Download Chapter 28 Pregnancy and Human Development

Chapter 28
Pregnancy and
Human
Development
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Preeclampsia-Eclampsia Syndrome
• Symptoms – Hypertension and proteinuria caused by
vascular spasms – decreased blood flow in fetus
• Classifications
– Mild – systolic increase of >30 mmHg or diastolic of >15
mmHg.
– Severe = Eclampsia – convulsive state
• Treatment – bed rest, high protein diet, reduced sodium
(?), Calcium and Mag supplements, drugs for hypertension
and sedatives – if severe give Mag sulfate
• Believed due to immunological abnormalities
• Correlated with number of fetal cells that enter
maternal circulation
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Lactation
• Production of milk by the mammary glands
• Toward the end of pregnancy
– Placental estrogens, progesterone, and
lactogen stimulate the hypothalamus to
release prolactin-releasing factors (PRFs)
– Anterior pituitary releases prolactin
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Lactation
• Colostrum
– Yellowish secretion rich in vitamin A, protein,
minerals, and IgA antibodies
– Released the first 2–3 days
– Followed by true milk production
• Suckling initiates a positive feedback
mechanism
• Oxytocin causes the letdown reflex
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Figure 28.19 Milk production and the positive feedback mechanism of the milk let-down reflex.
Hypothalamus releases prolactin
releasing factors (PRF)
to portal circulation.
Start
Positive feedback
Stimulation of
mechanoreceptors in
nipples by suckling
infant sends afferent
impulses to the
hypothalamus.
Hypothalamus
sends efferent
impulses to the
posterior
pituitary where
oxytocin is stored.
Anterior pituitary
secretes prolactin
to blood.
Oxytocin is
released from the
posterior pituitary
and stimulates
myoepithelial cells
of breasts to contract.
Prolactin targets
mammary glands
of breasts.
Milk production
Let-down reflex.
Milk is ejected
through ducts
of nipples.
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Advantages of Breast Milk
• Fats and iron are easily absorbed; amino acids
more easily metabolized, compared with cow’s
milk
• Beneficial chemicals: IgA, complement,
lysozyme, interferon, and lactoperoxidase
• Interleukins and prostaglandins prevent
overzealous inflammatory responses
• Natural laxative effect helps eliminate bile-rich
meconium, helping to prevent physiological
jaundice
• Encourages bacterial colonization of the large
intestine
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Development of Fetal Circulation
• First blood cells arise in the yolk sac
• By the end of the third week
– Embryo has a system of paired vessels
– Vessels forming the heart have fused
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Development of Fetal Circulation
• Unique vascular modifications
– Umbilical arteries and umbilical vein
– Three vascular shunts (all are occluded at
birth)
• Ductus venosus: bypasses liver (umbilical vein 
ductus venosus  IVC)
• Foramen ovale: opening in interatrial septum;
bypasses pulmonary circulation
• Ductus arteriosus: bypasses pulmonary circulation
(pulmonary trunk  ductus arteriosus  aorta)
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Figure 28.14a Circulation in fetus and newborn.
Fetus
Aortic arch
Superior vena cava
Ductus arteriosus
Ligamentum arteriosum
Pulmonary artery
Pulmonary veins
Heart
Lung
Foramen ovale
Fossa ovalis
Liver
Ductus venosus
Ligamentum venosum
Hepatic portal vein
Umbilical vein
Ligamentum teres
Inferior vena cava
Umbilicus
Abdominal aorta
Common iliac artery
Umbilical arteries
Medial umbilical ligaments
Urinary bladder
Umbilical cord
Placenta
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High oxygenation
Moderate oxygenation
Low oxygenation
Very low oxygenation
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Figure 28.14b Circulation in fetus and newborn.
Aortic arch
Superior vena cava
Ductus arteriosus
Newborn
Ligamentum arteriosum
Pulmonary artery
Pulmonary veins
Heart
Lung
Foramen ovale
Fossa ovalis
Liver
Ductus venosus
Ligamentum venosum
Hepatic portal vein
Umbilical vein
Ligamentum teres
Inferior vena cava
Umbilicus
Abdominal aorta
Common iliac artery
Umbilical arteries
Medial umbilical ligaments
Urinary bladder
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High oxygenation
Moderate oxygenation
Low oxygenation
Very low oxygenation
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Congenital Heart Defects
• Patent ductus arteriosis – duct does not
close which leads to increase pulmonary
BP
• Atrial septal defect – foramen ovale does
not close which leads to poor oxygenation
of blood
• Coarctation of aorta – aorta is constricted
which leads to increase workload on heart
• Tetralogy of Fallot – multiple defects
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Figure 18.25 Three examples of congenital heart defects.
Narrowed
aorta
Occurs in
about 1 in every
500 births
Ventricular septal defect.
The superior part of the
inter-ventricular septum fails
to form, allowing blood to mix
between the two ventricles.
More blood is shunted from
left to right because the left
ventricle is stronger.
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Occurs in
about 1 in every
1500 births
Coarctation of the aorta.
A part of the aorta is
narrowed, increasing the
workload of the left ventricle.
Occurs in
about 1 in every
2000 births
Tetralogy of Fallot.
Multiple defects (tetra =
four): (1) Pulmonary trunk
too narrow and pulmonary
valve stenosed, resulting in
(2) hypertrophied right
ventricle; (3) ventricular
septal defect; (4) aorta
opens from both ventricles.
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Neural Tube Defects
• Anencephaly – lack of cerebrum and parts
of brain stem
Spina bifida – incomplete formation of
lamina and spinous processes –
prevented by taking folic acid
And……..
• Idiopathic Respiratory Distress Syndrome
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Estrogen
Oxytocin
(+)
from
placenta
from fetus
and mother’s
posterior pituitary
Induces oxytocin
receptors on uterus
Stimulates uterus
to contract
Stimulates
placenta to make
(+)
Prostaglandins
Stimulate more
vigorous contractions
of uterus
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Figure 28.17
Umbilical
cord
Placenta
Uterus
Cervix
Vagina
(a) Dilation (early)
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Figure 28.18a
Pubic
symphysis
Sacrum
(b) Dilation (late)
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Figure 28.18b
Perineum
(c) Expulsion
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Figure 28.18c
Uterus
Placenta
(detaching)
Umbilical
cord
(d) Placental
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Figure 28.18d
Complications with Placenta
• Placenta previa – placenta partially covers
opening to cervix
• Placenta abruptio – placenta separates
from uterine wall prematurely
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Menopause
• Ovulation and menses cease entirely
• Without sufficient estrogen, reproductive
organs and breasts atrophy
– Irritability and depression result
– Skin blood vessels undergo intense
vasodilation (hot flashes occur)
– Gradual thinning of the skin and bone loss
• Males have no equivalent to menopause
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“Juno, honey, it’s because doctors are
sadists and like to watch lesser people
scream!”
In 2007, Juno and Knocked Up, two movies
about unexpected pregnancies, raked in
over $300 million at the box office
combined.
Who knew that unplanned parenthood could
be so much fun?
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