Chapter 2: Thorax (continued 2) Flashcards
Where are the alveolar macrophages derived from?
monoctyes that exit the blood vessels in the lungs
What are some other common names of alveolar macrophages?
dust cells or heart failure cells (because they have phagocytosed blood cells that have escaped into the alveolar space during CHF
The heart begins to develop from what embryological layer?
splanchnic mesoderm
The primitive heart tube has what 5 dilations?
Truncus arteriosus
bulbus cordis
primitive ventricle
primitive atrium
sinus venosus
The primitive ventricle fuses with what embryological part of the primitive heart tube?
bulbus cordis
The primitive atrium fuses with what part of the primitive heart tube to form the atrium?
the sinus venosus
Describe the embryological origin of the rough and smooth parts of the ventricle.
smooth part ventricle: bulbus cordis
rough part ventricle: primitive ventricle
Describe the embryological origin of the rough and smooth parts of the atria.
smooth part atria: sinus venosus
rough part atria: primitive atrium
The truncus arteriosus has what embryological origin?
neural crest cells
In fetal circulation, what are the 3 major venous systems that flow into the sinus venosus end of the heart tube?
The vitelline (omphalomesenteric) veins
umbilical vein
cardinal veins
What structures does the vitelline veins drain?
drains deoxygenated blood from the yolk stalk; they will coalesce and form the veins of the liver (sinusoids, hepatic portal vein, hepatic vein) and part of the inferior vena cava
What structures do the cardinal veins drain?
carry deoxygenated blood from the body of the embryo; they will coalesce and contribute to some of the major veins of the body (brachiocephalic, superior vena cava, inferior vena cava, azygos, renal)
What is the function of the ductus venosus? Describe flow of blood to heart and to systemic circulation.
allows oxygenated blood in the umbilical vein to bypass the sinusoids of the liver into the IVC and to the right atrium. From the right atrium oxygenated blood flows mostly through the foramen ovale into the left atrium then left ventricle and into the systemic circulation
Is the ductus arteriosus proximal or distal to the the left subclavian artery?
distal to
What does the ductus arteriosus become as an adult?
liagmentum arteriosum
What does the foramen ovale become after birth?
fossa ovalis
What does the ductus venosus become after birth?
ligamentum venosum
The left and right umbilical arteries become what structure of the adult?
medial umbilical ligaments
What does the closure of the umbilical v. become in the adult?
ligamentum teres of the liver
What factors lead to the closure of the ductus arteriosus?
- the rise in bradykinin
- immediate drop of PGs
- the increase in oxygenation
When does septation of the atria and ventricles typically begin and finish?
week 4 and is mostly finished by week 8
What is the foramen primum?
is located between the SP (septum primum) and endocardial cushion
is obliterated when the SP later fuses with the endocardial cushion
What is the foramen secundum?
forms within the upper part of the SP just before the FP closes to maintain the right to left shunting of oxygenated blood that entered the right atrium via the inferior vena cava
What is the septum primum?
flexible separation that grows inferiorly from the roof of the common atrium toward the endocardial cushions
In comparison, with the septum primum, is the septum secundum more rigid or flexible?
more rigid
Which type of shunts are cyanotic? Rt-left or left to right?
right to left shunts
What are the 2 ASD types?
Secundum type ASD
Primum type ASD
What is a septum secundum type ASD caused by? Where is this type of atrial septal defect located?
caused by either an excessive resorption of the SP or an underdevelopment and reduced size of the SS or both
results in variable opening between the right and left atria in the central part of the atrial septum above the limbus
Which ASD type is the most common?
secundum type ASD
Primum type ASD? What is the cause? Where is it usually located?
less common than secundum ASD and results from a failure of the septum primum to fuse with the endocardial cushions (endocardial cushion/neural crest defect really)
occur in lower aspect of the atrial wall usually with normal formed fossa ovalis
Primum type ASD is associated with defects of what structures of the heart?
the membranous interventricular septum and the atrioventricular valves
When does development of formation of ventricular septum start and end?
begins in week 4 and is usually completed by end of week 7
What is membranous VSD caused by?
associated with the failure of the neural crest cells to migrate into the endocardial cushions
Maternal rubella infection is associated with what congenital heart defect?
patent ductus arteriosus
Besides PGE inhibitors what can cause the closure of the ductus arteriosus?
acetylcholine, histamine, catecholamines;
therefore all used to promote closure in instances of premature birth
Which PGE inhibitor is the common choice to close the ductus arteriosus?
indomethacin
When does septation of the truncus arteriosus occur?
during week 8
What embryological issue occurs which results in Tetralogy of Fallot?
it is when the AP septum fails to align properly and shifts anteriorly to the right causing rt to lft shunting of blood with resultant cyanosis
What are the 4 major defects in tetralogy of Fallot?
- pulmonary stenosis
- membranous interventricular septal defect (VSD)
- right ventricular hypertrophy (develops secondarily)
- Overriding aorta
What is the embryological abnormality occurring which leads to transposition of the Great Vessels?
When the AP septum fails to develop in a spiral fashion
What is the embryological malformation which leads to persistent truncus arteriosus?
When there is partial development of the aorticopulmonary septum
How is the mediastinum divided into superior and inferior mediastina?
by a plane passing from the sternal angle (of Louis) anteriorly to the intervertebral disc between T4 and T5 posteriorly
What are the major parts of the anterior mediastinum
fat, areolar tissue, inferior part of the thymus gland
What borders designate the posterior mediastinum?
located between the posterior surface of the pericardium and T5 - T12
The esophagus lies immediately posterior to what major structures?
the left primary bronchus and left atrium
What are the 3 branches of the aortic arch?
brachiocephalic, left common carotid, left subclavian
The 3 branches of the aortic arch are anterior or posterior to the left brachiocephalic v.?
They are directly posterior to the left brachiocephalic v.
The vagus nerves give rise to what structures moving superiorly?
give rise the the right and left recurrent laryngeal nerves
What is coarctation of the aorta?
narrowing of the aorta distal to the origin of the left subclavian artery
Another name for preductal coarctation.
infantile type
Preductal coarctation?
less common and occurs proximal to the DA. the DA usually remains patent and provides blood flow via the DA to the descending aorta and the lower parts of the body.
What is postductal coarctation?
occurs distal to the DA
Another name for postductal coarctation?
adult type
How does anatomy of the body change when one has postductal coarctation?
results in intercostal arteries providing collateral circulation between the internal throracic artery and the thoracic aorta to provide blood supply to the lower parts of the body
Signs and symptoms of postductal coarctation?
patients hypertensive in the upper body (head, neck, and upper limbs) and hyptotensive with weak pulses in lower limbs
What is costal notching?
enlargement of the intercostal arteries on lower border of ribs usually associated with postductal coarctation
Where does the left recurrent laryngeal nerve course?
curves under aortic arch distal to the ligamentum arteriosum where it may be damaged by pathology
Damage to left recurrent laryngeal nerve may result in what pathology?
paralysis of the left vocal folds
Either the right or left recurrent layngeal nerve may be lesioned with what type of surgery?
thyroid gland surgery
