Why is it important that melanin is present in its highest concentration in the keratinocytes at or near the basale layer of cells?

Match the following terms describing electrical events with the correct phases of the cardiac cycle. the ventricular muscle cells depolarize at the start of this phase. during this phase, na+ entry through the funny channels causes the pacemaker potential of sa nodal cells to gradually become less negative until it reaches threshold. the ventricular muscle cells repolarize right before this phase. the cytosolic concentration of calcium in the contractile cells of the ventricle is highest during this phase. a. isovolumetric relaxation b. ventricular ejection c. isovolumetric contraction d. ventricular filling

Explain the source of radioactivity in uranium in earth’s crust by which it produces nuclear radiation

Explain the physiological changes that occur when the hypothalamus stimulates the sympathetic nervous system. you can make a flowchart or a simple step process. be sure to include all chemicals/hormones secreted, glands involved and the functions of each chemical/hormone.