contractile vacuole

(noun)

a vacuole that removes waste or excess water

Related Terms

Examples of contractile vacuole in the following topics:

  • Contractile Vacuoles in Microorganisms

    • Contractile vacuoles absorb excess water and wastes from a microorganism's cell and excrete them into the environment by contracting.
    • A contractile vacuole (CV) is an organelle, or sub-cellular structure, that is involved in osmoregulation and waste removal .
    • Previously, a CV was known as a pulsatile or pulsating vacuole.
    • In some unicellular eukaryotic organisms (e.g., amoeba), cellular wastes, such as ammonia and excess water, are excreted by exocytosis as the contractile vacuoles merge with the cell membrane, expelling wastes into the environment.
    • Structure of Euglena: 1 - Flagellum; 2 - Eye spot / Pigment spot / Stigma; 3 - Photoreceptor; 4 - Short second flagellum; 5 - Reservoir; 6 - Basal body; 7 - Contractile vacuole; 8 - Paramylon granule; 9 - Chloroplasts; 10 - Nucleus; 11 - Nucleolus; 12 - Pellicle

  • Osmoregulation

    • For example, paramecia and amoebas, which are protists that lack cell walls, have contractile vacuoles.
    • A paramecium's contractile vacuole, here visualized using bright field light microscopy at 480x magnification, continuously pumps water out of the organism's body to keep it from bursting in a hypotonic medium.

  • Vesicles and Vacuoles

    • Vesicles and vacuoles are membrane-bound sacs that function in storage and transport.
    • Vacuoles are an essential component of plant cells.
    • As the central vacuole shrinks, it leaves the cell wall unsupported.
    • The central vacuole also supports the expansion of the cell.
    • Contractile vacuoles are found in certain protists, especially those in Phylum Ciliophora.

  • Chromalveolata: Alveolates

    • The apicomplexan protists are so named because their microtubules, fibrin, and vacuoles are asymmetrically distributed at one end of the cell in a structure called an apical complex .
    • Food captured in the oral groove enters a food vacuole where it combines with digestive enzymes.
    • In addition to a vacuole-based digestive system, Paramecium also uses contractile vacuoles: osmoregulatory vesicles that fill with water as it enters the cell by osmosis and then contract to squeeze water from the cell.
    • Contractile vacuoles allow the organism to excrete excess water.

  • Freshwater Environments

    • Some protists accomplish this using contractile vacuoles, while freshwater fish excrete excess water via the kidney.

  • Vacuoles

  • Comparing Plant and Animal Cells

    • Plant cells have a cell wall, chloroplasts and other specialized plastids, and a large central vacuole, whereas animal cells do not.
    • In plant cells, the digestive processes take place in vacuoles.
    • The central vacuole plays a key role in regulating the cell's concentration of water in changing environmental conditions.
    • As the central vacuole shrinks, it leaves the cell wall unsupported.
    • The central vacuole also supports the expansion of the cell.

  • Characteristics of Eukaryotic Cells

    • Vesicles and vacuoles are membrane-bound sacs that function in storage and transport.
    • Other than the fact that vacuoles are somewhat larger than vesicles, there is a very subtle distinction between them: the membranes of vesicles can fuse with either the plasma membrane or other membrane systems within the cell.
    • In addition, plant cells have a cell wall, a large central vacuole, chloroplasts, and other specialized plastids, whereas animal cells do not.
    • The cell wall protects the cell, provides structural support, and gives shape to the cell while the central vacuole plays a key role in regulating the cell's concentration of water in changing environmental conditions.
    • Plant cells have a cell wall, chloroplasts, plasmodesmata, and plastids used for storage, and a large central vacuole, whereas animal cells do not.

  • Exercise-Induced Muscle Damage

    • Previously attributed to the accumulation of lactic acid during exercise, it is now understood that DOMS is due to structural damage in sarcomeres, particularly to the z-disks and contractile filaments.
    • Z-disks provide the structural support for the contractile filaments of the sliding filament mechanism.
    • Overloading of muscles damages these connections and the orientation of the contractile filaments .
    • High tension in the contractile-elastic system of muscle results in structural damage to the muscle fiber and plasmalemma and its epimysium, perimysium, and endomysium.

  • Myocardial Thickness and Function

    • The myocardium (cardiac muscle) is the thickest section of the heart wall and contains cardiomyocytes, the contractile cells of the heart.
    • The myocardium, or cardiac muscle, is the thickest section of the heart wall and contains cardiomyocytes, the contractile cells of the heart.
    • Cardiac muscle, like skeletal muscle, is comprised of sarcomeres, the basic, contractile units of muscle.
    • Together, myosin and actin form myofibril filaments, the elongated, contractile threads found in muscle tissue.