Questions and Answers
Osmotic pressure (π) is measured in what units?
units of atmospheres (atm) or millimeters of mercury (mm Hg).
What is 1 atm equal to?
760 mm Hg.
Define osmotic pressure.
It is the amount of pressure that must be applied to oppose osmosis.
How is osmolarity defined?
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Define molarity.
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What is the dissociation constant?
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What is the osmolarity of the human body?
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How is osmotic pressure created by water?
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How is osmosis defined?
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What are the units of osmolality?
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Is the ICF negatively or positively charged relative to ECF?
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Lipids function as what in the cell membrane in relation to transmembrane potential?
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The transmembrane potential at rest is also known as?
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At about what value is the resting potential in most cells?
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The Nernst equation is used to calculate what?
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What is the equilibrium potential (Eion) for Na+?
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What is the equilibrium potential (Eion) for K+?
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What is the equilibrium potential (Eion) for Ca2+?
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What is the equilibrium potential (Eion) for Cl-?
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What is the equilibrium potential (Eion) for HCO3-?
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What is the equilibrium potential (Eion) for H+?
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What three molecules contribute to the cell membrane's resting potential in addition to impermeable ions and proteins?
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Study Notes
Osmotic Pressure and Osmolarity
- Osmotic pressure (π) is measured in atmospheres (atm) or millimeters of mercury (mm Hg).
- 1 atm is equivalent to 760 mm Hg.
- Osmotic pressure is the pressure required to oppose water movement across a semipermeable membrane.
- Osmolarity is defined as the number of particles per liter (osmol/L); it can be calculated using the formula: osmol/L = molarity (mol/L) x dissociation constant.
- Molarity is expressed in moles per liter (moles/L).
- The dissociation constant for common biological solutes is around 1.8.
- The osmolarity of the human body typically ranges from 280-296 milliosmoles/L, approximately 300 mOsM.
Osmosis and Water Movement
- Osmotic pressure is generated by water moving down its concentration gradient.
- Osmosis is the movement of water from an area of high water concentration to an area of low water concentration.
- Osmolality is measured in osmols per kilogram (osmols/kg).
Resting Membrane Potential
- Intracellular fluid (ICF) is negatively charged relative to extracellular fluid (ECF).
- Lipids act as insulators in the cell membrane, influencing transmembrane potential.
- The resting transmembrane potential is also referred to as resting potential, typically around -70 mV.
Equilibrium Potential and Nernst Equation
- The Nernst Equation is utilized to calculate the equilibrium potential (Eion) for a specific ion, represented as Eion = (61/z)(log([ion out]/[ion in])), where z is the ion's valence.
- The equilibrium potential for specific ions is as follows:
- Sodium (Na+): +60 mV
- Potassium (K+): -87 mV
- Calcium (Ca2+): +124 mV
- Chloride (Cl-): -47 mV
- Bicarbonate (HCO3-): -12 mV
- Hydrogen (H+): -12 mV
- The resting potential of cell membranes is primarily influenced by potassium (K+), with sodium (Na+) and chloride (Cl-) contributing secondarily.
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Description
This quiz explores key concepts in physiology related to osmosis, ion equilibria, and resting membrane potential. It features flashcards covering terms like osmotic pressure and osmolarity, providing a concise review of essential definitions and measurements. Ideal for students seeking to reinforce their understanding of physiological principles.