Skip to main content

The Umbilical Cord

     The umbilical cord is a life support system, containing two arteries and one vein that connects the baby to the placenta. Very small molecules oxygen, water, salt, food from the mother's blood. It is necessary to note that large molecules cannot pass through the placental wall, these include red blood cells and harmful substances, such as most bacteria, material wastes, and hormones. The mechanisms that govern the transfer of substances across the placental barrier are complex.
    The amnion, a bag or an envelope that contains a clear fluid, in which the developing embryo floats, is another important life support system. Like the placenta and umbilical cord, the amnion develops from the fertilized egg, not from the mother's own body. At approximately 15 weeks, the Kidneys of the foetus begin to produce urine. This fetal urine remains the source of the amniotic fluid until the third trimester, when some of the fluid is excreted from the lungs of growing foetus. Although the amniotic fluid increases in the volume tenfold from the 12th to the 40th week of pregnancy, it is also removed in various ways. Some are swallowed by the foetus, and some are absorbed through the umbilical cord and the membranes covering the placenta. The amniotic fluid provides an environment that is temperature and humidity controlled as well as shockproof.
   
   We should know that before some women are aware that they are pregnant, some important embryonic development take place. In the third week, the neural tube that eventually becomes the spinal cord forms. At about 21days, eyes begin to appear, and at 24 days the cells for the heart begin to differentiate. During the fourth week, the first appearance of the urogenital system is apparent and arm and leg buds emerge. Four chamber of the heart take shape, and blood vessels surface. From the fifth to the eighth week arms and legs differentiate further, at this time, the face starts to form but still is not very structures fuse. 
     Organogenesis is the process of organ formation that takes place during the first two months of the prenatal development. It is necessary to note that when organs are being formed, they are especially vulnerable to environmental changes. 

Comments

Post a Comment

Popular posts from this blog

Natural soil

 Natural soils are influenced by rainfall and temperature,heavy rain causes the soil to become leached. High temperatures increase the rate of decomposition of organic matter in the soil, thereby lowering its humus content. Thus, climatic conditions tend to produce poor soils in the tropics and rich soils in the temperate regions. Besides climate and vegetation, the parent rock material also contributes to the quality of the soil. For example volcanic rocks tend to produce fertile soils.    Laterite, a red soil which is a product of leaching, is commonly found in the tropics. It is composed mainly of iron and aluminium compounds,and poor in humus and essential plant nutrients, such as phosphorus, nitrogen and potassium. The black and brown soil of the temperate grasslands are the world's richest soils, with a high mineral and humus content. The light coloured desert soils tend to be very rich in minerals but have a low humus content.    Mainly the soils ar...
Post a Comment
Read more

READING AND UNDERSTANDING

All reading is geared to understanding. There would be no point in reading if we did not understand what we are reading. However there are many different obstacles in the way of easy understanding of a passage. It is your task as a reader to actively seek to break down the barriers to understanding.    One block to understanding is caused by references in the passage to things that are outside it. Pronoun are the first examples of words that refer to people and objects. Sometimes, it is easy to follow the reference at other times, it is more difficult. Look at the opening sentence of the passage you've just read that begins this way  "She was waiting for us:small, dowdy, dirty..."  Who was waiting? Who was the person waiting for? (Perhaps you would also like to know why she was waiting.)Answers to these questions will surely help you to understand and thus follow the reference. The first thing to do is to ask questions like the ones we have just asked and to read t...
Post a Comment
Read more

Frequent masturbation

Frequent masturbation in young men is linked to higher risk of early prostate cancer , but it lowers prostate cancer risk for men in their 50s, a study shows. High levels of male sex hormones, or androgens, may increase a man's risk of prostate cancer . But different studies of this question, done in different ways, have reached different conclusions. To look at the question in a new way, a team of researchers  looked at whether men with more intense sex drives were at higher risk of prostate cancer.  About half the men got prostate cancer by age 60, and about half did not have cancer . The findings were surprising. Sexual intercourse did not affect prostate cancer risk. But frequent masturbation did -- in different ways, at different times of life. "Frequent masturbation during men's 20s and 30s increased their risk of prostate cancer. For men in their 20s, "frequent masturbation" was two to seven times per week. Compared to same-age men who reported mas...
Post a Comment
Read more