The autonomic nervous system can change the rate of the heart by: Group of answer choices beta1 adrenergic receptor activation. Increases in cAMP lead to increased amounts of Na influx (though If channels) and Ca2 influx of the pacemaker cells. This increases the frequency of APs of the pacemaker, and increases the rate of contraction. beta2 adrenergic receptor activation. Increases in cAMP lead to increased amounts of Na influx (though If channels) and Ca2 influx of the pacemaker cells. This increases the frequency of APs of the pacemaker, and increases the rate of contraction. muscarinic ACh receptors activation. Activation leads to reduced activity of Ca2 channels, and increasing activation of K channels, hyperpolarizing cells and reducing the rate of contraction. alpha1 adrenergic receptor activation.

The correct answer is: β1  adrenergic receptor activation. Increased in cAMP lead to increased amounts of Na influx (though if channels) and calcium influx of  pacemaker cells. This increases the frequency of APs of the pacemaker and increases the rate of contraction.

Explanation:

cAMP generated in response to β1 adrenergic receptors,results in excitation contraction coupling by initiating PKA and causing phosphorylation of L type Ca2+ channels and ryanodine receptors. This increases the concentration of intracellular Ca2+ ions in atrial cells, ventricular cells and AV pacemaker cells. This increase in firing rate. As a result rate of contraction increases.

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genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).