Understanding Bioelectricity, Thermodynamics, and Respiratory System
Bioelectricity
Coulomb’s Law: The magnitude of the electrical force between two point charges at rest is directly proportional to the product of the magnitudes of the charges and inversely proportional to the square of the distance between them.
Ohm’s Law: The electric current flowing through a conductor is directly proportional to the potential difference and inversely proportional to its resistance.
Electric Current: Electrical current is the flow of electric charge carriers, typically through a metal cable or other electrically conductive material, due to a potential difference created by a generator.
Electric Potential: The electric potential at a point is the work required to move a unit charge from that point to infinity, where the potential is zero.
Electric Field: A model describing the interaction between bodies and systems with electrical properties.
Nernst Potential: Relates the potential difference across a biological membrane at equilibrium to the characteristics of ions in the external and internal environments of the membrane.
Insulators and Conductors: Substances differ in how easily charges can move through them. A conductor allows charges to move freely, while an insulator restricts charge movement.
Thermodynamics
Man as an Integrated System: The human body uses chemical signals and mechanisms to integrate its trillions of cells into a cohesive system.
Systems:
- Open System: Exchanges both matter and energy with the environment.
- Closed System: Exchanges only energy with the environment.
- Isolated System: Exchanges neither matter nor energy with the environment.
First Law of Thermodynamics: The total energy of an isolated system remains constant.
Forms of Energy:
- Chemical Energy: Energy stored within atoms.
- Thermal Energy: Energy associated with the random movement of atoms and molecules.
- Mechanical Energy: Potential energy, which can be further divided into pressure energy and kinetic energy.
Reversible and Irreversible Processes: A reversible process proceeds through a succession of equilibrium states, allowing it to proceed in either direction. A process that does not meet this condition is irreversible.
Second Law of Thermodynamics: For any spontaneous process, the entropy of the system plus the entropy of the surroundings increases.
Entropy: A state function.
- Free Energy < 0: The process releases energy.
- Free Energy = 0: The system is at equilibrium.
- Free Energy > 0: The process consumes energy.
Respiratory System
The respiratory system consists of the airways, alveoli, and the musculoskeletal structure.
Lung Compliance: The change in lung volume for each unit change in transpulmonary pressure.
Pressures Involved in the Respiratory Tree:
- Pleural Pressure: The pressure in the fluid between the visceral and parietal pleura.
- Alveolar Pressure: The pressure of the air inside the lung alveoli.
- Transpulmonary Pressure: The difference between alveolar pressure and pleural pressure.
Pulmonary Ventilation: The movement of air into and out of the lungs, involving the external intercostal muscles and the sternocleidomastoid.
Henry’s Law: At a constant temperature, the amount of gas dissolved in a liquid is directly proportional to the partial pressure of that gas above the liquid.
Additional Concepts
- Analogy Between Electric Field and Gravitational Field: Both are forces acting at a distance; the greater the distance, the smaller the repulsive force.
- What a Capacitor Stores: Electric charges.
- What Allows a Capacitor to Store Electric Charge: The electric field between the plates.
- What is Needed to Carry a Charge: Work is needed.
- What is Needed to Perform the Work: A fully charged battery with electromotive force is necessary.
- What Must Be Placed Between the Plates of a Capacitor: An insulator.