Menstrual Cycle Day 28 No implantation of fertilization ovum Uterus lining breaks down – menstruation starts

Fertilization oviduct ovary uterus cervix vagina 1st day 2nd day 6th day 3rd day cervix vagina 4th day

sperms

Events Happened after fertilization Sperms reach the upper part of the fallopian tube Egg is fertilized at the fallopian tube Fertilized egg is carried to the uterus After reaching the uterus, the embryo fixed firmly onto the thick uterus wall – Implantation

Ovulation and fertilization

Placenta

Functions of the Placenta The placenta is an organ that is made up of tissues from the mother and the baby. It allows food and oxygen to pass from the mother to the baby. It allows waste to pass from the baby to the mother for removal. Harmful substances such as drugs and alcohol can also pass in to the baby and cause damage.

Embryo at 2 weeks

Embryo at 4 weeks

Embryo at 8 weeks

Development of Human Foetus uterus foetus placenta umbilical cord amniotic fluid

Functions of Uterus During embryo development During birth of baby – Protect the embryo – Provide a constant environment for the embryo to develop – Allow placenta to attach on During birth of baby – Push the baby out by muscular contraction

Birth At the end of the pregnancy the womb begins to contract and labour begins. These contractions cause the amniotic sac to burst and the amniotic fluid to be released – “the breaking of the waters” The cervix and the vagina expand or dilate. The contractions of the womb push the baby out through the vagina and it is born. The umbilical clamped and cut. The contractions of the womb continue and they push out the placenta and umbilical cord. This called the afterbirth.

Labour and birth

Contraception Contraception is any method that tries to prevent fertilisation or pregnancy occur. There are 2 types of contraception Natural methods – abstinence and avoiding sex during the fertile period. Artificial methods – artificially preventing sperm meeting egg or implantation.

Artificial Methods Female Male Tying or cutting of fallopian tubes Taking “the pill” – prevents ovulation IUD (the coil) – prevents implantation Diaphragm (the cap) – prevents the sperm entering the uterus/fallopian tubes Male Vasectomy – cutting the sperm duct, no sperm released into vagina Condom – prevents sperm being released into vagina

Contraception