Circulatory System Flashcards
What are the two components of the circulatory system?
The blood vascular system
The lymph vascular system
What does a vessel do?
deliver blood to the body
regulate the flow of blood to the various organs
Why must vessels be elastic?
to accomodate changes in blood volume during systole and distole
what controls arteriole size?
the ANS
Where is blood flow the slowest and why?
capillaries. allows nutrient and gas exchange
What are the 3 layers of a vessel?
tunica intima
tunica media
tunica adventitia
Function of large elastic arteries
to smooth out fluctuations of pressure and flow caused ventricular contraction
function of medium muscular arteries?
to distribute and control blood flow to organs
function of small arteries and arterioles
regulate blood flow to capillaries by vasoconstriction and vasodilation (ANS control)
What are Vasa vasorum
Vasa vasorum (VV) are defined literally as vessels of vessels
What are nervi vasorum
nerves which innervate arteries and veins
What are the 3 different types of capillaries?
Continuous
Fenestrated
Sinusoidal
What are continuous capillaries and where are they found
endothelium is continuous. only small molecules can pass through. found in muscle, skin, fat, nerve tissue
What are fenestrated capillaries and where are they found
have lots of holes. allow small molecules through. found in gut, endocrine cells, kidneys
What are sinusoidal capillaries and where are they found
have large open pores and are the “leakiest” of the capillaries. Allow blood cells to pass through. Found in bone marrow, lymph nodes, spleen.
What type of capillaries are involved in gas exchange?
continuous capillaries
The BBB (Blood Brain Barrier) is what type of capillary?
continuous
what are the layers of venules?
mostly tunica intima and adventitia, not much media.
What are the layers of small/medium veins?
Tunica intima and adventitia, and have tunica media with 2-4 smooth muscle layers
What are the layers of large veins
All 3. Thin tunica media. adventitia can have considerable smooth muscle to maintain proper tension of the wall.
do venules have valves?
no
do small/medium veins have valves?
maybe
do large veins have valves?
yes, often.
how can you distinguish a vein from an artery?
larger lumen, irregular shape, and no distinct layers
How does blood flow toward the heart in veins?
contraction of adjacent musculature and movement of organs
describe epicardium
collagenous external covering of the heart
describe myocardium
- middle, muscular layer of the heart wall
- bundles of cardiac muscle cells
- capillary network and lymph drainage
- houses mutiple cardiac (ANS) nerve conduction fibers
describe endocardium
three layers: endothelium and subendothelial layer, subendocardial layer
Heart valves are an extension of the ?
endocardium
Where can you find purkinje fibers?
myocardium and subendocardium layer of the endocardium
What do purkinje fibers do
promote rapid conduction of impulses from the AV node
valve leaflets are an extension of the ?
endocardium
what is the importance of the cardiac skeleton?
it’s what the myocardium attaches to
What is the importance of SA and AV nodes?
SA node is the pacemaker system of the heart
AV node conducts APs from the atria to the ventricles
