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Anatomy & Physiology
SIXTH EDITION
Chapter 29, part 2
Development and Inheritance
PowerPoint® Lecture Slide Presentation prepared by
Dr. Kathleen A. Ireland, Biology Instructor, Seabury Hall, Maui, Hawaii
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Frederic H. Martini
Fundamentals of
SECTION 29-5
The Second and Third Trimesters
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Second and Third Trimesters
• Second trimester
• Organ systems increase in complexity
• Third trimester
• Many organ systems become fully functional
• Fetus undergoes largest weight change
• At end of gestation fetus and uterus push
maternal organs out of position
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Figure 29.9 The Second and Third Trimesters
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Figure 29.9a, b
Figure 29.10 Growth of the Uterus and Fetus
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Figure 29.10a, b
Figure 29.10 Growth of the Uterus and Fetus
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Figure 29.10c, d
Developing fetus totally dependent on maternal
organs
• Maternal adaptations include increased
• Respiratory rate
• Tidal volume
• Blood volume
• Nutrient and vitamin uptake
• Glomerular filtration rate
PLAY
Animation: Anatomy comparison of pregnant and nonpregnant
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Structural and Functional Changes in the Uterus
• Progesterone inhibits uterine muscle contraction
• Opposed by estrogens, oxytocin and
prostaglandins
• Multiple factors interact to produce labor
contractions in uterine wall
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Figure 29.11 Factors Involved in the Initiation of
Labor and Delivery
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Figure 29.11
SECTION 29-6
Labor and Delivery
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Goal of labor is parturition
• Stages of labor
• Dilation
• The cervix dilates and fetus moves toward
cervical canal
• Expulsion
• The cervix completes dilation and fetus
emerges
• Placental
• Ejection of the placenta
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Figure 29.12 The Stages of Labor
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Figure 29.12
Other labor and delivery situations
• Premature labor
• True labor begins before fetus has completed
normal development
• Difficult deliveries
• When the fetus faces the pubis rather than the
sacrum
• The legs or buttocks enter the vaginal canal
first (breech births)
• Multiple births
• Twins, triplets, etc.
• Dizygotic or monozygotic situations
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SECTION 29-7
Postnatal Development
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Postnatal life stages
• Neonatal period
• Infancy
• Childhood
• Adolescence
• Maturity
• Senescence begins at maturity and ends in
death
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The neonatal period
• From birth to one month
• Respiratory, circulatory, digestive and urinary
systems adjust
• Infant must thermoregulate
• Maternal mammary glands secrete colostrum
first few days
• Milk production thereafter
• Both secretions are released via the milk letdown reflex
• Body proportions change during infancy and
childhood
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Figure 29.13 The Milk Let-Down Reflex
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Figure 29.13
Figure 29.14 Growth and Changes in Body Form
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Figure 29.14
Adolescence
• Begins at puberty
• The period of sexual maturation
• Ends when growth is completed
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Puberty marked by
• Increased production of GnRH
• Rapid increase in circulating FSH and LH
• Ovaries and testes become sensitive to FSH / LH
• Gamete production initiated
• Sex hormones produced
• Growth rate increases
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Hormonal changes at puberty produce gender
specific differences in system
• Differences are retained throughout life
• Adolescence continues until growth completed
• Further changes occur when sex hormones
decline
• Menopause
• Male climacteric
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Senescence
• Aging affects functional capabilities of all system
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SECTION 29-8
Genetics, Development, and Inheritance
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Genes and chromosomes
• Every somatic cell carries copies of the 46
original chromosomes in the zygote
• Genotype – Chromosomes and their
component genes
• Phenotype – physical expression of the
genotype
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Patterns of inheritance
• Somatic cells contain 23 pairs of chromosomes
• Homologous chromosomes
• 22 pair of autosomes and one pair of sex
chromosomes
• Chromosomes contain DNA
• Genes are functional segments of DNA
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Figure 29.15 Human Chromosomes
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Figure 29.15
Various forms of a gene are called alleles
• Homozygous if homologous chromosomes carry
the same alleles
• Heterozygous if homologous chromosomes carry
different alleles
• Alleles are either dominant or recessive
depending on expression
• Punnett square diagram predicts
characteristics of offspring
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Figure 29.16 Predicting Phenotypic
Characteristics by Using Punnett Squares
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Figure 29.16a, b
Inheritance
• Simple inheritance
• Phenotypic characteristics are determined by
interactions between single pair of alleles
• Polygenic inheritance
• Phenotypic characteristics are determined by
interactions among alleles on several genes
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Sources of individual variation
• Genetic recombination
• Gene reshuffling
• Crossing over and translocation
• Occurs during meiosis
• Spontaneous mutations
• Random errors in DNA replication
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Figure 29.17 Crossing over and Translocation
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Figure 29.17a-c
Sex-linked inheritance
• Sex chromosomes are X chromosome and Y
chromosome
• Male = XY
• Female = XX
• X chromosome carries X-linked (sex linked)
genes
• Affect somatic structures
• Have no corresponding alleles on Y
chromosome
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Figure 29.18 X-Linked inheritance
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Figure 29.18
The Human Genome Project
• Mapped more than 38,000 of our genes
• Including some responsible for inherited
disorders
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Figure 29.19 A Map of the Human
Chromosomes
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Figure 29.19
You should now be familiar with:
• The relationship between differentiation and
development, and the various stages of
development
• The process of fertilization
• The three prenatal periods and describe the
major events associated with each
• The importance of the placenta as an endocrine
organ
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You should now be familiar with:
• The structural and functional changes in the
uterus during gestation
• The events that occur during labor and delivery
• The basic principles of genetics as they relate to
the inheritance of human traits
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