Slide 1 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. Chapter 21 Growth and Development

Slide 2 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. PRENATAL PERIOD  Prenatal period begins at conception and continues until birth (about 39 weeks)  Science of fetal growth and development called embryology

Slide 3 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. PRENATAL PERIOD (cont.)  Fertilization to implantation requires about 10 days  Fertilization normally occurs in outer third of oviduct (Figure 21-2)  Fertilized ovum called a zygote; zygote is genetically complete—all that is needed for expression of hereditary traits is time and nourishment  After 3 days of cell division, the zygote has developed into a solid cell mass called a morula  Continued cell divisions of the morula produce a hollow ball of cells called a blastocyst  Blastocyst implants in the uterine wall about 10 days after fertilization  Blastocyst forms the amniotic cavity and chorion of the placenta (Figure 21-4)  Placenta provides for exchange of nutrients between the mother and fetus

Slide 4 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc.

Slide 5 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc.

Slide 6 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. PRENATAL PERIOD (cont.)  Periods of development  Length of pregnancy, or gestation period, is about 39 weeks  Embryonic phase extends from the third week after fertilization to the end of week 8 of gestation  Fetal phase extends from week 8 to week 39 of gestation  All organ systems are formed and functioning by month 4 of gestation (Figure 21-6)

Slide 7 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc.

Slide 8 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. PRENATAL PERIOD (cont.)  Stem cells—unspecialized cells that reproduce to form specific lines of specialized cells  Three primary germ layers appear in the developing embryo after implantation of the blastocyst (Table 21-1):  Endoderm—inside layer  Ectoderm—outside layer  Mesoderm—middle layer

Slide 9 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc.

Slide 10 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. PRENATAL PERIOD (cont.)  Histogenesis and organogenesis  Formation of new organs (organogenesis) and tissues (histogenesis) occurs from specific development of the primary germ layers  Each primary germ layer gives rise to definite structures such as the skin and muscles  Growth processes include cell differentiation, multiplication, growth, and rearrangement  From 4 months of gestation until delivery, the development of the baby is mainly a matter of growth

Slide 11 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. PRENATAL PERIOD (cont.)  Birth defects  Any structural or functional abnormality present at birth  May be caused by genetic factors Abnormal genes Abnormal genes Abnormal number of chromosomes Abnormal number of chromosomes  May be caused by environmental factors Environmental factors are called teratogens Environmental factors are called teratogens Include radiation, chemicals, and infections Include radiation, chemicals, and infections Especially harmful during the first trimester (Figure 21-7) Especially harmful during the first trimester (Figure 21-7)

Slide 12 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc.

Slide 13 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. BIRTH, OR PARTURITION  Process of birth called parturition (Figure 21-8)  At the end of week 39 of gestation, the uterus becomes “irritable”  Fetus takes head-down position against the cervix  Muscular contractions begin, and labor is initiated  Amniotic sac (“bag of waters”) ruptures  Cervix dilates  Fetus moves through vagina to exterior

Slide 14 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc.

Slide 15 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. BIRTH, OR PARTURITION (cont.)  Stages of labor  Stage one—period from onset of uterine contractions until dilation of the cervix is complete  Stage two—period from the time of maximal cervical dilation until the baby exits through the vagina  Stage three—process of expulsion of the placenta through the vagina

Slide 16 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. POSTNATAL PERIOD  Postnatal period begins at birth and lasts until death  Divisions of postnatal period into isolated time frames can be misleading; life is a continuous process; growth and development are continuous  Obvious changes in the physical appearance of the body—in whole and in proportion—occur between birth and maturity (Figure 21-9)  Divisions of postnatal period  Infancy  Childhood  Adolescence and adulthood  Older adulthood

Slide 17 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc.

Slide 18 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. POSTNATAL PERIOD (cont.)  Infancy  First 4 weeks called neonatal period (Figure 21-10)  Neonatology—medical and nursing specialty concerned with the diagnosis and treatment of disorders of the newborn  Many cardiovascular changes occur at the time of birth; fetus is totally dependent on mother, whereas the newborn must immediately become totally self-supporting (in respect to respiration and circulation)  Respiratory changes at birth include a deep and forceful first breath  Developmental changes between the neonatal period and 18 months include: Doubling of birth weight by 4 months and tripling by 1 year Doubling of birth weight by 4 months and tripling by 1 year 50% increase in body length by 12 months 50% 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 months Ability to raise head by 3 months Ability to crawl by 10 months Ability to crawl by 10 months Ability to stand alone by 12 months Ability to stand alone by 12 months Ability to run by 18 months Ability to run by 18 months

Slide 19 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc.

Slide 20 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc.

Slide 21 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. POSTNATAL PERIOD (cont.)  Childhood  Extends from end of infancy to puberty—13 years in girls and 15 in boys  Overall rate of growth remains rapid but decelerates  Continuing development of motor and coordination skills  Loss of deciduous (baby) teeth and eruption of permanent teeth

Slide 22 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. POSTNATAL PERIOD (cont.)  Adolescence and adulthood  Average age range of adolescence varies; usually considered to be from 13 to 19 years  Period of rapid growth resulting in sexual maturity (adolescence)  Appearance of secondary sex characteristics regulated by secretion of sex hormones  Growth spurt typical of adolescence; begins in girls at about 10 and in boys at about 12 (Figure 21-12)  Growth plates fully close in adult; other structures such as the sinuses assume adult placement  Adulthood characterized by maintenance of existing body tissues  Degeneration of body tissue begins in adulthood

Slide 23 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc.

Slide 24 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. POSTNATAL PERIOD (cont.)  Older adulthood (Figure 21-13)  Degenerative changes characterize older adulthood (also called senescence)  Every organ system of the body undergoes degenerative changes  Senescence culminates in death

Slide 25 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc.

Slide 26 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. EFFECTS OF AGING  Integumentary system (skin)  With age, skin “sags” and becomes thin, dry, wrinkled  Pigmentation problems are common  Frequently thinning or loss of hair occurs  Skeletal system  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  Physical activity can reduce loss of bone mass and mobility  Central nervous system  Increased risk of dementia  Mature reasoning ability

Slide 27 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. EFFECTS OF AGING (cont.)  Special senses  All sense organs show a gradual decline in performance with age  Eye lenses become hard and cannot accommodate for near vision; result is farsightedness in many people by age 45 (presbyopia, or “old eye”)  Loss of transparency of lens or cornea is common (cataract)  Glaucoma (increase in pressure in eyeball) is often the cause of blindness in older adulthood  Increased risk of retinal degeneration or detachment  Loss of hair cells in inner ear produces frequency deafness in many older people  Decreased transmission of sound waves caused by loss of elasticity of eardrum and fixing of the bony ear ossicles is common in older adulthood  Some degree of hearing impairment is universally present in the aged  Smell and taste may be reduced; only about 40% of the taste buds present at age 30 remain at age 75

Slide 28 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. EFFECTS OF AGING (cont.)  Cardiovascular system  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  Respiratory system  Calcification of costal cartilages causes rib cage to remain in expanded positionbarrel chest  Calcification of costal cartilages causes rib cage to remain in expanded position—barrel chest  Wasting of respiratory muscles decreases respiratory efficiency  Respiratory membrane thickens; movement of oxygen from alveoli to blood is slowed

Slide 29 Mosby items and derived items © 2012 by Mosby, Inc., an affiliate of Elsevier Inc. EFFECTS OF AGING (cont.)  Urinary system  Nephron units decrease in number by 50% between ages 30 and 75  Blood flow to kidney decreases and therefore ability to form urine decreases  Bladder problems such as inability to void completely are caused by muscle wasting in the bladder wall