FETAL DEVELOPMENT

FERTILIZATION Begins with 46 pair of chromosomes, splits off to 23 then combine for a unique new 46 pair.

TRIMESTERS Trimester 1st= week’s nd= week’s rd= week’s 27 and on (38-40 WEEKS)

1 Month First Trimester At the end of four weeks: Baby is 1/4 inch in length Heart, digestive system, backbone and spinal cord begin to form Placenta (sometimes called "afterbirth") begins to develop The single fertilized egg is now 10,000 times larger than size at conception

Month 2 First Trimester At the end of 8 weeks: Baby is 1-1/8 inches long Heart is functioning Eyes, nose, lips, tongue, ears and teeth are forming Penis begins to appear in boys Baby is moving, although the mother can not yet feel movement

Month 3 First Trimester At the end of 12 weeks: Baby is 2 1/2 to 3 inches long Weight is about 1/2 to 1 ounce Baby develops recognizable form. Nails start to develop and earlobes are formed Arms, hands, fingers, legs, feet and toes are fully formed Eyes are almost fully developed Baby has developed most of his/her organs and tissues Baby's heart rate can be heard at 10 weeks with a special instrument called a Doppler

Month 4 Second Trimester At the end of 4 months: Baby is 6 1/2 to 7 inches long Weight is about 6 to 7 ounces Baby is developing reflexes, such as sucking and swallowing and may begin sucking his/her thumb Tooth buds are developing Sweat glands are forming on palms and soles Fingers and toes are well defined Sex is identifiable Skin is bright pink, transparent and covered with soft, downy hair Although recognizably human in appearance, the baby would not be able to survive outside the mother's body

Month 5 Second Trimester At the end of 5 months: Baby is 8 to 10 inches long Weight is about 1 pound Hair begins to grow on baby's head Soft woolly hair called lanugo will cover its body. Some may remain until a week after birth, when it is shed. Mother begins to feel fetal movement Internal organs are maturing Eyebrows, eyelids and eyelashes appear

Month 6 Second Trimester At the end of 6 months: Baby is 11 to 14 inches long Weight is about 1 3/4 to 2 pounds Eyelids begin to part and eyes open sometimes for short periods of time Skin is covered with protective coating called vernix Baby is able to hiccup

Month 7 Third Trimester At the end of 7 months: Baby is 14 to 16 inches long Weight is about 2 1/2 to 3 1/2 pounds Taste buds have developed Fat layers are forming Organs are maturing Skin is still wrinkled and red If born at this time, baby will be considered a premature baby and require special care

Month 8 Third Trimester At the end of 8 months: Baby is 16 1/2 to 18 inches long Weight is about 4 to 6 pounds Overall growth is rapid this month Tremendous brain growth occurs at this time Most body organs are now developed with the exception of the lungs Movements or "kicks" are strong enough to be visible from the outside Kidneys are mature Skin is less wrinkled Fingernails now extend beyond fingertips

Month 9 Third Trimester At the end of 9 months: Baby is 19 to 20 inches long Weight is about 7 to 7 1/2 pounds The lungs are mature Baby is now fully developed and can survive outside the mother's body Skin is pink and smooth Baby settles down lower in the abdomen in preparation for birth and may seem less active

AMNIOTIC FLUID Clear, yellowish fluid surrounding the developing fetus. Average amount 1000 ml. Having < 300ml – Oligohydramnios, associated with fetal renal abnormalities. Having > 2 L – Hydramnios, associated with GI and other malformations.

AMNIOTIC FLUID Protects Fetus Controls Temperature Supports Symmetrical Growth Prevents Adherence to amnion Allows Movement Source of oral fluid Acts as a excretion-collection repository

UMBILICAL CORD Connecting link between fetus and placenta. Transports oxygen and nutrients to fetus from the placenta and returns waste products from the fetus to the placenta. Contains: 2 arteries and 1 vein supported by mucoid material (wharton’s jelly) to prevent kinking and knotting. Contains NO pain receptors.

PLACENTA

VIABILITY Capability of fetus to survive outside uterus at the earliest gestational age weeks Survival depends on: –Maturity of fetal central nervous system –Maturity of lungs

Areas of Human Development Knowledge of how the human body grows and develops is important because it allows us to understand how people respond to the demands of exercise at different stages in the developmental process 4 areas of human development –Physical –Cognitive –Motor or skills development –Social development

Cognitive Development Individual’s ability to interpret and process information Emotional development Development of person’s self-concept or awareness of one’s self

Motor or Skills Development Combination of cognitive and physical development Humans develop ability to perform a wide range of tasks

Social Development Development of relationships with peers, friends, relatives, adults and others in the “outside world”

Stages of Physical Human Growth and Development Four basic stages Infancy/Toddler (zero to 2-3 years) Childhood (4-10 years) Puberty/Adolescence (11-18 years) Adulthood (18+ years)

Infancy/Toddler Most marked growth in humans –Double birth weight in 6 months and triple it in a year –By end of second year brain is 75% of adult weight –Weight typically increases 300% during stage –Body length will increase by about 50% Considerable muscular development Gains in ability to perform basic tasks –Grasp, crawl, pull to stand, walk Most master walking by age 2 Most master running by age 3

Childhood Relatively long compared to other animals From 6-10 years the body “stabilizes” –Uniform relationship between bone and tissue growth and development occurs Rapid stage of growth from 4-6 years Challenge is to accommodate wide range of sizes and ability and/or development levels in unified activity

Puberty/Adolescence Growth (physical and psychological) speeds up during this phase “growth spurt” where boys become men and girls become women; in other words, sexual maturity Pituitary gland triggers growth in both sexes Marked changes in physical appearance –Pubic hairs, breasts, body curves, menstruation for girls –Semen, facial and body hair, deepening voice for boys

Adulthood Most growth has taken place Other physical changes –Weight gain, reduced oxygen capacity, rise in blood pressure, joint deterioration Diminished exercise, diet and nutrition issues, increased stress and responsibilities

Phases of Movement Reflexive Movement –0-4 months; humans show controlled motor development Rudimentary Movement –Birth-2 years; overlaps reflexive; locomotor, manipulation and stability movements begin Fundamental Movement –2-7 years; basic movement skills; 3 phases (initial, elementary and mature) Sport-Related Movement –7-adulthood; 3 phases (general, specific and specialized)