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Questions and Answers
What is the equation for diffusion time?
What is the equation for diffusion time?
In what scenario is diffusion most efficient?
In what scenario is diffusion most efficient?
Which of the following best describes a solvent?
Which of the following best describes a solvent?
Which ion is considered a cation?
Which ion is considered a cation?
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What is the key characteristic of an electrolyte?
What is the key characteristic of an electrolyte?
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What is the primary mechanism involved in transporting oxygen in the bloodstream?
What is the primary mechanism involved in transporting oxygen in the bloodstream?
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Which of the following correctly describes diffusion?
Which of the following correctly describes diffusion?
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What impact does increasing size have on organisms regarding surface area and volume?
What impact does increasing size have on organisms regarding surface area and volume?
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Which transport mechanism involves the transport of uncharged dielectric particles?
Which transport mechanism involves the transport of uncharged dielectric particles?
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The Nernst-Plank Equation is fundamental to which type of transport?
The Nernst-Plank Equation is fundamental to which type of transport?
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What does a higher Peclet number indicate in terms of transport mechanisms?
What does a higher Peclet number indicate in terms of transport mechanisms?
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Which scenario best exemplifies osmosis?
Which scenario best exemplifies osmosis?
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What is required for effective material exchange in larger organisms?
What is required for effective material exchange in larger organisms?
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What type of charge carriers are involved in ionic conduction?
What type of charge carriers are involved in ionic conduction?
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Which material has the highest electronic conductivity based on the provided data?
Which material has the highest electronic conductivity based on the provided data?
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What is the unit used to measure the amount of electric charge transported in one second by a current of 1 ampere?
What is the unit used to measure the amount of electric charge transported in one second by a current of 1 ampere?
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What is the conductivity of 0.9% NaCl in water at 37C?
What is the conductivity of 0.9% NaCl in water at 37C?
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What role does the electric field play on the electrode-electrolyte interface?
What role does the electric field play on the electrode-electrolyte interface?
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Which of the following describes the conductivity of undoped silicon?
Which of the following describes the conductivity of undoped silicon?
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What defines one mole according to chemists?
What defines one mole according to chemists?
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Which of the following materials displays the lowest electronic conductivity?
Which of the following materials displays the lowest electronic conductivity?
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What is the unit of current flow represented in the equations?
What is the unit of current flow represented in the equations?
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How does Faraday's constant relate current flow to moles per second?
How does Faraday's constant relate current flow to moles per second?
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What is the primary function of sodium (Na+) and potassium (K+) ions in excitable cells?
What is the primary function of sodium (Na+) and potassium (K+) ions in excitable cells?
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Which of the following describes molarity?
Which of the following describes molarity?
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If 2 grams of NaCl are dissolved in 15 mL of water, which formula would help calculate molarity?
If 2 grams of NaCl are dissolved in 15 mL of water, which formula would help calculate molarity?
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Which ion is typically present at a higher concentration in extracellular fluid compared to intracellular fluid?
Which ion is typically present at a higher concentration in extracellular fluid compared to intracellular fluid?
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What does it mean if a solution is described as 'millimolar' (mM)?
What does it mean if a solution is described as 'millimolar' (mM)?
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What is the significance of diffusion in cellular processes?
What is the significance of diffusion in cellular processes?
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What does Fick's first law state about diffusion flux?
What does Fick's first law state about diffusion flux?
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What effect does temperature have on the diffusion coefficient?
What effect does temperature have on the diffusion coefficient?
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In osmosis, where does the solvent move?
In osmosis, where does the solvent move?
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Which of the following correctly describes a hypertonic solution?
Which of the following correctly describes a hypertonic solution?
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What is a primary factor affecting the mobility of charged particles in an electric field?
What is a primary factor affecting the mobility of charged particles in an electric field?
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What does the equation for diffusion coefficient indicate about ΔE?
What does the equation for diffusion coefficient indicate about ΔE?
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Why do fingers develop creases after prolonged exposure to water?
Why do fingers develop creases after prolonged exposure to water?
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What does a selectively permeable membrane allow during osmosis?
What does a selectively permeable membrane allow during osmosis?
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Study Notes
Bioelectricity and Biophotonics Engineering
- The course is titled WSC331
- Taught by Felipe Iza at Loughborough University, UK
- The course material covers bioelectricity and biophotonics engineering
- The course is on slide set Bioelec 4
- The course website is http://www.lboro.ac.uk/departments/meme/staff/felipe-iza
Recap from Previous Lecture
- This section reviews neuronal structure and function.
- The structure of neurons is depicted with a diagram, highlighting components like protein channels (transport proteins), globular proteins, cholesterol, glycolipid, peripheral proteins, extracellular fluid, glycoprotein, integral proteins, filaments, cytoskeleton, cytoplasm, and various parts of neurons including dendrites, axon hillock, axon, myelin sheath.
- The diagram also shows different types of synapses (axodendritic, axosomatic, axoaxonic)
- Action potential time course is shown graphically
- The graph indicates resting potential, threshold potential, and the excitory and inhibitory stimulus times
- The graph demonstrates the propagation of ions in the nerve fiber and the result is an action potential.
Today's Lecture
- The lecture covers transport phenomena
- Transport mechanisms, including diffusion and conduction
- The Nernst-Plank equation (drift-diffusion equation)
Transport Mechanisms
- Advection (Convection): Transport of a substance with a moving fluid (e.g., oxygen in the bloodstream).
- Diffusion: Transport from high concentration to low concentration due to random particle motion. Examples include osmosis (solvent diffusion, often water) across a semi-permeable membrane.
- Electric field mediated: Electrophoresis (for charged particles), and dielectrophoresis (for non-charged dielectric particles in an inhomogeneous field).
- Other transport mechanisms, like electrorotation, Pearl chain formation, and electro-osmosis, are also mentioned
Surface Area and Diffusion
- As organisms get larger, their surface area to volume ratio decreases.
- Smaller organisms (like bacteria) have a higher surface area to volume ratio, making diffusion efficient.
- Larger organisms (like whales) have a lower surface area to volume ratio, making diffusion less efficient.
Main Transport Mechanism
- The Peclet number (Pe) compares convection and diffusion rates
- Values of Pe and diffusion times for various molecules are displayed in a table.
- Tables show molecules like oxygen, glucose, insulin, antibodies, viruses and bacteria. And their relation to size and diffusion time.
Diffusion vs Convection
- Diffusion time scales with L².
- Convection time scales with L.
- Diffusion is critical for short distances.
- Convection is more efficient for long distances.
A Few Definitions
- Solution: A homogeneous mixture of two or more substances (Solvent + Solute).
- Solute: The substance dissolved in a solution.
- Solvent: The liquid that dissolves the solute. Water is the most common biological solvent.
- Electrolyte: An ionic solution containing ions (e.g., Na+, K+, Ca2+, Cl-) that conducts electricity.
- Anion: A negatively charged ion. Ions move towards the anode
- Cation: A positively charged ion. Ions move towards the cathode
Ionic vs Electronic Conduction
- Ionic conduction: Involves ions as charge carriers, allowing mass transfer.
- Electronic conduction: Involves electrons as charge carriers, but no mass transfer.
Electronic/Ionic Conductivity
- This section presents a table comparing the conductivity of various materials (metals, semiconductors, biological materials).
Moles/sec vs Amperes
- Chemists: Use moles to measure the amount of a substance. One mole contains Avogadro's number of entities (6.022x10^23). Unit for current = moles/sec
- Electrical Engineers: Use Coulombs to measure electric charge. One Coulombs (1C) = charge carried by an 1 amp current in 1 second. Charge of electron (unitary charge) is 1.6x10⁻¹⁹C. Unit for current = A (C/sec)
Faraday's Constant
- Faraday's constant (F) relates the unit of current measurement in chemistry (moles/sec) to electrical engineering unit (A).
Electrolyte Composition
- Important ions include sodium (Na+), potassium (K+), chloride (Cl-), and calcium (Ca2+).
- Concentrations vary between intracellular and extracellular regions
Molarity
- Molarity (or molar concentration, C): Moles of solute per unit volume of solution.
- Typically measured in mol/litre (M), although the SI unit is mol/m³.
- Millimolar (mM) equals 10⁻³ mol/L, and micromolar (µM) equals 10⁻⁶ mol/L.
Exercise (Example Calculations)
- Example problems, like calculating molarity of substance dissolved in water or molar concentration of protein.
Solution
- Exercise Problems.
Diffusion
- Diffusion is the movement of particles from an area of high concentration to an area of low concentration.
Fick's First Law
- Fick's First law describes the rate of diffusion as proportional to the concentration gradient
- The flux tends to remove spatial inhomogeneities.
Diffusion: Temperature Dependence
- The diffusion coefficient (D) increases with temperature (T) following the Arrhenius equation.
Osmosis
- Osmosis is the movement of solvent (usually water) across a selectively permeable membrane from an area of low solute concentration to an area of high solute concentration
Tonicity
- Hypotonic Solution: Lower solute concentration compared to another solution
- Hypertonic Solution: Higher solute concentration compared to another solution
- Isotonic Solution: Same solute concentration in two solutions
Question
- Why do creases appear on the fingers after prolonged exposure to water.
Mobility
- Charged particles experience forces in an electric field.
- Mobility (μ) quantifies the speed of a particle in a field.
Flux Induced by the Electric Field
- Chemists (moles/sec) and engineers (Amps/currents) approaches to the flux equation
Conductivity
- One species: The relationship between current, charge, mobility, and concentration
- Multiple species: Conductivity in a solution with multiple ions considered.
Transference Number
- The fraction of current carried by each ion in a solution.
Transference Numbers
- Values of transference numbers for various salts (e.g., KCI, HCI, LICI, NaCl) in different molar ranges.
Einstein Relation
- The relationship between diffusion coefficient (D) and mobility (μ) of an ion, derived from Brownian motion and collisions.
Diffusion + Conduction
- The Nernst-Plank Equation describing diffusion and conduction of ions simultaneously, accounting for concentration gradients and electric field influences
Nernst-Plank Equation
- Two different perspectives considering the equation from chemist's and engineer's prospective.
Today's Lecture
- Transport Phenomena, Transport mechanisms, Diffusion, Conduction, Nernst-Plank Equation
Next Lecture
- Transport across cell membranes
- Nernst Potential
- Membrane parallel conductance model
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Test your knowledge on diffusion processes and electrolytes with this engaging quiz. Explore concepts such as diffusion time, solvent characteristics, and the nature of ions. It's a great way to reinforce your understanding of these fundamental topics in chemistry.
