From Fetus to Baby!

Signs of pregnancy Missing menstrual period Pregnancy tests these tests detect the presence of hCG (human chorionic gonadotrophin) in the urine hCG is produced by the developing embryo and is present is a woman’s urine only when she is pregnant

Embryo Development & Stages of Pregnancy Once sperm is deposited in the vagina, it travels through the cervix and into the Fallopian tubes. Conception usually takes place in the outer third of the Fallopian tube. A single sperm penetrates the mother's egg cell (ovum) and the developing child gets half of its genetic information (in the form of DNA) from the mother (this is contained in the egg), and half from the father (from the sperm). The resulting single cell is called a zygote. The zygote spends the next few days traveling down the Fallopian tube and divides to form many attached cells. A ball of cells is produced, each cell including a copy of the genes that will guide the development of the baby. Once there are about 32 cells, the developing baby is called a morula. With additional cell division, the morula becomes an outer shell of cells with an attached inner group of cells. Now the developing baby is in the "blastocyst" stage. The outer group of cells will become the membranes that nourish and protect the inner group of cells, which will become the embryo (the next stage for the future baby). The blastocyst reaches the uterus at roughly the fifth day, and implants into the uterine wall on about day six. At this point in the mother's menstrual cycle, the endometrium (lining of the uterus) has grown and is ready to support a fetus. The blastocyst adheres tightly to the endometrium where it receives nourishment via the mother's bloodstream. During the time between implantation and the eighth week, the cells of what is now called the embryo not only multiply, but begin to take on specific functions. This process is called differentiation, and is necessary to produce the varied cell types that make up a human being (such as blood cells, kidney cells, nerve cells, etc.). There is rapid growth, and the main external features begin to take form. It is during this critical period of differentiation (most of the first trimester) that the growing baby is most susceptible to damage from external sources including: teratogens (substances that cause birth defects including alcohol and certain prescription and recreational drugs) infection (such as rubella or cytomegalovirus) radiation (ionizing radiation such as X-rays, radiation therapy, or accidental exposure to radiation) nutritional deficiencies Specific changes by week for the embryonic stage: Week 3 beginning development of the brain, spinal cord, and heart beginning development of the gastrointestinal tract Weeks 4 to 5 formation of tissue that develops into the vertebra and some other bones further development of the heart which now beats at a regular rhythm movement of rudimentary blood through the main vessels beginning of the structures of the eye and ears the brain develops into five areas and some cranial nerves are visible arm and leg buds are visible Week 6 beginning of formation of the lungs further development of the brain arms and legs have lengthened with foot and hand areas distinguishable hands and feet have digits, but may still be webbed heart and circulation more fully developed Week 7 straightening of trunk nipples and hair follicles form elbows and toes visible bones more mature all essential organs have at least begun to form Week 8 rotation of intestines facial features continue to develop the eyelids are more developed the external features of the ear begin to take their final shape Note: The end of the eighth week marks the beginning of the "fetal period" and the end of the "embryonic period" Weeks 9 to 12 the fetus reaches a length of 3.2 inches the head comprises nearly half of the fetus' size a neck is present the face is well formed eyelids close and will not reopen until about the 28th week tooth buds appear for the baby teeth limbs are long and thin digits are well formed the fetus can make a fist with its fingers urogenital tract completes development genitals appear well differentiated red blood cells are produced in the liver Weeks 13 to 16 the fetus reaches a length of about 6 inches a fine hair develops on the head called lanugo fetal skin is almost transparent more muscle tissue and bones have developed, and the bones become harder the fetus makes active movements sucking motions are made with the mouth amniotic fluid is swallowed meconium is made in the intestinal tract lungs further develop sweat glands develop the liver and pancreas produce their appropriate fluid secretions Week 20 the fetus reaches a length of 8 inches lanugo hair covers entire body skin becomes less transparent as fat begins to deposit eyebrows and lashes appear nails appear on fingers and toes the fetus is more active with increased muscle development "quickening" usually occurs (the mother can feel the fetus moving) fetal heartbeat can be heard with a stethoscope Week 24 the fetus reaches a length of 11.2 inches the fetus weighs about 1 lb. 10 oz. hair on the head is longer eyebrows and eyelashes are well formed all the eye components are developed the fetus has a hand and startle reflex footprints and fingerprints forming alveoli (air sacs) forming in lungs Weeks 25 to 28 the fetus reaches a length of 15 inches the fetus weighs about 2 lbs. 11 oz. rapid brain development nervous system developed enough to control some body functions eyelids open and close respiratory system, while immature, has developed to the point where gas exchange is possible a baby born at this time may survive, but the possibilities for complications and death remain high Weeks 29 to 32 the fetus reaches a length of about 15-17 inches the fetus weights about 4 lbs. 6 oz. rapid increase in the amount of body fat increased central nervous system (CNS) control over body functions rhythmic breathing movements occur lungs are not fully mature bones are fully developed, but still soft and pliable fetus begins storing iron, calcium, and phosphorus Week 36 the fetus reaches a length of about 16-19 inches the fetus weighs about 5 lbs. 12 oz. to 6 lbs. 12 oz. lanugo begins to disappear increase in body fat fingernails reach the end of the fingertips a baby born at 36 weeks has a high chance of survival, but may require some medical interventions Weeks 38 to 40 considered full-term at 38 weeks may be 19 to 21 inches in length lanugo is gone except for on the upper arms and shoulders fingernails extend beyond fingertips small breast buds are present on both sexes head hair is now coarse and thicker mother supplies fetus with antibodies against disease fetus fills entire uterus

First Trimester: (week 1- week 13) Week 1- 7: “Embryo” Week 8: “Fetus” Week 12: Sex of fetus can be determined The fetus can move

Second Trimester: (week 14- week 26) Fetus can hear sounds Can suck it’s thumb Hair begins to grow Use it’s digestive system by swallowing amniotic fluid Week 24: Mother can feel the baby moving (kicks from the legs)

Third Trimester: (week 27 – week 40) Rapid development of the fetus which requires a large quantity of nutrients from the mother  it’s crucial for the mother to eat a healthy diet Week 28: Fetus can open it’s eyes Week 32: fetus settles into a head down position in preparation for birth Week 36: Recognizes mother’s voice

Embryo development & stages of pregnancy Functions of the placenta, umbilical cord Placenta Membrane that forms between the mother’s uterus and the developing embryo Allows for exchanges of nutrients and oxygen between mother and embryo (it serves as a filter) N.B. Mother’s blood does not enter the embryo Umbilical cord connects fetus to the placenta, cut at birth

Functions of amniotic fluid In the uterus, the fetus is suspended in a fluid called amniotic fluid This fluid has 3 functions To protect the fetus from injury To keep body temperature of the fetus constant To protect the fetus against dehydration

Identical and fraternal twins Identical twins (30% of the time) From a single egg and sperm Great deal of resemblance Same chromosomes Same sex Same blood type Fraternal twins (70% of the time) Two ova, two sperms Little resemblance 3D finished here

Important factors to consider during pregnancy Nutrition Physical exercise Tobacco (harmful chemicals pass through the placenta to the fetus) Alcohol Fetal alcohol syndrome is characterized by growth, mental, and physical birth defects associated with the mother's high levels of alcohol use during pregnancy Alcohol ingested by a pregnant woman easily passes across the placental barrier to the fetus

Process of birth

Signs of the onset of labour Process of birth Signs of the onset of labour Uterine contractions are triggered to begin by the hormone oxytocin secreted by the pituitary gland Initially are irregular but they become: More frequent Stronger Regular Rupturing of the amniotic sac (“water breaks”) As result of the contractions… Rupture the membrane surrounding the fetus Cause the amniotic fluid to flow out of the body It lubricates the baby’s passage out of the body

4 Stages of labour (8-20 hours) Process of birth 4 Stages of labour (8-20 hours) Dilatation of the cervix (2-20 hours) The cervix is the lower end of the uterus It must open to allow the mature fetus to leave the mother’s body Opens wider over time and with each contraction Engagement of the baby’s head in the vagina (30 min – 2 hours) The baby moves through the cervix into the vagina The baby’s head rotates to help it’s body pass out of the vagina more easily

4 Stages of labour Process of birth Expulsion of the baby (5 to 60 min) Physician holds the baby’s head and gently eases the shoulders, trunk, and finally the lower limbs out of the mother’s body Baby’s head might be slightly deformed Expulsion of the placenta (10-15 min after birth) Once the baby is born, the contractions continue and cause the placenta to detach and be expelled

Different types of delivery Process of birth Different types of delivery Natural childbirth: with the active participation of the mother, no anesthetic Caesarean delivery of a baby through an abdominal incision performed when a vaginal birth is not possible or is not safe for the mother or child C-sections have become fairly common Induced labour: stimulated by the injection of a hormone Administering of a local anesthetic Epidural (injection into the spine)

Human Reproduction Test Friday, April 20th Female and male anatomy Know how to label a diagram (* you will not be given a word bank!) Know functions of all organs Puberty and hormones Menstrual Cycle Stages of development (zygote  embryo  fetus  Baby!) Process of birth

Test Format Same as usual: Multiple choice Labelling Matching (important vocabulary and definitions) Short answer Long answer