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Flashcards in Circulatory system Deck (53):

what part of the heart pumps for the systemic circuit ?

left ventricle pumps oxygenated blood


what part of the heart pumps deoxygenated blood to pulmoary circuit

right ventricle


where would you find fibrous skeleton connective tissue in the heart

-4 fibrous rings around valve orifices
-2 fibrous trigones connecting the rings
-membranous portion of IV and IA septums


what are the main layers of the heart from out to in

-myocardium - muscle layer and fibrous skeleton


what are the 3 individual layers of the endocardium, which is the inner layer of the heart

-endothelial cells (directly next to blood)
-subendothelial layer
-subendocardial layer


what layer of the endocardium contains the intrinsic conduction system

subendocardial layer


what type of epithelium is the epicardium made up of ?

mesothelium (simple squamous) w/a little underlying connective tissue


what are the 4 valves associated w/the heart

-Tricuspid (R atrioventricular valve)
-Bicuspid or mitral valve (L atrioventricular valve)
-Aortic Semilunar valve (b/w aorta and L ventricle)
-Pulmonary semilunar ( b/w pulmonary trunk and R ven.)


what is the function of the valves in the heart

enforce one-way flow in response to pressure changes


what wall of the heart is the thickest and why ?

Left ventricular wall, b/c thats pumping blood to systemic circuit which has 3x more friction to overcome than pulmonary circuit


what type of tissue are the heart valves made up of ?

connective tissue w/overlying endocardium (endothelial cells)


what are the 3 histological layers of the heart valves

spongiosa - atria side of valves
fibrosa - fibrous skeleton portion
ventricularis - ventricle side of valve


what histological layer of heart valves is the "shock absorber"

spongiosa layer


what type of tissue layer will you find anywhere that is in contact with blood

endothelium (simple squamous tissue)


T/F the heart needs input from the nervous system in order to depolarize

F - can do so W/O nervous system input via the intrinsic cardiac conduction system


how do the SNS and PNS play a role in the intrinsic conduction system of the heart

SNS accelerates heart beat
PNS decelerated heart beat


what layer of the heart is the intrinsic conduction system found

subencocardial layer (layer of the Endocardium)


cells found where are known as the "pacemaker: cells" why do they get this name ?

SA node
-called this b/c they get to threshold the fastest


Explain the pathway of the intrinsic conduction system starting w/depolarization

1 - depolarization at SA node
2 - AV node (delayed .1 s to allow atria to contract)
3 - AV bundle / Bundle of His
4 - R and L bundle branches
5 - Perkinje fibers


what are the 2 cell types in the intrinsic conduction system

-nodal cardiac cells
-purkinje fibers


where would you find nodal cardiac cells in the intrinsic conduction system, and what are some characteristics of them ?

SA node, AV node
-smaller than contractile cells
-NO intercalated discs


where would you find purkinje fibers in the intrinsic conduction system, and what are their characteristics

AV bundle, bundle branches
-larger than contractile cells
-intercalated discs


what type of cells found in the intrinsic conduction system can be identified histologically ?

perkinje cells/fibers (Cant find nodal cells)
-stain pos. in PAS stain cuz glycogen
-stain pale in H&E


explain the pathway of blood as it moves from different types of vessels starting and ending at heart

heart ---> arteries ---> arterioles ---> capillaries ---> venules ----> veins ---> heart


which type of blood vessel would have the most pressure, which has the least pressure

large arteries
large veins


There are 3 layers in the walls of blood vessels, what are they ?

tunica interna -
tunica media
tunica externa/tunica adventitia


which layer of the walls of blood vessels is thickest in arteries ? what about veins ?

arteries thickest layer = tunica media
veins thickest layer is = tunica externa or adventitia


what are the 3 specific parts of the tunica interna layer of the vessel wall

basal lamina
subendothelial layer


where would you find an internal elastic membrane ?
what about an external elastic membrane

internal elastic membrane - outermost part of tunica interna in arteries and arterioles
external elastic membrane - outermost part of tunica media in arteries


what is the "vasa vasorum" and where can it be found ?

an actual small vessel w/in the wall of a vessel
-in the tunica externa/adventitia layer


what is the nervi vascularis and where can it be found

a small nerve w/in the wall of a blood vessel
-in tunica externa/adventitia


in cross section what vessel will appear open and which will appear more collapsed

artery - open
vein - collapsed


in cross section which type of blood vessel will appear to have a larger lumen

vein will have larger lumen


Large arteries are also called _______ ? Why ?

Elastic or conducting arteries
-b/c contain elastic fibers allowing for expand and recoil, also serve as a pressure reserve


Medium arteries are also called _____ ? Why ?

Muscular or distributing arteries
-contain lots of smooth muscle responsible for vasoconstriction and vasodilation


how may layers of smooth muscle are present in the tunica media in small arteries vs. arterioles ?

Small a. 3-8 layers
arterioles : 1-2 layers


what is the size in mm or um of the 4 types of arteries

Large a - greater than 10 mm
medium a - 2-10 mm
small a - 0.1-2 mm
arterioles - 10 - 100 um


what is the best thing to identify when looking at large arteries

elastic lamellae in the tunica media


the left ventricle contracts and ejects blood during __________ and relaxes/fills w/blood during ______ ?

contract = systole
relax = diastole


elastic arteries will stretch during ventricular ________ and recoil during ventricular ____________ ?

systole and diastole


which type of arteries is known to have a very prominent internal and external elastic membranes

medium arteries (muscular or distributing aa.)


what type of vessel is the smallest in the human body ? how small are they, and what is their purpose ?

capillaries, 4-10 um
-function in exchange b/w blood and tissues


what are the 3 different types of capillaries

1 - continuous capillaries
2 - fenestrated capillaries
3 - discontinuous capillaries


where would you find continuos capillaries and what is the distinguishing feature for identification ?

muscle, lung and CNS
-uninterrupted endothelial cell lining w/tight junctions


where would you find fenestrated capillaries and what is their distinguishable feature ?

endocrine glands
-oval pores (fenestrations) which allow for transport of larger molecules like hormones


where would you find discontinuous capillaries, and what is their main function ?

liver, spleen, and bone marrow
-function to exchange larger molecules
****makes sense cuz have largest diameter and discontinous endothelial lining ****


what type of capillaries are referred to as sinusoids ?

discontinuous capillaries


what is microcirculation

flow of blood from arterial ----> capillary network ----> venule


what are the 3 functional units of a microcirculatory bed or microvascular bed

arteriole, capillary network, postcapillary venule


what are the 2 types of vessels in the capillary network, and what is their respective functions

-true capillaries - where exchange occurs
-arteriovenous anastomoses (shunts) - bypass areas


what is the size in mm or um of the 4 different types of veins

large veins : greater than 10 mm
medium veins : 1-10 mm
small veins : 0.1-1 mm
venule: 10-100 um


what are the 2 types of venules, and what are the specific layers found w/in each

postcapillary venule - only endothelial cells (No tunica media or adventitia)
muscular venule - Have endothelial layer, tunica media and tunica adventitia


what layer of the wall in veins have one way valves, and why are these nesccesary

tunica interna
-need cuz very low pressure in veins and dont want backflow