1. Growth and Development
Chapter 33
Growth and Development

2. New Human Life Begins with the production of sex cells
In males called spermatogenesis
In females called oogenesis
Occurs due to meiosis (remember IPMATPMAT)
Gametes special cells in that they are haploids, not diploid, like somatic cells

4. Spermatogenesis
Begins about the time of puberty, continues throughout life
A primary spermatocyte (in seminiferous tube) undergoes meiotic division I, forms two secondary spermatocytes
Secondary spermatocytes undergo meiotic division II to form four spermatids
Spermatids differentiate to form head and tail

6. Oogenesis Production of female gametes
During fetal period oogonia (stem cells) multiply by mitosis
Oogonia transformed into primordial oocytes (marked by one layer of cells suurounding the oocyte)
Primary oocyte begin the first meiotic division BUT stop at prophase I (about 500,000 present at birth, around 100,000 will die before puberty)
During childhood, ganulosa cells develop around primary oocyte to form primary follicle
Puberty initiates the continuation of oogenesis
Each cycle, 1000 primary oocytes resume meiosis
Granulosa cells become theca cells—produce androgen (estrogen); now secondary follicles
Only 1 will survive and mature into antrum. A mature follicle ready to burst open from ovary surface is called a Graafian follicle

7. Meoisis I results in two daughter cells: a large cell called a secondary oocyte and a small cell called a first polar body
Just before ovulation meiosis stops again, at metaphase II
LH (luteinizing hormone) causes ovulation to happen
Meiosis II resumes only if the oocyte is penetrated by the head of a sperm
If fertilization doesn’t happen, the ova disentegrates
If fertilization does occur, meiotic division continues to produces a secondary polar body and a mature, fertilized ovum called a zygote

8. differences Spermatogenesis produces four spermatozoa
Oogenesis produces only one mature ovum and three polar bodies that disintegrate. The cytoplasm is not equally divided among the daughter cells, one large fluid filled cell is necessary to store all of the organelles, nutrients, and regulatory molecules.

9. Ovulation and Insemination
Ovulation-the expulson of a mature ovum from the mature ovarian follicle into the abdominopelvic cavity
Insemination-expulsion of the seminal fluid from the male urethra to female vagina

10. Fertilization
After ovum is released into the abdominopelvic cavity, it enters into the fallopian tube
Conception, fertilization, occurs here
An ovum only lives a day or so after ovulation.
Because sperm may live for a few days in the female body, fertilization can occur if sex occurs any time three days before up to a day after ovulation
A fertilized ovum (zygote) is a diploid. LIFE BEGINS—all it needs now is time to go through growth and development

11. Prenatal Period Runs from time of conception to birth (39-40 wks)
The study of this period of development is called embryology

12. Cleavage and Implantation
A zygote immediately begins to cleave (divide), after 3 days it becomes a mass of cells called a morula
The morula continues to divide to form a blastocyst by the time it reaches the uterus
10 days from conception, the blastocyst implants itself into the uterine lining
As the bastocyst develops further, it forms two cavities called the yolk sac and amniotic cavity

13. In humans, the yolk sac is not nutritive, it has other purposes like blood cell production
The inner lining mass of the blastocyst that will form the tissues of the offspring
The outer layer of the blastocyst called the trophoblast, that forms the support for the child

14. The amniotic cavity becomes fluid filled, shock absorbing sac, in which the embryo floats
The chorion develops into a vital fetal membrane in the placenta. This allows for embryonic cirulation
The placenta anchors the developing offspring to the uterus and provides and exchange for nutrients and waste products from mom to child

15. Placenta
Contains maternal and fetal blood supplies—kept separated by a very thin layer of placental tissue
Important endocrine function
Secretes human chorionic gonadotropin (HCG)
HCG stimulates the corpus luteum to secrete estrogen and progesterone—stopping menstruation
After week ~16, placental starts secreting its own estrogen and progesterone
At home preg. Test measure the HCG in urine

16. Periods of Development
Pregnancy is about 39 weeks, called gestation period
Is divided into trimesters
1st goes from first day of last menstrual period to the end of 12 wks
2nd goes from end of 12 wks to end of 28wk
3rd goes from end of 28 wk until the delivery

17. 1st trimester Use term zygote when first fertilized
Use term morula (a solid mass of cells after 3 days) and then a blastocyst until it implants itself into the uterus
Embryonic starts from fertilization until end of 8wks, after 8wks until birth use term fetus

18. 1st trimester con’t
The first trimester ( weeks), is one of the most crucial for the baby.
Week 1 to week 4
Gender is determined
Implantation occurs—bleeding may occur days after fertilization as the blastocyst imbeds itself in uterus
Neural tube forms—will become basis of nervous system (brain, spinal cord, hair, and skin)
Heart and primitive circulatory system forms

19. Week 5 First heartbeats begin – ultrasounds show heart beat
Umbilical cord develops - This the baby's lifeline in utero. It bears the responsibility of pumping in oxygen, removing waste, and supplying the necessary nutrients for the remainder of the pregnancy.
Blood is now pumping - All four heart chambers are now functioning
Most other organs begin to develop - infant's lungs start to appear, along with the brain.
Arm and leg buds appear

20. Week 6 The arms and legs continue to develop Brain continues growing
Lenses of the eyes appear
Nostrils are formed - The position of the nose seems to shift into its proper place as well. Soon, the nerves running from the nose to the brain appear.
Intestines grow - Initially these are actually located outside the baby's body within the umbilical cord.
Pancreas - The baby is now equipped to deal with digestive enzymes and take on processing the insulin and glucagons the body needs to function.

21. Week 7 Elbows form, fingers develop
Feet start to appear with tiny notches for the toes
Ears eyes and nose start to appear - Although they may resemble an alien life form, these all "shift" soon enough into a more normal appearance.
Intestines continue to form in the umbilical cord
Teeth begin to develop under the gums

22. Week 8 Cartilage and bones begin to form
The basic structure of the eye is well underway
The tongue begins to develop
Intestines move out of the umbilical cord into the abdomen
Body grows and makes room
The fingers and toes have appeared but are webbed and short
Baby's length (crown to rump) is 0.61 inch (1.6cm) and weight is 0.04 ounce (1gm)

23. Week 9 Baby has begun movement—too small to be felt by mother
Most joints are formed
Fetus will curve its fingers around an object placed in the palm of its hand
Fingerprints are already evident in the skin
Average size this week -- length 0.9 inch (2.3cm), weight 0.07 ounce (2gm)

24. Week 10
The most critical part of infant's development is complete. Now headed into a period of rapid growth.
baby's head is now about half its length
Eyelids fuse shut and irises begin to develop - Eye color is also determined by this point.
Placenta begins to function this week or next
baby will be about 1.22 inch long (3.1cm) and weigh 0.14 ounce (4gm) at the end of this week

25. Week 11
Nearly all structures and organs are formed and beginning to function.
Fingers and toes have separated
Hair and nails begin to grow
The genitals begin to take on the proper gender characteristics
Amniotic fluid begins to accumulate as the kidneys begin to function - This fluid, consisting primarily of water, helps provide a cushion for baby
The muscles in the intestinal walls begin to practice contractions that digest food
Baby is about 1.61 inches (4.1 cm) long and weighs 0.25 ounce (7gm).

26. Week 12 Vocal cords begin to form eyes begin to move closer together
Ears shift to their normal place on the side of the head
Intestines move farther in child's body
liver begins to function
pancreas begins to produce insulin
baby's average size is now at a whopping length: 2.13 inches (5.4cm) and weight: 0.49 ounce (14gm)

27. Week 13
infant is about 2.91 inches (7.4cm) and weighs around 0.81 ounce (23gm)
begins to practice inhaling and exhaling movements
Eyes and ears continue to move and develop
Baby's neck is getting longer, and the chin no longer is resting on chest
hands are becoming more functional—starts playing with fist
At this point all nourishment is received from the placenta
should be able to hear heartbeat with a Doppler

28. Week 14 Thyroid gland has matured and baby begins producing hormones
In boys, the prostate gland develops
In girls, the ovaries move from the abdomen to the pelvis
may have learned to suck his thumb
child's bones are getting harder and stronger
baby's skin is very transparent
Lanugo (very fine hair) covers the baby's body
baby is 3.42 inches (8.7cm) long and weighs about 1.52 ounces (43 grams)

29. Week 1
Week 2
Week 3
Week 4
Week 5
Week 8
Week 6
Week 10
Week 9
Week 7
Week 11
Week 12
Week 14
Week 13

30. Second Trimester the honeymoon stage of pregnancy Week 15
may begin to feel some fluttering movements as baby kicks, flails, twists and turns
baby's legs have grown longer than the arms and the body is now longer than the head.
skin is very thin -- so thin blood vessel are visible. It's covered by a fine, soft layer of hair called lanugo. Lanugo comes from a Latin word meaning "down." This hair is thought to help insulate.
Incus, malleus,and stapes in middle ear have begun to harden.
Fingernails and toenails are growing; Eyebrows are beginning to grow
Baby is 3.98 inches (10.1cm) long and may weigh 2.47 ounces (70gm).

31. Week 16 Fat begins to form underneath skin
baby and placenta are now about the same size
Baby is 4.57 inches (11.6cm) and approximately 3.53 ounces (100gm).
head and neck are held straighter
might hear the tiny thumps of his heartbeat with an external monitor; might be able to determine gender
Heart is pumping as much as 6 gallons of blood a day and beats at a rate about double maternal heart rate.
Sucking, swallowing and blinking are now evident
baby has learned to breathe—inhales and exhales small amounts of amniotic fluid

32. Week 17
baby weighs about 4.97 ounces (140gm) and is 5.12 inches (13cm) long
has a much more normal "human" appearance
Pads are forming on his tiny fingertips and toes
eyes are looking forward now, but they are still firmly closed.
Meconium (composed of products of cell loss, digestive secretion and swallowed amniotic fluid), is accumulating in the bowel. This black gooey substance will become baby's first poop!
The umbilical cord is growing thicker and stronger
the prostate begins to develop in males
skeleton is transforming from cartilage to bone

33. Week 18
Vernix (a white cheese-like protective material) forms on baby's skin with the lanugo (soft, lightly pigmented hair covering the body and limbs); both serving to protect baby's skin during the months in water.
Tiny air sacs called alveoli begin to form in lungs
vocal chords are formed. Baby goes through the motions of crying but without air doesn't make a sound
Features of baby's heart, including ventricles and chambers, should be visible during an ultrasound.
baby measures about 5.59 inches (14.2cm) this week and weighs about 6.7 ounces (190gm)

34. Week 19 baby has the same awake and sleep patterns of a newborn.
nerves are being coated with a fatty substance called myelin, which insulates the nerves so that impulses can flow smoothly.
Scalp hair becomes apparent
The milk teeth buds have already developed and over the next few days the buds for the permanent teeth will begin to form behind the milk teeth.
If baby is female the uterus starts to develop--the vagina, uterus, and fallopian tubes are in place.
If it's a boy, the genitals are distinct and recognizable.
baby is swallowing amniotic fluid and his or her kidneys are making urine
size is around 6.02 inches (15.3cm) and 8.47 ounces (240gm)

35. Week 20 The rapid growth stage is about over
The baby's heart grows stronger—may be able to feel heartbeat through abdomen
legs are reaching their relative size
Immunities are being transferred from mother to baby now. These immune cells will protect baby from viruses mother has already had for up to six months after birth
The nerve cells for taste, smell, hearing, seeing, and touch are now developing in specialized areas of the brain. Production slows down as existing nerve cells grow larger and make more complex connections.
baby may startle in reaction to loud sounds. Amazingly, can actually hear noises outside of the womb. Familiar voices, music, and sounds that baby becomes accustomed to during development stages often are calming after birth.
girl, uterus is starting to develop. She has approximately six million eggs in her ovaries. About one million will remain at birth.
Baby is about 6.46 inches (16.4cm) and weighs around ounces (300g )

36. Week 21 White blood (leukocytes) cells are under production
skin has changed from translucent to become more opaque.
infant's tongue is fully formed
womb and vagina are formed
Baby swallows more this week. After baby takes in amniotic fluid, body absorbs the water in the liquid and moves the rest into the large bowel--- good practice for digestive system
Wake and sleep periods become more consistent
Baby measures about inches (26.7cm) and weighs nearly 12.7 ounces (360g).

37. Week 22
When mother talks, reads, or sings, expect baby to hear you. Studies have found that newborns will suck more vigorously when read to from a book they heard frequently in utero.
Eyelids and eyebrows are fully formed.
Fingernails have grown to the end of the fingers
Baby's brain has entered a stage of rapid growth, especially in what's called the germinal matrix. This structure deep in the middle of the brain serves as a kind of factory for brain cells and disappears shortly before birth. But the brain's amazing expansion program continues until around the five birthday.
baby's liver is starting to break down bilirubin, a substance produced by red blood cells that is involved in the catabolism of biological molecules. What causes yellow color in bruise and brown color in feces
Testes begin their descent to the scrotum--Primitive sperm have formed and he is producing testosterone.
Length is inches (27.8cm); weight is nearly 1 pound (430gm).

38. Week 23
Proportions of the body are now quite similar to a newborn—little to no fat
eyes are formed, though the iris still lacks pigmentation
The pancreas, essential in the production of hormones, is developing steadily –insulin is now being produced
If born now, baby has a 15% chance of survival
average baby at this stage weighs 1.1 pound (501gm) and is inches (28.9cm) long

39. Week 24
Baby gains about 6 ounces this week. The weight is in muscle, bone mass and organs
Taste buds begin to form. If mom drinks something strange or bitter, baby may be observed showing distaste
Little creases have appeared on palms. The muscular coordination of hands has improved as sucks thumb
lungs are developing "branches “
baby is officially considered viable
Baby weighs 1.3 pound (600gm) and is 11.8 inches (30cm) long

40. Week 25 structures of the spine begin to form
Blood vessels of the lungs develop
Nostrils open--study out of Belfast that suggests babies at this stage have the capability of scent preferences
nerves around the mouth and lip area are showing more sensitivity
Dexterity is improving
approximate length of 13.6 inches (34.6cm) and weighs 1.46 pound (660gm)

41. Week 26
weigh about two pounds now (average is 1.7 pound, 760gm) and is 14 inches (35.6cm) in length
the spine is getting stronger and more supple
Air sacs in the lungs form--Lungs begin to secrete a greasy substance called surfactant. Without surfactant the fetal lungs would stick together and couldn't expand after the baby is born
baby's eyes are opening and beginning to blink
Retinas begin to form.
Brain wave activity for hearing and sight begins to be detectable.
Fetal brain scans show response to touch

42. Week 27
Response to sound grows more consistent –baby recognizes mother and father’s voice
Lungs continue to grow and prepare for functioning outside of the womb
Eyelids are now open more-- baby can distinguish between light and dark
Average size is now 14.4 inches (36.6cm) and 1.9 pound (875gm)

43. Week 28 Eyebrows and eyelashes are now very noticeable
Eyes are completely formed now
baby's body is getting plump and rounded. Most of that increase is muscle tissue and bone. Fat will be added during the third trimester
Muscle tone is improving
Lungs are capable of breathing now (but baby would still struggle and require medical attention if born now )
baby weighs in now at 2.2 pounds (1005gm) and is 14.8 inches (37.6cm).

44. Third Trimester Week 29 Fat continues to accumulate under the skin
Baby's brain can control primitive breathing and body temperatures.
eyes can move in their sockets
moving from side to side---still in head up position
length is now approximately 15.2 inches (38.6cm) and weight is 2.54 pounds (1153gm)

45. Week 30 Early lanugo is beginning to disappear
Toenails are entering their final growth stage.
Bone marrow is now in charge of red blood cell production
Baby produces tears
baby is now 15.7 inches (39.9cm) long and weighs 2.91 pounds (1319gm)

46. Week 31 Fat continues accumulating
Calcium, phosphorus and iron are being stored and bones are growing and hardening
baby is 16.2 inches (41.1cm) long and weighs 3.3 pounds (1502gm)
may move to the rhythm of music. Studies with heart rates show that prefers some types of music to others
Lungs are the only major organ left to complete development

47. Week 32
baby is up to 3.75 pounds (1702gm) now and is 16.7 inches (42.4cm) long
not moving around as much---running out of room
All five senses are working
babies have periods of dream sleep (REM) starting around the eight month

48. Week 33
Amniotic fluid is at its highest level
Neurons and synapses are developing in huge numbers—can now coordinate sucking, swallowing, and breathing
testicles will be descending from abdomen to scrotum
Baby is now 17.2 inches (43.7cm) long and weighs 4.23 pounds (1918gm).

49. Week 34
baby may have already turned to a head-down position in preparation for birth
length is 17.7 inches (45cm) and weight is 4.7 pounds (2146 g).
Week 35
Most babies born now will survive and without many long-term problems
baby is now taking up most of the uterus
baby is 18.2 inches (46.2cm) long and weighs 5.3 pounds (2383gm).
The testes have completed their descent in males

50. Week 36 baby may drop into the birth canal
Fat is dimpling your baby's elbows and knees, and forming creases in the neck and wrists
average size is now inches (47.4cm) and 5.78 pounds (2622 g). Between now and birth will gain about an ounce a day

51. Week 37
average size is about 6.3 pounds (2859gm) now and 19.1 inches (48.6cm) length
official full term now but can still benefit from extra days in the womb
turns towards light outside the uterus
develops definite daily activity cycles—keep yourself on sleep cycle to develop night/day differentiation in baby

52. Week 38
average baby," weights 6.8 pounds (3083gm)and is 19.6 inches (49.8cm) long
amniotic fluid to get into windpipe---resulting in Hiccups
child's intestines are accumulating lots of meconium
Circumference of head and abdomen are about the same size for baby

53. Week 39 The lanugo has mostly disappeared
lungs are maturing and surfactant production is increasing
body continues laying on the fat stores that will help regulate body temperature after birth. In addition to normal fat, is accumulating Brown adipose tissue (BAT) "brown" fat in the nape of neck, between shoulders and around organs. Brown fat cells are important for thermogenesis (generating heat) during first weeks of life.
infant's weight is around 7.25 pounds (3288gm) and length is 19.9 inches (50.7cm)

54. Week 40 15% of your child's body is fat
Small breast buds are present on both sexes
Birth occurs at any time
Average baby now weighs 7.6 pounds (3462gm) and is 20.2 inches (51.2cm) long

55. labor Term used to describe the process that results in birth
Three stages:
One: period from the onset of uterine contractions until dilation of cervix is complete (10cm)
Two: period from the time of maximal cervical dilation until baby exits vagina
Three: process of expulsion of the placenta through the vagina

56. Average time of stage one labor is 6-24 hrs
Average time of stage one labor is 6-24 hrs. (first pregnancies usually the longest and hardest)
Stage two lasts up to one hour
Stage three 15 minutes after birth

57. Ultrasound Pictures

58. 3-D Sonogram Pictures

59. Problems during Pregnancy and parturition
Implantation Disorders
Ectopic pregnancy: blastocyst implants itself in endometriosis region, normal peritoneal membranes, or in the oviduct
If the tissue can stretch, may be able to develop child full term—must be delivered C-section
Tubal pregnancies result in rupture and life-threatening hemorrhaging (most common type of ectopic pregnancy)

60. Placenta previa
Blastocyst implants in the uterine wall at or near cervix
May cause massive blood loss during third trimester—threatens both mother and child
Will be placed on bed rest

61. Abruptio placentae
Separation occurs of the placenta from the uterine wall
Occurs around 20 wks
Complete separation causes immediate death of fetus; severe hemorrhaging occurs causing circulatory shock and death of mother in minutes
C section and/or historectomy must be performed immediately to save mother

62. Blood Pressure—Unknown cause
PIH
Pregnancy induced hypertension raises bp in women—will be on bed rest if not able to control with meds.
6-8% of PIH results in preeclampsia (toxemia)
Severe blood pressure increase, edema, protein in urine (kidney failure)
May result in abruptio placentae, stroke, hemorrhage, fetal malnutrition, low birth weight
Symptoms
Rapid weight gain
Swelling of the arms or face
Headache
Changes in vision (blurred vision, seeing double, seeing spots of light)
Dizziness, faintness
Ringing in the ears
Abdominal pain
Decreased production of urine
Nausea, vomiting
Blood in vomit or urine
Confusion

63. Preeclampsia may lead to eclampsia
life threatening
Causes severe convulsions, coma, kidney failure, heart related problems, death of mother and fetus
Risk factors
First pregnancies (first child with new partner)
Mother or sister having preeclampsia or eclampsia
Teenage pregnancies
Being 35 or older
Being African-American
Multiple pregnancies (twins, triplets, etc.)
History of diabetes, hypertension, or renal disease

64. Sensory and coordination changes
Hiatal hernia
Upward pressure causes abdominal organs to push against diaphram, stomach protrudes into the thoracic cavity
Sensory and coordination changes
Control systems often do not compensate for shift in center of gravity

65. Fetal Death Miscarriage Loss of embryo before 12th wk
Spontaneous abortion
May be caused by hypertension, uterine abnormalities, and hormonal imbalances
After 20 wks, called stillbirth (labor and delivery of a dead fetus)

66. Birth Defects
Congenital abnormalities—will study further during genetics.
Any structural or functional abnormality that is inherited or acquired during gestation or delivery
Alcohol, antibiotics, radiation, microorganisms, etc. that cause defect are called teratogens

67. Postpartum disorders
Preeclampsia and eclampsia may continue to cause problems after birth
Puerperal fever: a syndrome characterized by bacterial infection that becomes septicemia (infection of blood) and possible death (leading cause of ~ 20% maternal death until 1930s)

68. Depression: hormonal changes may cause clinical depression in postpartum mother
Mastitis: breast inflammation