The four stages will be described below briefly to help you understand what the basic of the human life cycle are.Infancy- From the age of being a newborn to the age of two years (2), you were an infant. Changes you may have experienced were more coordination and teeth growing rapidly. The body was also quite out of proportion. These were all part of the infancy stage.
Childhood- Childhood lasts from the age of two years to adolescence (puberty). Your bones and teeth were growing rapidly and soon changes such as teeth being replaced with permanents happen. You also develop your intellectual skills and pretty much you have quite changed from being an infant.
Adolescence- Adolescence is the age where the body becomes sexually mature. Changes you may be going through are acne, increased growth and deeper voice (for boys). Girls also gain extra weight during this time. It is sometimes a emotionally distressing time for teenagers.
Adulthood- Adulthood is the age where the body slowly slows down. Certain changes such as hair falling out and physical activity decreasing are normal as you age (thirties and above). If you are over forty, you are considered a older adult. This however doesn't stop someone from doing the things they enjoy.
• Fertilization and Fetal Development
Day 1: fertilization: all human chromosomes are present; unique human life begins.Day 6: embryo begins implantation in the uterus.
Day 22: heart begins to beat with the child's own blood, often a different type than the mothers'.
Week 3: By the end of third week the child's backbone spinal column and nervous system are forming. The liver, kidneys and intestines begin to take shape.
Week 4: By the end of week four the child is ten thousand times larger than the fertilized egg.
Week 5: Eyes, legs, and hands begin to develop.
Week 6: Brain waves are detectable; mouth and lips are present; fingernails are forming.
Week 7: Eyelids, and toes form, nose distinct. The baby is kicking and swimming.
Week 8: Every organ is in place, bones begin to replace cartilage, and fingerprints begin to form. By the 8th week the baby can begin to hear.
Weeks 9 and 10: Teeth begin to form, fingernails develop. The baby can turn his head, and frown. The baby can hiccup.
Weeks 10 and 11: The baby can "breathe" amniotic fluid and urinate. Week 11 the baby can grasp objects placed in its hand; all organ systems are functioning. The baby has a skeletal structure, nerves, and circulation.
Week 12: The baby has all of the parts necessary to experience pain, including nerves, spinal cord, and thalamus. Vocal cords are complete. The baby can suck its thumb.
Week 14: At this age, the heart pumps several quarts of blood through the body every day.
Week 15: The baby has an adult's taste buds.
Month 4: Bone Marrow is now beginning to form. The heart is pumping 25 quarts of blood a day. By the end of month 4 the baby will be 8-10 inches in length and will weigh up to half a pound.
Week 17: The baby can have dream (REM) sleep.
Week 19: Babies can routinely be saved at 21 to 22 weeks after fertilization, and sometimes they can be saved even younger
Week 20: The earliest stage at which Partial birth abortions are performed. At 20 weeks the baby recognizes its' mothers voice.
Months 5 and 6: The baby practices breathing by inhaling amniotic fluid into its developing lungs. The baby will grasp at the umbilical cord when it feels it. Most mothers feel an increase in movement, kicking, and hiccups from the baby. Oil and sweat glands are now functioning. The baby is now twelve inches long or more, and weighs up to one and a half pounds.
Months 7 through 9: Eyeteeth are present. The baby opens and closes his eyes. The baby is using four of the five senses (vision, hearing, taste, and touch.) He knows the difference between waking and sleeping, and can relate to the moods of the mother. The baby's skin begins to thicken, and a layer of fat is produced and stored beneath the skin. Antibodies are built up, and the baby's heart begins to pump 300 gallons of blood per day. Approximately one week before the birth the baby stops growing, and "drops" usually head down into the pelvic cavity.
• Pregnancy, Birth, and Development
Changes women go through during pregnancy may include: weight gain, constipation, heartburn, darkening of certain skin areas, and pregnancy-induced diabetes, all due to the placenta's addtitional hormones.
The process of human childbirth is categorized in 3 stages of labour:
In the first stage, the uterus begins rhythmic contractions which steadily increase in strength and frequency, gradually widening and thinning the cervix.
During the second stage, the infant passes from the uterus, through the cervix and birth canal.
In the third stage, the placenta pulls from the uterine wall and is expelled through the birth canal.
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