Test 2: Cardiopulmonary System Development

what is the first system to function in utero

Cardiovasulcar system

Contractions of the heart begin at

17 days

Blood is circualting by

4 weeks

cardiovacular system is derived from

mesoderm

fetal heart sounds detected by

8-10 weeks gestation

Normal newborn heart rate

120-125 (150-160 when crying)

Normal newborn BP

73/55

placenta acts at the

lungs bring O2 to the heart and body of teh embryo

Three shunts permit most of the blood to bypass liver and lungs

ductus venosus, forament ovale, ductus arteriosus

What bypasses the liver

ductus cenosus

What by pass the lungs

forament ovale and ductus arteriosus

there is a high resistance to blood flow into the lung whcih only recieves

10% of the total blood volume (just enough for development)

at birth the placenta disconnects from the baby which

occuldes placental circulation

There is an immediate decrease in blood pressure in the

inferior vena cava and right artrium which occurs at the same time the baby takes strong breath

aeration of the lungs occurs which dramaically decreased the pulmonary resistance and

allows the pulmonary arteries to dialate

Increase pulmonary blood flow=

increase pressure L atrium> declining pressure in R atrium causing foramen ovale to close `

When does ductus arteriosus closes

within 15-24 hours after birth

The high oxygen content of aortic blood cuases teh lungs to stop releasing

prostaglandinP

prostaglandin is

a chemical that keeps the ductus arteriosus open

Theumbilical vein and arteries close or constrict when

the umbilical cord is cut, these closures are functional at first but become anatomical as tissue proliferates and forms ligaments in their place

how does a newborn heart lies

horizontally in chest cavity and as lung expand the chest cavity growths and it assumes a more veritcal position

Irredular newborn is not unusual because

the ANS/conductiivty/heart position time to stabilize

at birth the thickness of R and L ventricle walls are

equal

Stroke volume of a child is

3-4ml (compare to adult 60ml)

Boys and girls HR are similar <10yo, after puberty girls HR

slightly higher than boys

Traneient heart murmurs (Lub dub dub) are

common in childhood

To check for cyanosis

look arund nose, lips, nasal bridge

Respiratory system arises fron the

endoderm

The cheif cause of perinatal death is

failure of the repiratoy system to function adequately

With regards to the respiratory system what occurs at the 4th week

laryngotracheal tube develops with bronchial buds

With regards to the respiratory system what occurs at the 17th weeks

bronchioles and all major elements of lungs developed except those involved in gas exchange

With regards to the respiratory system what occurs at the 24th week

each terminal bronchiole has become wider and given rise to two or more respiratory bronchioles.

Respiration is now possible at 24 weeks because

thin-walled saccules, called terminal sacs (immature alveoli) have developed at the ends of teh respiratory bronchioles.

A preme born at 24 weeks is unliekly to survive because

decrease alveoli surface area, underdeveloped vascularity, and surfactant begins to be secrete

Surfactant is important because

it lowers the surface tension in alveoli and precents atelectasis of the lungs

With regards to the respiratory system what occurs at 28-32 weeks

fetus has sufficient casularized terminal sacs and surfactant to survive if born prematurely, at terminal sacs increase in size they become mature alveoli

pre-birth mature alveoli

do not exist before birth and gas exchange does not occur until birth

respiratory movements occur long before to cause aspiration of

amniotic fluid into the lungs to keep them slightly expanded

at birth areation of the lungs and liquid is replaced by air by 3 routes

1/3 expelled from the lungs through the mouth adn nose during delivery from pressure on bab'y’s thorax

1/3 enters the pulmonary capilaries also from the pressure on thorax

1/3 passes into the lymphatic

Pulmonary lymphatics in the fetus are

largers and more numerous than in the adult and lymph flow is very high during the first few hours after birth, then it diminishes

after birth the lung size increase due to an icnrease in teh number of

immature alveoli for up to four years of age

infants are obligatory nose breathers because

larynx is up high and soft

newborn diagphragm has less

type 1 fibers compared to an adult