Biological Development PDF

Human Development Functioning Prepared by: Ms. Mary Claudine N. Pineda Biological Development Objectives: At the end of the unit, the pre-service teachers should be able to: a) discuss the concepts and theories related to the biological/physical dev...

Human Development Functioning Prepared by: Ms. Mary Claudine N. Pineda Biological Development Objectives: At the end of the unit, the pre-service teachers should be able to: a) discuss the concepts and theories related to the biological/physical development of children and adolescents; and b) make connections, using knowledge of current research literature, between biological development theories and developmentally appropriate teaching approaches suited to learners’ gender, needs, strengths, interests, and experiences. A. BIOLOGICAL BEGINNINGS THE BEGINNING OF LIFE Fertilization – the union of sperm and ovum to produce a zygote, also called conception. Zygote – one-celled organism resulting from fertilization. Ovulation – rupture of a mature follicle in either ovary and expulsion of its ovum. The prenatal stage typically covers 40 weeks or 280 days including the additional two weeks to account for the last menstrual period and ovulation. Hence, the average human gestation is from 37 – 41 weeks. Infants that are born earlier than 37 weeks are considered pre-term while those that are born 42 weeks or more are called post-term. Gestation – period of development between conception and birth. Gestational Age – the age of an unborn baby, usually dated from the first day of an expectant mother’s last menstrual cycle. Early signs and symptoms of Pregnancy Tender, swollen breasts or nipple; Fatigue, need to take extra naps; Slight bleeding, or cramping; Food cravings; nausea with or without vomiting; frequent urination; frequent, mild headaches; constipation; mood swings; faintness and dizziness; and raised basal body temperature. MULTIPLE BIRTHS Dizygotic Twins – fraternal twins; Twins conceived by the union of two different ova (or a single ovum that has split) with two different sperm cells; they are no more alike genetically than any other siblings. Monozygotic twins – identical twins; twins resulting from the division of a single zygote after fertilization; they are genetically similar. Conjoined twins - twins who are physically joined at birth, sometimes sharing organs, and in some cases separable by surgery (depending on the degree of fusion). Human Development Functioning Prepared by: Ms. Mary Claudine N. Pineda Both before and after birth, development proceeds according to two fundamental principles: 1. The cephalocaudal principle, from Latin, meaning ―head to tail,‖ dictates that development proceeds from the head to the lower part of the trunk. 2. the proximodistal principle, from Latin, meaning ―near to far,‖ development proceeds from parts near the center of the body to outer ones. STAGES OF PRENATAL DEVELOPMENT 1. Germinal Stage – first 2 weeks of prenatal development, characterized by rapid cell division, blastocyst formation, and implantation in the wall of the uterus. implantation – attachment of the blastocyst to the uterine wall; occurring at about day 6. The embryonic disk, a thickened cell mass from which the embryo begins to develop. This mass will differentiate into three layers: a) The ectoderm, the upper layer, will become the outer layer of skin, nails, hair, teeth, sensory organs, and the nervous system, including the brain and spinal cord. b) The endoderm, the inner layer, will become the digestive system, liver, pancreas, salivary glands, and respiratory system. c) The mesoderm, the middle layer, will develop and differentiate into the inner layer of skin, muscles, skeleton, and excretory and circulatory systems. The amniotic sac is a fluid-filled membrane that encases the developing embryo, protecting it and giving it room to move and grow. The placenta allows oxygen, nourishment, and wastes to pass between mother and embryo. It is connected to the embryo by the umbilical cord. Nutrients from the mother pass from her blood to the embryonic blood vessels, which carry them, via the umbilical cord, to the embryo. 2. Embryonic Stage – the second stage of gestation (2 to 8 weeks), characterized by rapid growth and development of major body systems and organs. 3. Fetal Stage – the final stage of gestation (from 8 weeks to birth), characterized by increased differentiation of body parts and greatly enlarged body size. FACTORS AFFECTING PRENATAL DEVELOPMENT A. Threats to Prenatal Considering the delicate condition during pregnancy, there could be some threats to a successful pregnancy. 1. Miscarriage. This happens when the baby is lost before the 20th week of gestation. Beyond this, it is already considered a stillbirth. There are several reasons why pregnant women will experience miscarriage. But the most common reason for such is the chromosomal abnormalities. 2. Ectopic pregnancy. While it is expected that the zygote will implant itself in the uterus, there could be instances where it is implanted along the fallopian tube or elsewhere outside the Human Development Functioning Prepared by: Ms. Mary Claudine N. Pineda uterus. Since it is not designed to grow a zygote, it is rather detrimental to have a successful pregnancy. 3. Complications Associated with Pregnancy. Upon gestation, hormonal and biological changes are expected rapidly. This may cause medical-related complications that can cause loss of pregnancy. Some of them are gestational diabetes (sudden imbalance of sugar level), preeclampsia (high blood pressure), and infections. 4. Bleeding or Spotting. This is a blood discharge while on gestation most especially during the first trimester. The danger of bleeding depends on the frequency as well as the amount of bleeding. One of the primary reasons for the occurrence of bleeding is the implantation process. When the amount of bleeding is extraordinarily plenty, this is something that should be reported immediately to the medical doctor as it may signal irregularities in the development of the baby. B. Factors Affecting Pregnancy The following are factors that can contribute to the easiness or difficulty of the pregnancy and child’s development. 1. Maternal Factors. Because the prenatal environment is the mother’s body, virtually everything that influences her well-being, from her diet to her moods, may alter her unborn child’s environment and affect its growth. Teratogen – is an environmental agent, such as a virus, a drug, or radiation that can interfere with normal prenatal development. An event, substance, or process may be teratogenic for some fetuses but have little or no effect on others. Sometimes, vulnerability may depend on a gene either in the fetus or in the mother. NUTRITION AND MATERNAL WEIGHT Pregnant women typically need 300 to 500 additional calories a day, including extra protein. Women of normal weight and body build who gain 16 to 40 pounds are less likely to have birth complications or to bear babies whose weight at birth is dangerously low or overly high. Folic acid – or folate; derived from fresh fruits and vegetables; deficiency causes anencephaly and spina bifida. MALNUTRITION Malnourished women who take caloric dietary supplements while pregnant tend to have bigger, healthier, more active, and more visually alert infants and women with low zinc levels who take daily zinc supplements are less likely to have babies with low birth weight and small head circumference. PHYSICAL ACTIVITY AND STRENUOUS WORK The American Congress of Obstetricians and Gynecologists (2002) recommends that women in low-risk pregnancies be guided by their own abilities and stamina. Human Development Functioning Prepared by: Ms. Mary Claudine N. Pineda The safest course seems to be for pregnant women to exercise moderately, not pushing themselves and not raising their heart above 150, and as with any exercise, to taper off at the end of the session rather than stop abruptly. DRUG INTAKE Thalidomide – tranquilizer that alleviates morning sickness but was banned after it was found to have caused stunted or missing limbs, severe facial deformities, and defective organs in some 12,000 babies. This drug sensitized medical professionals and the public to the potential dangers of taking drugs while pregnant. Alcohol – prenatal alcohol exposure is the most common cause of mental retardation and the leading cause of birth defects in the United States. Fetal alcohol syndrome – a combination of mental, motor, and developmental abnormalities affecting the offspring of some women who drink heavily during pregnancy. Nicotine – maternal smoking during pregnancy has been identified as the single most important factor in low birth weight in developed countries. Women who smoke during pregnancy are more than 1 ½ times as likely as nonsmokers to bear low-birth-weight babies. Even light smoking is associated with a greater risk of low birth weight. Caffeine – 4 or more cups of coffee a day during pregnancy may increase the risk of sudden death in infancy. Heavy marijuana use can lead to birth defects, low birth weight, withdrawal-like symptoms, and increased risk of attention disorders and learning problems later in life. MATERNAL ILLNESSES Acquired Immune Deficiency Syndrome – a viral disease that undermines the effective functioning of the immune system. Rubella – German measles; if contracted by a woman before her 11th week of pregnancy, is almost certain to cause deafness and heart defects in her baby. Toxoplasmosis (infection caused by a parasite harbored in the bodies of cattle, sheep and pigs and in the intestinal tracts of cats) – can cause fetal brain damage, severely impaired eyesight or blindness, seizures, miscarriage, stillbirth, or death of the baby. MATERNAL AGE The risk of miscarriage or stillbirth reaches 90 percent for women age 45 or older. Women 30 to 35 are more likely to suffer complications due to diabetes, high blood pressure, or severe bleeding. There is also a higher risk of premature delivery, retarded fetal growth, birth defects, and chromosomal abilities, such as Down Syndrome. Human Development Functioning Prepared by: Ms. Mary Claudine N. Pineda Adolescent mothers tend to have premature or underweight babies – perhaps because a young girl’s still-growing body consumes vital nutrients the fetus needs. 2. Outside Environmental Hazards. Pregnant women who regularly breathe air that contains high levels of combustion-related particles are more likely to bear infants who are premature or undersized. Infants exposed prenatally even to low levels of lead, especially during the third trimester, tend to show IQ deficits during childhood. 3. Paternal Factors. A man’s exposure to lead, marijuana, or tobacco smoke, large amounts of alcohol or radiation, pesticides, or high ozone levels may result in abnormal or poor quality sperm. A pregnant woman’s exposure to the father’s secondhand smoke has been linked with low birth weight, infant respiratory infections, sudden infant death and cancer in childhood and adulthood. Older fathers may be a significant source of birth defects due to damaged or deteriorated sperm. B. THE BIRTH PROCESS Labor – apt term for the process of giving birth. Braxton-Hicks contractions – mild and irregular false contractions (2 mins.) STAGES OF CHILDBIRTH 1. Dilation of the cervix Regular and increasingly frequent uterine contractions – 15-20 minutes apart at first – cause the cervix to shorten and dilate, or widen, in preparation for delivery. Toward the end of the first stage, contractions occur every 2 to 5 minutes. It lasts until the cervix is fully open (10cm or about 4 inches) so the baby can descend into the birth canal. 2. Descent and Emergence of the baby Typically lasts up to an hour or two. It begins when the baby’s head begin to move through the cervix into the vaginal canal, and it ends when the baby emerges completely from the mother’s body. At the end of this stage, the baby is born but is still attached to the placenta in the mother’s body by the umbilical cord, which must be cut and clamped. 3. Expulsion of the placenta It lasts between 10 minutes and 1 hour. During this stage, the placenta and the remainder of the umbilical cord are expelled from the mother. Human Development Functioning Prepared by: Ms. Mary Claudine N. Pineda VAGINAL VERSUS CESAREAN DELIVERY Vaginal delivery – usual method of childbirth. Cesarean delivery – delivery of a baby by surgical removal from the uterus. The operation is commonly performed when labor is too slow, the fetus is in trouble, the fetus in breech position/transverse, the mother is bleeding vaginally, the head is too big to pass the pelvis, for multiple births, premature infants, and increases revenue generated by hospitals. Cesarean deliveries carry risks of serious complications for the mother, such as bleeding, infection, damage to pelvic organs, postoperative pains, risks of problems in future pregnancies, and it affects breastfeeding. Babies are deprived of important benefits of normal birth such as the surge of hormones that clear the lungs of excess fluid, mobilize stored fuel to nourish cells and send blood to the heart and brain. Vaginal delivery stimulates the release of oxytocin. Vaginal birth after cesarean (VBAC) should be attempted only with caution. VBACs have been associated with greater (though still low) risks of uterine rupture and brain damage as well as infant death. Today, if a woman had CS delivery, chances are about 92% that any subsequent deliveries will be by CS. Overall, women who attempt a trial of labor following one or two cesarean deliveries are successful 60 to 80% of the time and represented 12.4% of total births in 2016. VBAC is not recommended for home births or women who have conditions that make it less likely to be successful, such as advanced age, high body mass index, a very large baby, or a previous cesarean that was the result of a failure of the cervix to dilate. C. PHYSICAL AND MOTOR DEVELOPMENT PHYSICAL DEVELOPMENT ACROSS STAGES A. Infancy The neonatal period is the first 4 weeks of life, it is a time of transition from intrauterine to independent existence. The average neonate is about 20 inches long and weighs about 7 ½ pounds. In their first few days, neonates lose as much as 10% of their body weight, primarily because of a loss of fluids. They begin to gain weight again at about the 5th day and are generally back to birth weight by the 10th to the 14th day. § Meconium – stringy, greenish-black waste matter formed in the fetal intestinal tract. § Fontanels – areas on the neonate’s head where the bones of the skull do not meet. § Lanugo – fuzzy prenatal hair that has not yet fallen off which makes some neonates very hairy. Human Development Functioning Prepared by: Ms. Mary Claudine N. Pineda § Almost all newborns are covered with vernix caseosa (cheesy varnish) – oily protection against infection that dries within the first few days. Before birth, blood circulation, respiration, nourishment, elimination of waste, and temperature regulation are accomplished through the mother’s body. Once born, a neonate needs more oxygen than before. Most babies start to breathe as soon as they are exposed to air. The heartbeat at first is fast and irregular, and blood pressure does not stabilize until about 10 days after birth. The Apgar Scale (1min after delivery, again 5 mins after) Named after Virginia Apgar with the following subtests‖ A – ppearance (color) P – ulse (heart rate) G – rimace (reflex irritability) A – ctivity (muscle tone) R – espiration (breathing) The newborn is rated 0,1, or 2 on each measure, for a maximum score of 10. A 5-minute score of 7-10 = Baby is in good to excellent condition 5-7 = Baby needs help to establish breathing