Pinocytosis: Difference between revisions

Latest revision as of 03:51, 13 February 2025

Pinocytosis[edit]

Diagram illustrating the process of pinocytosis

Pinocytosis is a form of endocytosis where a cell engulfs liquid from the surrounding environment. This process is essential for the uptake of extracellular fluids and dissolved substances, allowing cells to sample the extracellular environment and take in nutrients.

Mechanism[edit]

Pinocytosis involves the invagination of the cell membrane to form a pocket that encloses the extracellular fluid. This pocket then pinches off to form a vesicle within the cytoplasm. The vesicle, known as a pinosome, contains the ingested fluid and any dissolved solutes.

The process of pinocytosis can be divided into several steps:

Initiation: The cell membrane begins to invaginate, forming a small pocket.
Engulfment: The pocket deepens and encloses the extracellular fluid.
Vesicle Formation: The pocket pinches off from the membrane, forming a vesicle within the cell.
Vesicle Fusion: The vesicle may fuse with lysosomes for digestion of its contents.

Types of Pinocytosis[edit]

Pinocytosis can be classified into two main types:

Macropinocytosis: This involves the formation of large vesicles and is often triggered by growth factors. It is a non-specific form of endocytosis.
Micropinocytosis: This involves the formation of smaller vesicles and can be receptor-mediated, allowing for more specific uptake of substances.

Biological Significance[edit]

Pinocytosis plays a crucial role in nutrient absorption, particularly in cells lining the intestine and kidney tubules. It also allows cells to regulate their internal environment by sampling the extracellular fluid.

In the immune system, pinocytosis is important for the uptake of antigens by antigen-presenting cells, which is essential for the initiation of an immune response.

Related pages[edit]

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-'''Pinocytosis''' is a form of [[Endocytosis|endocytosis]], a process by which cells absorb molecules (such as proteins) from outside the cell by engulfing it with their cell membrane. It is a type of [[Phagocytosis|phagocytosis]] that involves the intake of liquid into a cell via vesicles that are formed from the [[Cell membrane|cell membrane]].
+== Pinocytosis ==
-== Process ==
+[[File:Pinocytosis.svg|thumb|right|Diagram illustrating the process of pinocytosis]]
-Pinocytosis is primarily used for the intake of extracellular fluids (ECF), and not for the intake of larger particles. The process involves the invagination of the cell membrane around the desired fluid or solute, forming a small vesicle. The vesicle then travels into the cell and fuses with endosomes and lysosomes to break down the contents.
-== Types ==
+'''Pinocytosis''' is a form of [[endocytosis]] where a cell engulfs liquid from the surrounding environment. This process is essential for the uptake of extracellular fluids and dissolved substances, allowing cells to sample the extracellular environment and take in nutrients.
-There are two types of pinocytosis: fluid-phase (non-specific) and adsorptive (specific).
-* '''Fluid-phase pinocytosis''' is when the cell engulfs some of its extracellular fluid (ECF) containing dissolved substances, and is also known as "cell drinking".
+=== Mechanism ===
-* '''Adsorptive pinocytosis''' is when the cell intakes extracellular fluids through the use of specific binding proteins on the cell membrane.
+Pinocytosis involves the invagination of the cell membrane to form a pocket that encloses the extracellular fluid. This pocket then pinches off to form a vesicle within the cytoplasm. The vesicle, known as a [[pinosome]], contains the ingested fluid and any dissolved solutes.
-== Role in disease ==
+The process of pinocytosis can be divided into several steps:
-Pinocytosis plays a role in many diseases, including [[Cancer|cancer]], [[Atherosclerosis|atherosclerosis]], and [[Alzheimer's disease|Alzheimer's]]. In cancer, pinocytosis can be used by tumor cells to intake nutrients from the extracellular fluid, allowing them to grow and multiply. In atherosclerosis, pinocytosis is used by cells in the artery wall to intake lipoproteins, leading to plaque formation. In Alzheimer's, pinocytosis is thought to be involved in the formation of amyloid plaques.
-== See also ==
+# '''Initiation''': The cell membrane begins to invaginate, forming a small pocket.
+# '''Engulfment''': The pocket deepens and encloses the extracellular fluid.
+# '''Vesicle Formation''': The pocket pinches off from the membrane, forming a vesicle within the cell.
+# '''Vesicle Fusion''': The vesicle may fuse with [[lysosomes]] for digestion of its contents.
+=== Types of Pinocytosis ===
+Pinocytosis can be classified into two main types:
+* '''Macropinocytosis''': This involves the formation of large vesicles and is often triggered by growth factors. It is a non-specific form of endocytosis.
+* '''Micropinocytosis''': This involves the formation of smaller vesicles and can be receptor-mediated, allowing for more specific uptake of substances.
+=== Biological Significance ===
+Pinocytosis plays a crucial role in nutrient absorption, particularly in cells lining the [[intestine]] and [[kidney]] tubules. It also allows cells to regulate their internal environment by sampling the extracellular fluid.
+In the immune system, pinocytosis is important for the uptake of antigens by [[antigen-presenting cells]], which is essential for the initiation of an immune response.
+== Related pages ==
 * [[Endocytosis]]
 * [[Phagocytosis]]
 * [[Exocytosis]]
 * [[Cell membrane]]
+* [[Lysosome]]
 [[Category:Cell biology]]
-[[Category:Membrane biology]]
-[[Category:Cellular processes]]
-{{stub}}