Talk:Cardiac conduction

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Minutes

signal transmission from pacemaker to cardiomyocyte ontology development discussion

• Control of heart rate
  • Automomic regultion
    • parasympathetic and sympathetic
    • afferents via baroreceptors, chemoreceptors
    • G-protein receptor.beta adrenergic receptors modulate SA node
    • heart reate variablity

• Ionic mechasnisms

intrinsic rhythm set by SA node, moducation by vagus node, or activity If current funny current - depolarising current (similar system in gut) general channel If moduated by antomi, increased cAMP increases If modulates pace maker 2 types of clocks ca2+ cycling, membrane clock Diastolic Ca2+ leak, ca

• action potential
  • sodium spike
  • calcium current
  • pot current - turns of depolarisation
  • Chloride channels more important in smooth muscle action potential, does not seem to be important in heart.
  • SA node action potential mediated by calcium current, whereas by the venticals sodium current starts action potential.
  • Atria has potassium channel not present in other parts of the heart
• ion channels and transporters
  • control membrane excitabliliy
    • alpha subunits forms the actual channel, beta subunits modulate activity of channel, many involved in transport of channels
    • voltage gated potassium channels, alpha and beta subunits as above, but as tetramers varius combinations, involved in membrane repolarisation
    • rectifier channel dimers set resting membrane potential, more metabolically sensitive
    • Long QT syndrome
    • P type atpase pumps ensure there is na and k+ to generate gradient main one is sodium,
• Arrhythimia
  • site of origin
  • rate
  • ?not sure what this was

Lots of processes inferred from ECG surface electricity P wave atrial depol QRS ventricular depol T-wave ventricular repol Atrial fibrillation - chaotic action potential Ventricalur tachycardia, independant pacemaker

• EC coupling
  • calium induced calcium release

Calcium activates RyR to release more calcium p type ATP ase pump in SR brings CA back into SR CA antiporter/Exchanger extrudes ca out of cell L-type first ones cloned in heart RyR2 tetrameric complex, with modulating interacting proteins Sodium calcium excanger uses 3 NA+ to electrogenic exchange for single Ca2+ (passive) SERCA2A major Ca uptake into SF, modulated by phospholamban PKA phosphorylates phospholam, which deactivates SERCA2A

David's talk

Rate and force of heart contraction need to be separate aspects, but intrinsically linked short PR interval, increased conduction, or abnormal structure Map of Medicine similar ontology idea (Pier)

Becky's talk Neuro signaling is a multicellular process (as is action potential)

Paola's talk

Membrane repolarization term required

Also more specific cell type depolarization and repolarization terms required (eg pace maker)

Pacemaker Regulation of heart rate automatic regulation of heart rate

need to qualify that pacemaker term are cardiac (c-kit expressed by pacemaker) Sinoatrial node rather than sinuatrial node GO editors need to specify Purkinje cell not Purkinje fibre Transmission of nerve impulse is not a cellular process as this represents a collection of cells.

David summary Cellular attack

• enumerate the cells/anatomy in the heart, cardiomyocytes contracting, cardiomyocytes regulating contraction
• Action potential as regulation of cardiac contraction

Add specific cardiomyocytes that are contracting

New GO term: Regulation of vetricular cardiac muscle cell action potential annotate with channels: Sodium and calcium channels annotate to depolarising pot channels to repolarising

Sodium channel beta subunits should be annotated to reg of membrane depolarization, but not having Na channel regulator activity.

Relaxation removal of ca2+ from cytoplasm, mitochondrial uptake, SR uptake, pump ca2+ out of cell.

G-protein receptor signaling beta(mostly 1) adrenergic receptor regulates ionotrophic, etc (all 3)

Processes involved in regulation of heart rate ontology development discussion