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Chapter 23Lecture
PowerPoint
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2402Anatomy and Physiology II
Chapter 23
Susan Gossett
sgossett@parisjc.edu
Department of Biology
Paris Junior College
3
Hole’s Human Anatomyand Physiology
Twelfth Edition
Shier Butler Lewis
Chapter 23
Pregnancy, Growth,And Development
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23.1: Introduction• A sperm and a secondary oocyte unite, forming a zygote, and the journey of prenatal development begins• After 38 weeks of cell division, growth and specialization into distinctive tissues and organs, a new human being enters the world• Humans grow, develop and age
• Growth is an increase in size• Development, which includes growth, is the continuous process by which an individual changes from one life phase to another
• Prenatal period is from fertilization to birth• Postnatal period is from birth to death
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23.2: Pregnancy
• Pregnancy is the presence of a developing offspring in the uterus• It consists of three periods, or trimesters, each three months long
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Transport of Sex Cells• Before fertilization can occur, a secondary oocyte must be ovulated and enter a uterine tube• Only 200 of between 200 to 600 million sperm reach a secondary oocyte
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Infundibulum
Egg cell
Path of egg cellSperm cells
Cervix
Body of uterus
Ovary
Semen deposited in vaginaduring sexual intercourse
Path ofSperm cells
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
From M. Tegner and D. Epel. 16 February 1973. "Sea Urchin Sperm." Science, 179:685-688. © 1973 American Association for the Advancement of Science
Vagina
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23.1 From Science to Technology
Assisted Reproductive Technologies
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Fertilization• Fertilization is the union of an egg cell (secondary oocyte) and a sperm cell
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First polar bodyCorona radiata
Zona pellucidav
1 3
2
4
5
Second meioticspindle
Cell membraneof secondaryoocyte
Cytoplasm of secondaryoocyte
Acrosome containingenzymes
Nucleus containingchromosomes
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23.3: Prenatal Period
• The prenatal period usually lasts 38 weeks from conception• It can be divided into:
• A period of cleavage• An embryonic stage• A fetal stage
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Period of Cleavage
• The rapid cell division and distribution of the zygote’s cytoplasm into progressively smaller cells is cleavage• The cells produced during cleavage are called blastomeres
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(a) (b) (c)a: © A. Tsiara/Photo Researchers, Inc.; b: © Omikron/Photo Researchers, Inc.; c: © Petit Format/Nestle/Photo Researchers, Inc.
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Zona pellucida
ZygoteDay 0
Ovulation Uterus
Endometrium
Stem cells
Cleavages (first cleavage completed about 30 hours after fertilization) Stem cells
Spermnucleus
Eggnucleus
Polarbodies
Day 4Late morula
Day 3Early morula
Day 24-cell stage
Day 12-cell stage
Pronucleusformationbegins
First cleavage division
Fertilizationoccurs about12-24 hoursafter ovulation
Day 6-7Blastocystimplantation
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Blastocyst
(a)
Trophoblast
Inner cellmass
Uterinewall
(b)
Invadingtrophoblast
c: Courtesy of Ronan O'Rahilly, M.D. Carnegie Institute of Washington(c)
Inner cell mass Endometrium
Trophoblast
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Courtesy of Ronan O'Rahilly, M.D. Carnegie Institute of Washington
Lumen
Endometrium
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23.2 From Science to Technology
Preimplantation Genetic Diagnosis
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Hormonal Changes During Pregnancy
• Secretion of hCG maintains the corpus luteum• The corpus luteum secretes estrogens and progesterone• The placenta secretes large amounts of estrogens and progesterone• Estrogens and progesterone stimulate and maintain the uterine lining, inhibit FSH and LH, inhibit uterine contractions, and enlarge the reproductive organs• Relaxin from the corpus luteum inhibits uterine contractions and relaxes the pelvic ligaments• Placental lactogen stimulates breast development• Aldosterone promotes sodium retention• PTH maintains calcium concentrations in the blood
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Trophoblast cellssecrete hCG
hCG maintains corpus luteum
Corpus luteum continuesto secrete estrogens andprogesterone
Estrogens and progesteronepromote growth, development,and maintenance of uterine wall
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0 2 4
Months of pregnancy
1 3 5 7 96 8
Incr
easi
ng
ho
rmo
ne
con
cen
trat
ion
Estrogens
Progesterone
Human chorionicgonadotropin
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Other Changes During Pregnancy
• Growth of the uterus can displace abdominal organs and disrupt meals, including the development of heartburn and increased urinary frequency• More oxygen is needed and more waste is excreted causing increases in blood volume, cardiac output, breathing rate, and urine production• To obtain adequate nutrition, intake must be sufficient to supply needed vitamins, minerals and proteins
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(a) (b) (c)a: © A. Tsiara/Photo Researchers, Inc.; b: © Omikron/Photo Researchers, Inc.; c: © Petit Format/Nestle/Photo Researchers, Inc.
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Embryonic Stage
• The embryonic stage extends from the beginning of the second week through the eighth week, when the placenta forms, the main internal organs develop, and the major external body structures appear Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Chorion
Extraembryonic cavity
EctodermMesodermEndoderm
Chorionic villi
Connecting stalk
Amniotic cavity
Endometrium
Amnion
Lumen ofuterus
Yolk sacof embryo
Germ layers ofembryonic disc
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Yolk sac
Ectoderm
Mesoderm
Connecting stalk
Skin
Brain
Chorion
Heart
Amnion
Neural tube(Spinal cord)
Amnioticfluid
Digestivetract
Chorionic villi
Tail end
Allantois
Endoderm
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a,b: © 2007 Landrum B. Shettles; c: © Petit Format/Nestle/Photo Researchers, Inc.
(a) (b) (c)
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b: © Carroll Weiss/Camera M.D. Studios
(b)
Actual length4 weeks
5 weeks
6 weeks
7 weeks
(a)
Actuallength
Actuallength Actual
length
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–
(e) 49 ± 1 day (28–30 mm)
Developing ear
External ear
ForebrainElbow
Handplate
Lens
Midbrain
EarEyelid
Heart prominence
Hindlimb
External ear
Digital rays
Pigmentedeye
Paddle-shapedfoot plate
Notchesbetweentoe rays
Webbed fingers
Mandibularprocess
Paddle-shapedforelimb
External acousticmeatus
Fingersseparated
Toesseparated
Fan-shapedwebbed toes
(c) 40 ± 1 day (16–21 mm)
(a) 35 ± 1 day (10–12 mm) (b) 37 ± 1 day (12.5–15.75 mm)
(d) 45 ± 1 day (22–24 mm)
(g) 56 ± 1 day (34–40 mm)(f) 52 ± 1 day (32–34 mm)
Maxillaryprocess
Developingeye
Toe rays
Wrist
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Chorion
Endometrium
Amniotic cavity
Amnion Allantois
Umbilicalcord Maternal
bloodvessels
Developingplacenta
Extraembryoniccavity
Yolksac
• As the amnion develops, it surrounds the embryo, and the umbilical cord begins to form from structures in the connecting stalk
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Artery
Chorion
Chorionic villi Connective tissue
Section of villus
Lacunafilled withmaternalblood
Placentalmembrane
Wall of villus
Maternalblood
Embryoniccapillaries
Vein
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Umbilical cord
Umbilical arteries
Umbilical vein P
lacenta
En
do
metriu
mLacuna
Chorion
Myometrium
Decidua basalis(maternal portionof placenta)
Maternalblood vessels
Embryonicblood vessels
Villi (embryonic portion of placenta)
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Chorion
Placenta
Umbilical cord
Amniochorionic membrane
Endometrium Myometrium
Amniotic fluid
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© Donald Yaeger/Camera M.D. Studios
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0
Accutane
1 2 3 4 5 6 7 8 9
Month
(b) When different teratogens disrupt development
0 1 2 3 4 5 6 7 8 9
Eyes
Ears
Heart
Month
(a) When physical structures develop
Reproductive system
Upper and lower limbs
Central nervous system
Diethylstilbestrol
Thalidomide
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Fetal Stage
• The fetal stage begins at the end of the eighth week of prenatal development • Here growth is rapid, and body portions change considerably• At the beginning of this stage, the head is disproportionately large, and the lower limbs are relatively short
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13 years2 monthembryo
3 monthfetus
22 yearsNewborn 2 years 5 years
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Genital tubercle
Urogenital folds
Labioscrotal folds
Fused urogenital folds
Perineum
Anus
Urethral groove
(a)
Urogenital fold
Developing penis
(c)
(e)
(d) (f)
Glans penis
Scrotum
Genital tubercle
Glans
Urogenital fold
Labioscrotal fold
(b)
Developing clitoris
Embryonic tail
Urethral groove
Glans clitoris
Hymen
Labia minora
Labia majora
Perineum
Anus
Urethral orifice
Prepuce
Male Female
Vaginalorifice
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Umbilical cord
Placenta
Uterine wall
Cervix
Amniochorionicmembrane
Amniotic fluid
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23.1 Clinical Application
Some Causes of Birth Defects
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Fetal Blood and CirculationCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Placenta
Fetal capillaries
Umbilical vein
Umbilical arteries
Uterine wall
Maternal bloodin lacuna
Diffusion Oxygen and nutrients into fetal blood
DiffusionW aste substancesinto maternal blood
Chorionicvillus
Blood flow from fetus, branch of umbilical artery
Blood flow to fetus, branch of umbilical vein
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Aortic arch
Superior vena cava
Inferior vena cava
Hepatic portal vein
Pulmonary artery
Left atrium
Pulmonary veins
Abdominal aorta
Pulmonary trunk
Left ventricle
Left renal artery
Common iliac artery
Internal iliac artery
Umbilical vein
Umbilical arteriesPlacenta
Foramen ovale(becomes fossa ovalis)
Ductus venosus(becomes ligamentumvenosum)
Umbilical vein(becomes ligamentumteres)
Umbilical arteries(become medialumbilical ligaments)
Ductus arteriosus(becomes ligamentumarteriosum)
Decreasingbloodoxygenlevel
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Placenta
Liver
Lungs
Ductus venosus
Right atrium
Right ventricleForamen ovale
Left atrium
Left ventricle
Aortic arch
Aorta
Umbilical vein(oxygen, nutrients)
Superiorvena cava
Inferiorvena cava
Heart, brain,upper limbs
Ductusarteriosus
(most of the blood)
Pulmonarytrunk
Trunk andlower limbs
Umbilicalartery
(carbon dioxide,wastes)
Umbilicalartery
(carbon dioxide,wastes)
Internal iliacarteries
Decreasingbloodoxygenlevel
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23.2 Clinical Application
Joined For Life
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Birth Process• Pregnancy terminates with the birth process called parturition• The process is complex as noted in Table 23.5
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Fetal head is forcedtoward cervix
Cervix isstretched
Stretch receptorsare stimulated
Fetus is moveddownward
Reflex is elicitedthat causes strongeruterine contractions
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Placenta
Urethra
Vagina
Cervix
Rectum
Amniotic sac
(b)(a)
(c) (d)
Placenta Placenta
Uterus
Symphysispubis
Urinarybladder
Rupturedamnioticsac
Umbilicalcord
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Milk Production and Secretion
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© Biophoto Associates/Photo Researchers, Inc.
(a) (b)
Glandular tissuewith secretionsGlandular
tissue
Connectivetissue
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Release
Duct
Lumen
Myoepithelial cells
Secretion Milk
Nipple or areola of breastis stimulated
Nerve impulses travelto hypothalamus
Hypothalamus signals posteriorlobe of pituitary gland torelease oxytocin
Oxytocin causes myoepithelialcells surrounding alveolarglands to contract
Milk is released from ductilesystem through nipple
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23.3 Clinical Application
Human Milk – The Perfect Food for Human Babies
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23.4: Postnatal Period
• Following birth, both mother and newborn experience physiological and structural changes• The postnatal period lasts from birth until death• It can be divided into:
• The neonatal period• Infancy• Childhood• Adolescence• Adulthood• Senescence (including dying)
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Neonatal Period
• Neonatal period• From birth to the end of the 4th week• The newborn begins to carry on respiration, obtain nutrients, digest nutrients, excrete wastes, regulate body temperature, and make cardiovascular adjustments
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Infancy
• Infancy• From the end of the 4th week to one year• The growth rate is high• The teeth begin to erupt• The muscular and nervous systems mature• Communication begins
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Childhood
• Childhood• From one year to puberty• The growth rate is high• Permanent teeth appear• Muscular control is achieved• Bladder and bowel controls are established• Intellectual abilities mature
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Adolescence
• Adolescence • From puberty to adulthood• The person becomes reproductively functional and emotionally more mature• Growth spurts occur• Motor skills continue to develop• Intellectual abilities continue to mature
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Adulthood
• Adulthood• Adolescence to old age• The person remains relatively unchanged anatomically and physiologically• Degenerative changes begin
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Senescence
• Senescence • Old age to death• Degenerative changes continue• The body becomes less able to cope with the demands placed on it• Death results from various conditions and diseases
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23.4 Clinical Application
Living To 100 – And Beyond
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The End of Life
• Nearing the end of life is a personal process, influenced by belief as well as circumstance• A person who has been chronically ill may show signs of impending death, often in a sequence• Two stages of the dying process include:
• Preactive dying which may take up to three months• Active dying with a distinct set of signs
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23.5: Aging
• The aging process is difficult to analyze• The medical field of gerontology examines the biological changes of aging at the molecular, cellular, organismal, and population levels• Aging is both active and passive
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Passive Aging
• Aging as a passive process is a breakdown of structures and slowing of functions
• Molecularly a degeneration of elastin and collagen proteins• Biochemically lipids breakdown• Cellular degradation is associated with free radicals
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Active Aging
• Aging also entails new activities or the appearance of new substances
• Lipofuscin granules from the breakdown of lipids• Autoimmunity• Apoptosis: the process of programmed cell death
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The Human Life Span
• The human life span is approximately 120 years• Life expectancy is a realistic projection of how long an individual will live• The current U.S. life expectancy is 75.4 years for men and 83.2 years for women• Medical advances contribute to improved life expectancy
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Important Points in Chapter 23:Outcomes to be Assessed
23.1: Introduction
Distinguish between growth and development.
Distinguish between prenatal and postnatal.
23.2: Pregnancy
Describe fertilization.
23.3: Prenatal Period
List and provide details of the major events of cleavage.
Describe implantation.
Discuss the hormonal and other changes in the maternal body during pregnancy.
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Important Points in Chapter 23:Outcomes to be Assessed
Explain how the primary germ layers originate and list the structures each layer produces.
Describe the major events of the embryonic stage of development.
Describe the formation and function of the placenta.
Define fetus, and describe the major events that occur during the fetal stage of development.
Trace the path of blood through the fetal cardiovascular system.
Explain the role of hormones in the birth process and milk production.
23.4: Postnatal Period
Describe the major cardiovascular and physiological adjustments that occur in a newborn.
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Important Points in Chapter 23:Outcomes to be Assessed
Name the postnatal stages of development of a human, and indicate the general characteristics of each stage.
23.5: Aging
Distinguish between active and passive aging.
Contrast lifespan and life expectancy.
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Quiz 23
Complete Quiz 23 now!
Read Chapter 24.