Transcript PowerPoint to accompany

PowerPoint Lecture Outlines
to accompany
Hole’s Human
Anatomy and Physiology
Eleventh Edition
Shier w Butler w Lewis
Chapter
23
Copyright © The McGraw-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 6th
day of development
• trophoblast will help
form the placenta
• trophoblast secretes
hCG 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 hCG 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
Placenta
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
9th –12th week
• ossification centers appear
• sex organs differentiate
• fetal limbs begin to move
13th – 16th week
• body grows rapidly
• ossification continues
27
Major Events of
Fetal Development
17th – 20th week
• muscle movements stronger
• skin is covered with lanugo
• skin is covered with vernix caseosa
21st – 38th 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 5th 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 4th week
• newborn begins to carry on respiration, obtain
nutrients, digest nutrients, excrete wastes, regulate
body temperature, and make cardiovascular
adjustments
Infancy
• end of 4th 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