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Embryo Final Exam > Development Of The Heart > Flashcards

Flashcards in Development Of The Heart Deck (36)
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0
Q

What tissue is responsible for forming the horse-shoe shaped endothelial cord?

A

Splanchnic mesoderm cells

1
Q

The heart develops in what region?

A

Cardiogenic mesoderm

2
Q

Describe the formation of the primitive heart tube from the paired angioplasties cords.

A

The lateral sides of the horse shoe shaped endothelial tube fold in centrally and medially, approaching each other at the midline to fuse, forming a single heart tube.

3
Q

How does head folding in the 4th week reposition the heart and pericardial cavity? Prior to head fold

A

The heart is

  • rostral to oropharyngeal membrane
  • ventral to pericardial cavity
4
Q

How does head folding in the 4th week reposition the heart and pericardial cavity? Post head fold

A

The heart is:

  • caudal to oropharyngeal membrane
  • dorsal to pericardial cavity
  • ventral to the foregut
  • rostral to the septum transversum
5
Q

What is the fate of the dorsal mesocardium?

A

Degenerates to form the transverse pericardial sinus

6
Q

Heart folding/ formation of the cardiac loop forms in what days?

A

22-28

7
Q

Heart septation occurs in what days?

A

27-37

8
Q

What is the adult derivative of the sinus venosus right horn?

A

Sinus venarum

9
Q

What is the adult derivative of the sinus venosus left horn?

A

Coronary sinus

10
Q

What is the adult derivative of the primordial atrium?

A

Right and left auricles and portions of the atria

11
Q

What is the adult derivative of the primordial ventricle?

A

Only left ventricle

12
Q

What is the adult derivative of the proximal bulbus cordis?

A

Right ventricle

13
Q

What is the adult derivative of the conus cordis?

A

Outflow tract of ventricles

14
Q

What is the adult derivative of the truncus arteriosus?

A

Pulmonary trunk and aorta

15
Q

Describe how the cranial and caudal ends of the heart tube come to be repositioned in the formation of the cardiac loop

A

As the heart folds, it’s cranial end will shift centrally, caudally, and to the right. It’s caudal end will shift dorsally and superiorly.

16
Q

Describe the direction of blood flow through the tubular heart.

A

Sinus venosus-> through sinoatrial canal-> to primordial atrium-> through atrioventricular canal-> to atrioventricular sulcus-> to primordial ventricle-> through primary interventricular foramen -> to bulboventricular sulcus-> to bulbus cordis-> to aortic sac and pharyngeal arch aa.

17
Q

Describe the changes developing in the sinus venosus as blood flow to the heart gradually shifts to enter the right atrium

A

Originally the sinus venosus opens directly into the central dorsal wall of the primordial atrium. Blood flow to the heart gradually shifts to the right side due to the remodeling of the vitelline, umbilical, and anterior cardinal vv. As a result, the right horn of the sinus venosus becomes larger than the left.

18
Q

Describe the direction of blood flow through the primordial heart prior to septation

A

Sinus venosus-> primordial atrium-> AV canal -> left ventricle ( primordial ventricle)-> interventricular foramen-> right ventricle-> conus cordis-> truncus arteriosus-> aortic sac -> pharyngeal aa-> dorsal aortae

19
Q

What are the three paired veins that drain into the sinus venosus?

A

Vitelline vv, umbilical vv, common cardinal vv.

20
Q

From what structure is the smooth walled portion of the right atrium derived?

A

Sinus venosus rt horn

21
Q

From what structure is the smooth walled portion of the left atrium derived?

A

the primordial pulmonary v and portions of its branches

22
Q

Describe ventricular septal defect

A
  • most common congenital heart defect (1:1000)
  • failure of IV septum to completely form
  • most cases it’s the membranous portion that fails to form
23
Q

Describe transposition of the great vessels

A
  • occurs 1:2500
  • the aorticopulmonary septum grows in straight instead of spiraling
  • aorta arises from the right ventricle
  • pulmonary trunk arises from left ventricle
24
Q

Describe Tetralogy of Fallot

A

The aorticopulmonary septum divides outflow tract unequally, resulting in stenosis of pulmonary trunk and overriding aorta.

International house of pancakes

  1. Interventricular septal defect
  2. Hypertrophy of right ventricle
  3. Overriding aorta
  4. Pulmonary stenosis
25
Q

Describe the formation of the atrioventricular septum that develops to separate the atria from the ventricles

A

Dorsal and ventral endocardial cushions develop and fuse together, forming a AV septum that divides the AV canal into right and left AV canals.

26
Q

Describe the formation of the first step (septum primum) of the interatrial septum that develops to separate the right and left atria.

A
  • Septum primum grows inferiorly to fuse with the endocardial cushions. The opening between the inferior edge of the septum & the endocardial cushions is the foramen primum.
  • Septum primum fuses with endocardial cushions, and foramen primum gradually closes off. As this happens, holes are forming in center of septum primum through apoptosis. These holes will unite to form the foramen secundum.
27
Q

Partitioning the primordial atrium involves what two septa that will fuse together to form the interatrial septum?

A

Septum primum (1st) and septum secundum (2nd)

28
Q

Describe the formation of the first step (septum secundum) of the interatrial septum that develops to separate the right and left atria.

A
  • As holes in the septum primum coalesce to form the foramen secundum, a thicker septum secundum develops from the roof of the primordial atrium, slightly to the right of the septum primum.
  • Septum secundum grows inferiorly and develops an opening: the foramen ovale (oval foramen)
29
Q

Describe fetal circulation as compared to adult circulation.

A

Before birth: blood flows from right to left atrium through the foramen ovale

After birth: foramen ovale closes off and there is no flow between atria

30
Q

What happens to the cranial portion of the septum primum?

A

It degenerates

31
Q

What happens to the caudal portion of the septum primum?

A

It forms the valve of the foramen ovale

32
Q

What is the fossa ovalis?

A

After birth, blood pressure within L atrium now exceeds that in the R atrium. This pushes the valve of foramen ovale against septum secundum and they fuse, closing off the foramen ovale. The foramen ovale closes off as a depression in the wall of the R atrium - the fossa ovalis (oval fossa)

33
Q

Describe the formation of the interventricular septum

A

The muscular portion if the IV septum grows crainally toward the AV septum, but does not fuse with it. The opening between the R and L ventricles is the IV foramen. The final portion of the IV septum is formed by the membranous portion.

34
Q

From what is the membranous portion of the septum derived?

A

Mesenchyme of the endocardial cushion tissue.

35
Q

Describe the formation of the aorticopulmonary septum that will divide the common outflow tract into two separate outflow tracts: the aorta (receiving blood from the left ventricle) and pulmonary trunk ( receiving blood from the right ventricle).

A

Aorticopulmonary septum fuses inferiorly with membranous IV septum, closing off blood flow between the ventricles and creating a separate outflow tract for each ventricle