Membranes
The plasma membrane forms a semipermeable barrier between the cytoplasm and the exterior of the cell. Movement of materials across the plasma membrane can occur by: (1) simple diffusion for lipid soluble and small uncharged molecules; (2) active or passive transport via membrane transport proteins; and (3) vesicular transport (endocytosis and exocytosis), which involves the fusion and formation of small vesicles at the membrane (seen here). Capillary endothelial cell 40,000x
Endothelial cell >
Capillaries are the smallest blood vessels and are composed of a simple squamous epithelium, called endothelium, and its basal lamina. Metabolites, wastes and gases are exchanged between the capillary lumen and extravascular tissues.
- Basal lamina
Capillaries are the smallest blood vessels and are composed of a simple squamous epithelium, called endothelium, and its basal lamina. Metabolites, wastes and gases are exchanged between the capillary lumen and extravascular tissues.
- Plasma membrane
Capillaries are the smallest blood vessels and are composed of a simple squamous epithelium, called endothelium, and its basal lamina. Metabolites, wastes and gases are exchanged between the capillary lumen and extravascular tissues.
- Vesicles >
Vesicles are membrane-bound sacs that either form from the plasma membrane to bring materials into a cell or fuse with the plasma membrane to release materials from the cell. In addition to this transcellular transport, vesicles also provide transport between cellular organelles.
Endocytosis >
The internalization of material occurs by a process called endocytosis, by which the plasma membrane folds inwards, capturing extracellular material in a single, membrane-bound structure called a vesicle. The vesicle and its contents are transported into the cell. Endocytosis can occur by a receptor-mediated mechanism or by a nonselective process called pinocytosis.
Exocytosis >
The release of material from a cell (e.g., glandular secretion or transport across an epithelium, as here) occurs by exocytosis, by which vesicles migrate to the cell surface, fuse with the plasma membrane and release their contents to the exterior. In addition to the movement of materials, endocytosis and exocytosis are the means by which the cell recycles its plasma membrane.
Loose connective tissue
The release of material from a cell (e.g., glandular secretion or transport across an epithelium, as here) occurs by exocytosis by which vesicles migrate to the cell surface, fuse with the plasma membrane and release their contents to the exterior. In addition to the movement of materials, endocytosis and exocytosis are the means by which the cell recycles its plasma membrane.
Capillary lumen
The release of material from a cell (e.g., glandular secretion or transport across an epithelium, as here) occurs by exocytosis by which vesicles migrate to the cell surface, fuse with the plasma membrane and release their contents to the exterior. In addition to the movement of materials, endocytosis and exocytosis are the means by which the cell recycles its plasma membrane.
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