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Human Structure - Block 2 > Embryology 6 > Flashcards

Embryology 6 Flashcards

(100 cards)

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1
Q

Describe the formation of the intraembryonic mesoderm during gastrulation.

A

cells migrate through primitive streak of embryo to form intraembryonic mesoderm

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2
Q

The intraembryonic mesoderm is partitioned into (3)

A

paraxial mesoderm

intermediate mesoderm

lateral mesoderm

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3
Q

What is the ultimate fate of the paraxial mesoderm? (2)

A

segmented into somites, which develop into bones of axial skeleton + associated musculature

develops into dermis

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4
Q

What is the ultimate fate of the intermediate mesoderm?

A

urogenital tract

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5
Q

The lateral mesoderm gets split into

A

two layers: parietal lateral mesoderm + visceral lateral mesoderm

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6
Q

Which embryonic structure develops into a “tube within a tube?”

A

lateral mesoderm

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7
Q

What embryonic structure gives rise to the cardiovascular system?

A

visceral portion of the lateral mesoderm

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8
Q

Label the following diagram.

A
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9
Q

When does the formation of the primitive heart begin?

A

week 3

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10
Q

What is the first step of primitive heart formation?

A

angioblastic cords form from lateral mesoderm

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11
Q

Describe how the angioblastic cords formed from lateral mesoderm further develop. (2)

A

angioblastic cords → 2 endothelial heart tubes

tubes fuse → primitive heart

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12
Q

What are the three layers of the primitive heart?

A

endocardium = lines cavity

myocardium = heart muscle

epicardium = outermost layer

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13
Q

All three layers of the primitive heart derive from what embryonic structure?

A

visceral portion of lateral mesoderm

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14
Q

Where is the primitive heart positioned relative to the foregut and oropharyngeal membrane?

A

ventral to foregut

caudal to oropharyngeal membrane

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15
Q

What five structures are distinguishable along the heart tube?

A

sinus venosus

primitive atrium

primitive ventricle

bulbus cordis

truncus arteriosus

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16
Q

When and how do heart contractions begin in the embryonic heart?

A

begin on day 21-22 as peristaltic waves in sinus venosus

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17
Q

What is the direction of embryonic heart blood flow by week 4?

A

unidirectional

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18
Q

Describe the pathway of embryonic blood flow in the primitive heart. (7)

A

blood enters heart through sinus venosus

enters primitive atrium

goes to primitive ventricle

exits primitive ventricle via bulbus cordis + truncus arteriosus

goes to aortic sac

goes to aortic arches

dorsal aorta

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19
Q

What structures feed blood into the sinus venosus of the embryonic heart? (3)

A

common cardinal veins

umbilical vein

vitelline vein

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20
Q

How does the embryo receive nutrients and oxygen?

A

from mother, via placental transfer

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21
Q

Describe the vascular resistance of the embryonic lung.

A

high vascular resistance, because the lungs are not yet filled with air

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22
Q

Describe blood supply to the lungs and liver in embryonic development.

A

lungs and liver don’t have much of a function in the embryonic stage, so they are bypassed in fetal circulation

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23
Q

Draw a diagram of fetal circulation after its heart has developed.

A
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24
Q

What are the two primary structures of the fetal heart that allow blood to bypass the lungs?

A

foramen ovale

ductus arteriosus

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25
What are the three major changes to the cardiovascular system after birth?
lungs inflate = lower resistance to blood flow in lungs foramen ovale closes ductus arteriosus closes
26
What is the remnant of the ductus arteriosus in the adult heart?
ligamentum arteriosum
27
What is the effect of clamping the umbilical cord?
reroutes neonatal blood from oxygenation in placenta to oxygenation in aerated lungs
28
What is the remnant of the ductus venosus in the adult?
ligamentum venosum
29
What is the remnant of the umbilical vein in the adult?
ligamentum teres, a.k.a. round ligament of liver
30
What is the remnant of the umbilical artery/arteries in the adult?
medial umbilical ligaments
31
How many chambers are there in the primitive heart?
only 2 - one atrium and one ventricle
32
What does it mean for the heart to develop a double pump system?
right atrium and ventricle drive pulmonary circulation left atrium and ventricle drive systemic circulation
33
What anchors the superior end of the primitive heart tube?
aortic arches
34
What anchors the inferior end of the primitive heart tube?
septum transversum
35
What is the embryonic precursor to the diaphragm?
septum transversum
36
What is the result of the rapid growth of the bulbus cordis and primitive ventricle in the embryonic heart?
formation of bulboventricular loop
37
Describe the positioning of the sinus venosus and bulbus cordis within the bulboventricular loop.
sinus venosus is dorsal and superior to bulbus cordis
38
What is the remnant of the bulboventricular loop in adults?
transverse pericardial sinus
39
What structures define the transverse pericardial sinus? (2)
anterior = aorta + pulmonary trunk posterior = SVC + pulmonary veins
40
What is the structural function of the atrioventricular canal in the primitive heart?
connects primitive atrium to primitive ventricle
41
What structure connects the primitive atrium to the primitive ventricle in the primitive heart?
atrioventricular canal
42
What are endocardial cushions?
outgrowths of dorsal + ventral walls of atrioventricular canal
43
What eventually happens to the endocardial cushions?
grow until they fuse, at which point the atrioventricular canal is now separated into a right and left canal
44
Draw a diagram of the steps that occur in the partitioning of the primitive atrium.
45
Describe how the foramen ovale between the atria is closed after birth.
higher pressure in left atrium pushes septum primum against septum secondum, which closes foramen ovale
46
What is the remnant of the foramen ovale after birth?
fossa ovalis
47
Describe how the primitive ventricle is partitioned.
ridge from floor of common ventricle grows upward but a gap (interventricular foramen) persists
48
What is the fate of the interventricular foramen?
membranous septum bridges interventricular foramen in week 7, which completely separates the ventricles
49
Describe how the aorticopulmonary septum is formed. (2)
bulbar ridges grow out from bulbus cordis and extend into truncus arteriosus as truncal ridges bulbar and truncal ridges spiral + fuse to produce aorticopulmonary spetum
50
In adults, the bulbus cordis become
conus arteriosus (infundibulum)
51
Describe the changes in the sinus venosus at week 7.
paired venous system (left and right common cardinal veins draining into sinus venosus) becomes unpaired w/ IVC and SVC
52
Describe the significance of the right portion of the sinus venosus integrating into the right atrial wall.
the point of integration is the _crista terminalis_: rough surface derives from primitive atrium smooth surface derives from sinus venosus
53
What is the crista terminalis?
the border between smooth and rough portions of the atrial wall
54
What is the embryonic origin of the coronary sinus?
left portion of sinus venosus
55
What is the function of the coronary sinus?
drains venous blood from heart muscle into right atrium
56
From where do the pharyngeal arches receive the aortic arches?
common aortic sac
57
The common aortic sac is a continuation of
the truncus arteriosus
58
The third pair of aortic arches develops into (2)
the common carotid arteries (from the proximal portion of the third aortic arches) the internal carotid arteries (from the distal portion of the third aortic arches)
59
What is the embryonic origin of the common carotid arteries?
proximal portions of third aortic arches
60
What is the embryonic origin of the internal carotid arteries?
distal parts of the third aortic arches
61
The left fourth aortic arch becomes
the arch of the aorta
62
The right fourth aortic arch becomes
right subclavian artery
63
What is the embryonic origin of the arch of the aorta?
left fourth aortic arch
64
What is the embryonic origin of the right subclavian artery?
right fourth aortic arch
65
The left sixth aortic arch becomes
the left pulmonary artery (proximal portions) ductus arteriosus (distal portions)
66
What is the embryonic origin of the left pulmonary artery?
proximal portions of the left sixth aortic arch
67
What is the embryonic origin of the ductus arteriosus?
distal portions of the left sixth aortic arch
68
The right sixth aortic arch becomes
the right pulmonary artery (proximal portions) nothing/degenerates (distal portions)
69
What is the embryonic origin of the right pulmonary artery?
proximal portions of the right sixth aortic arch
70
Describe the location of the recurrent laryngeal nerves in the embryonic heart, and how this location changes. (3)
initially supply sixth pair of branchial arches and loop around sixth pair of aortic arches _degeneration of 5th/6th aortic arches causes:_ right recurrent laryngeal nerve to hook around right subclavian artery left recurrent laryngeal nerve to stay anchored around ductus arteriosus
71
What are cardiac shunts?
patterns of cardiac blood flow that deviate from normal pattern
72
How do cardiac shunts typically occur?
when two spaces of the heart (e.g. R and L atria) are abnormally connected
73
What is a left-to-right shunt? (2)
abnormal flow from systemic to pulmonary circuit oxygenated blood is redirected to pulmonary circulation instead of going out to the periphery
74
What is a right-to-left shunt? (2)
abnormal flow from pulmonary circuit to systemic circuit deoxygenated blood enters systemic circulation
75
What is cyanosis?
blue appearance of skin/mucous membranes due to lack of oxygen
76
What is the long term effect of a left-to-right shunt?
right atrial and ventricular hypertrophy, because the pulmonary circulation has to pump an increased amount of blood
77
What are three classes of congenital heart defects causing left-to-right shunts?
atrial septal defects ventricular septal defect patent ductus arteriosus
78
Give four subtypes of atrial septal defects.
foramen secundum defects foramen primum defects sinus venosus atrial septal defects common atrium
79
If you have defects in the septa that divide the left and right atria in an embryo, what are the consequences?
no consequences [assuming this is prior to birth], because the atria are connected by the foramen ovale anyways
80
What are foramen secundum defects?
patent foramen ovale due to defects in formation of septum primum or septum secundum
81
What are foramen primum defects?
septum primum does not completely fuse with endocardial cushion, resulting in patent foramen primum
82
When do the symptoms of a foramen secundum defect typically manifest?
do not manifest in childhood or early adulthood, but typically start at the age of 30
83
What is a common symptom of foramen secundum defects?
pulmonary hypertension
84
How are foramen secundum defects treated?
with an easy and low-mortality-rate surgery
85
Foramen primum defects are often associated with what other heart defect?
cleft in one cusp of mitral valve
86
Sinus venosus atrial septal defects result from
incomplete integration of the right sinus venosus into the right atrium
87
A common atrium is the result of
complete failure to form septum primum and septum secundum
88
Ventricular septal defects are caused by
incomplete growth of membranous or muscular part of interventricular septum
89
Patent ductus arteriosus results from
failure of closure of ductus arteriosus after birth
90
Give four examples of congenital heart defects that cause right-to-left shunts, with cyanosis.
persistent truncus arteriosus (PTA) transposition of great arteries tetralogy of Fallot (TF) coarctation of aorta
91
Persistent truncus arteriosus is the result of
the aorticopulmonary septum (separating aorta from pulmonary trunk) failing to form
92
Transposition of great arteries occurs when
aorticopulmonary septum develops in a non-spiral manner, causing aorta to arise from right ventricle and pulmonary trunk arising from left ventricle
93
How is the transposition of the great arteries treated?
it's not compatible with life, unless there's another shunt
94
Tetralogy of Fallot is caused by
defects in development of aorticopulmonary septum and endocardial cushions
95
List the four malformations associated with tetralogy of Fallot.
pulmonic stenosis ventricular septal defect overriding aorta hypertrophy of right ventricle
96
What is coarctation of the aorta?
narrowing of aorta proximally or distally to junction of aorta and ductus arteriosus
97
What is the function of the ductus arteriosus?
connects pulmonary trunk to descending aorta
98
Label the following diagram.
99
Label the following diagram.
100
Label the following diagram.

Human Structure - Block 2 (22 decks)

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