Edition by Brian K. Walsh 9780323793094 , All Chapters with
Answers and Rationals
The bronchial tree develops by ________________. - ANSWER: week 16 of intrauterine life
After birth, the alveoli develop in increasing numbers until the age of _____________. - ANSWER: 8
years (until the growth of the chest wall is finished).
The full-term infant - ANSWER: - Has an estimated 50 million alveoli
- Has the potential to add another 250 million alveoli
Phases of Intrauterine Lung Growth - ANSWER: 1. Embyronal
2. Pseudoglandular
3. Canalicular
4. Saccular
5. Alveolar
Embryonal Phase - ANSWER: - The lung begins to emerge as a bud from the pharynx 26 days after
conception
- Lung bud elongates and forms two bronchial buds
- The diaphragm also develops during the embryonal stage of lung development
- * Errors can occur in this stage resulting in laryngeal, tracheal, and esophageal atresia or stenosis.
Day 26-52: development of trachea and major bronchi, diaphragm
The lung begins to emerge as a bud from the pharynx ____________. - ANSWER: 26 days after
conception
Lung bud elongates and forms _____________. - ANSWER: two bronchial buds
Pseudoglandular Phase - ANSWER: - Conducting airways continue to develop and subdivide
Day 52-week 16: development of remaining conducting airways
Canalicular Phase - ANSWER: - Appearance of surfactant (reduces surface tension)
- Pulmonary acinar units form:
- alveolar ducts
- alveolar sacs
- Extrauterine viability
- 22 to 24 weeks
Week 17-week 26: development of the vascular bed, alveolar ducts, alveolar sacs
Extrauterine viability - ANSWER: - 22 to 24 weeks
- Structures for gas exchange begin at the end of this phase
Saccular Phase - ANSWER: - At the beginning of this phase, the terminal structures are referred to as
saccules
- Relatively smooth-walled, cylindrical structures
Week 26-week 36: increased complexity of saccules
Alveolar Stage - ANSWER: Week 36-term: development of alveoli
, Most of the postnatal formation of alveoli occurs over the ___________. - ANSWER: first 1.5 years of
life
Pulmonary hypoplasia - ANSWER: - Can develop during the pseudoglandular phase.
- An incomplete development of the lungs
- If the fetus is born during the canalicular phase, __________________. - ANSWER: severe
respiratory distress may develop (infant respiratory distress syndrome)
Surfactant Production - ANSWER: - The primary role of surfactant is to lower the surface tension
within the alveolus
- Surfactant prevents alveolar collapse
Fetal lung liquid ________. - ANSWER: is essential for normal lung development
How much lung fluid per day? - ANSWER: 250 to 300 mL
Embryonic Germ Layers - ANSWER: - Ectoderm
- Endoderm—respiratory system
- Mesoderm
Ectoderm - ANSWER: - Brain and spinal cord
- Nervous system (spinal and cranial nerves)
- Sensory Epithelia of the eyes, inner ears and nose
- Skin
- Enamel
Endoderm - ANSWER: - Digestive system
- Respiratory system (pharynx, lungs, epithelial lining of the trachea and lungs)
- Urinary system (bladder)
Mesoderm - ANSWER: - Cardiovascular system: heart and blood vessels
- Connective tissue: cartilage, bone marrow
- Kidneys, spleen
Wharton's jelly - ANSWER: - gelatinous substance inside the umbilical cord
- prevents kinking of the cord
Heart - ANSWER: - First complete organ formed
- Begins during the 3rd week of gestation
Blood Flow through the Heart - ANSWER: - Blood enters the heart through two large veins, the
inferior and superior vena cava, emptying oxygen-poor blood (blue blood) from the body into the
right atrium of the heart. As the atrium contracts, blood flows from your right atrium into your right
ventricle through the open tricuspid valve.
- Blood leaves the right atrium through the pulmonary trunk and enters the lungs through the
pulmonary arteries.
- After blood passes through the lungs, it returns to the left atrium via the pulmonary veins. The
oxygen rich blood "Red Blood" travels from the left atrium to the left ventricle through the bicuspid
valve (mitral valve).
- The blood then travels to the aorta
The fetal circulation pathway ______________. - ANSWER: allows blood flow to be shunted around
the fetal liver and lungs.
Foramen ovale - ANSWER: - Between right and left atria