Module 1D: Development Of The Cardiovascular System

Question 1

What germ layer contributes to early blood and blood vessel formation?

Answer 1

Lateral plate mesoderm

Question 2

Development during the Embryonic period

Answer 2

Wk 3-8

Question 3

Cells close to the mid-line proliferate and form a thickened
plate of tissue known as the ______ ______ (elongate
from cranial to caudal)

Answer 3

paraxial mesoderm

Question 4

The mesoderm between the paraxial and the
lateral plate is called the _______ ______
(image B)

Answer 4

Intermediate mesoderm

Question 5

Lateral plate mesoderm can be divided into

Answer 5

Somatic/parietal mesodermal

Visceral/Splanchnic mesoderm

Question 6

Blood and Blood Vessels:
• Arise from lateral plate (Visceral/Splanchnic) mesoderm division • Blood vessels form in two ways:

Answer 6

1. Vasculogenesis - vessels arise from blood islands. Islands of mesoderm cells that are induced to form Hemangioblasts

Hematopoietic stem cells * - Colonize the liver (Major hematopoietic
organ 2-7 months embryo)
After 7 months of gestation, hematopoietic stem cells move to the bone marrow

2. Angiogenesis - Which entails sprouting from existing vessels

Question 7

Hemangioblasts are what?

Answer 7

Blood producing cells

Question 8

Blood Islands

Answer 8

aggregates of
isolated differentiated mesenchyme
that form primitive blood cells and
vessels

Cavities develop in Blood Islands,
and mesenchymal cells there
arrange in the cavities to form the
endothelium of primitive BV’s (
Vasculogenesis)
• Primitive endothelial vessels fuse to
form networks of vessels
• Vessels extend to adjacent areas
and fuse with others to create early
circulatory vessels (Angiogenesis)

Question 9

Cranial migration of Cardiogenic mesoblasts

Answer 9

Part of the invaginating
epiblast during gastrulation
that is differentiating and
migrates further through the
mesodermal layer, settling
between visceral/splanchnic
mesoderm and the endoderm

Question 10

The intraembryonic cavity over the PHF later develops into the

Answer 10

pericardial cavity

Question 11

Movement of the progenitor heart cells from the cranial end to the ______ ______

Answer 11

Thoracic region

Question 12

Three stages of heart formation:

Answer 12

I. Formation of
the primitive heart tube
II. Cardiac
looping
III. Cardiac
septation

Question 13

I. Formation of the Herat tube (cardiac tube)

With time, the islands will form 2 tubes called

Answer 13

Endocardial tubes

Question 14

I. Formation of the heart tube

Later, the Left & Right endocardial tubes  fuse together to become the

Answer 14

Primitive heart tube

Question 15

The second source of cells for heart formation is the
cells residing in splanchnic mesoderm, ventral to the pharynx  called the

Answer 15

Secondary heart field

Question 16

The heart is formed from ?

Answer 16

Primary heart field —this originates from the
epiblast- comes to reside in the splanchnic
mesoderm just above the endoderm- PHF cells
make the myocardium of most of the heart

And secondary heart field — this layer originates from
the splanchnic mesoderm- it gives rise to the
dorsal mesocardium (check the image in this
slide). It also forms the myocardium of the blood
inflow and outflow channels of the heart.

Question 17

Primitive endothelial vessels
fuse form

Answer 17

Endocardial tubes

Question 18

Mesoderm  Lateral Plate  Visceral plate
mesoderm dorsal to PHF • Forms Dorsal mesocardium attaching the heart
tube to the dorsal wall of the pericardial cavity

Answer 18

1. Helps suspend heart tube in the pericardial
   cavity 2. Adds more cells to the developing mass of the
   heart tube

Question 19

The myocardium secretes a layer of extracellular matrix  called _______ ______(Collagen, GAGs, glycoproteins) which important for regulating cell shape, migration, proliferation, and differentiation of the heart cells

Answer 19

Cardiac jelly

Question 20

The heart tube consists of three layers:

Answer 20

1. Endocardium- originated from endoderm
2. Myocardium- originated from PHF and SHF
3. Epicardium- originated from dorsal mesocardium- SHF

Question 21

II. CARDIAC LOOPING:

Answer 21

Secondary heart field cells are added to the cranial end, causing elongation of the heart tube

This lengthening process is essential for:
1) Formation of part of the right
ventricle and the outflow tract region (that forms part of the aorta and pulmonary artery)
2) The looping process

Question 22

Specialized cardiomyocytes form the cardiac conduction system,
responsible for the control of rhythmic beating of the heart.

Answer 22

1.Sinoatrial (SA) Node: Forms in the right atrium near the sinus venosus, establishing the primary pacemaker. 2.Atrioventricular (AV) Node and Bundle of His: Develop from cells in the atrioventricular canal, linking atrial and ventricular conduction. 3.Purkinje Fibers: Evolve from ventricular myocardium to enable rapid impulse transmission. 4.Timing: Electrical activity starts the 4th week, with maturation of • Cardiac system (heart and blood vessels) is considered the
conduction pathways as heart first functional organ system in a developing embryo
chambers develop.

• This system ensures coordinated contractions and effective
with spontaneous contractions by blood flow to the cells in the growing embryo.

Question 23

III. CARDIAC SEPTATION  FORMATION OF THE CARDIAC SEPTA

Answer 23

The two methods of septum formation in the heart are:
1.Cushion Tissue Fusion: forms from
mesenchymal cells, dividing chambers by
merging at specific locations to create septa
(e.g., atrioventricular septa).
2.Tissue Growth and Fusion: A septum
grows from the heart wall toward the opposite
side and fuses to divide the chamber (e.g.,
interatrial septum).

Question 24

**look at slides 55-59 on heart development defects

Question 25

Patent Foramen Ovale (PFO):

Answer 25

• A flap-like opening persists if the foramen ovale fails to seal completely after birth, allowing intermittent right-to-left shunting. • ASDs can lead to increased pulmonary blood flow, right atrial and ventricular enlargement, and, if untreated, pulmonary hypertension or heart failure.

Question 26

DORV

Answer 26

Double Outlet Right Ventricle; both aorta and pulmonary artery arise from the right ventricle)

Question 27

Changes in the vascular system at birth are caused by:

Answer 27

1) Cessation of placental blood flow 2) Beginning of respiration

Question 28

Closure of Foramen ovale happens due to the following reasons:

Answer 28

The ductus arteriosus closes by muscular contraction of its wall  the amount of blood channeled to the lungs increases rapidly. This results in an increase in blood returning from the lungs, increasing the pressure in the left atrium. Simultaneously, the interruption of placental blood flow  pressure in the right atrium decreases. These simultaneous changes in pressure in the left and the right atria will cause the septum primum to press against the septum secundum and the foramen ovale closes. Full closure of the Foramen ovale  to form the Fossa ovale requires about 6 months During the first few days of life, this closure is reversible. Crying of the baby creates a shunt from right to left atria, which accounts for cyanotic periods in the newborn.

Question 29

Closure of the Ductus Venosus

Answer 29

This was a fetal blood vessel that connects the umbilical vein to the inferior vena cava, a major vein leading to the heart. This shunt allows oxygenated blood from the placenta to bypass the fetal liver and travel directly to the heart. After birth, the ductus venosus closes and becomes a fibrous remnant called the ligamentum venosum. Becomes the ligamentum venosum, redirecting blood through the liver.

Question 30

Umbilical Arteries and Vein

Answer 30

• The umbilical arteries become the medial umbilical ligaments. • The umbilical vein forms the ligamentum teres of the liver.

Question 31

Which structure divides the outflow tract into the aorta and the pulmonary artery? A. Spiral septum B. Septum primum C. Foramen ovale D. Dorsal mesocardium

Answer 31

A

Question 32

Which germ layer gives rise to the cardiovascular system? Ectoderm Neural crest Mesoderm Endoderm

Answer 32

Mesoderm

Question 33

Which process leads to the formation of three germ layers? Gastrulation Neurulation Vasculogenesis Organogenesis

Answer 33

Gastrulation

Question 34

What initiates the closure of the foramen ovale after birth? A. Decreased heart rate B. Increased pulmonary resistance C. Increased left atrial pressure D. Hormonal changes

Answer 34

C

Question 35

What structure allows fetal blood to bypass the lungs before birth? A. Ligamentum teres B. Ductus venosus C. Foramen ovale D. Septum intermedium

Answer 35

C

Question 36

What structure allows fetal blood to bypass the lungs before birth? A. Ligamentum teres B. Ductus venosus C. Foramen ovale D. Septum intermedium

Answer 36

C

Question 37

The primitive heart tube forms from the fusion of which structures? Pharyngeal arches Blood islands Neural crest cells Endocardial tubes

Answer 37

Endocardial tubes

Question 38

Which fetal structure becomes the ligamentum teres in the adult? Ductus venosus Umbilical artery Umbilical vein Ductus arteriosus

Answer 38

Umbilical vein

Question 39

The cardiac conduction system begins functioning around which week of development? Week 2 Week 6 Week 8 Week 4

Answer 39

Week 4

Question 40

What forms the atrioventricular septum and valves? Neural tube Endocardial cushions Septum primum Foramen ovale

Answer 40

Endocardial cushions

Question 41

Which of the following gives rise to the ascending aorta and pulmonary trunk? Neural crest Bulbous cordis Endocardial cushion Truncus Arteriosus

Answer 41

Truncus arteriosus

Question 42

After birth, the ductus arteriosus becomes the: A. Foramen ovale B. Ligamentum venosum C. Ligamentum arteriosum D. Medial umbilical ligament

Answer 42

C

Question 43

Failure of which structure to close can result in a patent foramen ovale (PFO)? Endocardial cushion Spiral septum Septum secundum Septum primum

Answer 43

Septum secundum

Question 44

Hemangioblasts differentiate to form: Blood islands Myotomes Somites Neural crest

Answer 44

Blood islands

Question 45

What is the function of the dorsal mesocardium? A. Separates atria from ventricles B. Develops into the myocardium C. Suspends the heart tube in the pericardial cavity D. Forms the atrial septum

Answer 45

C

Question 46

Which septum forms first in the developing atria? Septum secundum Septum primum Spiral septum Aorticopulmonary septum

Answer 46

Septum primum

Question 47

Which mechanism forms new blood vessels from existing ones? Angiogenesis Hematopoiesis Gastrulation Vasculogenesis

Answer 47

Angiogenesis

Question 48

Which of the following is a function of cardiac jelly? Becomes epicardium Prevents blood clotting Secretes surfactant Regulates cell migration and differentiation

Answer 48

Regulates cell migration and differentiation

Question 49

What is the first organ system to become functional in the embryo?

Answer 49

Cardiovascular

Question 50

Cardiac looping primarily enables what developmental outcome? Spatial arrangement of heart chambers Initiation of blood flow Closure of foramen ovale Chamber septation

Answer 50

Spatial arrangement of heart chambers

Question 51

*** read slides 73-76 because I can’t copy for some reason

Question 52

***look at slides 84, 85

Question 53

**Look over slides 88-111***

Question 54

Before birth, the fetal lungs are filled with: Air Amniotic debris Chloride-rich fluid and surfactant Blood

Answer 54

Chloride-rich fluid and surfactant

Question 55

Surfactant primarily functions to: A. Enhance immune defense B. Increase blood flow C. Promote mucus production D. Reduce surface tension

Answer 55

D

Question 56

Which lung has three lobes? Left lung Neither lung Right lung Both lungs

Answer 56

R

Question 57

What does the visceral mesoderm become in lung development? A. Pericardial sac B. Pulmonary artery C. Visceral pleura D. Alveolar lining

Answer 57

C

Question 58

What is the correct sequence of lung maturation stages? A. Embryonic ? Pseudoglandular ? Canalicular ? Saccular ? Alveolar B. Embryonic ? Canalicular ? Pseudoglandular ? Saccular ? Alveolar C. Embryonic ? Alveolar ? Canalicular ? Pseudoglandular ? Saccular D. Pseudoglandular ? Embryonic ? Canalicular ? Alveolar ? Saccular

Answer 58

A

Question 59

What structures are formed from the branching of the primary bronchi? A. Terminal bronchioles B. Trachea and esophagus C. Secondary (lobar) bronchi D. Alveolar sacs

Answer 59

C

Question 60

What regulates lung bud branching? A. Bone morphogenetic protein B. Thyroid hormone C. Retinoic acid D. Fibroblast growth factor (FGF)

Answer 60

D

Question 61

How does surfactant affect alveolar stability? A. Reduces surface tension more in smaller alveoli B. Increases surface tension uniformly C. Stimulates bronchoconstriction D. Equalizes oxygen content

Answer 61

A

Question 62

What germ layer gives rise to the epithelial lining of the respiratory tract? Mesoderm Ectoderm Endoderm Neural crest

Answer 62

Endoderm

Question 63

The respiratory diverticulum first appears during which week of development? Week 2 Week 8 Week 4 Week 3

Answer 63

Week 4

Question 64

During which stage does gas exchange first become possible? Canalicular Embryonic Alveolar Pseudoglandular

Answer 64

Canclicular

Question 65

What cells produce surfactant in the fetal lung? Type I pneumocytes Type II pneumocytes Macrophages Endothelial cells

Answer 65

Type II pneumocystis

Question 66

What structure separates the developing trachea and esophagus? A. Bronchial septum B. Pleuropericardial membrane C. Tracheoesophageal septum D. Laryngeal ridge

Answer 66

C

Question 67

What major structural changes occur in the lungs after birth? A. Alveoli and bronchioles increase in number B. The trachea splits again C. Type II cells disappear D. Pulmonary arteries shrink

Answer 67

A

Question 68

During which stage do the terminal sacs begin to develop? Canalicular Saccular Embryonic Pseudoglandular

Answer 68

Saccular

Question 69

Which pharyngeal arches contribute to the formation of the larynx? Arches 2 and 3 Arches 1 and 2 Arches 3 and 5 Arches 4 and 6

Answer 69

Arches 4 and 6

Question 70

According to the Law of LaPlace, smaller alveoli have: A. Greater pressure if surface tension is equal B. No pressure difference C. The same pressure as larger ones D. Less pressure than larger ones

Answer 70

A

Question 71

When do fetal breathing movements begin? After birth Week 36 only Immediately after surfactant is produced Before birth

Answer 71

Before birth

Question 72

The cartilage, muscle, and connective tissues of the lungs are derived from which source? Paraxial mesoderm Endoderm Visceral mesoderm Intermediate mesoderm

Answer 72

Visceral mesoderm

Question 73

How many alveoli are present at birth compared to adulthood? All alveoli are present at birth Only one-sixth are present at birth Half are present at birth Two-thirds are formed before birth

Answer 73

Only one-sixth are present at birth