unit 9 Flashcards
what kinds of cells make up cardiac muscle? what is their function?
cardiomyocytes
contraction for propelling blood
what is the fibrous skeleton
4 fibrous rings of valve orifices, 2 fibrous trigones, membranous CT portion of heart septa that acts as an electrical insulator
what does the fibrous skeleton do?
ensures blood movement is as efficient as possible
what cells make up the cardiac conducting system? what do they do?
modified cardiomyocytes
imitate and propagate myocardial depolarization
what is the function of intercalated discs?
increases SA between adjacent cells for communication
ensures cells don’t pull apart due to anchoring
what is the transverse component of intercalated discs?
fascia adherens and maculae adherens
bind cytoskeletal components of adjacent cells to ensure they stay together
what is the lateral component of intercalated discs?
gap junctions and maculae adherens
what do fascia adherens do?
couple actin cytoskeleton to plasma membrane
what do macula adherens do?
couples intermediate cytoskeleton filaments to plasma membrane
what do gap junctions do?
communication conduit for adjacent cells
steps for cardiac muscle excitation and contraction
what are the layers of the heart wall from external to internal?
epicardium
myocardium
endocardium
parts of the epicardium and what they contain
visceral layer of serous pericardium (mesothelium - simple squamous cells)
sub epithelial layer (loose CT and adipose) - contains coronary vessels/nerves
what is myocardium composed of? what does it due?
cardiomyocytes arranged in complex spiral
results in efficient chamber emptying
myocardium facts
thinner in atria compared to ventricles
thinner in RV compared to LV
thickest of the 3 layers
endocardium layers and what it contains
subendocardial layer (contains heart conduction system, continuous with CT of myocardium)
sub endothelial layer (dense CT)
endothelium (simple squamous cells)
what do valvular interstitial cells do?
maintain baseline levels of ECM ground substance and protein fiber
(have an endothelial origin so they resemble fibroblasts)
atrioventricular valve layers
atrialis (atrial side)
spongiosa
fibrosa
ventricularis
what is atrialis layer?
endothelium and dense CT deep to this
continuation of the atrial endocardium
what is spongiosa? what does it do?
loose CT, prominent at leaflet edge
seals gaps where leaflets meet and absorbs shock of valve vibration
what is fibrosa?
dense CT that is largely collagen
fibrosa is an extension from annulus fibrosus
in AV valves, collagen of chordae tendineae interfaces w/ dense CT collagen
what is ventricularis
endothelium and dense CT
minimal contribution from ventricular endocardium
semilunar valve layers
ventricularis
spongiosa
fibrosa
arterialis
what is arterialis
endothelium and loose CT
continuation, minimal contribution, from tunica intima
what make up SA and AV nodes?
pacemaker and transitional cells (are supportive cells)
pacemaker and transitional cell characteristics
smaller than atrial cardiomyocytes, limited myofibrils and lack intercalated discs
still contain gap junctions!
AV bundle characteristics
smaller proximally, enlarge distally
purkinje cell characteristics
larger than cardiomyocytes
limited myofibrils and intercalated discs
what is valvular heart disease?
degeneration of heart valves
transition of activated valvular interstitial cells to myofibroblast-like cells
leads to disruption of ground substance levels and protein fibers –> stenosis and regurgitation
what is a myocardial infarction?
cardiac ischemia of oxygen starved tissue
potentially leads to –> replacement of cardiomyocytes with dense CT and deficiency in conduction, contraction, chamber emptying
what are the parts of the microvascular bed?
arterioles
blood capillaries
lymphatic capillaries
venules
what is vasculogenesis? what drives the process?
formation of primitive blood vessel networks, “blood islands,” and primary capillary plexus
VEGF/R (vascular endothelial growth factor/receptor) family
when does adult vasculogenesis occur?
wound healing and neoplasm
what is angiogenesis? what drives the process?
formation of branches from existing vessels
VEGF/R and angiopoietin-1/R
what is vascular wall maturation?
completion of endothelial tunica (intima), muscular tunica (media), and CT tunica (adventitia)
what drives vascular wall maturation?
angiopoietin-1/R (intima)
platelet-derived growth factor (PDGF/R) and myocardin/R (media)
fibroblast growth factor (FGF) (adventitia)
what are the layers of the vascular wall from external to internal?
tunica adventitia
tunica media
tunica intima
what is the most robust layer in veins?
tunica adventitia
what is the most robust layer in arteries?
tunica media
what is tunica intima made of
internal elastic membrane (interfaces with tunica media)
subendothelial CT
endothelium
what is contained within tunica adventitia
collagen fibers, elastic fibers, nervi vasorum, vasa vasorum
what are the functions of endothelium in blood vessels
maintain selective permeability (tight junctions)
maintain non-thrombogenic barrier (anticoagulants)
regulate immune response (lymphocyte interaction)
modulate blood flow (vasodilation and constriction)
visceral (single-unit) smooth muscle
in walls of vasculature and hollow organs
only some cells receive direct neuronal input, gap junctions spread contraction signal to neighboring fibers
multiunit smooth muscle
in large arteries, bronchioles, arrestor pilli muscle, iris of eye
each cell receives neuronal input and acts independently
few gap junctions
smooth muscle excitation and contraction
different artery sizes
large/elastic - convey blood to systemic and pulmonary circulations
medium/muscular - “named”
small/arterioles - 8-10 SM layers/1-2 SM layers
different vein sizes
venules/small - 1-2 SM layers/2-3 SM layers
medium - “named”
large - receive blood from systemic and pulmonary circulations
large elastic vessels
medium muscular vessels
small vessels/arterioles/venules
what are capillaries? what are they made of?
vascular network that allows for fluid exchange of gases, metabolites, and waste products
single endothelial layer & basal lamina
what are the types of capillary morphology?
continuous, fenestrated, discontinuous/sinusoidal
which capillary type(s) has an uninterrupted endothelium?
continuous capillary
which capillary type(s) has a continuous basal lamina?
continuous and fenestrated
what promotes movement across the capillary vessel wall?
ratio of capillary volume to endothelial cell surface area and thickness
what are lymphatic capillaries similar to morphologically?
fenestrated capillaries
what are lymphatic vessels similar to morphologically?
small vein with less distinct layering
what are lymphatic ducts similar to morphologically?
medium vein with less distinct layering
what is atherosclerosis?
lesions primarily developing in the tunica intima leading to endothelial dysfunction
macrophages become foam cells
formation of a fatty LDL streak leads to fibrofatty plaque formation
