LSE 10B FLASHCARDS (prenatal)

Prenatal stage

from conception until birth

Approx. 9 months or 270-280 days

Characteristics of Prenatal stage

1. The hereditary endowment is fixed, once and for all, at this time.

2. Favorable conditions in the mother’s body can foster the development of hereditary potentials while unfavorable conditions can stunt their development.

3. The sex of the newly created individual is fixed at the time of conception and conditions within the mother’s body will not affect it.

4. Proportionally greater growth and development take place during the prenatal period.

5. The prenatal period is a time of many hazards, both physical and psychological.

6. The prenatal period is the time when significant people form attitudes toward newly created individual.

How life begins

union of male sex cell (spermatozoa) and female sex cell (ova)

Sperm and egg cells differ

1. number of chromosomes

2. number of preparatory stages

Number of chromosomes

mature ovum has 23 match chromosomes

mature spermatozoa has 22 match chromosomes and 1 unmatched chromosome (X or Y, determining the gender)

Number of preparatory stages

male: maturation → fertilization

female: maturation → ovulation → fertilization

Maturation

process of chromosome reduction through cell division (meiosis)

Ovulation

limited to female sex cells; it is a process of escape of one mature ovum during the menstrual cycle

Fertilization

occurs at the time conception; it is a beginning of new life; it takes place within 12-36 hours

Timetable of development

1. Period of ZYGOTE

2. Period of EMBRYO

3. Period of FETUS

Period of zygote

- Fertilization to end of 2nd week

- Size is like a pinhead

Period of Embryo

- End of 2nd week to end of second month

- Major development occurs

- The placenta, umbilical cord, and amniotic sac develop.

- It is regarded as critical time

First month of embryo

▪ 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

▪ Fertilization occurs

▪ Zygote implants itself in the lining of the uterus

▪ Rapid cell division occurs

▪ Cells differentiate into three distinct layers: the ectoderm, the mesoderm, and the endoderm

▪ Nervous system begins to develop

Second month of embryo

▪ Embryo is 1/2 inch long (Week 5)

▪ Heart and blood vessels form

▪ Head area develops rapidly

▪ Eyes begin to form detail

▪ Internal organs grow, especially the digestive system

End of 8 weeks of embryo

• 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 cannot yet feel movement

• Sex organs develop rapidly and sex is distinguished

• Arms and legs form and grow

• Heart begins to beat faintly

• Embryo weighs 1/10 ounce

Period of fetus

- End of 2nd month to birth

Third month of fetus

▪ By now the fetus is 2 1/2 to 3 inches long and is fully formed.

▪ Baby has begun swallowing and kicking.

▪ All organs and muscles have formed and are beginning to function.

▪ Head growth occurs rapidly

▪ Some internal organs are developed enough to begin to function

▪ Bone formation begins to form rapidly

▪ The digestive organs begin to function

▪ Arms, legs, and fingers make spontaneous movements

▪ Fetus weighs 1 ounce

Fourth month of fetus

▪ Your baby is covered with a layer of thick, downy hair called lanugo.

▪ Baby’s heartbeat can be heard clearly.

▪ This is when you may feel your baby's first kick.

▪ Fetus is 7 inches long and weighs 5 ounces

Lanugo

thick hair to protect baby (for heat regulation)

Fifth month of fetus

A protective coating called vernix caseosa begins to form on baby's skin.

▪ By the end of this month, your baby will be nearly 8 inches long and weigh almost a pound.

▪ Fetus shows hiccups, thumb sucking, and kicking

vernix caseosa

protective coating/skin protectant (acts as lotion)

Sixth month of fetus

▪ Eyebrows and eyelids are visible.

▪ Your baby's lungs are filled with amniotic fluid, and the baby has started breathing motions.

▪ If you talk or sing, the baby can hear you.

▪ Eyes and eyelids fully formed

▪ Fat is developing under the skin

▪ Fetus is 14 inches long and weighs 2 pounds

Seventh month of fetus

▪ By the end of the seventh month, your baby weighs about 3 1/2 pounds and is about 16 inches long.

▪ Baby’s body is well-formed.

▪ Fingernails cover the baby’s fingertips

▪ Well-developed enough to survive

▪ Cerebral cortex of brain develops rapidly

Eighth month of fetus

▪ Your baby is gaining about half a pound per week, and layers of fat are piling on.

▪ The baby has probably turned head-down in preparation for birth.

▪ The baby weighs between 4 and 6 pounds.

▪ Subcutaneous fat is deposited for later use

▪ Fingernails reach beyond the fingertips

Ninth month of fetus

▪ Hair covering the entire body is shed

▪ Organ systems function actively

▪ Vernix is present over the entire body

▪ Fetus settles into position for birth

▪ Your baby is a hefty 6 to 9 pounds and measures between 19 and 22 inches.

▪ As the baby becomes more crowded, you may feel him move around less.

Kinds of birth

1. Natural or spontaneous birth

2. Breech birth

3. Transverse birth

4. Instrument birth

5. Caesarean Section

Natural or spontaneous birth

headfirst position

Breech birth

buttocks down position

Transverse birth

positioned crosswise on the mother’s uterus

Instrument birth

instrument must be used to aid in delivery

Caesarean birth

a slit is made surgically in a mother’s abdominal wall