Chapter 23 Pregnancy, Growth, and Development

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Chapter 23Lecture

PowerPoint

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2402Anatomy and Physiology II

Chapter 23

Susan Gossett

[email protected]

Department of Biology

Paris Junior College

mailto:[email protected]

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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


Infundibulum

Egg cell

Path of egg cellSperm cells

Cervix

Body of uterus

Ovary

Semen deposited in vaginaduring sexual intercourse

Path ofSperm cells


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


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


(a) (b) (c)a: © A. Tsiara/Photo Researchers, Inc.; b: © Omikron/Photo Researchers, Inc.; c: © Petit Format/Nestle/Photo Researchers, Inc.


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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Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display

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


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


(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


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


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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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


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



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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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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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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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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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

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Chapter 23 Pregnancy, Growth, and Development