Week 4 Cardiology Flashcards
Depression Vs Cardiac Blues
Infective triggers for inflammatory heart disease
Bacterial, fungal, viral, parasitic
Non-Infective causes of inflammatory heart disease
Often autoimmune disease
Also hypersensitivity to medications, toxins or allergens
Endocarditis
Inflammation of the endocardium; characterised by vegetations composed of platelets, fibrin, microorganisms, and inflammatory cells, affects heart valves.
Myocarditis
Inflammation of the myocardium, presenting with myocardial necrosis or fibrosis,
Pericarditis
Inflammation of the pericardium, often presents with sharp pleuritic chest pain, pericardial effusion, and diffuse ST-elevation on ECG. Also elevated serum Troponin levels
Rheumatic heart disease
cause, effects, symptoms
-starts from Sterptococcus group a infection
-antibodies mistakenly attack and damage heart tissues especially valves
-causes scaring and inflammation or heart valves leading to stenosis (narrowing) or leaking (regurgitation)``
Symptoms include: Dyspnoea, Chest Pain, Fatigue and palpations
SA node location
Between superior venal cava and right atrium
AV node location
Border between right atrium and Right ventricle
Bundle of His location
Within the right atrium
Bundle branches location
In the subendocardial layer of the intraventicular septum
Cardiac Conduction system
- Resting membrane potential of -70mV
- Slow influx of Na+ deploarises membrane
- T-Type Ca2+ channels open, resulting in further depolarisation
- L-Type Ca2+ channels open, further depolarisation
- Membrane potential exceeds thresholds action potential occurs
- K+ channels open, efflux of K+ ions initiates hyper polarisation
- Hyper polarisation opens If (funny) Channels, resulting in slow influx of Na+ (restarts)
Pacemaker cells
Located in the SA and AV nodes, these cells generate spontaneous action potentials that initiate the heart’s electrical activity.
Cardiomyocytes
The muscle cells of the heart, responsible for the contractile force that pumps blood throughout the body.
Also allow propagation of electrical signals
Heart electrical signal propagation
- Electrical signal originates in SA
- Signal rapidly spreads across atria, causing atrial contraction
- Impulse reaches AV node, where it is briefly delayed, allowing ventricles to fill
- Signal travels down bundle of his, bundle branches and then to the Purkinje fibres that disturbed the signals through the ventricular myocardium
- Ventricular contraction
Excitation-Contraction Coupling
- Action poetical depolarise the sarcolemma (Cardiomyocyte Cell Membrane)
- Triggers opening of voltage gated L type calcium channels —> Ca2+ enters cell
- Induces further realse of Ca2+ from Sacroplasmic reticulum
- Intracellular Ca2+ binds to troponin, exposing actin binding sites for myosin, leading to muscle contraction
- Relaxation as Ca2+ is pumped out of the cell
Phase 0 of action potential in Cardiac cells
Depolarisation
- Initiated by rapid influx of sodium ions through voltage gated Na+ channels leading to sharp rise in membrane potential
Phase 1 Of Action potential in Cardiac cells
Initial Repolairsation
- Occurs as Na+ channels close and transient outward potassium (K+) channels
open, causing a brief, partial repolarisation.