Microanatomy Cardiovascular System

Week 4

Why is the cardiovascular system the first to develop in the embryo

because of how that embryo feeds, requires nutrients to be pumped throughout once it grows beyond what diffusion can sufficiently support

what embryonic origin does the cardiovascular tissues originate from

Mesoderm

Mesenchyme

Angiogenesis

process of blood vessel development

T/F: the progression of cardiovascular tissue development is

Mesoderm → mesenchyme (pluripotent cells) → angioblastic tissue (hemangioblasts) → cardiovascular system (blood and blood vessels)

True

Cardiogenic field

horseshoe shaped structure located around the anterior and lateral portions of the neural plate

how many regions of the primitive heart tube and what are they

5 regions

1. primitive atrium

2. primitive ventricle

3. bulbus cortis

4. truncus arteriosus

5. sinus venosus

what does the primitive atrium develop into in a fully developed heart

divided into anterior parts of left and right atria

what does the primitive ventricle develop into in the fully developed heart

divided into most of the left ventricle

what does the bulbus cordis develop into in the fully developed heart

right ventricle, conus cordis, and truncus arteriosus

what does the truncus arteriosus develop into in the fully developed heart

divided into outflow tracts of aorta and pulmonary trunk

what does the sinus venosus develop into in the fully developed heart

posterior portion of the right atrium, the sinoatrial node, and the coronary sinus

defects in ______ developments causes defects in the body’s great arteries

aortic arches

fetal heart has how many chambers and how many pumps

one chamber

one pump

ostium (foramen) primum

allows initial passage of blood from the right to the left atrium as the primary atrial septum grows

physiological closure of the foramen ovale

occurs after birth when lungs expand with first breaths, which causes a sudden blood pressure drop in pulmonary circulation, and this pushes primary atrial septum into secondary one

anatomical closure of the foramen ovale

primary and secondary atrial septa fuse and become the fossa ovalis

what do the primary atrial septum and secondary atrial septum fuse into and become

fossa ovalis

which happens first: physiological closure or anatomical closure of foramen ovale

physiological closure

the spiral formation of the aorticopulmonary septum separates the truncus arteriosus into

ascending aorta and pulmonary trunk

why is the spiral formation of the aorticopulmonary septum essential for life

if ensures blood from the RV flows into the pulmonary trunk and that blood from the LV flows into ascending aorta

what condition develops if the aorticopulmonary septum were straight, not spiral

transposition of the great vessels, where deoxygenated blood from the RV flows into the ascending aorta and highly oxygenated blood from the LV flows into pulmonary trunk (lungs)

ascending aorta should be receiving OXYGENATED blood from from LV and pulmonary trunk should be receiving DEOXYGENATED blood from RV

what structure in the mother oxygenates fetal blood

placenta

ductus venosus

vein in fetus that connects umbilical vein to the inferior vena cava, allowing oxygenated blood from the placenta to bypass the liver because the liver is not fully functioning

blood shunt

foramen ovale

opening in the fetal heart that allows blood to pass from RA to LA, bypassing the non-functional fetal lungs

blood shunt

ductus arterioriosus

a vessel in the fetus that connects the pulmonary artery to the aorta, bypassing the lungs

blood shunt

ductus venosus becomes ___ in adult liver

ligamentum venosus

fibrous remnant

foramen ovale becomes ______ in developed heart

fossa ovalis

T/F: a depression in the RA of the heart marks the spot where the foramen ovale was located in the fetus

true

ductus arteriosus becomes _______ in the adult heart

ligamentum arteriosum

fibrous remant

T/F: it’s okay if it takes a while after birth for the 3 blood shunts to close

false

they must close very soon after birth

what are the three layers of the heart

endocardium

myocardium

epicardium

types of vessels

arteries

capillaries

venules and veins

lymphatics

the heart is the ____ of the circulatory system

central pump

atrial system is blood ______ network

distribution

venous system is blood _______ network

collection

microcirculation

system for nutrient and waste products exchange between blood and extravascular tissue

how do lymphatics contribute to circulation

they are a network of vessels paralleling veins that drain fluid from the extravascular spaces into the blood vascular system

name 5 functions of the cardiovascular system

1. maintenance of adequate blood flow / cardiac output

2. delivery of O2, nutrients, hormones, electrolytes and water to peripheral tissues

3. removal of CO2 and other metabolic waste products

4. maintenance of normal thermoregulation

5. maintenance of normal glomerular filtration rate (GFR) and urine output

pulmonary circulation is also called ____ circulation

upper circulation

cranial circulation

system circulation is also called _____ circulation

lower circulation

caudal circulation

which has higher blood pressure and blood flow: atrial or venous system

atrial system

left or right heart pumps unoxygenated blood through pulmonary circulation

right heart

left or right heart pumps oxygenated blood through systemic circulation

left

left heart pumps oxygenated or unoxygenated blood, and through what system

oxygenated blood through systemic/lower/caudal circulation

right heart pumps oxygenated or unoxygenated blood, and through what system

unoxygenated blood through pulmonary/upper/cranial circulation

which vessel in cardiovascular system is where oxygenated and unoxygenated blood meet and exchange

capillaries

what is the first organ to form in the embryo

the heart

mammals and birds have hearts with ___ chambers

4

which ventricle is closer to apex of heart

LV

tricuspid valve is betweeen

RA → RV

mitral valve is between

LA → LV

aortic value is between

LV → aorta

pulmonary valve is between

RV → pulmonary artery

valves are a part of which heart layer

endocardium (innermost)

epicardium is also called

visceral pericardium

endocardium forms what

inner lining and valves

endocardium is equivalent to what of blood vessels

tunica intima

what type of cells on innermost surface of endocardium

endothelial cellsw

which heart layer has direct contact with blood, and through what cells

endocardium, through endothelial cells

endocardium is important in____

hemostasis

how many layers in endocardium and what are they

3 layers

1. endothelium

2. basal lamina (CT)

3. subendocardium / subendocardial layer (subendothelial CT)

which layer of endocardium contains part of conductive system and Purkinje fibers

subendocardium

what are purkinje fibers

fibers specialized in conducting action potential impulses throughout heart

T/FL=: Purkinje fibers have myocardiocyte origin and are the same as myocardial cells

false

they do have myocardiocyte origin but are DIFFERENT from myocardium

are Purkinje fibers large or small

large

T/F: purkinje fibers are in the ventricles and are modified cardiac muscle cells joined by intercalated disks but specialized for impulse conduction instead of contraction

true

purkinje fibers filled with large amounts of lightly stained ______ filling most of cytoplasm, displacing sparse _____ to the periphery

glycogen, myofibrils

T/F: purkinje fibers have T tubules

false

they do not

purkinje fibers are connected by

desmosomes and gap junctions

where on the heart do purkinje fibers extend from and where do they go to

from interventricular septum to the papillary muscles and up the lateral walls of the ventricles

cardiac skeleton

area with thick fibrous tissue that keeps vessels and valves in place

fibrous trigon

a triangular mass of fibrous connective tissue that connects the aortic ring and the L and R atrioventricular rings (L is mitral valve and R is tricuspid valve)

what area of the heart undergoes osseous differentiation and forms the Os Cordis primarily seen in cattle

fibrous trigon

T/F: 4 dense bands of fibrous connective tissue encircle the base of the pulonary trunk, aorta, and the AV valves, providing structural support to the heart

true

valves are largely dense or loose CT covered with a thin layer of endothelium

dense CT

is L or R ventricular myocardium thicker, and why

left - 2-4x thicker than the right in adults

due to higher pressure on left side

cardiomyocyte contraction is involuntary or voluntary

involuntary

myocardial cells multinucleate or uninucleate

uninucleate

T/F: cardiomyocytes contain SR

true

up to 20% of cell volume of cardiomyocytes is

mitochondria, requires a lot of O2

cardiomyocytes have high or low regeneration capacity

low, close to none

how might intercalated disks appear in histology of myocardium

dark, horizontal lines

what brown pigment is seen in myocardium in older animals or tissue with injury

lipofuscin

wear and tear pigment

branched fibers of myocardium connected via

intercalated disks

parietal pericardium is also called

pericardial sac

visceral pericardium is also called

epicardium

outermost layer of heart

the surface of epicardium is covered by

mesothelium (simple squamous epithelium), layer of dense CT, and depending on location, variably thick layer of adipose tissue with blood vessels (e.g. coronary arteries and veins)

T/F: epicardium is contiguous with the endocardium at the level of the endocardial cushion

true