3. PHYSIOLOGY OF THE NEWBORN Belen Amparo E. Velasco, M.D.

6. The fetus has a recognizable human form by the 12th week of development. The vital organs are not sufficiently developed to sustain life outside the uterus until the seventh month. While in the womb, the fetus is especially susceptible to the effects of drugs, alcohol, and X rays. "Human Fetus."Microsoft® Encarta® Encyclopedia 2001. © 1993-2000 Microsoft Corporation. All rights reserved.

7. CIRCULATORY SYSTEM FETAL CIRCULATION Presence of 3 shunts: Patent foramen ovale Patent ductus arteriosus Patent ductus venosus

8. CIRCULATORY SYSTEM FETAL CIRCULATION OXYGENATED BLOOD FROM MATERNAL BLOOD: PLACENTA (Clearing house)  Umbilical vein  Ductus venosus  liver  hepatic veins  Inferior vena cava  Superior vena cava  Right auricle  foramen ovale  left auricle  left ventricle  ascending aorta 

9. CIRCULATORY SYSTEM FETAL CIRCULATION UNOXYGENATED BLOOD:  Right ventricle  pulmonary artery  lungs  ductus arteriosus  descending aorta

10. CIRCULATORY SYSTEM CHANGES AT BIRTH  ADULT TYPE OF CIRCULATION Cessation of placental circulation Physiologic closure of foramen ovale (  L atrial pressure) Functional closure of patent ductus arteriosus (  O2 content)

12. RESPIRATORY SYSTEM FETAL LUNGS Filled with respiratory (filtrate of plasma) fluid Metabolic functions; Production of surfactant Occasional gasps

13. RESPIRATORY SYSTEM NEWBORN LUNGS Possess all equipment necessary for respiration incl. chemoreceptors and baroreceptors High negative intrathoracic pressure (10-70cms H2O) Clearance of respiratory fluid with replacement by air

14. RESPIRATORY SYSTEM NEWBORN LUNGS Establishment of FRC to permit gas exchange even during expiration Alveolar structure Periodic breathing with apneic pauses in premies

16. GASTROINTESTINAL SYSTEM FETAL GI SYSTEM Swallowing as early as the 12 th week of gestation Absence of excretion via the GIT unless with sphincter relaxation during hypoxic event. Accumulation of epithelial debris and conjugated bilirubin in small intestine

17. GASTROINTESTINAL SYSTEM NEWBORN GI SYSTEM Passage of meconium (mixture of epithelial debris & mucopolysaccharide with conjugated sbilirubin) within the 1 st 24 hours  transitional stools (greenish soft stools) in the next 4 days  milk stools (normal pasty consistency and yellow color) Adequate levels of pancreatic enzymes except for amylase and lipase

18. RENAL SYSTEM FETAL RENAL SYSTEM Production of urine as early as 4 th month Renal function (GFR, tubular mass and RPF) not reach adult levels till 2 nd year of life Glomerular filtration begins at about 9 weeks

19. RENAL SYSTEM NEONATAL RENAL SYSTEM Passage of dilute urine due to inability to concentrate urine adequately Transient metabolic acidosis due to inadequate removal of acid ions, limited formation of NH3 for acid removal with minimum loss of base and overproduction of lactic and pyruvic acid.

20. RENAL SYSTEM NEONATAL RENAL SYSTEM 6-10% physiologic weight loss (loss of body water)due to: Diuresis Expulsion of meconium Withholding of water and calories

22. CENTRAL NERVOUS SYSTEM FETAL CNS Rapid growth of fetal brain during last half of fetal life with peak near time of birth Posture of late fetal flexion attitude Generalized symmetric muscular activity Simple & stereotyped response to various environmental and internal stimuli

23. CENTRAL NERVOUS SYSTEM NEONATAL BRAIN

24. S oft spots on a baby’s head, called fontanels, are areas that have not yet hardened to bone. The skull is subjected to great pressure as it passes through the birth canal. Were it inflexible, the tight squeeze might injure the brain. Growth is complete by one year of age, and lines called sutures are visible where the plates fuse.

25. SPECIFIC REACTIONS: Moro reflex Grasp reaction Tonic and righting reflex Rooting, sucking, tongue retrusion and swallowing reflexes CENTRAL NERVOUS SYSTEM

26. RESPONSE TO STIMULI: Simple and stereotyped SENSES: Regards moving objects & changing light intensity Hears loud sound CENTRAL NERVOUS SYSTEM

27. ENDOCRINE SYSTEM FETAL ENDOCRINE SYSTEM The pituitary adrenal axis and thyroid gland function separately from that of the mother to ensure adequate growth of infant. Peculiarities in the fetus: Maternal estrogenic effects  urinary 17-ketosteroids

28. PITUITARY GLAND

29. ENDOCRINE SYSTEM NEONATAL ENDOCRINE SYSTEM MATERNAL ESTROGENIC EFFECTS Hypertrophied mammary glands Witch milk Mucoid to bloody vaginal discharge

30. ENDOCRINE SYSTEM NEONATAL ENDOCRINE SYSTEM NEONATAL OUTCOME IN MATERNAL DIABETES Immaturity of lungs – Hyaline membrane disease Hypoglycemia Hypocalcemia Anomalies: Ventricular septal hypertrophy Microcolon

31. HEMATOLOGIC SYSTEM FETAL HEMATOPOIETIC SYSTEM Erythropoietin: hormone produced in the glomerular tuft responsible for the production of RBC Due to relative hypoxia of the fetus stimulating the bone marrow, the fetal hemoglobin is as high as 20g/dl Blood formation as early as 3 rd wk after conception: Mesodermal tissue in the 1 st month Liver in the 2 nd month Medullary spaces from the 6 th month onward

32. HEMATOLOGIC SYSTEM NEOWBORN HEMATOPOIETIC SYSTEM At birth, still with high hgb. Starts to drop on the 3 rd day of life until a minimum of 10-12g/dl on the 2 nd -3 rd month of life – PHYSIOLOGIC ANEMIA - a result of the following:  in bone marrow activity  in rate of hemolysis hemodilution due to rapid expansion of blood volume Normal blood volume ranging from 80-90ml/kg WBC ranging from 10,000-30,000/mm 3 with PMN predominance

33. IMMUNOLOGIC SYSTEM FETAL IMMUNE SYSTEM Liver serves as the repository for lymphoid precursor cells during early intrauterine life. T cell functions begin as early as 7 weeks Circulating B cells are seen as early as 13 weeks. IgM antibodies are first to develop

34. IMMUNOLOGIC SYSTEM NEWBORN IMMUNE SYSTEM Considered completely developed immunological system but with inadequate antigenic stimulus

35. IMMUNOLOGIC SYSTEM NEWBORN IMMUNE SYSTEM Antibodies (maternal in origin) present – 7s or IgG antibodies Tetanus antitoxin Diphtheria antitoxin Smallpox agglutinins Antistreptolysin Toxoplasma antibodies Salmonella H antibodies Rh blocking antibodies

36. IMMUNOLOGIC SYSTEM NEWBORN IMMUNE SYSTEM Antibodies absent – 19s gammaglobulins Streptococcus agglutinins H. influenza antibodies Blood group isoagglutinins Shigella antibodies Poliomyelitis antibodies Salmonella O antibodies E. coli H and O antibodies Less capacity to produce antibodies and lower ameboid and phagocytic activities of neonatal leukocytes  susceptibility to infection esp of the preterm

37. T lymphocytes are specialized white blood cells that identify and destroy invading organisms such as bacteria and viruses. Some T lymphocytes directly destroy invading organisms, whereas other T lymphocytes regulate the immune system by directing immune responses.

38. Antibodies absent in the newborna.m EXCEPT: A. Streptococcus agglutinins B. H. influenza antibodies C. Poliomyelitis antibodies D. E. coli H and O antibodies E. Tetanus antitoxin Physiologic anemia: A. Increased RBC turnover due to hemolysis B. Decreased RBC turnover due to hyperoxia C. Decreased blood volume expansion D. Increased erythropoietic activity E. Depressed bone marrow activity due to hyperoxia

39. True of fetal circulation, EXCEPT: A. Ductus arteriosus shunts blood from pulmonary artery to aorta B. Foramen ovale shunts blood from right to left auricle C. Ductus arteriosus shunts blood from right to left side of heart D. Foramen ovale shunts blood from left to right auricle E. Oxygenated blood from placenta supplies upper half of body Physiologic weight loss due to: A. Polyuria B. Diuresis C. Adequate caloric intake D. Retention of meconium E. Transient metabolic acidosis