Fetal and Pediatric Development Flashcards
Gestational Age
Measured from first day of last menstrual period
Conception
Fertilization of egg with sperm
“embryonic” period
First 8 weeks post conception (all major organs formed)
“Fetal” period
remaining 30 weeks (organs grow larger and become more complex)
Blastocyst
Two distinct types of cells
- Inner mass cells: forms the embryo
- Trophoblast: layer of cells surrounding the cavity which helps form the placenta
Floats for about 3 days –> Implantation on about day 6 post conception: trophoblast erodes uterine wall (takes 1 week to complete)
Implantation
- Adherence of the trophoblast to the uterine wall
- Inner cell mass divides into epiblast and hypoblast
- Two fluid filled sacs
-amniotic sac from
epiblast
-Yolk sac from hypoblast
Beginning Tissue Formation
Primary Germ layers: Ectoderm, mesoderm, endoderm
Endoderm
Epithelium of Gi Tract, liver, pancreas, ureters, urinary bladder
Epithelial portions: pharynx, thyroid, thrachea, bronchi, lungs, tympanic cavity, pharyngotympanic tube, tonsils, parathyroids
Ectoderm
- Nervous Tissue: neural tube (CNS, Retina, Post pituitary, pineal gland)
- Neural crest: pigment cells, adrenal medulla, cranial and sensory nn, cranial and sensory ganglia
- Epidermis: hair, nails, mammary glands, cutaneous glands, anterior pituitary, teeth enamel, inner ear, eye lens
Mesoderm
Skeleton (head and body), muscle, connective tissue, circulatory system (cardio/lymph), urinary system, spleen, adrenal cortex, genital system: gonads, ducts, accessory glands), Dermis, Dentine of teeth
General Overview of Organ System Dev
By month 1, gross characteristics of all different organ systems have already begun to develop
By 4 month, organs are grossly the same as a neonate
By .birth, nervous system, kidneys, and liver are not fully developed
Gastrointestinal system development
- Midpregnancy: ingest and absorb large amounts of amniotic fluid
- last 2-3 months - small quantities of meconium formed
Kidneys:
Begin to excrete urine during second trimester
Fetal urine = 80
Fetal Circulation
Week 3 (heart beings to beat at week 4)
Fetal circulation just before birth
- Ductus venosus
- High pulmonary vascular resistance
- Ductus arteriosus
- Foramen ovale
Pediatric growth
Growth: increase in physical size
Ped development
- continuous, orderly series
- increase in function and complexity
- increase in capabilities
Patterns of Growth and Dev
Pace: rapid from birth to 2 and puberty to ~15 years
- Slower from 2 to puberty and 16-24
- Cepholocaudal: head to toe
- Proximodistal: midline to periphery
- Simple to complex
Factors influencing growth and dev
- Critical/sensitive period
- Genetics
- Environment - physical and psychosocial
- Culture
- Health Status
- Family
Ectoderm 2
External affairs; interactions with environment
Mesoderm 2
Architect and Engineer; structural organization of body
Endoderm 2
Chemist, metabolism and homeostasis
Fetal Blood
- By 3 month, bone marrow is producing most of RBC
- Even at low PO2 levels, fetal hemoglobin can carry 20-50% more oxygen than maternal hemoglobin
- Hemoglobin concentration of fetal blood is about 50% greater than that of the mother
