Leading toward a region or structure of interest.

In the nervous system, afferent fibers (i.e., neurons) transmit information from a peripheral receptor to the spinal cord or the brainstem. Afferent neurons are also referred to as sensory neurons.

In the kidneys, the afferent arteriole carries blood to the glomerular capillaries.

Efferent

Amiloride inhibits epithelial Na⁺ channels (ENaC), and in doing so, it acts as a diuretic by inhibiting sodium reabsorption in the late distal convoluted tubules, connecting tubules, and collecting ducts in the kidneys.

Amiloride (Wikipedia)

The ability of a tissue or organ to regulate its own function without extrinsic neural or hormonal input.

For example, in the kidneys, autoregulation ensures relatively constant blood flow and pressure through the kidney tubules in order to maintain a fairly constant glomerular filtration rate (GFR).

Leading away from a region or structure of interest.

In the nervous system, efferent fibers (i.e., neurons) transmit information from the central nervous system to peripheral effector organs (i.e., muscles or glands). Therefore, the cells bodies of efferent neurons reside within the central nervous system, whereas their axonal projections exit the central nervous system to make synaptic contact with effector organs in the periphery. Efferent neurons are also referred to as motor neurons.

In the kidneys, the efferent arteriole carries blood away from the glomerular capillaries.

Afferent

An electrogenic transport process is one that leads to the translocation of net charge across the membrane. For example, ion channels such as Na⁺, K⁺, Ca²⁺, and Cl⁻ channels are electrogenic.

The Na⁺/K⁺ ATPase is electrogenic because for every ATP molecule hydrolyzed, 3 Na⁺ ions are transported out of the cell and 2 K⁺ ions are transported into the cell (leading to the translocation of one net positive charge out of the cell).

Many secondary active transporters are also electrogenic. For example, the Na⁺/glucose cotransporter (found in the small intestine and kidney proximal tubules), transports 2 Na⁺ ions and 1 glucose molecule into the cell across the plasma membrane (leading to the translocation of two net positive charges into the cell per transport cycle).

Excretion refers to the elimination of waste substances from the body. The kidneys and lungs are mainly responsible for excreting metabolites and waste products.

Secretion