Power Point Lecture Outlines to accompany Holes Human

Power. Point Lecture Outlines to accompany Hole’s Human Anatomy and Physiology Eleventh Edition Shier w Butler w Lewis Chapter 23 Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. 1

Chapter 23 Pregnancy, Growth, and Development Pregnancy is the presence of a developing offspring in the uterus Growth is an increase in size and entails increases in cell numbers and cell sizes Development is the continuous process by which an individual changes from one life phase to another 2

Transport of Sex Cells • fertilization is the union of an egg cell and a sperm cell • figure shows paths of the egg and sperm cells through the female reproductive tract 3

Fertilization • • sperm cell reaches corona radiata of egg acrosome releases enzymes sperm cell penetrates zona pellucida sperm cell’s membrane fuses with egg cell’s membrane 4

Period of Cleavage • zygote • blastomeres • morula 5

Stages of Early Human Prenatal Development 6

Implantation • begins about the 6 th day of development • trophoblast will help form the placenta • trophoblast secretes h. CG which helps maintain the pregnancy 7

Summary of Stages and Events of Early Human Prenatal Development • fertilized ovum • 12 -24 hours after ovulation • zygote forms • cleavage • 30 hours to third day • mitosis increases cell number • morula • third to fourth day • solid ball of cell • blastocyst • fifth day through second week • trophoblast and inner cell mass form • gastrula • end of second week • primary germ layers form 8

Hormonal Changes During Pregnancy Mechanism that preserves uterine lining during early pregnancy 9

Hormonal Changes During Pregnancy Relative concentrations of three hormones in maternal blood during pregnancy 10

Hormonal Changes During Pregnancy • secretion of h. CG maintains corpus luteum • corpus luteum secretes estrogens and progesterone • placenta secretes large amounts of estrogens and progesterone • estrogens and progesterone stimulate and maintain uterine lining, inhibit FSH and LH, inhibit uterine contractions, and enlarge reproductive organs • relaxin from corpus luteum inhibits uterine contractions and relaxes pelvic ligaments • placental lactogen stimulates breast development • aldosterone promotes sodium retention • PTH maintains calcium concentrations in blood 11

Early Embryonic Stage Three primary germ layers form 12

Stages and Events of Early Human Prenatal Development 13

Derivatives of Each Primary Germ Layer 14

Embryos • three weeks; dorsal view • three and a half weeks; lateral view • four weeks; lateral view 15

Embryonic Development 16

Changes During Embryonic Development 17

Embryonic Membranes As the amnion develops, it surrounds the embryo, and the umbilical cord begins to form from structures in the connecting stalk 18

Placental membrane consists of • epithelial wall of an embryonic capillary • epithelial wall of a chorionic villus 19

Placenta Consists of an embryonic portion and a maternal portion 20

Placenta at Seventh Week 21

Embryo at Eight Weeks End of eighth week marks end of embryonic period 22

Teratogens • factors that cause congenital malformations during embryonic development • structures in developing embryo are sensitive to teratogens at different times 23

Fetal Stage • begins at the end of the eighth week of prenatal development • body portions change considerably during development 24

Development of External Reproductive Organs • differentiate from precursor structures 25

Position of Full-Term Fetus 26

Major Events of Fetal Development 9 th – 12 th week • ossification centers appear • sex organs differentiate • fetal limbs begin to move 13 th – 16 th week • body grows rapidly • ossification continues 27

Major Events of Fetal Development 17 th – 20 th week • muscle movements stronger • skin is covered with lanugo • skin is covered with vernix caseosa 21 st – 38 th week • body gains weight • subcutaneous fat deposited • eyebrows and eyelashes appear • eyelids open • testes descend 28

Stages of Prenatal Development 29

Fetal Blood and Circulation • oxygen and nutrients diffuse into the fetal blood from the maternal blood • waste diffuses into the maternal blood from the fetal blood 30

Fetal Cardiovascular Adaptations • fetal blood has greater oxygen-carrying capacity • umbilical vein carries oxygenated blood from placenta to fetus • ductus venosus conducts half the blood from umbilical vein to inferior vena cava; liver is bypassed • foramen ovale conveys blood from right atrium to left atrium; lungs are bypassed • ductus arteriosis conducts some blood from pulmonary trunk to aorta; lungs are bypassed • umbilical arteries carry blood from internal iliac arteries to placenta 31

Fetal Circulation 32

Fetal Circulation Summary 33

Birth Process Factors contributing to the labor process: • as birth approaches, progesterone levels decrease • prostaglandins synthesized which may initiate labor • stretching uterine tissue stimulates release of oxytocin • oxytocin stimulates uterine contractions • fetal head stretches uterus • positive feedback results in stronger and stronger contractions and greater release of oxytocin 34

Birth Process A positive feedback mechanism propels the birth process 35

Stages in Birth • fetal position before labor • dilation of the cervix • expulsion of the fetus • expulsion of the placenta 36

Milk Production and Secretion • placental estrogens and progesterone stimulate further breast development • estrogens cause ductile system to grow • progesterone causes alveolar glands to develop • placental lactogen also produces changes in breast • prolactin is released about the 5 th week of pregnancy • breast production does not begin until after birth 37

Release of Milk Myoepithelial cells contract to release milk from an alveolar gland 38

Mechanism of Milk Release 39

Hormonal Control of the Mammary Glands 40

Postnatal Period Neonatal period • birth to end of 4 th week • newborn begins to carry on respiration, obtain nutrients, digest nutrients, excrete wastes, regulate body temperature, and make cardiovascular adjustments Infancy • end of 4 th week to one year • growth rate is high • teeth begin to erupt • muscular and nervous systems mature • communication begins 41

Postnatal Period Childhood • one year to puberty • growth rate is high • permanent teeth appear • muscular control is achieved • bladder and bowel controls are established • intellectual abilities mature Adolescence • puberty to adulthood • person becomes reproductively functional and emotionally more mature • growth spurts occur • motor skills continue to develop • intellectual abilities continue to mature 42

Postnatal Period Adulthood • adolescence to old age • person remains relatively unchanged anatomically and physiologically • degenerative changes begin Senescence • old age to death • degenerative changes continue • body becomes less able to cope with demands placed on it • death results from various conditions and diseases 43

Major Changes in the Newborn’s Cardiovascular System 44

Stages of Postnatal Development 45

Aging-Related Changes 46

Causes of Death 47

Causes of Death 48

Clinical Application Preimplantation Genetic Diagnosis Probes diseasecausing genes in an eight-celled embryo 49