Week 7

Question 1

Lungs begin developing in what week?

Answer 1

BEGIN IN FOURTH WEEK

Question 2

What are the stages of lungs developing?

Answer 2

• EMBRYONIC

*PSEUDOGLANDULAR

• CANALICULAR
• TERMINAL SACCULAR
• ALVEOLAR

Question 3

The transition between developing lung stages is ______

there is considerable ______ from one stage to the next

Answer 3

gradual

overlap

Question 4

when is the EMBRYONIC STAGE

Answer 4

Week 4-5 from conception

Question 5

what occurs in the embryonic stage

Answer 5

Lungs arises as a respiratory diverticulum from the caudal end of the
laryngotracheal groove of the FOREGUT

➢ This diverticulum grows gradually caudally to form the PRIMITIVE TRACHEA

➢ The end of the diverticulum divides into two sacs, the lung buds

Question 6

what occurs in week 6

Answer 6

All bronchopulmonary segments are formed.

Question 7

when is the PSEUDOGLANDULAR stage?

what occurs?

Answer 7

Week 5 – 17

Repeated dichotomous (in
two) branching > tree on
narrow, thick, epithelial-
lined tubules.

Question 8

when is the canalicular stage?

what occurs?

Answer 8

Week 16 – 25, 28

➢ Formation of the
basic structure of gas-
exchanging portion of
the lung

➢ Vascularization

Question 9

when is the SACCULAR STAGE?

what occurs?

Answer 9

Week 28 – 36

➢ Airways terminate in large
smooth-walled cylindrical
structures

➢ They are subdivided by ridges
called CRESTS

➢ Thinning of the interstitium

Question 10

When is the ALVEOLAR STAGE?

what occurs?

Answer 10

Week 36 – term

➢ Thinning of the blood-
gas barrier

➢ Increase of surfactant
production

➢ Progressive branching of
the respiratory airways

Question 11

BREATHING MOVEMENTS THAT OCCUR BEFORE BIRTH RESULT IN

Answer 11

ASPIRATION OF FLUID INTO
LUNGS.

Question 12

LUNGS AT BIRTH ABOUT ______ FLUID FROM …

Answer 12

LUNGS AT BIRTH ABOUT HALF-FILLED WITH FLUID FROM AMNIOTIC CAVITY, TRACHEAL
GLANDS, AND LUNGS.

Question 13

FLUID IN LUNGS AT BIRTH CLEARS VIA THREE ROUTES:

Answer 13

1. THROUGH MOUTH AND NOSE
2. INTO PULMONARY CAPILLARIES
3. INTO LYMPHATICS AND PULMONARY VESSELS

Question 14

LUNGS IN FETAL THORAX

what is assessed for?
characteristic of it?
bordered by what?
surrounded by what?

Answer 14

• ASSESSED FOR SIZE, TEXTURE AND LOCATION
• FLUID FILLED IN UTERO
• MEDIALLY BORDERED BY THE HEART
• INFERIORLY BY THE DIAPHRAGM
• LATERALLY BORDERED BY THE RIB CAGE

Question 15

size comparison of thorax to abdominal cavity

Answer 15

• THORAX NORMALLY SLIGHTLY SMALLER THAN ABDOMINAL CAVITY.
• RATIO (THORACIC CIRCUMFERENCE TO ABDOMINAL CIRCUMFERENCE) REPORTED TO
  REMAIN CONSTANT THROUGHOUT PREGNANCY (0.94 ± 0.05).

Question 16

how do you measure chest biometry

what is the point?

Answer 16

• THORACIC CIRCUMFERENCE
  (OUTER TO OUTER)
• TAKEN AT LEVEL OF FETAL HEART
• RULES OUT PULMONARY
  HYPOPLASIA

Question 17

position of the heart?

Answer 17

• CENTRAL PORTION OF THORAX OCCUPIED BY MEDIASTINUM; MAJORITY
  OF HEART IS POSITIONED IN MIDLINE AND LEFT CHEST.
• APEX OF HEART SHOULD BE DIRECTED TOWARD SPLEEN.
• BASE OF HEART LIES HORIZONTAL TO DIAPHRAGM.

Question 18

texture of the lungs?

Answer 18

FETAL LUNGS APPEAR HOMOGENEOUS ON SONOGRAPHY, WITH
MODERATE ECHOGENICITY.

• EARLY IN GESTATION, LUNGS SIMILAR TO OR SLIGHTLY LESS ECHOGENIC
  THAN LIVER.
• AS GESTATION PROGRESSES, TREND IS TOWARD INCREASED PULMONARY
  ECHOGENICITY RELATIVE TO LIVER.

Question 19

echogenecity of lungs compared to heart

Answer 19

EVENLY ECHOGENIC ON EITHER SIDE OF THE HEART

Question 20

difference in echogeneicty of lungs in 2nd trimester VS 3rd trimester

Answer 20

2ND TRIMESTER → LUNGS ISOECHOIC TO THE LIVER

3RD TRIMESTER → LUNGS SLIGHTLY MORE ECHOGENIC

Question 21

FETAL BREATHING BECOMES MORE PROMINENT IN

Answer 21

SECOND AND THIRD
TRIMESTERS.

Question 22

MATURE FETUS SPENDS ALMOST _______ OF ITS TIME BREATHING.

Answer 22

One third

Question 23

SURFACTANT (PHOSPHOLIPOPROTEIN) PRODUCED BY…

Answer 23

TYPE II ALVEOLAR CELLS.

Question 24

what is the main function of surfactant

Answer 24

THE MAIN FUNCTION OF SURFACTANT IS TO LOWER THE SURFACE TENSION AT THE AIR/LIQUID
INTERFACE WITHIN THE ALVEOLI OF THE LUNG.

Question 25

what indicates lung maturity?

Answer 25

L/S RATIO (LECITHIN/SPHINGOMYELIN RATIO) BIOCHEMICAL TEST ( 2.0 TO 2.5 INDICATES LUNG MATURITY)

Question 26

range of lung maturity based on date

Answer 26

* < 34 WKS LUNGS IMMATURE * > 37 WKS LUNGS MATURE * 34-37 WKS TRANSITIONAL AGE

Question 27

IF CAESAREAN (c section) REQUIRED... IF LUNGS NOT MATURE... If the fetus does not have enough surfactant, the lungs are immature, and the baby would be at high risk for…

Answer 27

LS (LECITHIN/SPHINGOMYELIN) IS DONE BEFORE (Early C-section → do amniocentesis → measure L/S ratio → check lung maturity.) ↓ SURFACTANT If the fetus does not have enough surfactant, the lungs are immature, and the baby would be at high risk for respiratory distress syndrome (RDS) after birth. Surfactant keeps the lungs inflated and prevents collapse. Low surfactant = immature lungs. --> WITH CORTICOSTEROIDS (SURFACTANT) TO ACCELERATE FETAL LUNG MATURITY AND U/S FOR ACCURATE DATING, AMNIOCENTESIS FOR FETAL LUNG MATURITY IS NO LONGER AS FREQUENTLY PERFORMED. (Now, instead of doing amniocentesis to measure lung maturity: Doctors simply give the pregnant person corticosteroid injections (e.g., betamethasone). These steroids rapidly accelerate surfactant production in the fetal lungs. This makes the lungs mature without needing invasive testing.) Old way: Early C-section → do amniocentesis → measure L/S ratio → check lung maturity. New way: We know exact gestational age from ultrasound AND we can speed up lung maturity with steroids → so amniocentesis is usually unnecessary.

Question 28

Accurate ultrasound dating plus steroid injections to rapidly mature fetal lungs have replaced the need for amniocentesis (L/S ratio), so lung-maturity testing is rarely done before early C-sections now. True False

Answer 28

TRUE

Question 29

DIAPHRAGM

Answer 29

* THIN, HYPOECHOIC , DOME SHAPED MUSCULAR BAND * SEPARATES THE ABDOMINAL CAVITY FROM THE THORACIC CAVITY * RIBS CAST ACOUSTIC SHADOWS OVER CHEST

Question 30

FETAL LUNGS ARE MORE ECHOGENIC THAN THE FETAL LIVERIN THE: A) 1ST TRIMESTER B) 2ND TRIMESTER? C) 3RD TRIMESTER

Answer 30

C) 3RD TRIMESTER A) 1st Trimester — Lungs are LESS echogenic than liver The lungs are mostly fluid-filled and appear hypoechoic relative to the liver. B) 2nd Trimester — Lungs are STILL LESS echogenic than liver They begin to gain echogenicity but remain darker than the liver. C) 3rd Trimester — Lungs become MORE echogenic than liver With lung maturation and increasing surfactant production, the lungs become brighter/hyperechoic compared to the liver.

Question 31

RIBS

Answer 31

INDIVIDUAL RIBS CAN BE IMAGE BY OBTAINING TRANSVERSE VIEWS OF THE FETAL CHEST OR ABDOMEN