Cardiovascular Physiology - HP Flashcards
TB1 Year 1
What is the outer layer of the heart called?
Pericardium/Epicardium
What is the middle layer of the heart composed of?
Myocardium, composed of cardiomyocytes (contractile cells)
What is the inner layer of the heart called?
Endocardium
What are the characteristics of the atria?
Thinner walls
What are the characteristics of the ventricles?
Thick muscular walls (Left ventricle thicker than right)
What is the function of the pericardial cavity?
It provides a fluid-filled space that reduces friction between the heart and surrounding structures
What do coronary arteries supply?
Blood to myocardium
What can blockage or narrowing of coronary arteries lead to?
Heart disease
Which vessel does the left ventricle pump blood into?
Aorta
Which vessel does the right ventricle pump blood into?
Pulmonary artery
Where does oxygenated blood come from in the heart?
Pumped out from the left ventricles
What are autorhythmic cells?
Cells that generate pacemaker action potentials
Examples include Sinoatrial nodes.
What characterizes the resting membrane potential in autorhythmic cells?
No stable resting membrane potential
What is the pacemaker potential (phase 4) in autorhythmic cells?
Slow, spontaneous depolarization primarily due to the funny current (If)
Carried by Na+ and K+ ions.
What contributes to the depolarization in pacemaker potential?
T-type Ca2+ channels
What happens during depolarization/upstroke (phase 0) in autorhythmic cells?
Rapid depolarization occurs when the threshold potential is reached
Primarily mediated by L-type Ca2+ channels.
What occurs during repolarization (phase 3) in autorhythmic cells?
K+ efflux through voltage-gated K+ channels
What are contractile cells?
Cells that generate non-pacemaker action potentials
Examples include Ventricular Myocytes.
What is the resting membrane potential (phase 4) in contractile cells?
Stable negative potential around -90 mV
How is the resting membrane potential in contractile cells maintained?
By K+ leak channels and Na+/K+ ATPase pumps
What occurs during phase 0 in contractile cells?
Rapid depolarization due to fast Na+ channels opening
Causes rapid Na+ influx.
What is observed during phase 1 in contractile cells?
Early repolarization due to K+ efflux through transient outward K+ channels
What characterizes phase 2 in contractile cells?
Plateau phase with balanced influx of Ca2+ and efflux of K+
What happens during phase 3 in contractile cells?
Closure of Ca2+ channels and opening of additional K+ channels
What are the key differences between autorhythmic cells and contractile cells?
- Autorhythmic cells have spontaneous depolarization
- Contractile cells require external stimulation
- Upstroke in autorhythmic cells is primarily due to Ca2+ influx
- Upstroke in contractile cells is due to Na+ influx
- Contractile cells have a distinct plateau phase
- Action potential in contractile cells is longer (~300ms) compared to nerve or skeletal muscle (~2ms)
Continue from EEC of a cardiac myocyte from my lecture notes
