A+P: Peds I Flashcards
The heart is derived from what neural tissue?
mesoderm
What does the heart initially form from?
2 simple endothelial tubes
What do the simple endothelial tubes of the heart develop into?
4 slightly bulged areas representing early heart chambers
What gestational age does blood usually start pumping?
day 22
What gestational age does the heart tube contort into a structurally developed heart?
2nd month
What happens at day 22 of gestation?
blood is pumping in the heart
What is happening by the 2nd month of gestation?
the heart tube contorts into structurally developed heart
List the primitive chamber of the heart.
- Sinus venous
- Atrium
- Ventricle
- Bulbus cordis
Describe the sinus venosus:
Receives venous blood of embryo; becomes smooth wall of RA & coronary sinus. gives rise to SA node (early control & setting of heart rate as embryo)
What gives rise to the SA node & what does the SA node do?
- sinus venosus
- early control and setting of heart rate as embryo
What is the strongest pumping chamber of early heart?
the ventricle
What does the bulbus cordis include?
truncus arteriosus
What does the bulbus cordis give rise to?
pulm truck (1st part of aorta) and most of RV
Is fetal circulation high or low resistance circuit?
low-resistance circuit
Which side of the heart has a greater pressure?
right side > left side
What is the point of fetal heart structures?
help bypass pulmonary circulation in utero b/c lungs aren’t mature
List fetal heart structures.
- ductus venosus
- foramen ovale
- ductus arteriosus
Explain what the left umbilical vein does.
- send O2 blood to liver via portal vein
- deO2 blood levels the liver via hepatic vein to IVC
Primary function of ductus venosus?
to carry O2 blood from umbilical vein to the IVC then to RA bypassing the liver
What plays a key role in maintaining fetal circulation pattern?
ductus venosus
How does the ductus venosus close and when?
- secondary to incr cardiac pressures & decreased circulating PGs postpartum
- closes postpartum
Describe the foramen ovale.
patent structure during fetal circulation that connects the 2 atria
Functions (2) of the foramen ovale
- allows O2 rich blood to go from RA to LA & LV or aorta
- allows most O2 blood to go to the brain
Describe the foramen ovale.
Connecting structure that shunts blood from pulm artery to aorta
Function of the ductus arteriosus.
sends O2 poor blood (mixed blood) from RV for systemic circulation & lungs
Fetal systemic circulation includes:
- right/left common iliac arteries to internal/external iliac arteries & back to umbilical arteries to return deO2 blood to placenta
What happens to pressure in fetal circulation postpartum?
Pulm circulatory pressure decr & systemic circulation incr
Why does the ductus arteriosus close?
b/c decr blood flow related to pressure changes (due to back pressure)
How long does it take for the ductus arteriosus to close?
12-24 hrs after birth
The ductus arteriosus forms that structure postpartum?
ligamentum arteriosum
Why does the foramen ovale close?
related to falling pressure from the right side of the heart
The foramen ovale forms that structure postpartum?
fossa ovalis
Umbilical vein becomes what structure postpartum
round ligament of liver
Ductus venosus becomes what structure postpartum
ligament venosum of liver
Umbilical arteries become what structure postpartum
superior vesical arteries
Which EKG find is not uncommon is peds pts? why?
Sinus arrhythmia related to changing HR w/ respiration
What is coarctation of the aorta?
Portion of aorta is narrowed increasing the workload (pressure) of the LV
Results of coarctation of the aorta.
The LV must work harder to try to move blood through the narrowing in the aorta.
What do children have HA w/ coarctation or the aorta?
too much pressure in the vessels in the head, or cramps in the legs or abdomen from too little blood flow in that region.
B/C poor perfusions
Congenital heart defects are generally related to:
- prenatal infxs (ex. Rubella)
- environmental exposures
- industrial solvents
- drug use (both Rx & illicit)
What other birth defects are related to congenital heart defects?
cleft palate or Down syndrome
Assoc. Sx of congenital heart defects. (6)
- Abdo or periorbital edema
- Cyanosis
- Dyspnea
- Fatigue
- Poor feeding or eating habits
- Tachycardia
What complications should be looked out for in coarctation of the aorta?
- walls of the ascending aorta, aortic arch or any of the arteries in the head/arms may become weakened by high pressure.
- Spontaneous tears in any of these arteries can occur–> can cause a stroke or uncontrollable bleeding.
What defects are seen in Tetralogy of Fallot?
- narrow pulm trunk & pulm valve is stenosed
- RVH
- VSD
- Aorta receives blood from both ventricles
Causes of Tetralogy of Fallot
- alcoholism
- DM
- Adv maternal age
- viral illness
Describe a “tet” spell.
bluish skin during episodes of crying or feeding
General cause of innocent heart murmur:
normal flow of blood through the heart
Why are innocent heart murmurs usually heard?
b/c thin heart walls
Describe a holosystolic murmur.
Grade 3, harsh, prolonged
What does a diastolic murmur usually indicate?
structural heart dz
The 7 S’s: key features of innocent murmurs
- Sensitive (changes in position/resp)
- Short duration (not holosystolic)
- Single (no assoc. clicks or gallops)
- Small (murmur limited to small area and non-radiating)
- ** Soft** (low amp)
- Sweet (no harsh sound)
- Systolic (only during systole)
What part of the resp tract developed first?
upper respiratory
What is the epithelium of the lower resp organs develop from?
out pocket of endoderm foregut to become pharyngeal mucosa (laryngotracheal bud)
By what week does the lower resp tract develop?
5th week of development
What happens at 20wks gestation as far as the resp system?
reflexive breathing movements begin to “practice” using lungs, although amniotic fluid is ingested & eliminated through urination
“gulping”
What happens at (24) 28wks gestation as far as the resp system?
resp system is developed enough to handle premature birth, however, may experience infant resp distress from inadequate surfactant
What is the role of surfactant?
decr surface tension to keep lungs inflated
What can be given to help immature fetal lungs development?
steroids
When is surfactant PRO A (SP-A) produced?
weeks before delivery
What does surfactant PRO A trigger?
inflammatory response in cervix, causing it to soften in preparation of labor
How is the first breath initiated?
CO2 levels rise in the fetal blood b/c placenta is no longer doing it causing central acidosis
What happens to pulm circulatory pressure postpartum?
O2 diffuses into BVs surrounding alveoli + pulm arterioles relax + pulm resistance falls to promote blood flow into lungs
How long does it take before lungs fully inflate postpartum?
up to 2 weeks
Is respiration higher or lower in newborns?
higher
What is the average RR in newborns?
40-80 breath/min
At birth, how much of the alveoli are present?
1/6
Anatomically explain the rib cage in a newborn.
nearly horizontal & must use descent of diaphragm to incr thoracic volume for inspiration (may incr risk for infxs)
Babies are natural nose-breathers until what age?
2 yo
By 5yo, what does the RR drop to?
25 breaths/min
Describe the ribs by age 2.
ribs more oblique & adult form of breathing established
Describe RR by teenage years.
rate usually mirrors adulthood (12-20 breaths/min)
NOTE
lungs mature & form alveoli into young adulthood
What does smoking do in teen to the resp system?
stunt/block alveoli maturity (+/- permanent damage)
Unique Differences of Pediatric Respiratory System (6)
- smaller diameter & shorter length–> incr risk of choking
–> also have larger adenoids & tonsils - large tongue–> occlude airway
- Larynx located more superior & anterior
- large head–> neck flexion–> ?air obstruction
- long, floppy, narrow epiglottis
- <10yo narrow below glottis at level of cricoid cartilage
What is the most common cause of noisy breathing in infancy?
laryngomalacia
What is laryngomalacia?
congenital softening of the tissues of the larynx above vocal cords
Describe pathophys of laryngomalacia.
structure is malformed & floppy, causing the tissues to fall over the airway opening & partially block it.
