Human reproduction Male and female gametes Egg 23

Human reproduction

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

SIZE COMPARISONS 10 microns (0. 01 mm) VIRUS (0. 05 to 0. 1 microns) BACTERIA 100 microns (0. 5 to 1. 5 microns) RED BLOOD CELL (5 microns) WHITE BLOOD CELL (5 to 8 microns) SPERM (60 microns) OVUM

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

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

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