Question

1a) How does "Membrane Resting Potential" differ from "Membrane Equilibrium Potential"?

1b) What is Node of Ranvier?

1c) What is respiratory quotient?

1d) Is muscle contraction required for exhalation?

Answer 1

Solution [1(a)] - Difference between Membrane Resting Potential and Membrane Equilibrium Potential - The difference between the membrane potential and the equilibrium potential (-142 mV) represents the net electrochemical force driving Na⁺ into the cell at resting membrane potential. Therefore, while the resting potential is far removed from the E_Na, the peak of the action potential approaches E_Na.

Solution[1(b)] - Node of Ranvier - This is a periodic gap in the insulating sheath (myelin) on the axon of certain neurons that serves to facilitate the rapid conduction of nerve impulses.

or in other words Intermittent interval in the myelin sheath of an axon. Ranvir's nodes are densely populated with voltage-gated sodium channels; An action potential reaches each node of Ranvir, these sodium channels open and cause the influx of sodium ions. This prevents regeneration of action potentials as it travels down the axon.9shown in fig. below)

Solution [1(c)] - Respiratory Quotient (RQ) - Aerobic respiration is the process in which most living things go through to use food energy efficiently. This aerobic respiration consumes oxygen and emits carbon dioxide.

The actual ratio of the volume of carbon dioxide eliminated to the volume of oxygen consumed during the act of cellular respiration is called the respiratory quotient.it is also referred to as the respiratory ratio and is denoted by RQ.

The use of the respiratory part during the function of respiration depends on the type of respiratory substrate. Additionally, respiration is a dimensionless number used in the calculation of basal metabolic rate or BMR when estimated from carbon dioxide production. These measurements are forms of indirect calorimeters. It is measured using Gyeong's respirator.

When the carbohydrates are completely oxidized which are used as a substrate, the respiratory quotient becomes one. Here the equal amounts of carbon dioxide and oxygen are evolved and consumed, respectively.

Hence, the Respiratory Quotient for carbohydrates is approximately 1.

Application of Respiratory Quotient - Applications of the respiratory quotient can be found in severe cases of chronic obstructive pulmonary disease. Other applications include:

• Used as an indicator of over or underfeeding.
• Used for analyzing the functioning of the liver.
• Used to predict weight gain in non-insulin-dependent diabetic patients.
• Used for diagnosing the patient’s conditions, who are suffering from liver cirrhosis and non-protein respiratory quotient.

Solution [1(d)] - The exhalation process is caused by an elastic reorientation of the lung tissue that causes a decrease in volume, resulting in an increase in pressure compared to the atmosphere; Thus, air exits the airway. Muscle contraction does not occur during exhalation; It is considered a passive process. So No muscle contraction required for exhalation.