Cardiorespiratory Flashcards
At how many weeks of gestation do we see the formation of lung buds?
- 4 weeks
what are the 4 stages of lung development & when do they occur
- Psuedoglandular: week 5-17
- canalicular: week 15-25
- terminal sac period: 24-birth
- alveolar period: birth - 8 years
What occurs in the psuedoglandular phase/when does it occur
- begin development of the shape, no function yet
- form the acinus
- occurs in weeks 5-17
what is the functional unit of the lungs
- acinus
what occurs in the canalicular phase/when does it occur
- vascularization
terminal bronchioles give rise to respiratory bronchioles - alveolar ducts form by the end of this period
- 15-25 weeks
what occurs in the terminal sac period/when does it occur
- blood air barrier is formed formation of type 1
- epithelium - flat, squamous epithelium for exchange
- formation of type 2 epithelium - cuboidal, secrete surfactant
- 24 weeks - birth
what occurs in the alveolar period/when does it occur
- alveoli are present
- lungs continue to grow
- birth - 8
when does alveolar development take place; how many at birth; how many at 8 years
- last trimester, but mostly postnatally
- 20 million at birth
- 300 million at 8 years
what does lung weight best correlate with
- height
how does the respiratory rate/min change from birth
- decreases
how do measures of lung volume change after birth
- increase
what is the primary cause for preterm death
- infant respiratory distress syndrome
- due to surfactant deficiency or immature lung development
what stimulates a major increase in surfactant prior to birth
- increased catecholamines and glucocorticoids
At what week does the heart begin to form? When does it start to beat?
- 3 weeks; endothelial tubes begin to fuse forming the primitive heart
- 3 weeks + 1 day
What embryonic tissue does the heart originate from
mesenchyme??
what has occurred by week 6 in terms of the heart
- developed its general form minus the foramen ovale
what occurs by week 8 in terms of the heart
- blood vessels are formed
what vessels bring blood to the fetal heart, what takes blood away from the fetal heart
- 2 veins
- trunctus arteriosus
what structure provides O2 for the fetus
- placenta
which structure provides a connection between the umbilical vein and the IVC; when does this close/why
- Ductus venosus
- Closes within 1st 3 hrs
- due to decreased flow from umbilical vein (b/c it was cut)
which structure connects the two atria; when does it close/why
- foramen ovale
- closes after 3 days
- due to increased pressure in left atria
what structure connects the aorta and the pulmonary artery/when does it close
- ductus arteriosus
- closes after 1-2 days
- due to increased aortic pressure, increased atrial O2 and decreased prosteglandin
what makes up for the lesser O2 saturation in a fetus
- FHb has a greater affinity for O2 (O2 is 70% saturated, vs 97% saturated after birth
what structure assists in diverting blood through foramen ovale
- cista dividens
the release of what from the lungs results in constriction of smooth muscle in ductus arteriosus
bradykinin
what is the heart growth curve similar to
fat free mass growth curve
what happens to heart rate and blood pressure as we age
- heart rate decreases
- BP increases
how does the RBC/Hb of blood vary between girls and boys
- same until puberty
- girls lose blood vol during puberty
Differentiate the life span of fetal and adult Hb
- fetal: 65-100 days
- adult: 120 days
what contributes to poor heat regulation in newborns?
- mechanisms of shivering & sweating are poorly developed
- immature sweat glands
- large SA/weight ratio
- thin subcutaneous layer
