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# Cell and membrane

Homeostasis, compartments, membrane transport and the membrane potential.

14 pages

## Exam priority: high

- [**Body fluid compartments** Concept · About two thirds of the body's water is inside cells and one third outside them, between cells…](https://durgical.com/en/physiology/body-fluid-compartments/)
- [**Homeostasis and feedback control** Concept · The body measures its variables (temperature, glucose, pressure) and corrects them when they…](https://durgical.com/en/physiology/homeostasis-and-feedback-control/)
- [**Membrane transport: diffusion, channels and carriers** Mechanism · Substances cross the cell membrane by dissolving in it, through channels, on carriers, or by…](https://durgical.com/en/physiology/membrane-transport-diffusion-channels-and-carriers/)
- [**Osmosis, osmolarity and tonicity** Concept · Water crosses a membrane towards the side with more dissolved particles; that is how cells swell…](https://durgical.com/en/physiology/osmosis-osmolarity-and-tonicity/)
- [**The resting membrane potential** Mechanism · The inside of a resting cell is negative compared with the outside, mainly because potassium…](https://durgical.com/en/physiology/the-resting-membrane-potential/)

## Exam priority: medium

- [**Cell signaling for physiology** Concept · Hormones and neurotransmitters bind receptors that switch on chains of signals inside the cell](https://durgical.com/en/physiology/cell-signaling-for-physiology/)
- [**Diffusion and Fick's law** Concept · Molecules move from where there are more to where there are fewer; Fick's law says how fast](https://durgical.com/en/physiology/diffusion-and-fick-s-law/)
- [**Ion channels and gating** Concept · Channels are protein pores that open and close to let one specific ion through in microseconds](https://durgical.com/en/physiology/ion-channels-and-gating/)
- [**Primary and secondary active transport** Mechanism · Cells spend energy to move substances against their gradient, using ATP pumps or riding on the…](https://durgical.com/en/physiology/primary-and-secondary-active-transport/)
- [**The Nernst and Goldman equations** Measurement · Two formulas that work out a cell's voltage from the ion concentrations inside and outside it](https://durgical.com/en/physiology/the-nernst-and-goldman-equations/)
- [**Transport across epithelial sheets** Mechanism · Epithelia move salt and water in one direction because their two faces carry different…](https://durgical.com/en/physiology/transport-across-epithelial-sheets/)

## For completeness

- [**Cell movement: ameboid crawling, chemotaxis and ciliary beating** Mechanism · White cells crawl by pushing out a front edge and pulling up the back; cilia beat like oars…](https://durgical.com/en/physiology/cell-movement-ameboid-crawling-chemotaxis-and-ciliary-beating/)
- [**Cell volume regulation** Regulation · Cells guard against swelling or shrinking by moving ions and small molecules out or in, and…](https://durgical.com/en/physiology/cell-volume-regulation/)
- [**Endocytosis, exocytosis and vesicles** Mechanism · Cells wrap particles in little membrane bags to bring them in (endocytosis) or to release their…](https://durgical.com/en/physiology/endocytosis-exocytosis-and-vesicles/)

## A to Z

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- [D](https://durgical.com/en/physiology/a-z/d/)
- [E](https://durgical.com/en/physiology/a-z/e/)
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- [N](https://durgical.com/en/physiology/a-z/n/)
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- [P](https://durgical.com/en/physiology/a-z/p/)
- [R](https://durgical.com/en/physiology/a-z/r/)
- [S](https://durgical.com/en/physiology/a-z/s/)
- [T](https://durgical.com/en/physiology/a-z/t/)
- [U](https://durgical.com/en/physiology/a-z/u/)
- [V](https://durgical.com/en/physiology/a-z/v/)
- [W](https://durgical.com/en/physiology/a-z/w/)

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Educational physiology content; not a diagnostic or treatment guide and no substitute for a health professional's advice. Values are approximate references. No doses are given.

Representative model, for educational purposes only.

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Source: https://durgical.com/en/physiology/areas/cell/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/physiology/areas/cell/