cardiovascular embryology and histology Flashcards
average heart beats per min
70
what day does the heart start beating
day 22 in utero
what does the heart begin as developmentally
a tube of contractile myocardium lined by endothelium (endocardium)
what is the cardiogenic field
a horse shoe shaped endothelial tube (primitive heart tube) that develops as blood islands coalesce
where do blood islands form
in the visceral layer of the lateral plate mesoderm cranial to the developing brain
what brings the two sides of the cardiac region together
lateral body folding
what are the two poles of the heart tube
aortic and venous
the caudal pole forms the ___ end of the heart, the cranial pole forms the ____ end of the heart
venous
arterial
What happens in cardiac looping
the atrial portion (inferior) grows upward and to the left, the ventricular portion (superior) grows downward and to the right
What is the ductus venosus
the vein from the placenta that bypasses the embryonic liver and enters the inferior vena cava
what is the ductus arteriosus
the vessel that gors from the pulmonary trunk into the aortic arch in the embryonic heart, bypassing the lungs
what is the foramen ovale
an opening in the septum secundum through which blood moves from the right atria to the left, bypassing the embryonic pulmonary circut
what are the two things that form the interatrial septum
septum primum
septum secundum
when does the interatrial septum form
at birth
What are the two causes of ASD
- excessive resorption of the septum primum
2. absence of the septum secundum
what is the common atrium
atria without the septum secundum and primum
what is the most common heart defect
ventricular septal defects (VSD)
what is transpositions of the great vessels
the pulmonary trunk and aorta are attached to the wrong ventricles, leading to two separate circuits. respiratory and systemic
what are the four things that happen in the tetralogy of fallot
- ventricular septal defect
- pulmonary trunk sepsis
- overriding aorta
- right ventricle hypertrophy
what is persistent truncus arteriosus
when the conotruncal septum doesn’t form and the aorta and pulmonary trunk are combined
what are the parts of the conducting system of the heart in order
SA node (pacemaker) AV node AV bundle bundle branches perkinje fibers
how are electrical stimuli propegated through the heart
gap juntions
What are the three layers of the heart wall from external in internal
epicardium
myocardium
endocardium
what are the characteristics of the epicardium
same thing as the visceral layer of the pericardium
simple squamous epithelium
what are the characteristics of the myocardium
muscle cells (cardiac myocytes) makes up the majority of the heart wall
what are the characteristics of the endocardium
inner lining of the heart chambers
simple squamous epithelium
near perkinje fibers
continuous with great vessels
What are the layers of the vessels
tunica adventitia
tunica media
tunica intima
What are the characteristics of elastic arteries
thick tunica adventitia, broad media with elastin
what are the characteristics of muscular arteries
thick tunica media, IEL, EEL
what are the characteristics of capillaries
very thin endothelial membrane
precapillary sphincters
site of gas and nutrient exchange
What are the three types of capillaries
continuous
fenestrated
discontinuous (sinusoidal)
where are continuous capillaries found
most tissues
where are fenestrated capillaries found (increased permeability)
small intestines
kidney glomerulus
endocrine glands
Where are discontinuous capillaries found (high permeability)
liver, spleen, endocrine glands, hematopoetic
how do veins compare to arteries
lower pressure, thinner walls, closer to the skin and have valves (muscle pumps)
