29 - storage.googleapis.com

29 - storage.googleapis.com

PowerPoint Lecture Slides prepared by Vince Austin, Bluegrass Technical and Community College CHAPTER Elaine N. Marieb Katja Hoehn 28 PART B Human Anatomy & Physiology SEVENTH EDITION

Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings Pregnancy and Human Development Organogenesis Gastrulation sets the stage for organogenesis, the formation of body organs By the 8th week all organ systems are recognizable

Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings Specialization of Ectoderm Neurulation the first event of organogenesis gives rise to the brain and spinal cord Ectoderm over the notochord thickens, forming the neural plate The neural plate folds inward as a neural groove with prominent neural folds

Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings Specialization of Ectoderm By the 22nd day, neural folds fuse into a neural tube, which pinches off into the body The anterior end becomes the brain; the rest becomes the spinal cord Associated neural crest cells give rise to cranial,

spinal, and sympathetic ganglia Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings Specialization of Ectoderm: Neuralization Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 28.9a, b Specialization of Ectoderm: Neuralization Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 28.9c, d Specialization of Endoderm

Embryonic folding begins with lateral folds Next, head and tail folds appear An endoderm tube forms the epithelial lining of the GI tract Organs of the GI tract become apparent, and oral and anal openings perforate

Endoderm forms epithelium linings of the hollow organs of the digestive and respiratory tracts Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings Folding of the Embryonic Body Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 28.10ad Endodermal Differentiation Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings

Figure 28.11 Specialization of the Mesoderm First evidence is the appearance of the notochord Three mesoderm aggregates appear lateral to the notochord Somites, intermediate mesoderm, and double sheets of lateral mesoderm

Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings Specialization of the Mesoderm The 40 pairs of somites have three functional parts: Sclerotome produce the vertebrae and ribs Dermatome help form the dermis of the skin on the dorsal part of the body

Myotome form the skeletal muscles of the neck, trunk, and limbs Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings Specialization of the Mesoderm Intermediate mesoderm forms the gonads and the kidneys Lateral mesoderm consists of somatic and splanchnic mesoderm Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings

Specialization of the Mesoderm Somatic mesoderm forms the: Dermis of the skin in the ventral region Parietal serosa of the ventral body cavity

Bones, ligaments, and dermis of the limbs Splanchnic mesoderm forms: The heart and blood vessels Most connective tissues of the body Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings Specialization of the Mesoderm Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings

Figure 28.12 Development of Fetal Circulation By the end of the 3rd week: The embryo has a system of paired vessels The vessels forming the heart have fused Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings Development of Fetal Circulation

Unique vascular modifications seen in prenatal development include umbilical arteries and veins, and three vascular shunts (occluded at birth) Ductus venosus venous shunt that bypasses the liver Foramen ovale opening in the interatrial septa to bypass pulmonary circulation

Ductus arteriosus transfers blood from the right ventricle to the aorta Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings Circulation in Fetus and Newborn Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 28.13 Effects of Pregnancy: Anatomical Changes Chadwicks sign the vagina develops a purplish hue

Breasts enlarge and their areolae darken The uterus expands, occupying most of the abdominal cavity Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings Effects of Pregnancy: Anatomical Changes Lordosis is common due to the change of the bodys center of gravity

Relaxin causes pelvic ligaments and the pubic symphysis to relax Typical weight gain is about 29 pounds Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings Relative Uterus Size During Pregnancy Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 28.15

Effects of Pregnancy: Metabolic Changes The placenta secretes human placental lactogen (hPL), also called human chorionic somatomammotropin (hCS), which stimulates the maturation of the breasts hPL promotes growth of the fetus and exerts a maternal glucose-sparing effect Human chorionic thyrotropin (hCT) increases maternal metabolism

Parathyroid hormone levels are high, ensuring a positive calcium balance Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings Effects of Pregnancy: Physiological Changes GI tract morning sickness occurs due to elevated levels of estrogen and progesterone Urinary system urine production increases to

handle the additional fetal wastes Respiratory system edematous and nasal congestion may occur Dyspnea (difficult breathing) may develop late in pregnancy Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings Effects of Pregnancy: Physiological Changes Cardiovascular system blood volume increases

25-40% Venous pressure from lower limbs is impaired, resulting in varicose veins Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings Parturition: Initiation of Labor Estrogen reaches a peak during the last weeks of pregnancy causing myometrial weakness and irritability

Weak Braxton Hicks contractions may take place As birth nears, oxytocin and prostaglandins cause uterine contractions Emotional and physical stress: Activates the hypothalamus Sets up a positive feedback mechanism, releasing

more oxytocin Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings Parturition: Initiation of Labor Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 28.16 Stages of Labor: Dilation Stage From the onset of labor until the cervix is fully dilated (10 cm)

Initial contractions are 1530 minutes apart and 1030 seconds in duration The cervix effaces and dilates The amnion ruptures, releasing amniotic fluid (breaking of the water) Engagement occurs as the infants head enters the true pelvis

Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings Stages of Labor: Dilation Stage Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 28.17a, b Stages of Labor: Expulsion Stage From full dilation to delivery of the infant Strong contractions occur every 23 minutes and

last about 1 minute The urge to push increases in labor without local anesthesia Crowning occurs when the largest dimension of the head is distending the vulva Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings Stages of Labor: Expulsion Stage Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings

Figure 28.17c Stages of Labor: Expulsion Stage The delivery of the placenta is accomplished within 30 minutes of birth Afterbirth the placenta and its attached fetal membranes All placenta fragments must be removed to prevent

postpartum bleeding Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings Stages of Labor: Expulsion Stage Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 28.17d Extrauterine Life At 1-5 minutes after birth, the infants physical status is assessed based on five signs: heart rate, respiration, color, muscle tone, and reflexes

Each observation is given a score of 0 to 2 Apgar score the total score of the above assessments 8-10 indicates a healthy baby Lower scores reveal problems Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings

First Breath Once carbon dioxide is no longer removed by the placenta, central acidosis occurs This excites the respiratory centers to trigger the first inspiration This requires tremendous effort airways are tiny and the lungs are collapsed

Once the lungs inflate, surfactant in alveolar fluid helps reduce surface tension Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings Occlusion of Fetal Blood Vessels Umbilical arteries and vein constrict and become fibrosed Fates of fetal vessels

Proximal umbilical arteries become superior vesical arteries and distal parts become the medial umbilical ligaments The umbilical vein becomes the ligamentum teres The ductus venosus becomes the ligamentum venosum The foramen ovale becomes the fossa ovalis

The ductus arteriosus becomes the ligamentum arteriosum Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings Transitional Period Unstable period lasting 6-8 hours after birth The first 30 minutes the baby is alert and active Heart rate increases (120-160 beats/min.)

Respiration is rapid and irregular Temperature falls Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings Transitional Period Activity then diminishes and the infant sleeps about three hours

A second active stage follows in which the baby regurgitates mucus and debris After this, the infant sleeps, with waking periods occurring every 3-4 hours Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings Lactation The production of milk by the mammary glands

Estrogens, progesterone, and lactogen stimulate the hypothalamus to release prolactin-releasing hormone (PRH) The anterior pituitary responds by releasing prolactin Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings Lactation Colostrum

Solution rich in vitamin A, protein, minerals, and IgA antibodies Is released the first 23 days Is followed by true milk production Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings Lactation and Milk Let-down Reflex After birth, milk

production is stimulated by the sucking infant Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 28.18 Breast Milk Advantages of breast milk for the infant Fats and iron are better absorbed

Its amino acids are metabolized more efficiently than those of cows milk Beneficial chemicals are present IgA, other immunoglobulins, complement, lysozyme, interferon, and lactoperoxidase Interleukins and prostaglandins are present, which prevent overzealous inflammatory responses

Its natural laxatives help cleanse the bowels of meconium Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings

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