Body Fluid Compartments and Osmosis

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Questions and Answers

What is the process that involves the movement of water across a membrane?

Osmosis

What does osmolarity express in a solution?

Number of osmotically active particles

In which fluid compartment do solutes experience chemical disequilibrium and electrical disequilibrium?

Extracellular fluid

What determines tonicity?

The concentration of solutes within the cell Signup and view all the answers

Which factor influences the rate of diffusion?

Molecular weight and size Signup and view all the answers

What type of molecules can most easily diffuse across a cell membrane?

H2O only Signup and view all the answers

What is the function of carrier proteins?

Change conformation to move molecules across the membrane Signup and view all the answers

What is the role of secondary active transport?

Utilizes the Na+ gradient established by NKA Signup and view all the answers

What does the Nernst equation calculate?

Equilibrium potential for K (EK) Signup and view all the answers

What determines the actual resting membrane potential of a cell?

Permeability of the cell membrane to K and Na ions Signup and view all the answers

'Polarized' refers to which change in the membrane potential?

-70 mV Signup and view all the answers

'Depolarization' refers to which change in the membrane potential?

-70 mV to +30 mV Signup and view all the answers

How can a hypothetical cell be described with respect to equilibrium?

At chemical equilibrium only Signup and view all the answers

What electrical charge would exactly oppose any additional chemical diffusion of an ion into or out of a cell?

-70 mV Signup and view all the answers

What would be the voltage of the membrane potential if it were permeable only to one of the ions?

+80 mV Signup and view all the answers

Which of the following best describes osmolarity?

The expression of the number of osmotically active particles in a solution Signup and view all the answers

What does the term 'hyposmotic' mean in relation to osmolarity?

A solution with a lower osmolarity compared to another solution Signup and view all the answers

In which fluid compartment do solutes experience chemical and electrical disequilibrium?

Intracellular compartment Signup and view all the answers

What does osmosis primarily involve?

The movement of water across a membrane in response to a solute concentration gradient Signup and view all the answers

What is the mechanism by which membranes transport fluids within fluid compartments?

Bulk flow Signup and view all the answers

Which statement best describes the basic principle of diffusion?

Net movement from high concentration to low concentration Signup and view all the answers

In the context of diffusion, what is Fick's Law primarily concerned with?

Concentration gradients Signup and view all the answers

Which type of molecules will most easily diffuse across a cell membrane?

Hydrophobic molecules Signup and view all the answers

What is the primary function of channel proteins in the cell membrane?

Controlled and selective passage of substances Signup and view all the answers

What distinguishes carrier proteins from channel proteins in terms of their function?

They change conformation to move molecules across the membrane Signup and view all the answers

'Secondary active transport' makes use of which gradient for transportation?

Sodium gradient established by the NKA Signup and view all the answers

In the context of equilibrium, what does it mean for a cell to be 'polarized'?

At electrical equilibrium but not chemical equilibrium Signup and view all the answers

What would be the voltage of the membrane potential if it were permeable only to one of the ions?

The voltage would equal to potassium's equilibrium potential (EK) Signup and view all the answers

What does the Nernst equation calculate?

The equilibrium potential for specific ions Signup and view all the answers

What determines tonicity in a solution?

The concentration of nonpenetrating solutes in each compartment Signup and view all the answers

Study Notes

Cell Membrane Transport

Osmosis is the process that involves the movement of water across a membrane.
Osmolarity expresses the concentration of solutes in a solution.
Solutes experience chemical and electrical disequilibrium in the intracellular fluid (ICF) compartment.

Diffusion

The rate of diffusion is influenced by factors such as temperature, concentration gradient, and surface area.
Non-polar, small molecules can most easily diffuse across a cell membrane.
Fick's Law is primarily concerned with the rate of diffusion.

Carrier and Channel Proteins

Carrier proteins transport molecules across the cell membrane by binding to them and changing their conformation.
The primary function of channel proteins is to form a hydrophilic pore in the cell membrane, allowing ions to diffuse through.
Carrier proteins are distinguished from channel proteins by their ability to change conformation and bind to molecules.

Active Transport

Secondary active transport makes use of the electrochemical gradient for transportation.

Membrane Potential

The Nernst equation calculates the equilibrium potential of an ion.
The actual resting membrane potential of a cell is determined by the balance of ions on both sides of the membrane.
'Polarized' refers to a membrane potential that is more negative than the resting potential.
'Depolarization' refers to a membrane potential that is more positive than the resting potential.
A hypothetical cell can be described as being in equilibrium when there is no net movement of ions across the membrane.
The voltage of the membrane potential if it were permeable only to one of the ions would be the equilibrium potential of that ion.

Osmolarity and Tonicity

Osmolarity is a measure of the concentration of solutes in a solution.
'Hyposmotic' means a solution with a lower osmolarity than the cell.
Tonicity is determined by the osmolarity of a solution.
A solution with a higher osmolarity than the cell is hypertonic, while a solution with a lower osmolarity is hypotonic.