BackAnatomy & Physiology: Cell Structure and Membrane Transport
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Terms in this set (24)
The plasma membrane (outer boundary), cytoplasm (intracellular fluid with organelles), and nucleus (controls cellular activities).
1. Cells are the smallest units of life.
2. All living organisms are composed of one or more cells.
3. New cells come only from pre-existing cells by cell division.
A phospholipid bilayer with embedded proteins and cholesterol, forming a fluid mosaic structure with a carbohydrate-rich glycocalyx on the surface.
It provides identity molecules that help immune cells recognize self from foreign cells and aids in cell-to-cell recognition.
Phospholipids have a polar hydrophilic head facing water and nonpolar hydrophobic tails that face inward, forming a bilayer that acts as a barrier to water-soluble substances.
Integral proteins are embedded and often span the membrane; peripheral proteins attach loosely and may act as enzymes or motor proteins.
1. Transport
2. Receptors
3. Attachment to cytoskeleton and extracellular matrix
4. Enzymatic activity
5. Cell-to-cell joining
6. Cell-cell recognition
Tight junctions prevent passage between cells.
Gap junctions allow molecule passage.
Desmosomes anchor cells and reduce tension.
Movement of substances across the membrane without energy input, including diffusion, facilitated diffusion, osmosis, and filtration.
Passive movement of small, non-charged substances like oxygen and carbon dioxide directly through the phospholipid bilayer down their concentration gradient.
Passive transport of molecules through membrane proteins, either carrier-mediated or channel-mediated, for substances like glucose and ions.
Diffusion of water across a selectively permeable membrane from an area of low solute concentration to high solute concentration until equilibrium.
Tonicity is a solution's ability to change cell shape by altering water volume.
Isotonic: no net water movement.
Hypertonic: cell shrinks.
Hypotonic: cell swells.
Movement of substances across the membrane requiring energy (ATP) to move molecules against their concentration gradient.
It pumps Na+ out of and K+ into the cell, maintaining membrane potential and ion gradients essential for cell function.
Transport of large particles or macromolecules in vesicles via endocytosis (into cell) or exocytosis (out of cell), requiring ATP.
The voltage across the plasma membrane, typically -50 to -100 mV, with the inside of the cell negative relative to outside, maintained by ion gradients and active transport.
Cytosol: fluid medium.
Organelles: specialized structures.
Inclusions: chemical substances that may or may not be present.
Produce ATP, contain their own DNA and ribosomes, can self-replicate, and increase in number by fission to meet energy demands.
Rough ER: synthesizes proteins and membranes.
Smooth ER: metabolizes lipids, detoxifies drugs, stores calcium, and breaks down glycogen.
Modifies, concentrates, and packages proteins and lipids made by the rough ER for export or use in the cell.
Membranous organelles with digestive enzymes that break down ingested particles, worn-out organelles, and perform metabolic functions like glycogen breakdown.
Structures made of microtubule triplets that organize the mitotic spindle during cell division and form the bases of cilia and flagella.
Cilia: move substances across cell surfaces.
Microvilli: increase surface area for absorption, found on intestinal and kidney cells.