Transport Across Cell Membranes

Solutes are substances that are dissolved in a solvent, typically water. Examples include Na+ (sodium ions) and glucose.

Solute transport is crucial for absorbing oxygen for respiration and nutrients from the gut. It also helps maintain and change membrane potential.

Passive transport is the movement of substances across a cell membrane without energy input, whereas active transport requires energy to move substances against their electrochemical gradient.

<p>Carrier proteins facilitate the movement of specific molecules across cell membranes, either passively or actively depending on the transport type.</p> Signup and view all the answers

<p>The Resting Membrane Potential (RMP) of a typical cell is approximately -70 mV.</p> Signup and view all the answers

<p>Permeability refers to the ability of a membrane to allow substances to pass through it, influenced by factors such as membrane composition and size of molecules.</p> Signup and view all the answers

<p>Osmotic fragility refers to the susceptibility of red blood cells to hemolysis when exposed to hypotonic solutions, which can lead to cell lysis.</p> Signup and view all the answers

<p>The electrochemical gradient is the difference in ion concentration and charge across a membrane, crucial for driving processes like nerve signaling and muscle contractions.</p> Signup and view all the answers

<p>The rate of diffusion will also equal 0.</p> Signup and view all the answers

<p>Nerve impulses are transmitted via action potentials and neurotransmitter release.</p> Signup and view all the answers

<p>The diffusion time is 0.05 seconds.</p> Signup and view all the answers

<p>Diffusion is affected by membrane permeability, electrochemical gradients, and distance.</p> Signup and view all the answers

<p>Fick’s law describes the rate of diffusion based on concentration gradients.</p> Signup and view all the answers

<p>The RMP influences ion movement based on electrochemical gradients.</p> Signup and view all the answers

<p>Diffusion is rapid over short distances but becomes slow as distances increase.</p> Signup and view all the answers

<p>The time required is 500,000,000 seconds, or approximately 15 years.</p> Signup and view all the answers

<p>Passive transport does not require energy, while active transport does.</p> Signup and view all the answers

<p>They regulate the movement of ions and molecules into and out of cells.</p> Signup and view all the answers

<p>Isosmotic solutions have the same osmolarity as the cell's interior, but isotonic solutions do not allow solutes to cross the membrane. If a solute can cross the membrane, as with urea, the solution is isosmotic but not isotonic.</p> Signup and view all the answers

<p>RBC will take up water and potentially explode due to osmotic lysis as urea crosses the membrane, increasing the osmolarity inside the cell to 420 mOsm. The initial isosmotic condition becomes problematic because urea can penetrate the membrane.</p> Signup and view all the answers

<p>RBCs without urea transporters are resistant to lysis in high urea concentrations, such as 2 M urea, because urea cannot cross the membrane. This resistance protects them from osmotic swelling and bursting.</p> Signup and view all the answers

<p>Passive transport is the movement of solutes across a membrane without energy input, such as the diffusion of urea into RBCs. This process occurs down the concentration gradient until equilibrium is reached.</p> Signup and view all the answers

<p>The Resting Membrane Potential (RMP) of cells is typically around -70 mV, which is crucial for maintaining the cell's potential to perform functions like electrical signaling and muscle contraction. It reflects the balance of ions across the membrane.</p> Signup and view all the answers

<p>Lipid membranes selectively allow glucose to cross from the intestine into the blood and then from blood into muscle cells.</p> Signup and view all the answers

<p>The Resting Membrane Potential of -70 mV establishes an electrochemical gradient that influences the movement of ions and other substances across the membrane.</p> Signup and view all the answers

<p>Passive transport occurs without energy expenditure, relying on concentration gradients, whereas active transport requires energy to move substances against their gradients.</p> Signup and view all the answers

<p>Electrochemical gradients create a 'force' that drives substances to move from areas of high concentration to low concentration, facilitating their transport.</p> Signup and view all the answers

<p>Osmotic fragility indicates how red blood cells respond to changes in osmotic pressure, which is crucial for understanding their integrity during transport.</p> Signup and view all the answers

<p>Multiple intracellular membranes require molecules to cross various barriers, which complicates the transport of ions and molecules between organelles.</p> Signup and view all the answers

<p>The two main factors are membrane permeability and the electrochemical gradient acting on the substance.</p> Signup and view all the answers

<p>Substances naturally move from areas of high concentration to areas of low concentration, following the principle of diffusion.</p> Signup and view all the answers

<p>Interstitial space serves as a medium through which solutes must travel between cells, acting as a barrier to transport.</p> Signup and view all the answers

<p>It is crucial for glucose to enter muscle cells to provide the necessary energy for muscular activity and metabolic processes.</p> Signup and view all the answers

<p>Solutes or water cross the lipid bilayer via either passive or active transport mechanisms.</p> Signup and view all the answers

<p>The resting membrane potential (RMP) of a typical cell is about -70 mV.</p> Signup and view all the answers

<p>Isotonic solutions have the same osmolarity, hypotonic solutions have lower osmolarity, and hypertonic solutions have higher osmolarity than the intracellular fluid of red blood cells.</p> Signup and view all the answers

<p>Red blood cells in a hypertonic solution will shrivel up due to water moving out of the cells.</p> Signup and view all the answers

<p>A hypotonic solution causes red blood cells to swell and possibly burst as water moves into them.</p> Signup and view all the answers

<p>Differentiating these solutions is crucial because they have different effects on cell volume and can impact patient health.</p> Signup and view all the answers

<p>A glucose solution can be isosmotic but isotonic if glucose cannot cross the red blood cell membrane.</p> Signup and view all the answers

<p>Isosmotic refers only to osmolarity, while isotonic accounts for the permeability of the cell membrane to specific solutes.</p> Signup and view all the answers

<p>Osmotic fragility refers to the sensitivity of red blood cells to swelling and bursting in hypotonic solutions.</p> Signup and view all the answers