Circulatory system Flashcards
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
- epicardium
- myocardium - muscle layer and fibrous skeleton
- endocardium
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
endothelium
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
