Term
| What things are permeable to a membrane? |
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Definition
| O2, CO2, steroids and thyroid hormones |
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Term
| What things are non-permeable to the membrane? |
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Definition
glucose, proteins
ions, amino acids
nucleic acids |
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Term
Simple diffusion
without pores |
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Definition
- diffusion of permeable substances only |
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Term
| Simple diffusion with pores |
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Definition
- Always open (no gate)
- moves down its concentration gradient
- no conformational changes
- no saturation
Ficks law: J (rate of diffusion)
(P)(A)(C1-C2)
- rate is proportional to solute concentration |
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Term
| Simple diffusion with channens |
|
Definition
- Not always open (gated)
- moves down it gradient
- Most are selective
- No saturation
- ion channels regulated by:
-change in voltage, binding of chemical messenger, mechanical forces |
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Term
| Describe facilitated diffusion |
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Definition
- A transporter
- Not always open (molecules bind to carriers)
- There is a conformational change
- Can be saturated
- Move down its gradient w/o ATP
- Rate reaches a maximal flux
- based on how fast & how much |
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Term
| Describe Primary Active Transport |
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Definition
- Transport against a gradient
- energy comes from hydrolysis of ATP or GTP
- Not always open (no true gate)
- solute binds to pump
- undergo a conformational change
- Highly selective
- Can be saturated
ex/ Na/K ATPase (3 Na out and 2 K in) |
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Term
| Describe Secondary Active Transport |
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Definition
- A transporter
- Does not use ATP directly/ use energy from primary transport
- solute travel against gradient
- usually 1 substance moves downhill while another moves uphil
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Term
| Describe a Co-Transporter |
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Definition
-A symporter
- Energy from one gradient drives transport of another molecule
- 2 molecules move in one direction
ex/ Na/glucose, Na/AA, Na/phosphate |
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Term
| Describe a Counter-Transporter |
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Definition
- anti-porter or exchanger
- 2 molecules move in opposite directions
ex/ Na/Ca, Na/H, Na/HCO3, Cl/HCO3 |
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Term
What ions are dominant in
extracellular compartment? |
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Definition
Na, glucose, Cl-, HCO3, Ca |
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Term
What ions are dominant in
the intracellular compartment? |
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Definition
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