Chapter 21 Growth and Development. Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 2 PRENATAL PERIOD

Chapter 21Chapter 21Growth and DevelopmentGrowth and Development

Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 2

PRENATAL PERIODPRENATAL PERIOD

Prenatal period begins at conception and Prenatal period begins at conception and continues until birth (about 39 weeks)continues until birth (about 39 weeks)

Science of fetal growth and development Science of fetal growth and development called called embryologyembryology



Fertilization to implantation requires about 10 daysFertilization to implantation requires about 10 days Fertilization normally occurs in outer third of oviduct (Figure 21-Fertilization normally occurs in outer third of oviduct (Figure 21-

2)2) Fertilized ovum called a Fertilized ovum called a zygotezygote; zygote is genetically complete; zygote is genetically complete

—all that is needed for expression of hereditary traits is time —all that is needed for expression of hereditary traits is time and nourishmentand nourishment

After 3 days of cell division, the zygote has developed into a After 3 days of cell division, the zygote has developed into a solid cell mass called a solid cell mass called a morulamorula

Continued cell divisions of the morula produce a hollow ball of Continued cell divisions of the morula produce a hollow ball of cells called a cells called a blastocystblastocyst

Blastocyst implants in the uterine wall about 10 days after Blastocyst implants in the uterine wall about 10 days after fertilizationfertilization

Blastocyst forms the amniotic cavity and chorion of the Blastocyst forms the amniotic cavity and chorion of the placenta (Figure 21-4)placenta (Figure 21-4)

Placenta provides for exchange of nutrients between the Placenta provides for exchange of nutrients between the mother and fetusmother and fetus





Periods of developmentPeriods of development Length of pregnancy, or gestation period, is Length of pregnancy, or gestation period, is

about 39 weeksabout 39 weeks Embryonic phase extends from the third week Embryonic phase extends from the third week

after fertilization to the end of week 8 of after fertilization to the end of week 8 of gestationgestation

Fetal phase extends from week 8 to week 39 of Fetal phase extends from week 8 to week 39 of gestationgestation

All organ systems are formed and functioning All organ systems are formed and functioning by month 4 of gestation (Figure 21-6)by month 4 of gestation (Figure 21-6)




Three primary germ layers appear in the Three primary germ layers appear in the developing embryo after implantation of developing embryo after implantation of the blastocyst (Table 21-1):the blastocyst (Table 21-1): Endoderm—inside layerEndoderm—inside layer Ectoderm—outside layerEctoderm—outside layer Mesoderm—middle layerMesoderm—middle layer



Histogenesis and organogenesisHistogenesis and organogenesis Formation of new organs and tissues occurs Formation of new organs and tissues occurs

from specific development of the primary germ from specific development of the primary germ layerslayers

Each primary germ layer gives rise to definite Each primary germ layer gives rise to definite structures such as the skin and musclesstructures such as the skin and muscles

Growth processes include cell differentiation, Growth processes include cell differentiation, multiplication, growth, and rearrangementmultiplication, growth, and rearrangement

From 4 months of gestation until delivery, the From 4 months of gestation until delivery, the development of the baby is mainly a matter of development of the baby is mainly a matter of growthgrowth



Birth defectsBirth defects Any structural or functional abnormality present Any structural or functional abnormality present

at birthat birth May be caused by genetic factorsMay be caused by genetic factors

• Abnormal genesAbnormal genes

• Abnormal number of chromosomesAbnormal number of chromosomes

May be caused by environmental factorsMay be caused by environmental factors• Environmental factors are called Environmental factors are called teratogensteratogens

• Include radiation, chemicals, and infectionsInclude radiation, chemicals, and infections

• Especially harmful during the first trimester (Figure Especially harmful during the first trimester (Figure 21-7)21-7)



BIRTH, OR PARTURITIONBIRTH, OR PARTURITION

Process of birth called Process of birth called parturitionparturition (Figure (Figure 21-8)21-8) At the end of week 39 of gestation, the uterus At the end of week 39 of gestation, the uterus

becomes “irritable”becomes “irritable” Fetus takes head-down position against the Fetus takes head-down position against the

cervixcervix Muscular contractions begin, and labor is Muscular contractions begin, and labor is

initiatedinitiated Amniotic sac (“bag of waters”) rupturesAmniotic sac (“bag of waters”) ruptures Cervix dilatesCervix dilates Fetus moves through vagina to exteriorFetus moves through vagina to exterior







BIRTH, OR PARTURITIONBIRTH, OR PARTURITION

Stages of laborStages of labor Stage one—period from onset of uterine Stage one—period from onset of uterine

contractions until dilation of the cervix is contractions until dilation of the cervix is completecomplete

Stage two—period from the time of maximal Stage two—period from the time of maximal cervical dilation until the baby exits through the cervical dilation until the baby exits through the vaginavagina

Stage three—process of expulsion of the Stage three—process of expulsion of the placenta through the vaginaplacenta through the vagina


POSTNATAL PERIODPOSTNATAL PERIOD

Postnatal period begins at birth and lasts until Postnatal period begins at birth and lasts until deathdeath

Divisions of postnatal period into isolated time Divisions of postnatal period into isolated time frames can be misleading; life is a continuous frames can be misleading; life is a continuous process; growth and development are continuousprocess; growth and development are continuous

Obvious changes in the physical appearance of Obvious changes in the physical appearance of the body—in whole and in proportion—occur the body—in whole and in proportion—occur between birth and maturity (Figure 21-9)between birth and maturity (Figure 21-9)

Divisions of postnatal periodDivisions of postnatal period InfancyInfancy ChildhoodChildhood Adolescence and adulthoodAdolescence and adulthood Older adulthoodOlder adulthood




InfancyInfancy First 4 weeks called First 4 weeks called neonatal periodneonatal period (Figure 21-10) (Figure 21-10) Neonatology—medical and nursing specialty concerned with the Neonatology—medical and nursing specialty concerned with the

diagnosis and treatment of disorders of the newborndiagnosis and treatment of disorders of the newborn Many cardiovascular changes occur at the time of birth; fetus is totally Many cardiovascular changes occur at the time of birth; fetus is totally

dependent on mother, whereas the newborn must immediately dependent on mother, whereas the newborn must immediately become totally self-supporting (in respect to respiration and circulation)become totally self-supporting (in respect to respiration and circulation)

Respiratory changes at birth include a deep and forceful first breathRespiratory changes at birth include a deep and forceful first breath Developmental changes between the neonatal period and 18 months Developmental changes between the neonatal period and 18 months

include:include:• Doubling of birth weight by 4 months and tripling by 1 yearDoubling of birth weight by 4 months and tripling by 1 year• 50% increase in body length by 12 months50% increase in body length by 12 months• Development of normal spinal curvature by 15 months (Figure 21-11)Development of normal spinal curvature by 15 months (Figure 21-11)• Ability to raise head by 3 monthsAbility to raise head by 3 months• Ability to crawl by 10 monthsAbility to crawl by 10 months• Ability to stand alone by 12 monthsAbility to stand alone by 12 months• Ability to run by 18 monthsAbility to run by 18 months





ChildhoodChildhood Extends from end of infancy to puberty—13 Extends from end of infancy to puberty—13

years in girls and 15 in boysyears in girls and 15 in boys Overall rate of growth remains rapid but Overall rate of growth remains rapid but

deceleratesdecelerates Continuing development of motor and Continuing development of motor and

coordination skillscoordination skills Loss of deciduous (baby) teeth and eruption of Loss of deciduous (baby) teeth and eruption of

permanent teethpermanent teeth



Adolescence and adulthoodAdolescence and adulthood Average age range of adolescence varies; usually Average age range of adolescence varies; usually

considered to be from 13 to 19 yearsconsidered to be from 13 to 19 years Period of rapid growth resulting in sexual maturity Period of rapid growth resulting in sexual maturity

(adolescence)(adolescence) Appearance of secondary sex characteristics regulated Appearance of secondary sex characteristics regulated

by secretion of sex hormonesby secretion of sex hormones Growth spurt typical of adolescence; begins in girls at Growth spurt typical of adolescence; begins in girls at

about 10 and in boys at about 12 (Figure 21-12)about 10 and in boys at about 12 (Figure 21-12) Growth plates fully close in adult; other structures such Growth plates fully close in adult; other structures such

as the sinuses assume adult placementas the sinuses assume adult placement Adulthood characterized by maintenance of existing Adulthood characterized by maintenance of existing

body tissuesbody tissues Degeneration of body tissue begins in adulthoodDegeneration of body tissue begins in adulthood




Older adulthood (Figure 21-13)Older adulthood (Figure 21-13) Degenerative changes characterize older Degenerative changes characterize older

adulthood (also called adulthood (also called senescencesenescence)) Every organ system of the body undergoes Every organ system of the body undergoes

degenerative changesdegenerative changes Senescence culminates in deathSenescence culminates in death



EFFECTS OF AGINGEFFECTS OF AGING

Skeletal systemSkeletal system Aging causes changes in the texture, calcification, and Aging causes changes in the texture, calcification, and

shape of bonesshape of bones Bone spurs develop around jointsBone spurs develop around joints Bones become porous and fracture easilyBones become porous and fracture easily Degenerative joint diseases such as osteoarthritis are Degenerative joint diseases such as osteoarthritis are

commoncommon Integumentary system (skin)Integumentary system (skin)

With age, skin “sags” and becomes thin, dry, wrinkledWith age, skin “sags” and becomes thin, dry, wrinkled Pigmentation problems are commonPigmentation problems are common Frequently thinning or loss of hair occursFrequently thinning or loss of hair occurs



Urinary systemUrinary system Nephron units decrease in number by 50% Nephron units decrease in number by 50%

between ages 30 and 75between ages 30 and 75 Blood flow to kidney decreases and therefore Blood flow to kidney decreases and therefore

ability to form urine decreasesability to form urine decreases Bladder problems such as inability to void Bladder problems such as inability to void

completely are caused by muscle wasting in completely are caused by muscle wasting in the bladder wallthe bladder wall



Respiratory systemRespiratory system Calcification of costal cartilages causes rib Calcification of costal cartilages causes rib

cage to remain in expanded position—barrel cage to remain in expanded position—barrel chestchest

Wasting of respiratory muscles decreases Wasting of respiratory muscles decreases respiratory efficiencyrespiratory efficiency

Respiratory membrane thickens; movement of Respiratory membrane thickens; movement of oxygen from alveoli to blood is slowedoxygen from alveoli to blood is slowed



Cardiovascular systemCardiovascular system Degenerative heart and blood vessel disease is among Degenerative heart and blood vessel disease is among

the most common and serious effects of agingthe most common and serious effects of aging Fat deposits in blood vessels (atherosclerosis) decrease Fat deposits in blood vessels (atherosclerosis) decrease

blood flow to the heart and may cause complete blood flow to the heart and may cause complete blockage of the coronary arteriesblockage of the coronary arteries

Hardening of arteries (arteriosclerosis) may result in Hardening of arteries (arteriosclerosis) may result in rupture of blood vessels, especially in the brain (stroke)rupture of blood vessels, especially in the brain (stroke)

Hypertension or high blood pressure is common in older Hypertension or high blood pressure is common in older adulthoodadulthood



Special sensesSpecial senses All sense organs show a gradual decline in performance with All sense organs show a gradual decline in performance with

ageage Eye lenses become hard and cannot accommodate for near Eye lenses become hard and cannot accommodate for near

vision; result is farsightedness in many people by age 45 vision; result is farsightedness in many people by age 45 (presbyopia, or “old eye”)(presbyopia, or “old eye”)

Loss of transparency of lens or cornea is common (cataract)Loss of transparency of lens or cornea is common (cataract) Glaucoma (increase in pressure in eyeball) is often the cause Glaucoma (increase in pressure in eyeball) is often the cause

of blindness in older adulthoodof blindness in older adulthood Loss of hair cells in inner ear produces frequency deafness in Loss of hair cells in inner ear produces frequency deafness in

many older peoplemany older people Decreased transmission of sound waves caused by loss of Decreased transmission of sound waves caused by loss of

elasticity of eardrum and fixing of the bony ear ossicles is elasticity of eardrum and fixing of the bony ear ossicles is common in older adulthoodcommon in older adulthood

Some degree of hearing impairment is universally present in Some degree of hearing impairment is universally present in the agedthe aged

Only about 40% of the taste buds present at age 30 remain at Only about 40% of the taste buds present at age 30 remain at age 75age 75

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Chapter 21 Growth and Development. Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 2 PRENATAL PERIOD