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BMS02-1008 - Movement of Ions and Molecules in the body
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- 1What is the approximate ionic concentration inside living cells vs. Extracellular fluid for Na+, K+, Ca2+, and Cl-?Intracellular/Extracellular
Na+: 10/140
K+140/4
Cl-: 4/140
Ca2+: 10^-3, 2.5 - 2How do the following mass through the cell membrane: 1. Gases 2. Nonpolar/small uncharged polar 3. Ions 4. Larger molecules (eg. glucose)1. Passive diffusion
2. Passive diffusion
3. Via channels/pumps
4. Channels/pumps - 3What are 3 features of the cell membrane?1. Selective barrier (nutrients in, waste out)
2. Phospholipid bilayer
3. Fluid and self-sealing for endo/exocytosis - 4Water soluble is hydro... Water insoluble is hydro...Hydrophilic, polar
Hydrophobic, non polar - 5Simple diffusion (passive down a gradient) can occur through which two ways?1. Direct through membrane
2. Through channels - 6What are the two types of active transport? (moves against gradient)1. Antiport (eg. 3Na+ out /2K+ in ATPase
2. Symport (with a molecule moving passive down its gradient)
(eg. Na+ with sugar/amino acids) - 7How is the osmotic gradient maintained by cells?Na+/K+ pump maintains a much higher extracellular [Na+] compared to intracelluar. The membrane is relatively impermeable to Na+. As a result, if an increase in intracellular concentration arises (due to proteins etc. entering), the Na+ outside allows the osmotic pressure inside and outside to equal, so fluid doesn't move into the cell and cause it to burst.
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- State the approximate ionic concentrations inside living cells and inthe extracellular fluid for Na+, K +, Ca++ and C1 ̄. Explain the mechanism by which gases, ions and larger molecules pass across the cell membrane. Explain why active transport is an energy consuming mechanism whereas simple diffusion and carrier mediated (‘facilitated’) diffusion are not. Explain how animal cells maintain osmotic equilibrium with their environment.
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- Evian Chai
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