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83 Cards in this Set
- Front
- Back
What are the three layers of vessels in general?
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tunica intima= innermost layer
tunica media= middle layer tunica adventitia= outermost layer |
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Is the tunica intima closest to the lumen of the blood vessels?
What is the TI lined with? |
-yes
-endothelium |
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What type of cells is endothelium made of?
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simple squamous epithelial cells
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What is the tunica intima composed of?
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connective tissue and firbroblasts with some elastic and collagen fibers
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What forms the outer boundary of the tunica intima and is the boundary between the tunica intima and the tunica media?
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the internal elastic membrane
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Do the cells and fibers of the tunica intima run parallel or perpendicular in the vessel?
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parallel
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What is a function of the tunica intima?
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it provides a smooth surface to prevent blood clotting.
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What direction do the fibers and the cells of the tunica media run in relation to the long axis of the vessel?
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perpendicular in a circular manner around the vessel
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What type of cells and membranes are located in the tunica media?
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smooth muscle cells and elastic membranes
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Do the smooth muscle cells of the tunica media give rise to elastic tissue?
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yes
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What is the vasa vasorum?
Give an example of a vasa vasorum |
-small arteries and veins that lie in the wall of large vessels and give nutrients to the muscle tissue: the vessel of the vessel
-coronary arteries are the vasa vasorum of the heart |
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How do small blood vessels recieve nutrition?
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diffusion
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Where can one find the vasa vasorum in a blood vessel?
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in the tunica adventitia and the outskirts of the tunica media
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What does the connective tissue of the tunica adventitia contain?
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-collagen fibers
-fibroblasts -the external elastic membrane (is part of the TA, not boundary) -in larger vessels the vasa vasorum |
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Do tunica adventita fibers run parallel or perpendicular to the long axis of the blood vessel?
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parallel
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What are the three classifications of arteries?
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1. elastic arteries
2. muscular arteries 3. small muscular arteries/arterioles |
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What are elastic arteries?
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-the very large distributing arteries
-example=aorta and renal arteries |
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In elastic arteries is the tunica intima thick or thin?
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-It is a thick subendothelial layer of CT
-some elastic fibers making the internal elastic membrane but hard to see |
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In the elastsic arteries, what types of cells does the tunica intima contain?
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-some smooth muscle cells
-some elastic fibers making the internal elastec membrane |
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In the elastic arteries, is the tunica media thick or thin?
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thick
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In the elastic arteries, does the smooth muscle alternate with elastic membranes in the tunica media? Why?
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-yes
-because the smooth muscle is producing the elastic membranes |
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In the elastic arteries, what does the structure of the elastic membranes look like?
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the elastic tissue is full of fenestrations
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What are the fenestrations in the elastic tissue of the tunica media of the elastic arteries?
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holes in the wall to allow the passage of material such as nutrients, ions and wastes
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In the elastic arteries, is the tunica media fed by a vasa vasorum?
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yes
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In the elastic arteries, what does the tunica adventitia contain?
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the vasa vasorum
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What are the muscular arteries known as?
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most named arteries of the body wall and organs
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In the muscular arteries,is the tunica intima thick or thin?
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thin subendothelial CT layer
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In the muscular arteries, is the tunica intima bordered by an internal elastic membrane?
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yes
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In the muscular arteries, what does the tunica media contain?
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2-40 layers of circular smooth muscle
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In the muscular arteries, is there an external elastic membrane present in the tunica adventitia?
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only in larger arteries
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In the muscular arteries, is a vasa vasorum present?
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no, these vessels are small enough to suppply nutrients by diffusion
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What are the small muscular arteries/arterioles?
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the smallest of the arteries
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In the small muscular arteries/arterioles, what size is the tunic intima?
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less than .5mm in diameter
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In the small muscular arteries/arterioles, what does the tunica media contain?
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102 layers of circular smooth muscle
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In the small muscular arteries/arterioles, does the tunica adventitia contain an external elastic membrane?
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no
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How many red blood cells can travel through a capillary at a time?
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only one- if you see 2-3 cells side by side it is not a capillary
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What are general characteristics of capillaries?
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-composed of a single layer of endothelial cells that are simple squamous epthelium
-all cells rest on a basal lamina/basement membrane -pericytes are scattered along the surface |
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What is a pericyte?
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-a mesenchymal cell with long cytoplasmic processes that partly surround the endothelial cells of the capillary
- these cells are enclosed in their own basement membrane |
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What is the function of a pericyte?
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-is contractile, contains actin, myosin, and tropomyosin,helps move the fluid in the lumen of the capillary on through it
-can repair after tissue injury, can form new blood vessels and CT |
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What are continous or somatic capillaries?
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endothelium is characterized by an absence of fenestrae in the wall, all cells rest on a continuous basement lamina/membrane
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How do continous/somatic capillaries transport stuff without fenestrations?
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pinocytosis
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Where are continous/somatic capillaries located?
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-in muscle, CT, exocrine glands, and nervous tissue
**can not see this on a slide but must know from the type of tissue it is in -found where rapid exchange is not needed |
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What are fenestrated/visceral capillaries?
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endothelium is characterized by large fenestrae in the wall that are either uncovered or covered by a thin diaphragm (not trilaminar), all cells rest on a basement membrane/lamina
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How do fenestrated/visceral capillaries transport stuff?
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across the fenestrae
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Where are fenestrated/visceral capillaries located?
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-in organs where rapid transport between tissues and blood is needed
-kidneys, intestines, endocrine organs |
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What are sinusoids?
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-a specialized capillary which has an enlarged diameter and has a tortuous course that slows the circulation of blood
-these are fat capillaries -are wider & accomidate more than one blood cell -do not have pericytes -have endothelium and a basal lamina outside of endothelial cells |
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What are characteristics of fenestrated sunusoids?
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their cells have fenestrae, are in endocrine organs
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What are characteristics of discontinous sunusoids?
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there are gaps or spaces where two endothelial cells join, the basal lamina may be discontinuous, is in the liver and other organs
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What is the function of capillaries/sinusoids?
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-exchange of materials across the wall of the capillary
-materials = gas(CO2 or O2) or nutrients |
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What type of capilliary is in skeletal muscle?
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continous, this is why muscles fatigue
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What are the comparitive speeds through the different types of capillaries?
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slowest=continous
middle=discontinous fastest=fenestrated |
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What do veins do?
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return blood to the heart
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Are the walls of veins more or less organized than arteries?
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less
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Do veins have organized smooth muscle in them?
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no
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Are there more veins or arteries in the body?
Are the walls of veins thicker or thinner than arteries? Is the circumfrence of a vein larger or smaller than an aretery? |
-more veins
-thinner -larger |
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What are some general characteristics of veins?
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-low blood pressure
-contain valves -thickest layer in veins is the tunica adventitia |
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What is a venule?
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-a thin wall vessel, the endothelium is similar in function to the capillary but the diameter begins to enlarge.
-is a very small caliber vein |
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What are small veins?
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most of the veins in the body with the exception of the main trunks
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Do venules contain a tunic adventita?
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yes
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What does the tunica intima of the small veins contain?
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- a thin layer of CT covered by endothelium
-valves (folds of the intima) **facial veins do not have valves |
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What does the tunica media of small veins contain?
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a few poorly organized layers of smooth muscles
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What does the tunica adventitia of small veins contain?
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has well developed, numerous collagen fibers w/ no smooth muscle
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What are some examples of large veins?
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vena cava and renal veins
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Is the tunica intima well developed in the large veins?
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yes
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What are characteristics of the tunica media of large veins?
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a few layers or circular arranged smooth muscle
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What are characteristics of the tunica adventitia of the large veins?
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-thick layer, contains longitudinal clusters of smooth muscle parallel to the long axis of the blood vessel
-this gives structural support to the wall and helps move vascular contents -there is collagen fibers in between the smooth muscle |
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What is the normal capillary blood flow?
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arteriole
metarterioles(precapillary sphincters) capillary venules(postcapillary venule) vein |
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What are arteriovenous anastamoses/shunts?
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-places where blood bypasses capillary beds completely or reduces flow in a capillary bed for the purpose of thermoregualtion
-direct connections between the arterial and venous systems |
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What is the function of arteriovenous anastamoses/shunts?
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-shuts down blood flow in cold and increases blood flow in fever
-function is to regulate blood pressure, blood flow and conservation of heat |
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Is the arteriovenous anastamoses/shunts in addition to the capillary beds?
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yes
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What are precapillary sphincters?
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-sphincters that are at the end of metarterioles
-these regulate blood flow through the capillary bed |
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What are postcapillary venules?
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-sometimes referred to as venous portion of the capillary bed
-functions similar to capillaries -is modified in lymphatic organs for transport of the T-lymphocytes -is surrounded by contractile pieces -5-6 times of the capillary |
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Arteries compared to veins
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lumen A=circular V=irregular
T.intima A=I. elastic memb V= valves T. media A=thick V=thin T.adventitia A=thin,no SM V=thick |
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Is the heart a modified blood vessel?
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yes
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What are the three layer of the heart?
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epicardium-T. adventitia
myocardium-T. media endocardium-T. intima |
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What is the epicardium analagous to?
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the visceral pericardium
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Where is the epicardium on the heart?
What type of epithelium is the epicardium made of? |
-external layer of the heart
-simple squamous epithelium |
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Where is the subepicardial CT?
What is its function? |
-the subepicardial CT is under the simple squamous epithelium of the epicardium
-it contains coronary vessels, nerves, and fat of the heart |
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What is the myocardium?
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-the middle, largest layer of the heart
-contains cardiac muscle w/ intercalated disks and the sliding filament theory -has a rich vascular supply |
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What is the endocardium composed of and where is it?
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-simple squamous epithelium and subenodcardium
-is the internal layer of the heart, lines the chambers |
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What is subendocardial tissue?
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-thin CT tissue
-contains the impulse conducting system of the heart (perkinje cells) -does not contain large coronary vessels |
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What are perkinje cells?
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-specialized modified cardiac muscle cells of the endocardium in the subendothelium
-this is the only kind of nervous/impulse to supply cardiac muscle (the heart does not get a direct nervous supply) |
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What is the cardiac conducting system composed of?
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-sinoatrial node
-atrioventricular node -bundle of His |