ANAT 215 Lecture Notes - Lecture 20: Purkinje Fibers, Atrioventricular Node, Sinoatrial Node
28 Apr 2018
School
Department
Course
Professor
ANAT 215 week 7 lecture 2
Cardiovascular sys- histology
Heart wall
Epicardium
Outer, visceral layer of pericardium supported by loose CT
myocardium
Cardiac muscle cells, forms bulk of heart
Endocardium
Inner, endothelium lines inside of heart
Fibrous skeleton
Prevent overstretch where large vessels come off, retains valve shape, connects cardiomyocytes forming spiral
bundles to propel blood, acts as lig + insertion point for cardiac cells giving them something to exert their force
against
Cardiac
muscle
fibers
Characteristics
Involuntary, branched, short, staut, interconnected
Sorta striated due to myofilaments going around centrally located nucleus
Endomysium
Space b/n muscle cells, contains blood cap
Intercalated discs
Allows syncytium
Desmoses: physically holds cell together
Gap junctions: allows muscle cell comm
Contains
lots of mito due to 24/7 pumping, few t tubules that enter at Z line, no terminal
cisternae and thus no triads
Conducting
sys
(120ms)
SA node
Pacemaker 80-100 BPM, contains non-contractile cells electrically coupled to AV
node via intermodal pathway
AV node
Sends pulse to Bundle of His via conducting fibers
Bundle of His
Aka atrioventricular bundle, found in intervent septum, branches into R and L
bundle branches stim myocardium muscle cells in subendocardial layer (stim
spread via intercalated discs)
Purkinje fibers
Large and puffy, modified cardiac muscle cells
Para vs. symp
Symp increases rate vs para decreases rate
Both innervate AV, SA node and cardiac muscle cells
Neural reg
of HR
Medulla oblongata
Contains cardiac center
Cardioacceleratory
center
Symp stim (NE)
cardioinhibitory
Para stim (Ach)
find more resources at oneclass.com
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Document Summary
Outer, visceral layer of pericardium supported by loose ct. Prevent overstretch where large vessels come off, retains valve shape, connects cardiomyocytes forming spiral bundles to propel blood, acts as lig + insertion point for cardiac cells giving them something to exert their force against. Sorta striated due to myofilaments going around centrally located nucleus. Gap junctions: allows muscle cell comm lots of mito due to 24/7 pumping, few t tubules that enter at z line, no terminal cisternae and thus no triads. Pacemaker 80-100 bpm, contains non-contractile cells electrically coupled to av node via intermodal pathway. Sends pulse to bundle of his via conducting fibers. Aka atrioventricular bundle, found in intervent septum, branches into r and l bundle branches stim myocardium muscle cells in subendocardial layer (stim spread via intercalated discs) Both innervate av, sa node and cardiac muscle cells. One heart-beat, atrial and ventricular systole and diastole.
