Block IV - Cardiovascular System Flashcards by Ali Rashid

Cardiogenic Field

Horseshoe shaped tubes surrounding anterior/lateral areas of neural plate

forms heart, blood vessels, blood cells

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What is the cardiac tube composed of?

Bulbus Cordis, primitive ventricle, primitive atrium

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Loop formation

division of cardiac tube into 4 chambers

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Truncous arteriosus

Splits into the ascending aorta and pulmonary trunk

divided by spiral aortica pulmonary septum (what is the function of the spiral portioning?)

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What is the function of the spiral arotica pulmonary septum?

The spiral shape ensures that blood flows from the right ventricle to the pulmonary trunk and the left ventricle to the ascending aorta

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What is the physiological closure of the foramen ovale?

After parturition, the infant lungs expand –> leads to a drop in BP, pushing the primary septum against the secondary

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What is the anatomical closure of the foramen ovale?

The primary and secondary septum fuse

the Foramen ovale becomes the fossa ovalis

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What are the 3 blood shunt present in fetal circulation

Ductus venosus (liver), Foramen ovale (right lung), Ductus arteriosus (left lung)

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After parturition, what does the Ductus venosus become?

Ligamentum venosum

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After parturition, what does the Foramen ovale become?

Fossa ovalis

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After parturition, what does the Ductus arteriosus become?

Ligamentum arteriosum

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What is the function of the blood shunts present in the fetal cardiovascular system?

The shunts are used to bypass the liver and lungs as these organs are not fully developed and do not require as much blood as the rest of the body. A small amount of blood will be directed towards these organs to provide minimal O2 and nutrients and the fetal blood is instead oxygenated by the placenta.

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Foramen Ovale

Hole between the Left and Right Atria in fetal hearts; used to bypass the right lung.

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Which part of the heart serves as a valve for foramen ovale and what is its function?

Primary septum; stops blood from the L. Atrium returning to the R. Atriam

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Ostium primum

allows for blood to travel from R –> L atrium while the primary septum grows

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Ostium secundum

Replaces the ostium primum when it closes

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Septum Primum

Primary septum that separates the Left and Right atriums; serves as the valve for foramen ovale

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Septum Secundum

Forms to right of the septum primum (in the right atrium)

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What are some functions of the cardiovascular system?

Blood flow,
CO2/waste removal,
O2/nutrient delivery to tissue
Thermoregulation
GFR/Urine output

What is the direction of blood flow in ADULT hearts?

Unoxygenated blood transported by Inferior/Superior Vena Cava -> Right Atrium -> Right Ventricle -> Pulmonary Artery -> Lungs -> Pulmonary vein -> Left Atrium -> Left Ventricle -> Aorta -> Oxygenated blood returns to body

What is the direction of blood flow in FETAL hearts?

Fetal vein (oxygenated) -> Liver (Ductus venosous) -> Inferior vena cava -> Right atrium -> Foramen ovale -> Left Atrium -> Aorta -> Umbilical arteries (mixed blood) -> placenta

What is the vascular pattern of microcirculation?

Artery -> Arteriole -> Metarteriole -> Capillaries -> Venule -> Vein

Endocardium

Internal lining of the heart and valves;

Direct contact w/ blood and important for hemostasis;

Eqv. to the Tunica intima of blood vessels

What are the three layers of the endocardium and what is an important characteristic of the 3rd layer?

(Deepest to Surface)
Endothelium
Basal Laminae (BM)
Subendothelial CT (contains Purkinje Fibers)

Myocardium

Middle layer Composed of cardiomyocytes Cross-striated w/ a central nucleus Held together by gap and anchoring junctions Often contains lipofuschin as myocardium has low regeneration Eqv. to the tunica media in BV

Epicardium

AKA the visceral pericardium Outermost layer composed of simple squamous epithelium --> mesothelium Supported by CT and adipocytes Contains serous fluid Eqv. to the Tunica adventitia in BV

Purkinje Fibers

Specialized myocardiocytes that help with conduction

Valves

Specialized tissue that prevents backflow in certain vessels. Sit in between the endo- and epicardium (no myocardium cells present)

Tunica intima

Innermost tunic; composed of endothelium, internal elastic membrane, and subendothelial CT

Tunica media

Middle tunic; composed of smooth muscle and elastic lamallae/fibers

Tunica adventitia

AKA Tunica externum Outermost tunic; composed of collagen

Arteries

carries blood away from the heart

Elastic Arteries

Composed of all 3 tunics and has a thick Tunic media with repeating elastic lamallea Tunica adventitia will have a vasa vasorum which provides nutrients to the T. media

Muscular Arteries

Round appearance due to thick Tunica media composed of smooth muscle and regulates vasodilation and vasocontriction

Veins

Carries blood towards the heart

Arterioles

1-3 layers of smooth muscle that have the highest effect on BP

Capillaries

Thinnest type of blood vessels; site of blood exchange between surrounding tissue Originates from mesenchymal cells and are composed of simple squamous cells that are rolled to create a tube

Continuous capillaries

most common type; impermeable to macromolecules, instead using pinocytotic vesicles (micromolecules)

Fenestrated capillaries

Gaps in the vessel that allow for fluid exchange i.e. contains glomerulus which is filtration of plasma in kidneys

Discontinuous (sinusoidal) capillaries

Located in the liver and spleen; large molecules (i.e. RBCs) can exit has a large and irregular lumen with discontinuous endothelial lining

Pericytes

AKA Rouject cells Wrap around the capillaries and venules Functions: -Communicate with endothelial cells (physical contact and paracrine signaling) -fix damaged capillaries -stem cell source (imp. for vessel formation)

Podocytes

KIDNEYS ONLY! Nephrons - Bowman's Capsules Prevents filtration of macromolecules into urine Pedicels (feet) wrap around capillaries to form filtration slits (increases area of cells for ULTRAFILTRATION)

Lymphatic Vessels

Transports lymph and has valves to prevent backflow all 3 tunics present; tunica adventitia binds lymph to surrounding tissue LYMPH IS CLEAR B/C OF LACK OF RBCs

Cardiac Skeleton

Fibrous CT that surrounds the pulmonary trunk, Aorta, and AV Valves

Vascular Endothelium

Roles in hemostasis and inflammation and modulates perfusion of blood; It has a healing mechanism that provides a seal for injured vessels to stop blood loss