zygote/morula becomes a blastocyst. once fluid begins accumulating in this center cavity. The fluid is a combination of uterine fluids and secretions from the cells themselves. Outer layer of cells form on the blastocyst referred to as the trophblast and replaces the zona pellucida
Where does the zygote normally implants?
Zygote attaches itself to the lining of the uterus ( for nourishment). Implantation occurs in the upper portion of the uterus
What are the names of the three germ layers that form during fetal development?
ENDODERM; The Innermost layer.; includes; respiratory tract* epithlium of the disgestive tract, bladder, thyroid* primary tissue of the liver and pancreas*
MESODERM; In between the endoderm and ectoderm;includes; dermis* muscle* bone* connective tissue* lymphnoid tissue* reproductive organs* cardiovascular system
ECTODERM; outermost layer and the thickest; includes; epidermis*nails*hair* lens of the eye* central and peripheral nervous system* Skin glands
What is the period of lung development that mature surfactant is produced?
It is during the alveolar period that mature surfactant is produced in increasing amounts by the type II cells. 27 weeks to term
what L/S ratio signifies lung maturity?
The fetal lung is considered mature when the L/S (lecithin sphingomyelin) ratio is 2:1. This usually occurs around week 35. This also coincides with the onset of mature surfactant production and indicates little chance of developing in RDS
What are High- frequency sound waves used for in obstetric ultrasound?
they are well below the level that could cause damage to tissue and are used to locate and visualize organs and tissue
What is used to transmit obstetric high-frequency ultrasounds?
Either a hand-held or transvaginal transducer
How can fetal age be determined with the use of ultrasound?
by using measurements of crown-rump length, biparietal diameter, abdominal circumference, and femur length
How can Fetal weight be estimated?
by combining head size, abdominal circumference, and femur length
How can Intrauterine growth retardation (IUGR) and excessive growth (macrosomia) be determined?
once fetal age and weight are determined
What is normal, low, and high fetal heart rates during early gestation?
normal heart rate 120-160
What is the most common method used to estimate deliver date?
-Nagels rule; subtract 3 months from last menstrual period, then add seven days
-Fundal height; measures distance from the symphysis pubis to the top of the uterine fundus, which is located on opposite end of the cervix. 1cm = 1 week, 20cm = 20 weeks
What is the test used for the biophysical profile of the newborn.
- Contraction stress test; stress comes from an interruption of maternal blood to the intervillous spaces during contractions. A positive CST is defined a more than 50% of contractions having late decelerations. No decelerations after any contractions indicate a negative CST
- The nonstress test; where the heart accelerates to greater than 15BPM for at least 15sec with fetal movement 2 times in a 20min window. Nonreactive NST occurs when the fetal heart rate does not accelerate during fetal body movement over a two 20min periods. A fetus suffering from prolonged hypoxia will have a positve CST with a negative NST. A negative CST results in the presence of a negative NST indicate the problem is one of fetal sleep or maternal narcotic or sedative ingestion
What are the three cardinal signs of respiratory distress?
1. Nasal flaring
What are the differences between the cardiopulmonary systems of adults and infants?
INFANT- tongue is proportionally larger than the adult tongue
INFANT-have a large amount of lymphoid tissue in the larynx
INFANT EPIGLOTTIS- proportionally larger, less flexible, and is omega-shaped.
INFANT EPIGLOTTIES - lies more horizontally than the
narrowest part of the infant airway is the cricoid ring ADULT is the glottis
INFANT LARYNX lies higher in the neck in relation to the cervical spine
*ALL THESE FACTORS MAKE THE INFANT AIRWAY MORE SUSCEPTABLE TO OBSTRUCTION*
What is . the quickest way of determining gestational age?
Ballard gestational age assessment; 6 physical, 6 neurological signs
Dubowitz gestational age assessment; 11 physical 10 neurological signs
What is the physical and mental characteristics used during the Ballard gestational age assessment?
dose the fetus is exposed to, the length of exposure, age of the fetus, other drug interactions
What is the most critical time for teratogens to have an effect?
What is the term pharmacokinetics used to describe?
The process by which drugs enter the body(absorption), are distributed throughout the system(distribution), are changed or altered from the original compound(metabolism), and eventually leave the body(excretion)