Unit 2 HHD Prenatal development

The 23 chromosomes from a male are carried in:

• A muscle

• A skin cell

• A hair folicle

• Sperm

23 chromosomes from a female are carried in:

• An ova (egg)

• A zygote

• A blastocyst

• A gene

The cervix:

• Is the entrance to the uterus (from the vagina)

• Dilates to about 10 cm before the baby's arrival is imminent

• Stops urine from escaping from the bladder

• Opens up enough to allow sperm to swim into the uterus

An ovum is released from:

• The bladder

• A testicle

• An ovary into the Fallopian tubes

• The uterus

The millions of sperm swim:

• Through the cervix

• Through the uterus

• Into the fallopian tubes

• Into the right ovary

Sperm usually meet an ovum in:

• The vagina

• The uterus

• The left ovary

• A Fallopian tube

Fertilisation occurs:

• When an ovum implants into the sperm

• When a few sperm penetrate an ovum

• When one sperm penetrates an ovum

• When gypsum is spread on the worked up soil

Prenatal development consists of:

• The germinal stage (Weeks 1 and 2)

• The embryonic stage (Weeks 3 to 8)

• The foetal stage (Weeks 9 to 38)

• The baby stage (Weeks 40 to 400)

The germinal stage begins and ends:

• With fertilisation of sperm and ovum and Implantation in endometrium

• Over two weeks

• With a fully grown baby which becomes a child

• With a zygote which becomes a morula and then an embedded blastocyst

During the embryonic stage:

• Cells change to take on specialised roles (differentiation)

• Organogenisis occurs (organs begin to be formed)

• The embryo is protected from teratogens by the placenta

• The brain becomes active