Term
- The lung buds grow into the primitive pleural cavities and are covered by the ________ layer of lateral plate mesoderm (________ pleura).
- The cavity is lined by the parietal layer of lateral plate mesoderm that forms the parietal pleura. (________ mesoderm)
- The visceral and parietal layers are continuous at the ________ (hilum) of each lung
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Definition
- visceral, visceral
- somatic
- root
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Term
________ ________ occurs when too much fluid collects in the pleural space (the space between the two layers of the pleura). It is commonly known as "water on the lungs." It is characterized by shortness of breath, chest pain, difficulty breathing (dyspnea)
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Definition
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Term
- The lung matures in a proximal–distal direction, beginning with the ________ ________ and proceeding ________.
-These are called ________ of development or stages.
-Lung development is ________
-________ pulmonary tissue will be in a more advanced period of development than ________ pulmonary tissue. |
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Definition
- largest bronchi, outward
- periods
-heterogeneous
-proximal, distal
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Term
Lung development controlled by signaling pathways and transcription factors
ThyroidTF1
Hepatocyte nuclear factor 3 beta
GATA6
These pathways are controlled by genes
________
SHH |
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Definition
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Term
Periods (stages):
________ stage
________ stage
________ sac stage
________ stage |
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Definition
Pseudoglandar stage
Canalicular stage
Terminal sac stage
Alvelolar stage
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Term
-Pseudoglandular period (weeks ________–________).
§The numerous endodermal tubules (ETs) are lined by simple ________ epithelium and are surrounded by ________ containing a modest capillary network.
§Each endodermal tubule branches into 15–25 terminal ________ (TBs).
§During this period, respiration is not possible, and premature infants cannot survive. |
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Definition
7,16
columna, mesoderm
bronchioles |
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Term
Canalicular period
¡Weeks ________–________
¡During this period, the TBs branch into three or more respiratory ________ (RBs).
¡The respiratory bronchioles subsequently branch into three to six alveolar ________ (ADs).
¡The terminal bronchioles, respiratory bronchioles, and alveolar ducts are now lined by a simple cuboidal epithelium and are surrounded by ________ containing a prominent capillary network.
¡Premature infants born before week 20 rarely survive. |
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Definition
-16,24
-bronchioles
- ducts
- mesoderm |
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Term
¡ < ________ weeks fetal death
§Fetus goes to path lab for examination
¡ >________ stillbirth
§Fetus goes to the morgue and parents can take the fetus for burial |
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Definition
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Term
Terminal sac:
--Week ________ to birth
-- During this period, terminal sacs (TSs) bud off the ADs and then dilate and expand into the surrounding mesoderm.
--The simple cuboidal epithelium within the terminal sacs differentiates into ___eumocytes (thin, flat cells that make up part of the blood–air barrier)
-Type ________ (I or II) (responsible for gas exchange)
- Type (I or II) pneumocytes ( produce surfactant). |
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Definition
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Term
▪ The terminal sacs are surrounded by ________ containing a rapidly proliferating capillary network.
▪The capillaries make intimate contact with the terminal sacs and thereby establish a blood–________ barrier |
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Definition
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Term
¡Type II alveolar cells secrete surfactant, the phospholipid that reduces surface tension in the alveoli so they can remain ________ during breathing. If not for surfactant, alveoli would collapse.
¡Type II cells do not develop until late in gestation (6.5-7 months)
¡Only 16% of lung cells are present at birth; the remainder form for the next 10 years. |
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Definition
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Term
¡In the last two months of prenatal life & for several years postnatally the # of terminal sacs (alveoli or bronchi) increases.
¡Alveolar epithelial cells lining the sacs
§Type I (majority or minority)
▪Become thinner allowing capillaries to protrude into sacs ... rust in a respiratory (membrane or fold)
§Type II (majority or minority)
▪Develops at end of (6th or 8th) month
▪Produces surfactant
▪phospholipid which ß surface tension |
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Definition
alveoli
majority
membrane
minority
6th |
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Term
Type I alveolar cells = (gas or liquid) exchange
Type II alveolar cells (6.5-7 months) = surfactant = (decreased or increased) surface tension
16% of alveolar cells are present at birth; remainder develop for 10 years |
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Definition
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Term
Alveolar period
¡Week (32 or 42)–age (8 or 16) years
¡Terminal sacs are partitioned by____ary septae to form adult alveoli.
¡ The major mechanism for the increase in the number of alveoli is formation of ____ary septae that partition existing alveoli. |
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Definition
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Term
¡With subsequent growth in both caudal and lateral directions the lung buds penetrate into the (intracoelomic or coelomic) cavity
§This space is narrow on each side and are called the pericardioperitoneal canals
¡Ultimately the pericardioperitoneal canals are seperated from the peritoneal and pericardial cavities by the ____peritoneal and ____pericardial folds |
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Definition
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Term
• The fetal metanephric kidneys make urine which constitutes the major component of (amniotic or chorionic) fluid
• The fetus swallows the amniotic fluid and reabsorbs it through the intestines.
• Some amniotic fluid enters the lungs and expands them
• Lung maturation requires this process |
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Definition
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Term
¡Before birth the lungs are filled with fluid
§(Low or High) Chloride concentration
§Little protein
§Some mucus from (bronchial or tracheal) glands
§Surfactant from type (II or I) alveolar epithelial cells
▪Amount increases especially during last 2 weeks before birth |
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Definition
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Term
§Most of lung fluid rapidly resorbed by: (C)
▪Blood
▪Lymph capillaries
§Small amount expelled via bronchi & trachea during delivery (suction) |
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Definition
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Term
§Fluid is resorbed surfactant remains deposited as a thin phospholipid coat on the alveolar cell (membranes or cytoplasm)
▪preventing a water-air interface during breathing thus keeping surface tension minimized
§Without surfactant alveoli would collapse during expiration [atelectasis (lack of gas exchange within alveoli)] |
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Definition
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Term
¡Alveoli can be compared to gas in water, as the alveoli are wet and surround a central air space.
¡The surface tension acts at the air-water interface and tends to make the bubble (larger or smaller) (by decreasing the surface area of the interface). |
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Definition
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Term
¡As the alveoli increase in size, the surfactant becomes (more or less) spread out over the surface of the liquid.
¡This (increases or decreases) surface tension effectively slowing the rate of increase of the alveoli. This also helps all alveoli in the lungs expand at the same rate |
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Definition
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Term
(Neoconium or Meconium) Aspiration (entry of foreign material)
¡It occurs when meconium is present in their lungs during or before delivery. Meconium is the first stool of an infant, composed of materials ingested during the time the infant spends in the uterus.
¡Meconium is normally stored in the infant's intestines until after birth, but sometimes (often in response to fetal distress) it is expelled into the amniotic fluid prior to birth, or during labor
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Definition
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Term
Respiratory Distress Syndrome (hyaline membrane disease)
¡(Lack of OR too much) surfactant in premature infant
¡Increased risk that the alveoli will collapse during expiration causing respiratory distress syndrome
¡Common cause of death in premature infants
▪20% of all infant deaths in newborn period
§Partially collapsed alveoli contain fluid with (high or low) protein content,
§ looks like hyaline in aveolar membrane under the microscope,
§ lamellar bodies seem under the microscope are probably from surfactant layer
¡Treatment
§Give steroids mother
§Treat infant with artificial surfactant
▪reduces mortality |
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Definition
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Term
Tracheo-esophageal fistula
¡Abnormal development of the tracheoesophageal septum results in a variety of atresia and fistula type defects (tracheo-esophageal fistulas) in this region.
¡Ninety percent result in the (cranial or caudal) portion of the esophagus ending in a blind pouch and a fistula (abnormal connection or passageway between two epithelium-lined organs or vessels) between the caudal part of the esophagus and the trachea.
¡In several of these examples, it is easy to see that, when the baby nurses, milk can be aspirated and flow into the trachea and lungs. |
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Definition
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Term
Congenital defects
¡Congenital cysts
§Formed by dilation of terminal or larger (alveoli or bronchi)
▪May be small & multiple giving the lung a honeycombed appearance on X-ray
▪May be restricted to one or more larger ones
▪Drain poorly & frequently cause chronic infections
A cyst is a closed sac
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Definition
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