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Solutes are substances that are dissolved in water, such as Na+, glucose, vitamins, and drugs.
True
The resting membrane potential (RMP) of a cell is measured at +70 mV.
False
Active transport processes require energy to move substances against their concentration gradient.
True
Passive transport occurs when molecules move from an area of lower concentration to an area of higher concentration without energy input.
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Maintaining membrane potential is crucial for the functioning of all tissues in the body.
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The electrochemical gradient plays no significant role in how substances cross cell membranes.
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Osmotic fragility refers to the resistance of red blood cells to lysis due to osmotic pressure.
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Bio-electric potentials are solely responsible for transporting oxygen during respiration.
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Na+ ions provide energy to move glucose against its concentration gradient using 1˚ active transport.
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Passive transport processes require energy input from ATP.
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The resting membrane potential (RMP) of cells is typically -70 mV.
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Uniporters can transport multiple substances simultaneously.
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Channel proteins are classified as regulated or non-regulated in passive transport mechanisms.
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Antiporters utilize 2˚ active transport to move solutes in opposite directions across the membrane.
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ATP-pumps are a type of passive transporter.
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Osmotic fragility of red blood cells refers to their susceptibility to hemolysis due to osmotic changes.
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Symporters facilitate the movement of solutes in the same direction across the membrane utilizing 1˚ active transport.
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The permeability of the lipid bilayer can affect how solutes or water cross the membrane.
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Uniporters can only transport larger molecules like glucose down a concentration gradient without the formation of a permanent pore.
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The passive transport of ions through channels is always regulated and never non-regulated.
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Active transport always requires an ATP-Pump to function and involves movement against the concentration gradient.
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Antiporters transport two different molecules in the same direction across the membrane.
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Channels are selective for specific ions or substances and can be either gated or constitutive.
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Symporters can transport only one type of molecule at a time, moving it against its concentration gradient.
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Regulated uniporters, such as GluT1, control their activity by being inserted or removed from the cell membrane.
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Channels that are non-regulated maintain a consistent opening at all times.
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The flow of H2O through channels is predominantly active and requires energy input to facilitate transport.
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All types of transporters, whether uniporters, symporters, or antiporters, are classified as active transport mechanisms.
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The concentration of water is defined as 1000g per litre.
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The molarity of H2O is 55.5 moles per litre.
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Water moves from an area of high osmolarity to a region of low osmolarity.
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Infusing 2 litres of water instead of saline can have no significant effects during operations.
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The osmolarity of a solution containing 55.5 moles of H2O with no additional solutes is 100 mOsm.
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In a solution of 140 mM NaCl, the RBC experiences net osmosis.
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Pure water creates an osmotic gradient leading to the explosion of RBCs.
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The intracellular fluid (ICF) of RBCs has an osmolarity of 140 mOsm.
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Sea water has a lower osmolarity than the ICF of RBCs.
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Aquaporins in the RBC membrane facilitate the movement of water by osmosis.
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Water moves spontaneously against its concentration gradient during osmosis.
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In isosmotic conditions, RBCs maintain their normal size and shape.
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Osmosis is defined as the same process as diffusion.
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In solutions that are isosmotic, there is a net movement of water into the RBCs.
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The osmotic fragility of RBCs can be influenced by the surrounding solution's osmolarity.
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Study Notes
Transport Across Cell Membranes
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Solutes cross membranes for various reasons including absorbing oxygen, transporting food through the gut, and maintaining membrane potential.
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Cell membrane permeability determines how easily substances can cross the cell membrane.
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Substances move across cell membranes by passive or active transport.
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Passive transport does not require energy and occurs down concentration gradients.
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Active transport requires energy (ATP) and moves substances against concentration gradients.
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Channels are pores in the membrane that allow specific molecules (e.g., Na+, H2O) to pass through passively.
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Transporters are proteins that bind to specific molecules and move them across the membrane.
- Uniporters move single molecules down their concentration gradient.
- Symporters move two or more molecules in the same direction, at least one of which is moving down its concentration gradient, thus providing energy for the movement of another molecule against its concentration gradient.
- Antiporters move two or more molecules in opposite directions, often utilising the energy from one molecule moving down its concentration gradient to power the movement of the other against its concentration gradient.
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Active transport can be further divided into:
- Primary Active Transport: Directly uses ATP
- Secondary Active Transport: Uses energy indirectly, often utilising the concentration gradient created by primary active transport.
Osmotic Fragility of Red Blood Cells
- Red blood cells have a resting intracellular osmolarity of approximately 280 mOsm.
- Red blood cell membranes contain aquaporins which allow water to move freely across them.
- Isotonic solutions have the same osmolarity as the red blood cells, maintaining their normal size and shape.
- Hypotonic solutions have a lower osmolarity than red blood cells, causing water to move into the cell and potentially leading to cell lysis (bursting).
- Hypertonic solutions have a higher osmolarity than red blood cells, causing water to move out of the cell and potentially leading to crenation (shrinking).
Water Concentration and Osmolarity
- Water concentration is defined as 1000g per litre or 55.5 M (moles per litre).
- Water moves down its concentration gradient, which is the same as saying it moves from an area of low osmolarity to an area of high osmolarity.
- The concentration of water can be changed by adding solutes, which decreases the concentration of water and increases osmolarity.
- Understanding the influence of osmolarity on water movement is vital when administering fluids intravenously. Infusion of pure water can lead to cell lysis due to the rapid movement of water into cells.
Applications of Transport Principles
- Understanding transport processes across cell membranes is essential for understanding how all tissues function.
- This knowledge is vital for the safe administration of drugs, intravenous fluids, and other medical interventions.
- The incorrect administration of medical solutions can have serious consequences for patients.
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Description
Explore the mechanisms of transport across cell membranes, including passive and active transport. Understand the roles of channels and transporters in facilitating solute movement. This quiz covers essential concepts related to membrane permeability and transport dynamics.
