Human Physiology Day 3

Introduction to Flux and Resistance

• Concept of Flux

  • Flux is defined as the movement of a substance per unit time.

  • Mathematically related to gradient and resistance: flux = gradient / resistance.

Resistance in Equations

• Resistance Units

  • Resistance is expressed as some variation of 1/time; notably can be derived from Ohm's law (V = IR).

  • Rearranged, the equation relates flux to charge movement and resistance.

• Definition

  • 'I' (current) represents movement of charge, 'V' is the voltage difference, and 'R' is resistance.

Discussion Questions

• Chime-in Questions

  • Topics include math related to flux, inhalation mechanics, and identification of flux gradient resistance.

  • Encouragement to discuss and share insights openly, valuing incorrect answers for learning opportunities.

Key Relationships in Physics

• Pressure and Flux

  • Adding pressure increases flux, but resistance remains unchanged under elastic conditions.

  • Resistance defined as factors that oppose flux: includes the diameter of airways/lungs and viscosity of the medium.

• Interpretations of Resistance

  • Resistance properties affecting biological systems depend on structure and flow conditions.

Applications of Flux in Physiology

• Flux Examples in Biochemistry

  • Example 1: Rate of glucose movement across cell membranes as flux measured in mol/s, where gradient would be the concentration difference.

  • Example 2: Household example like measuring the volume of vomit over time to calculate flux.

  • Resistance linked to membrane properties and transport proteins that regulate flux.

Deriving the Resistance Equation

• Algebraic Derivation

  • Starting from the basic flux equation, rearrange to isolate resistance (R).

  • Flux (F) = Gradient (D) / Resistance (R) leads to R = D / F.

Study Guide Approach

• Review Study Guide Objectives

  • Emphasizing the importance of reviewing submitted study guides for exam preparation.

  • Focus on practice problems, linking topics to objectives covered in class.

Metabolic Rate Overview

• Types of Metabolic Measurements

  • Differences between whole animal metabolic rate and mass-specific metabolic rate.

  • Explanation of terms based on unit measurements (e.g., millimoles of oxygen per kilogram per hour).

• Estimating Metabolic Rates

  • Practice converting between whole animal rates and unit rates through example calculations (e.g., fruit flies).

Animal Physiology Case Study: Etruscan Shrew

• Characteristics

  • Described as having a high surface area to volume ratio, leading to a fast metabolism.

  • Notably consumes twice its body weight in food daily due to high energy expenditure.

True/False Practice Questions

• Identifying True/False Statements

  • Review statements regarding circulatory systems, discussing relationships between resistance, pressure, and blood flow rates.

  • Clarification on how to adjust false statements to identify underlying truths and misconceptions.

Summary

• Wrapping Up

  • Review and discussion covered topics of flux, resistance, metabolic rates, and physiological examples.

  • Emphasis on the importance of understanding the relationships between resistance, flux, and physiological processes.