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061018L - THE CYCLES OF LIFE: THE INTRA-UTERINE PERIOD

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Background reading material by Professor Omar Hasan Kasule Sr. for Year 1 Semester 1 PPSD session on 18th October 2006.


ORIGINS
The first human was created de novo and not from any previous life. The rest of humans start life when maternal and paternal DNAs are combined in the process of fertilization. The rest of the human body is then built from basic elements of the earth: water and soil. Human biological life manifests cyclicity. The human physical body is derived from the earth. On death of cells or the whole organism, elements found in one body return to the earth. Humans have one origin and are all from the earth. Various human races are one species that can interbreed. Humans however have different colors and structures. The biological differences among humans were created in a deliberate fashion by and did not arise by chance.

CONCEPTION
The male gamete is the sperm and the female gamete is the ovum. About 50-100 sperms reach the ovum but only one penetrates it. The statistical probability of a particular genetic individual is low because only one sperm out of so many fertilizes the ovum. Chromosomal rearrangements are millions of possible combinations and permutations. An individual human is a unique creation of selected out of trillions of possibilities.

The start of a new human life legally recognized is at conception. Any interference with the zygote after conception would be considered destruction of life. Sex determination involving the X and Y chromosomes is not a random process but a deliberate design by the Creator to make some offspring male or female. The offspring resembles both parents because they both contribute to its heredity. The fetus and child can acquire biological features not inherited from either parent due to environmental effect on the genotype. Behavioral characteristics can be transmitted from the parent as learning and culture but not as inheritance.

STAGED EMBRYOLOGICAL GROWTH and DEVELOPMENT
Intra-uterine growth and development occur in stages. The Creator had the power to make an adult de novo as He did with the first human. The likely reason for staged growth is to allow gradual interaction and adaptation to the external environment.

EXTERNAL AND INTERNAL ENVIRONMENTS
The placenta mediates between maternal and fetal circulations. It enables exchange between the fetus and the external environment so that the fetus to satisfy its respiratory, circulatory, and excretory needs without laboring its growing organs. The organs still play a role because they need testing and preparation for later independent existence. The blood-placental barrier protects the fetus from environmental toxins by being very selective in what molecules are allowed to transit. It also protects the mother from some fetal products that could give rise to immune reactions. The amniotic membranes provide some mechanical protection. The amniotic fluid absorbs mechanical forces and thus cushions the fetus from harm. The fluid in the amniotic cavity plays a role in regulation of temperature. The growing fetus can respond to environmental stimuli. Scientific research in this area will yield more information in the future. The fetus is calmed and is reassured by hearing and feeling the maternal heartbeat. The fetus exercises all its muscles constantly. This is necessary for their growth.

DISORDERS OF INTRA-UTERINE GROWTH
The common disorders of intrauterine growth are growth retardation, immaturity of organ systems, malformations, fetal disease, and fetal death.