Growth and Development Chapter 24 Notes

Conception until birth

Science of fetal growth and development.

Fusion of one sperm with the ovum, also called conception.

Outer third oviduct (uterine or Fallopian tube)

Fertilized ovum, single-celled organism formed by union of one sperm with ovum; zygote is genetically complete

morula

An ovum is released from the ovary and it begins its journey through the uterine tube.

A hollow called a blastocyst so that implantation may occur

˜the amniotic cavity and chorion of the placenta.

a fluid-filled, protective amniotic sac.

The placenta

Chorionic villi

10 days after ovulation

Diffusion from uterine fluids

• anchors the developing fetus to the uterus
• provides a “bridge” for the exchange of nutrients and waste products between mother and baby
• functions as an excretory, respiratory, and endocrine organ.

The maternal side is lacunae filled with maternal blood; a very thin layer of placental tissue separates maternal blood from fetal blood

alcohol, rubella, etc.

From the third week after fertilization to to the end of week 8 of gestation.

From week 8 to week 39 of gestation?

About 39 weeks

Formation of tissues happens before tissues become organs.

• week 39, uterus becomes irritable 
• fetus takes head-down position against the cervix
• contractions begin then labor is initiated
• amniotic sac (water) ruptures
• cervix dilates
• fetus moves through vagina to exterior

Generally 6 to 25 hours

Uterine contractions and maternal pushing.

˜period from onset of uterine contractions until dilation of the cervix is complete

period from the time of maximal cervical dilation until the baby exits through the vagina

˜process of expulsion of the placenta through the vagina

the recovery period immediately following delivery of placenta

General condition of a newborn infant

˜surgical delivery, usually through an incision in the abdomen and uterine wall (2 incisions req.)

Identical twins develop from one ovum and one sperm. Fraternal twins develop from multiple ova and sperm.

• implantation outside the uterus (tubal pregnancy)
• treated by surgical removal of products of pregnancy

• growth of the placenta at or near cervical opening, often resulting in separation of the placenta from the uterine wall
• treated by delivery of the fetus by C-section

• separation of a normally placed placenta from the uterine wall; causes fetal death within minutes and mother can hemorrhage
• treated by emergency C-section

• toxemia of pregnancy
• hypertension, proteinuria and edema
• may progress to eclampsia, a severe toxemia that may result in death
• occurs in about 1 out of 20 pregnancies 
• causes largely unknown

Radiation [like x-rays], chemicals [like alcohol or drugs], and infections [like herpes or cytomegalovirus]

The difference is the length of gestation at which it occurs; miscarriage occurs before the twentieth week. After 20 weeks, delivery of a lifeless infant is termed a stillbirth.

Teratogens

˜caused by bacterial infection that may progress to septicemia and death; occurs in mothers after delivery (postpartum)

anemia, malnutrition and other factors

inflammation or infection of the breast

Bacteria that infects the mother through contaminated hands or equipment

It may be contraindicated if the milk is contaminated with pathogenic organisms

infancy, childhood, adolescence, adulthood

The head becomes proportionately smaller, and the legs become proportionately longer and the trunk shorter

• Birth to about 18 months
• First 4 weeks called neonatal period

medical and nursing specialty concerned with the diagnosis and treatment of disorders of the newborn

• cardiovascular - at birth newborn must immediately become totally self-supporting 
• respiratory - deep and forceful first breath

• ˜Doubling of birth weight by 4 months and tripling by 1 year
• ˜Fifty percent increase in body length by 12 months
• ˜Development of normal spinal curvature by 15 months
• ˜Ability to raise head by 3 months˜
• Ability to crawl by 10 months˜
• Ability to stand alone by 12 months˜
• Ability to run by 18 months

• infancy to puberty 
• ˜overall rate of growth remains rapid but decelerates˜
• continuing development of motor and coordination skills˜
• loss of deciduous or baby teeth and eruption of permanent teeth

girls—12 to 14 years; boys—14 to 16 years

• average age range of adolescence is from 13 to 19 years
• period of rapid growth resulting in sexual maturity 
• appearance of secondary sex characteristics
• growth spurts at about 10 and boys about 12

• many body traits don’t become apparent until adulthood, such as normal balding patterns.
• growth plates fully close in adult
• adulthood is characterized by maintenance of existing body tissues
• degeneration of body tissue begins in adulthood

the study of aging

another term for older adulthood

• degenerative changes
• every organ system of the body undergoes degenerative changes
• number of oxygen free radicals increases as one ages, thus increasing the rate of cellular damage
• culminates in death

It is a genetic disease that causes rapid apparent aging. Cells do not reproduce quickly enough and children begin to look old quickly. Most people die of cardiovascular disease in their teens or twenties.

• free radicals increase the rate of cellular damage over time
• nutrition, injury, disease and other environmental facts affect aging process
• cellular changes due to "aging" viruses found in all living cells
• "Aging" genes cause preprogrammed aging
• diminished capacity of cells to reproduce over time

highly reactive forms of oxygen that are normal by-products of cellular respiration in the mitochondria and other cell processes.

• Aging causes changes in the texture, calcification, and shape of bones
• Bone spurs develop around joints
• Bones become porous and fracture easily
• Degenerative joint diseases, such as osteoarthritis, are common

Older bones develop indistinct and shaggy-appearing margins with spurs. This can restrict mobility.

• ˜with age, skin “sags” and becomes thin, dry, and wrinkled (or inelastic)
• ˜pigmentation problems are common
• ˜frequent thinning or loss of hair occurs

It becomes inelastic and that contributes to some of the other changes.

• ˜risk of dementia, or loss of memory, with aging
• ˜other degenerative conditions affecting nervous system
• ˜some risk of depression

Through the use of bifocals, or glasses with two lenses, to help people see up close

age-related farsightedness

Loss of transparency of lens or cornea is common

˜All sense organs show a gradual decline in performance with age

Loss of hair cells in the organ of Corti results in decline in ability to hear certain frequencies.

increase in pressure in the eyeball; often the cause of blindness in older adulthood

• ˜Degenerative heart and blood vessel disease is among the most common and serious effects of aging
• ˜Fat deposits in blood vessels (atherosclerosis) decrease blood flow to the heart and may cause complete blockage of the coronary arteries˜
• Hardening of arteries (arteriosclerosis) may result in rupture of blood vessels, especially in the brain (stroke)
• ˜Hypertension, or high blood pressure, is common in older adulthood

A blockage or hemorrhage of an artery in the brain; cerebrovascular accident [CVA].

a heart attack or myocardial infarction (MI)

• calcification of costal cartilages which leads to a barrel chest
• wasting of respiratory muscles decreases respiratory efficiency 
• respiratory membrane thickens; movement of oxygen from alveoli to blood is slowed

Ribs become “fixed” to the sternum; rib cage remains in a more expanded position; respiratory efficiency decreases.

it decreases the strength of the muscles associated with inspiration and expiration

• ˜Nephron units decrease in number by 50% between ages 30 and 75˜
• Blood flow to kidney, and therefore ability to form urine, decreases˜
• Bladder problems, such as inability to void completely, are caused by muscle wasting in the bladder wall
• Benign prostatic hypertrophy in the male contributes to difficulty starting the urinary stream and completely emptying the bladder, there is also decreased bladder capacity.

• ˜Changes in the sexual response
• Men—erection is more difficult to achieve and maintain; urgency for sex may decline
• Women—lubrication during intercourse may decrease
• ˜Changes in fertility
• Men—may continue to be fertile throughout later adult years
• Women—experience menopause (cessation of reproductive cycling) between the ages of 45 and 60

hotflashs, sleep disturbances, dryness and thinning of the vaginal wall

HRT is used in younger women when they first enter menopause. Medications that do not contain estrogen are now available to help with symptoms.

• ˜Not a disease condition, but a natural period of change
• ˜Decreased blood estrogen levels leads to symptoms like hot flashes, sleep disturbances, and dryness in the vagina

˜increased risk of some cancers, stroke, and blood clotting disorders

• Sperm (male gamete) and ovum (female gamete) fuse during fertilization 
• Zygote
• Morula
• Blastocyst
• Embryo 
• Fetus 
• Neonate 
• Infant

Fertilized egg becomes blastocyst then attaches to uterus

the blastocyst forms chorion that have yet to be differentiated and the chorion forms the placenta