Circulatory System Flashcards
What makes up the endocardium?
endothelium
loose CT layer
dense irregular CT
sub-endothelial layer
What makes up the subendothelial layer?
losse CT layer and dense irregular CT layer
Where are the purkinjie fibers located?
sub-endothelial layer
What is stored in purkinje fibers?
glycogen
What are purkinje fibers?
modified cardiac myocytes
How are purkinje attached?
gap junctions and macula adherens
What is the difference between atria and ventricles?
- atria: less muscle, more elastic fibers
- ventricles: well-developed muscle layer
Which part of intercalated discs are described as the “risers of stairs”?
transverse portion
What is the transverse portion of intercalated discs made up of?
macula adherens
fascia adherens
What portion of the intercalated discs are described as the “step of stairs”?
longitudinal portion
What makes up the longitudinal portion of intercalated discs?
large gap junctions
What are the functions of intercalated discs?
- attach cardiac myocytes using macula adherens
- attach and stabalize myofibrils using fascia adherens
- cell to cell communication using large gap junctions
What affect does the sympathetic NS have on heart rate and contraction force?
increases both
What affect does the parasympathetic NS have on heart rate and contraction force?
decreases both
What specialized cardiac cells deal with hormone secretion in the atria and interventricular septum?
myoendocrine cells
What will the hormones from the myoendocrine cells target?
- fluid and electrolyte balance = target kidneys
2. decrease BP = target muscle in arterioles, small arteries and arterioles
What is another name for the pericardium?
serous pericardium
What makes up the pericardium?
epicardium & parietal pericardium
What is another term for epicardium?
visceral pericardium
What is contained in the sub-epicardial layer?
coronary vessels
nerves
adipose (sometimes)
What is the function of the mesothelium in the epicardium?
secretes a serous lubricating fluid
What is the function of the mesothelium in the parietal pericardium?
secretes serous fluid
What composes the pericardial sac?
parietal pericardium
fibrous pericardium
What is found between the parietal pericardium and visceral pericardium?
pericardial cavity
What are valves made up of?
endothelium with dense irregular CT below
What are some characteristics of the dense irregular CT in valves?
- has many collage I and elastic fibers
- almost avascular
What is the cardiac skeleton made up of?
dense irregular CT
What are the three components of the cardiac skeleton?
- annuli fibrosi
- trigonum fibrosum
- upper portion of interventricular septum
Where do you find annuli fibrosi?
around base of aorta, pulmonary artery and openings to chambers
Where do you find the trigonum fibrosum?
by cusps of aortic valve
What is the septum membranaceum?
upper portion of interventricular septum
What is the general function of the cardiac skeleton?
isolate atrial and ventricular chambers to ensure individual chamber contractions
What type of CT is found in the chordae tendinae?
dense regular CT
The tunica intima is a conitnuation of the…?
endocardium
The tunica media is a continuation of the…?
myocardium
The tunica aventitia is a continuation of the…?
epicardium
What type of tissue composed the endothelium?
simple squamous
What are the 6 basic functions of vascular endothelium?
- maintain selective permeability
- prevent & promote clotting along surface
- influence blood flow
- regulate cell growth in surrounding tissues
- influence local immune responses
- maintain extracellular matrix
Which major luminal wall layer is thicker in elastic arteries?
tunica intima
What are the two primary components of the tunica media in elastic arteries?
thin layers of smooth muscle alternating with fenestrated sheets of elastic lamina
What structure is typically on the outer portion of the tunica media?
vasa vasorum
What is another term for muscular arteries?
distributing arteries
Which major luminal wall layer is very thin in muscular arteries?
tunica intima
What is an important structural componant in the tunica intima of muscular that helps with differentiation?
internal elastic lamina
Which major luminal wall layer is the thickest in muscular arteries?
tunica media
>this is also the case in arterioles
How does the smooth muscle in the tunica media in arterioles contribute to an individual’s BP?
smooth muscle is typically partially contracted
The width of elastic arteries increase in your 20s due to an increase number of elastic lamina in which major luminal wall layer?
tunica media
What happens to collagen & proteoglycans in muscular arteries as you age?
increase causing a decrease in flexibility
What is a cause of HTN?
decrease in elastic fibers and increase in collagen I
How can the tunica media be affected in HTN?
collagen I and sulfated GAG’s can accumulated
Why is the endothelium of the tunica intima prone to develop problems?
blood is moving fast
What major luminal wall layer is absent in metarterioles?
tunica media
>(thoroughfare channels)
What do the metarterioles allow?
blood to pulse through true capillaries
Where are metarterioles found?
in all capillary beds
What major luminal wall layer is thicker in arteriovenous anastomosis?
tunica media & tunica adventitia
What is the function of ANS nerves on arteriovenous anastomosis?
control AVA lumen size and therefore the amount of blood into capillaries
Are AVAs typically closed or open in the skin & stomach?
closed: blood goes into capillary beds
if open it bypasses capillary beds
Are AVAs typically closed or open in erectile tissues?
open: less blood into erectile tissue capillaries
What controls blood flow into capillaries?
- metarterioles
- AVAs (some locations)
- lumen size of terminal arteriole
- pre-capillary sphincters*
What type of cells are seen in capillaries?
single layer of flattened endothelial cells
What is the function of pinocytic vesicles in capillaries?
movement of large molecules
What type of cell junctions are seen in capillaries?
fasciae occludens (tight junctions)
What is the function of cell junctions in capillaries?
- move macromolecules
- allows cell movement
What is the most common capillary type?
continuous capillary
What are some locations for continous capillaries?
muscle, CT, many organs
What are some characteristics of pericytes?
- considered residual mesenchyme cells
- numerous in capillaries and venules
- secrete basement membrane & matrix components
- can DIVIDE
What can pericytes change into?
smooth muscle, endothelial cells & fibroblasts
What are some functions of pericytes?
healing
regulate blood flow?
What type of capillary is found in the CNS?
modified continuous capillary
What type of gap junction is found on the capillaries in the CNS?
zonula occludens (instead of fasciae occludens)
What are some locations of fenestrated capillaries?
pancreas, intestines, endocrine organs, kidneys*
What is the function of fenestrated capillaries?
allow greater movement of molecules and cells
What are some locations of sinusoidal capillaries?
bone marrow, liver, spleen, lymphatic organs & certain endocrine organs
What is the function of fenestrated capillaries?
enhanced exchange between blood and tissues
How are veins different than arteries?
- not as uniform in structure
- often larger diameter
- higher number*
What are the function of valves?
- protection by preventing backflow
2. works with skeletal muscle to keep blood moving
What are valves made of?
tunica intima & fibroelastic CT
Do postcapillary venules have all luminal wall layers?
Not all
-no tunica media or adventitia
What is there a lot of in the tunica intima of postcapillary venules?
pericytes
Do collecting venules have all luminal wall layers?
Not all
-no tunica media
Do muscular venules have all luminal wall layers?
yes
What is different about the tunica media in muscular venules?
they have an incomplete smooth muscle layer
What happens when venules become inflamed?
will end up with leaky venules since it has an incomlete tunica media
Small veins are similar to muscular venules except…?
they have a complete tunica media
What is the most dominant major luminal wall layer in medium veins?
tunica adventitia
What is the most dominant luminal wall layer in large veins?
tunica adventitia
What is the major luminal wall layer in superficial veins of the legs?
tunica media: pump blood back up
What is different about pulmonary veins?
- well-developed tunica media
- tunica adventitia has some cardiac muscle close to heart
What is different about the superior vena cava?
the tunica adventitia has some cardiac muscle close to the heart
What is different about the inferior vena cava?
the tunica adventitia has some cardiac muscle clos to the heart and some longitudinal smooth muscle
What are 5 things that make lymphatic capillaries different than blood capillaries?
- blind ended - begin suddenly
- no pericytes
- endothelial cells can overlap but create clefts
- no fenestrae or tight junctions
- contain bundles of lymphatic anchoring filaments
What do the lymphatic anchoring filaments contain?
elastic fibers
What is the function of lymphatic anchoring filaments?
support endothelial walls so capillaries stay open and hold to CT
