Jimmy Nguyen Linh Bui Jane Stanfield HUMAN DEVELOPMENT

FUN FACTS � Human gestation lasts about 266 days. � Rodent gestation lasts about 21 days. � Dog gestation: 70 days � Cow Gestation 270 Days � Giraffe Gestation: 420 days � Elephant gestation: 600 days. � People used to think that the head of the sperm carried a tiny infant that grew into the baby that was born.

� Pregnancy is split up into three periods called trimesters. � Each trimester is 3 months.

TRIMESTER 1 � � � 24 hours after fertilization, the zygote forms a cleavage. The embryo reaches the uterus 3 -4 days after fertilization. HCG (Human Chorionic Gonadotropin) is a hormone that controls the mother’s reproductive system when a fetus is present. It maintains the progesterone and estrogen secretion. A Blastocyst is formed during the first trimester. A blastocyst is a sphere of cells containing a flat cavity. Organogenesis plays a huge role here. Organogenesis is the development of body organs.

TRIMESTER 1 Organogenesis forms the neural tube, notochord and somites first. � All the major organs are formed from the three germ layers. (Ectoderm, Endoderm, and Mesoderm) � The Ectoderm forms the skin, nervous system and sensory organs. � The Endoderm forms the lining of the respiratory and digestive system, liver, pancreas, thymus, and thyroid. � The Mesoderm forms the skeleton, muscles, blood vessels, heart, blood, gonads, kidney, and dermis. �

TRIMESTER 2 � The Fetus grows rapidly and movement can be felt. � The Hormone levels stablilize.

TRIMESTER 3 � Estrogen and oxytocin and prostaglandin induce and regulate labor. � Oxytocin is produced here. � Estrogen reaches its highest level in mother’s blood during last weeks of pregnancy. �

TRIVIA TIME � 1 - How long does Human Gestation last ? � 2 - After how many hours odes the first cleavage appear ? � 3 -What is HCG ? � 4 -What is organogenesis ? � 5 -Name the 3 layers of a blastocyst � 6 -Cite the organs developed from each layers. � 7 -What happens during the second semester ? � 8 -Name an hormone that regulates labor.