Question

This week two big concepts discussed are electric fields and electric potential, with electric potential being the basis for voltage. Along with the general discussion of these concepts, some interesting and common applications were briefly talked about like copiers, printers, TVs, etc.

Can you find two examples - one for electric field, one for electric potential - that are connected to the field of biology

Please no handwritten or picture responses - only typed replies.

Answer 1

The electric fields are the result of concentrations of ions maintained by the body in various places through chemical processes , different chemicals have different electrical potentials when in various ionization states, and when they are close to each other there will consequently be an electric field between them. For example, in cerebral and other neurons, sodium and potassium ions are separated across the membranes lining the long connectors (known as axons) that reach from one neuron to another.

Neurons, when getting ready to transmit a signal from another neuron, chemically isolate sodium and potassium atoms from other atoms (like chlorine, which makes salts with sodium and potassium) and concentrate them differentially inside and outside of their cell membranes.

This creates an electric field across the membrane, directed from inside outwards. Then, when the neuron is triggered by another one the membrane sucks sodium ions in and pushes potassium ions in, reversing the potential locally. This process continues in a sort of wave down the axon, also creating a moving electric field along the length of the axon.

Electrocardiography ( also known as ECG) is the process of recording the electrical activity of the heartover a period of time using electrodes placed over the skin. These electrodes detect the tiny electrical changes on the skin that arise from the heart muscle's electrophysiologic pattern of depolarizing and repolarizing during each heartbeat. It is very commonly performed to detect any cardiac problems.

In a conventional ECG, ten electrodes are placed on the patient's limbs and on the surface of the chest. The overall magnitude of the heart's electrical potential is then measured and is recorded over a period of time . In this way, the overall magnitude and direction of the heart's electrical depolarization is captured at each moment throughout the cardiac cycle.^[5] The graph of voltage versus time produced by this noninvasive medical procedure is an electrocardiogram.

Electroretinography measures the electrical responses of various cell types in the retina, including the photoreceptors (rods and cones), inner retinal cells (bipolar and amacrine cells), and the ganglion cells. During a recording, the patient's eyes are exposed to standardized stimuli and the resulting signal is displayed showing the time course of the signal's amplitude (voltage). Signals are very small, and are measured in microvolts or nanovolts. The ERG is composed of electrical potentials contributed by different cell types within the retina, and the stimulus conditions (flash or pattern stimulus, whether a background light is present, and the colors of the stimulus and background) can elicit stronger response from certain components.