Term
Extracellular Fluid (ECF) Nutrient Levels |
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Definition
- Sodium (Na+)= 142
- Potassium (K+)= 4.2
- Calcium (Ca+2)= 1.2
- Glucose= 85 mg/dl
- pH= 7.4
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Term
Intracellular Fluid Nutrient Levels |
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Definition
- Sodium (Na+)= 10
- Potassium (K+)= 140
- Calcium (Ca+2)= .0001
- Glucose = 0-20 mg/dl
- pH= 7.0
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Term
Mechanisms of Solute Movement Through The Cell Membrane |
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Definition
1) Simple Diffusion
2) Facilitated Diffusion
3) Active Transport
a. primary active transport
b. secondary active transport |
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Term
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Definition
•Net movement of solutes through the cell membrane down their concentration gradients, so no energy requirement
•No carrier proteins are required
•Lipid soluble substances easily cross the plasma membrane (O2, N2, CO2, ETOH )
•Most other small lipid insoluble molecules such as water move through transmembrane protein pores (passive transport)
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Term
Factors Influencing Diffusion |
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Definition
1. Membrane Permeability (P)
2.Concentration Difference across the membrane
3.Pressure difference across the membrane
4. Effect of Electrical Potential
Nernst Equation
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Term
Factors Affecting Membrane Permeability |
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Definition
1)Thickness of the membrane
2)Lipid solubility of the substance diffusing
3)Number of protein channels available for passage
4)Molecular size of the diffusing substance
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Term
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Definition
•Active Transport is carrier-facilitated to move substances against their concentration gradient
•Allows for the concentration of certain solutes inside the cell even if external concentrations are quite low, and vice versa
•It requires energy – direct cleavage of ATP or other high-energy phosphate compound on the carrier protein
•Saturation of carrier occurs, same as in facilitated diffusion
•Prototype example is Na+/K+ “pump”
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Term
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Definition
•Present in all cells in the body
•Has three internal binding sites for Na+ and two external sites for K+ (2 K+ move in, 3 Na+ move out)
•Electrogenic pump (3 + out, 2 + in)
•Maintains the plasma membrane resting potential
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Term
Secondary Active Transport |
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Definition
•Utilization of ion gradients generated by 1° active transport to move a second solute against its concentration gradient
•Examples include: Na+/ glucose co-transporter, Na+/ amino acid co-transporter, Na+/Ca2+ counter-transporter, Na+/H+ counter-transporter
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Term
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Definition
•Process of water moving from a high concentration to a low concentration through a semi-permeable membrane
•Water equilibrates across the membrane moving to regions where solute concentration is higher
•Net movement of water into or out of a cell can cause the cell to shrink or swell
•Can create pressure differences if solutes are trapped on one side of a membrane (osmotic pressure)
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