The document discusses two types of channels that facilitate water movement across cell membranes: pores and gated channels. Pores are always open and include porins, aquaporins, and nuclear complexes. Gated channels can open or close depending on conditions, with voltage-gated channels responding to the voltage across the cell membrane. For example, voltage-gated calcium channels in the heart open when the membrane reaches a certain depolarization level.

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(LOW TO HIGH)
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- WATER MOVES FROM HIGH TO LOW CONCENTRATIONS
Types:
1). Pores
2). Gated channels

5. 1. Pores
Pore Are always open
Example: Porin, Aquaporin, Nuclear
complex

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2. Gated Channels

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3. Voltage-Gated Channels
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• Open or close depending on voltage across the cell
membrane.
• Example: Voltage-gated calcium channels in the heart
open when the membrane depolarizes to a certain level.