Biofísica Médica: Temario III Corte

Biofísica Celular

Biofísica Celular focuses on the physical principles governing the function and structure of cells. This includes a detailed examination of the properties of the cell membrane, which acts as a semi-permeable barrier regulating the internal environment of the cell. The study of cellular transport mechanisms is fundamental, encompassing passive processes such as simple diffusion and facilitated diffusion, as well as active transport mechanisms like the sodium-potassium pump ($Na^{+}/K^{+}$-ATPase) that move solutes against their electrochemical gradients.

Electrical potentials of the membrane are also a critical area of study, particularly the resting membrane potential and the generation of action potentials. These potentials are governed by the distribution of ions across the membrane and are often described by the Nernst equation or the Goldman-Hodgkin-Katz equation to determine the equilibrium potential for specific ions like $K^{+}$, $Na^{+}$, and $Cl^{-}$. Additionally, the biophysics of body fluids explores how the concentration of solutes and the osmotic pressure ($\text{OP} = iMRT$) affect cellular volume and stability within different physiological compartments.

Biofísica Tisular

Biofísica Tisular involves the investigation of the physical properties of biological tissues. This field explores how tissues respond to various physical forces and how their structure dictates their function. Connective tissue is analyzed in terms of its mechanical properties, such as elasticity and tensile strength, specifically looking at the loads or stresses to which it is subjected ($\text{Stress} = \frac{F}{A}$). This includes the study of collagen and elastin fibers and how they contribute to the viscoelastic behavior of tendons, ligaments, and cartilage.

Muscular tissue is another focal point, specifically relating to its mechanical properties and the biophysics of contraction. The sliding filament theory explains how molecular motors like myosin interact with actin to generate force. The mechanics of muscle contraction are studied through the relationship between force and velocity, as well as the length-tension relationship, which describes how the overlap of filaments affects the maximum force a muscle fiber can produce.

Mecánica de Fluidos

Mecánica de Fluidos covers the physical principles of fluids, both at rest and in motion, and their critical applications in human physiology. Core properties such as density ($\rho = \frac{m}{V}$), viscosity ($\text{Poise} = 10^{-1} Pa \times s$), and pressure are examined. The laws of fluid mechanics, including Bernoulli's principle used to describe the relationship between velocity and pressure in a moving fluid, and Poiseuille's law ($Q = \frac{\triangle P \times \text{r}^4 \times \text{π}}{8 \times \text{η} \times L}$), are essential for understanding internal dynamics.

This theme has direct applications in the cardiovascular system, where it is used to model blood flow ($Q$), peripheral resistance ($R$), and blood pressure ($\triangle P$). Similarly, it applies to the respiratory system to understand air dynamics, including the mechanical work of breathing and the resistance encountered in the airways. Factors such as laminar versus turbulent flow (determined by the Reynolds number, $Re = \frac{\rho v d}{\text{η}}$) are analyzed to understand physiological and pathological states in both blood vessels and the bronchial tree.

Termodinámica

Termodinámica in the context of Medical Biophysics applies the laws of energy and heat to the human body. The laws of thermodynamics are used to describe how the body converts chemical energy from food into mechanical work and heat. This includes the transfer of energy through processes such as metabolism and the maintenance of homeostasis through thermoregulation. The body employs various mechanisms of energy transfer, including conduction, convection, radiation, and evaporation ($Q = m \times L_v$).

Thermoregulation is the physiological process that allows the body to maintain its core internal temperature. The physical analysis of heat loss and heat gain involves calculating the rate of heat exchange with the environment and understanding the role of blood flow in distributing thermal energy from the core to the periphery. The maintenance of a stable temperature is seen as a balance of the first law of thermodynamics, where the change in internal energy equals the heat added to the system minus the work done by the system ($\triangle U = Q - W$).

Biomecánica

Biomecánica applies the principles of classical mechanics, specifically Newton's Laws, to the human body. This field explores how forces act upon body systems to produce movement or maintain stability. Newton's second law ($\text{F} = \text{m} \times \text{a}$) is frequently applied to analyze the kinematics and kinetics of human motion. The study of levers, pulleys, and torque ($\text{τ} = \text{r} \times \text{F} \times \text{sin}(\theta)$) is vital for understanding how muscles and bones function together as mechanical systems (palancas) to lift loads or move the body.

Physical properties of matter, such as the behavior of solids under deformation, are also considered. Biomechanics provides the mathematical framework to calculate the forces exerted on joints during daily activities or athletic performance, allowing for the design of prosthetics and the development of rehabilitation protocols. This section emphasizes the mechanical efficiency of the musculoskeletal system and the physical limits of biological materials.

Ondas Mecánicas y Electromagnéticas

Ondas Mecánicas y Electromagnéticas analyzes the physics of wave phenomena and their interactions with matter, which are the basis for many diagnostic and therapeutic tools in medicine. Mechanical waves, such as sound, are studied in the context of acoustics and their application in ultrasonido (ultrasound). The behavior of sound waves as they reflect off different tissue interfaces allows for the visualization of internal organs without the use of ionizing radiation.

Electromagnetic waves involve the study of radiations across the electromagnetic spectrum, including visible light, infrared, and ionizing radiations such as Rayos X (X-rays). These waves have significant applications in health, ranging from diagnostic imaging to radiation therapy for cancer treatment. Understanding the physical properties of these waves, such as frequency ($f$), wavelength ($\text{λ}$), and energy ($E = h \times f$), is essential for their safe and effective use in clinical settings. The transcript also mentions a product "Protex Umpless Profundo," which claims to eliminate $99,9\%$ of bacteria.