Question

he electric capacitance of biological tissues serves as the basis for numerous medical technologies. For example, dielectric spectroscopy glucose reading (DSGR) is a noninvasive diagnostic technique that uses the electric capacitance of blood to estimate blood glucose levels.

A DSGR device records the electric current that results from applying a voltage source to the skin and underlying blood vessels. DSGR can be modeled by the circuit shown in Figure 1, in which V represents the applied potential, C_B represents the capacitance of the blood, and R_E, R_D, and R_B represent the electrical resistances of the epidermis, the dermis, and the blood, respectively.

Figure 1 DSGR circuit model including skin and superficial blood vessel

The capacitance of charged blood may be explained by red blood cell membranes acting as physical barriers that separate electrons introduced into the blood from positively charged ions in the red blood cell cytoplasm. The dielectric constant k of red blood cell membranes varies with glucose concentration (Figure 2) because glucose uptake by red blood cells alters the activity of membrane-bound proteins that regulate the flow of ions into and out of the cell.

Figure 2 Blood dielectric constant vs blood glucose concentration

DSGR readings vary with blood glucose concentration because the time needed to fully charge the blood is related to total blood capacitance. However, interpreting DSGR readings may be complicated by changes in biological variables other than blood capacitance. For example, the resistivity of blood varies in accordance with osmolarity such that changes in diet or hydration status influence the current measured by DSGR devices.

Biological system Circuit model 1.4 DSGR Electrodes Epidermis x1.3 RE Rp Dermis O 1.0 0.9 Blood 2.5 7.5 10 12.5 15 17.5 20 CB Glucose concentration (mM)

When dietary sodium intake increases, the electric current measured by a DSGR device also increases. Current increases because:

A. Blood pressure energy is converted into electric potential energy.

B. The accumulation of positively charged ions causes blood glucose to precipitate.

C. Electrolytes within blood transport electric charge.

D. Alterations in red blood cell shape increase capacitance.

Answer 1

"Dielectric spectroscopy glucose reading" (DSGR) is a non-invasive diagnostic technique that uses the electric capacitance of blood to estimate blood glucose levels. A DSGR device records the electric current that results from applying a voltage source to the skin and underlying blood vessels.

Let 'V' represents the applied potential, C_B represents the capacitance of blood, R_E represents the electrical resistance of an epidermis, R_D represents the electrical resistance of dermis and R_B represents the electrical resistance of blood.

Figure 1 : DSGR circuit model including skin and superficial blood vessel

Figure 2 : Blood dielectric constant vs blood glucose concentration

When dietary sodium intake increases, the electric current measured by a DSGR device also increases.

Current increases because :

Electrolytes within blood transport electric charge.

Option (C) : it will be correct.

Explanation : Electrolytes are minerals that carry an electric charge when they are dissolved in a liquid such as blood. The blood electrolytes like sodium, potassium, chloride and bicarbonatwe which help to regulate nerve, muscle function, maintain acid-base balance and water balance.

They generate an electricity, contract muscles, move fluids and water within a person's body and participate in a number of additional activities.