module 3 OB

the thoracic cavity encompasses the ________________

heart, lungs, great vessels, and mediastinal structures

what borders the thoracic cavity

ribs, spine, and diaphragm

what is the main reason that some neonates die shortly after birth

pulmonary immaturity

a fetus under _____ weeks gestation are typically considered non-viable due to pulmonary immaturity

24

what are the two periods important in lung development

embryonic period and alveolar period

when is the embryonic period

3-6 in conceptual weeks and 5-7 in menstrual weeks

____ is when the presence and integrity of normal anatomic structures in the chest are established

embryonic period

when does the alveolar period begin

36 weeks

what period determines the maturity and proper functionality of the lungs at birth

the alveolar period

abnormalities occurring in the alveolar period can be ____

lethal

at what week does pulmonary development begin

5 weeks

during week 5 a single lung bud appears at the distal end of each _______

primordial bronchus

what is the first stage of lung development that occurs from 9 - 19 weeks

pseudoglandular or embryonic phase

during the _____ phase of lung development air conducting bronchi and terminal bronchioles form

pseudoglandular or embryonic

what is the second phase of lung development that occurs from 19- 29 weeks

canalicular phase

during the ____ phase of lung development the lung tissue becomes vascularized and the lumen of the bronchioles and alveolar ducts enlarge

canalicular

what is the third phase of lung develop that occurs from 30-38 weeks

saccular phase

during the ____ phase of lung development the appearance of
primordial alveoli and a capillary bed that is formed to permit respiratory function adequate for survival outside the uterus

saccular

what is the last phase of lung development that occurs from 38 weeks to term

alveolar phase

during the ____ phase of lung development the number of terminal bronchioles and alveoli increase

alveolar

what is an important biochemical component in the last two stages of lung development

pulmonary surfactant

what produces pulmonary surfactant

alveolar cells

pulmonary surfactant increases the _____ of the fetal lung and help it to _____

compliance; expand

what are the four main determining factors of fetal lung development

• Adequate thoracic space
• Normal Fetal Breathing Movements
• Fluid Production in the Lungs
• Adequate Amniotic Fluid Volume

T/F: absent in just one of the four main developing factors of the fetal lungs will not hurt the fetus

false

____ plays a huge roll in the development of the fetal lungs

amniotic fluid

how does oxygen get to the fetus

through the umbilical cord

during 15-20 weeks amniotic fluid is produced by _________

maternal profusion activity from the choriamnion

during the 2nd and 3rd trimester amniotic fluid is produced by

fetal urine

amniotic fluid ____ the fetus against injury

cushions

amniotic fluid allows ___ movement of the fetus

free

amniotic fluid is ____ for lung development

essential

amniotic fluid gives a source if fetal ___

nutrition

amniotic fluid ____ fetal temperature

maintains

when does amniotic fluid stop producing and start to decrease

33 weeks

what makes the amniotic fluid to decrease

fetal swallowing and urine output

amniotic fluid is directly related to _____

kidney function

what may cause polyhydramnios

Fetal Swallowing Abnormalities,
Fetal Renal Insufficiency, GI Tract absorption abnormalities

what anomalies are associated with polyhydramnios

neural Tube defects, GI
obstruction, Hydrops, Trisomy 18, Cystic Hygroma

what might cause oligohydramnios

Premature rupture of
membranes, Post-term pregnancy,
Intrauterine Infection, Placental
insufficiency

what are some anomalies associated with oligohydramnios

Renal atresia, renal
anomalies, IUGR, Bladder obstruction

T/F: a BPP can prove lung maturity

false just movements of breathing and how often it occurs

what does L/S ratio stand for

Lecithin/sphingomyelin ratio

what is the most accurate way of measuring fetal lung maturity

L/S ratio

an L/S ratio greater than ____ indicates there likely will not be any postnatal respiratory distress

2:1

when does the Phosphatidylglycerol (PG) appear in the amniotic fluid

35 weeks

what measures the levels of a protein synthesized in the alveoli of the lung and secreted into Amniotic fluid

Surfactant-protein A (SP-A)

diminished levels of SP-A are associated with ______________

respiratory distress neonatally

how are the values for lung maturity taken

by amniocentesis

should the abdominal or thoracic cavity be smaller during pregnancy

thoracic cavity

what might pulmonary hypoplasia cause

reduction in thoracic size

a significantly small thorax can mean

asphyxiating thoracic dystrophy

what is asphyxiating thoracic dystrophy associated with

several syndromes

what ratio do we use to determine the size of the heart

cardiothoracic ration

cardiomegaly is present when the cardiothoracic ratio is greater than ____ standard deviations

2

the heart begins as a ___________ that begins beating at 22 days

single primitive tube

by the 6th week there is a vascular connection with maternal circulation in the chorion with embryonic circulation through the ____ and ______

cardinal veins and intersegmental arteries

when are most congenital heart defects created

early development

development of the heart occurs between ___ weeks

3-8

what does the heart begin as

cells from the mesoderm; cardiogenic cells

what do the cells from the mesoderm form

two endocardial tubes

the endocardial tubes merge during embryonic folding around week 4 to form the ______________

single primitive heart tube

when does cardiac looping begin

4-5 weeks

what does the bulbus cordis become

right ventricle

what does the primitive ventricle become

left ventricle

by day ____ the heart has taken an s shape where everything is mostly in the correct location

28

the _______ partitions into the two great vessels which later become the aorta and pulmonary trunk

truncus arteriosus

when should the great vessels cross over each other

during embryology

if the great vessels do not cross what is this called

transposition of the great arteries

by the end of embryology where should the pulmonary artery be

crossed over and anterior to the aorta making an x or v pattern

the pulmonary artery is connected to the ____

right ventricle

the aorta is connected to the _____

left ventricle

when does septation of the heart happen

week 7

what happens during septation of the heart

tissue between the bulbus cordis will spiral into the aorticopulmonary septum and form the interventricular septum

what grows from the roof of the single atrium chamber toward the endocardial cushion

septum primum

what grows adjacent to septum
primum- together they form the ATRIAL SEPTUM and leave a gap for blood to shunt through, called Foramen Ovale

septum secundum

what is the foramen ovale

a normal anatomical hole in the heart found only in the fetus that closes after birth

what makes the foramen ovale close after birth

pressure changes

what is the interventricular septum

the structure that separates the right and left ventricles

if the interventricular septum would have a whole what is this called

a VSD - ventricular septal defect

what forms the interventricular septum

tissue arising from the apex of the heart

by ___ weeks heart development is completed

9

since blood carries oxygen when it comes into contact with cells what happens

it causes them to proliferate and grow

if there is a lock of blood flow in an area what happen to those cells

they lack growth and maybe hypoplastic

by 11 weeks the fetal heart has ___ chambers

4

a fetus gets blood through a ____ input system

venous

blood goes into the fetus heart in the right atrium via the ______ and ______

superior and inferior vena cava

blood flow: blood enters the heart during ____ and exits during ______

diastole; systole

blood flow (right): vena cava → Right atrium → ________ → right ventricle → _______ → lungs

tricuspid valve; pulmonary artery

blood flow (left): ________ → left atrium → _____ → left ventricle → aorta → systemic circulation

pulmonary vein; mitral valve

where does all cardiovascular circulation begin at

the placenta

the majority of the fetal blood is shunted ____ from the fetal lungs as they are not functioning

away

oxygen from the placenta travels through the ______ to the abdominal wall

umbilical vein

what shunts blood to the liver in the fetus

portal sinus

blood circulation through the ductus venosus goes directly to the _____

IVC

what is a shunt

an anatomical structure that allows passing of blood

what happens to the shunts once the baby takes its first breath

they naturally begin to close

what are the three fetal shunts vital to circulation of blood

ductus venosus, ductus arteriosus, foramen ovale

what connects the umbilical vein to the IVC

ductus venosus

what does the ductus venosus become

ligamentum venosum