Which of the following physiological changes in blood chemistry is an indication of acidosis?

a. Decrease in hydrogen ions: A decrease in hydrogen ions (H+) would indicate a condition of alkalosis, not acidosis.

b. Decrease in carbon dioxide: A decrease in carbon dioxide (CO2) usually leads to respiratory alkalosis because CO2 is acidic in nature.

c. Decrease in ketones: Ketones are acidic compounds, and their decrease is not associated with acidosis. In fact, an increase in ketones can cause ketoacidosis.

d. Decrease in bicarbonate ions: Bicarbonate (HCO3-) is a base, and a decrease in its concentration can lead to metabolic acidosis, as it reduces the buffering capacity of the blood against excess H+.

a. Purkinje fibers: Purkinje fibers are the last structures to receive the signal within the ventricles, causing them to contract.

b. Bundle of His: The correct sequence of the cardiac conduction system is as follows: The electrical impulse originates in the sinoatrial (SA) node, then travels to the atrioventricular (AV) node. From the AV node, the impulse travels to the Bundle of His. After the Bundle of His, the impulse travels through the bundle branches and finally reaches the Purkinje fibers, which facilitate the contraction of the ventricles.

c. Bundle branches: The electrical impulse for heartbeat originates in the SA node (sinoatrial node). It then travels to the AV node (atrioventricular node), which delays the signal before sending it to the Bundle of His. The Bundle of His splits into right and left bundle branches, which distribute the electrical signal to the Purkinje fibers in the ventricles, causing them to contract in a coordinated fashion.

d. SA node: The SA node initiates the electrical impulse, not receive it after the AV node.