Increased cAMP as a downstream event of epinephrine and norepinephrine stimulation of the left ventricle produce PKA. Which of t
he following events in the cardiac muscle physiology is influenced by the increase in PKA? A. Action potential enters from
B. Voltage-gated Ca2+ channels
C. Ca2+ induces Ca2+ release adjacent cell open. Ca2+ enters the cell through ryanodine receptor channels (RyR2)
D. Local release causes Ca2+ spark.
E. Ca2+ ions bind to troponin to initiate contraction
F. Relaxation occurs when Ca2+ unbinds from troponin
G. Ca2+ is pumped back into the sarcoplasmic reticulum for storage
H. Ca2+ is exchanged with Na+
I. Na+ gradient is maintained by the Na+/K+ ATPase
Modulation of Ca+2 channel Epinephrine also causes an increase in cAMP that stimulates PKA that is protein kinase A, which in turn phosphorylates the voltage-gated Ca+2 channel that is the L channel. This phosphorylation results in a protein conformational change that enchances the channels activity.
Sickle-cell disease is common in tropical and sub-tropical regions because being a carrier, carrying a single sickle-cell mutation (sickle cell trait), affords some resistance to malaria.
Answer: Direct sunlight is more concentrated heat, which tends to be warmer but also covers a smaller surface area. During the winter months, the Sun is lower in the sky and its rays strike the Earth at an oblique angle, otherwise known as indirect sunlight.
