Development Of Heart Part1 | Heart embryology | Cardiovascular system | First Aid Lectures | Lec1
Channel: Dr. Jamil Lectures
Date: 28/04/2023

Our official Website from where you can get lecture notes free:
https://whmenotes.blogspot.com
You can find the notes and illustrations for this lecture on our website at:
https://whmenotes.blogspot.com/2023/07/heart-embryology-cardiovascular-system.html




I this lecture we will discuss about Heart embryology ,development of heart,Heart Tube and its divisions,Cardiac Looping,Dextrocardia,septa and Valvular Anomalies.


Get complete cardiovascular and neurology & special senses medical lectures on subscription  with very low price. 
contact on social media
whatsapp = +923015721801
Instagram account    Dr_jamil56

https://youtu.be/gXGK6F_vDJQ
https://youtu.be/U3aD-wn2zMM
https://youtu.be/r9yQe_u8keQ

Development of Heart
● Heart is the first functional organ in vertebrates that develops in
the fetus → Heart begins to develop as early as the 3rd week of
gestation and starts to beat spontaneously by week 4.
● Inner cells mass of blastula differentiates into embryoblast that
forms the bilaminar disk (epiblast and hypoblast)→Bilaminar
disk transforms into trilaminar disk (ectoderm,mesoderm and
endoderm).
Cross-section
● Mesoderm has 3 parts
1) Paraxial mesoderm 2) Intermediate mesoderm 3) Lateral mesoderm
● Lateral mesoderm has further 2 layers
1) Somatic layer 2) Splanchnic layer
● Heart tube develops from the splanchnic layer of lateral mesoderm.
● Vascular Endothelial Growth Factor (VEGF) →Endoderm
secrets VEGF which stimulates the mesoderm to differentiate
into 2 structures
1. outer angioblasts that will form the heart tube and blood vessels
2. Inner hemocytoblasts that will form the blood cells
→ VEGF also stimulates the lateral mesoderm to grow
and form the 2 cavities.
1. Heart tubes
2. Pericardial cavities
● Lateral Folding → During the lateral folding lateral ends of
all layers fuse together to forms a tube
➢ Lateral ends of ectoderm layers fuse together
➢ Lateral ends of mesoderm layers fuse together
➢ Heart tubes from both lateral mesoderm also fuse together
and make 1 heart tube
➢ Pericardial cavities from both lateral mesoderm also fuse
together and make 1 pericardial cavity
➢ Dorsal mesocardium connects the heart tube with the pericardial cavity.
● Heart Tube Layers → Heart tube has 2 layers
➢ Inner layer which forms endocardium
➢ Outer layer which forms myocardium (cardiomyocytes)
➢ Cardiomyocytes secrete jelly-like connective tissue between
endocardium and myocardium called cardiac Jelly.

Heart Tube
★ Divisions
● Heart tube has following divisions and these divisions develop into
following structures.
➢ Aortic sac which leaves out via dorsal aortae
➢ Truncus arteriosus (T.A.) which gives rise
to ascending aorta and pulmonary trunk.
➢ Bulbus cordis (B.C.) which gives rise to the
right ventricle & outflow tract of left and right
ventricles.
➢ Primitive ventricle (P.V.) which gives rise to
trabeculated part of left and right ventricles.
➢ Primitive atria (P.A) which gives rise to
Trabeculated part of left and right atria
➢ Sinus venosus (S.V.) has 2 horns
1) Right horn 2) Left horn
➔ Right horn gives rise to the smooth part of the right atrium.
➔ Left horn gives rise to coronary sinus
➔ Common cardinal veins (outside) ,Umbilical veins (middle) and
Vitelline veins (inside) enter into right and left horns of S.V → These
veins are called inflow tract of S.V.
● Blood enters the heart tube from inflow tract to S.V,through P.A,through P.V,through
B.C,through T.A and leaves out through outflow tract (dorsal aortae) of Aortic sac.
Cardiac Looping
● During Cardiac looping the heart tube changes into shape of the
heart and it happens inside the pericardial cavity →Cardiac looping
begins in week 4 of gestation → steps of cardiac looping are given
below.
1. Step1
● Truncus arteriosus and Bulbus cordis move down and towards the
right
2. Step2
● Truncus arteriosus and Bulbus cordis keep moving down and towards
the right.
● Primitive ventricle (P.V.) moves up and towards the left.
● Primitive atria (P.A.) moves back and towards the up.
2
3. Step3
● Some cells from sinus venosus (S.V.) move into the pericardial cavity and form a
layer around the heart called visceral pericardium (epicardium).
Dextrocardia
● Cardiac looping determines the left-right polarity of heart i.e heart will
be on right or left side of body→ this cardiac looping depends on
dynein proteins that helps in transport → defect in dynein proteins
causes failure in cardiac looping that results in dextrocardia (heart
towards right side of body instead left due to transport problems) →It
is also associated with kartagener syndrome or situs inversus in which all internal
organs on opposite side of body due to transport problems →It is also called 1° ciliary
Dyskinesia (cilia immotile syndrome).

#Drjamillectures
#firstaidlectures
#firstaidstep1lectures
#firstaidstep2lectures
#usmlelectures
#plablectures
#Nlelectures
#Nbelectures
#Amclectures
#Firstaidlecturesinurdu
#Drjameellectures
#MBBSlectures
#firstaidlecturesinurduhindi