cerebrospinal fluid

Examples of cerebrospinal fluid in the following topics:

• Glia

  • They provide nutrients and other substances to neurons, regulate the concentrations of ions and chemicals in the extracellular fluid, and provide structural support for synapses.
  • Ependymal cells line fluid-filled ventricles of the brain and the central canal of the spinal cord.
  • They are involved in the production of cerebrospinal fluid, which serves as a cushion for the brain, moves the fluid between the spinal cord and the brain, and is a component for the choroid plexus.
  • Ependymal cells produce cerebrospinal fluid that cushions the neurons.

• Animal Body Planes and Cavities

  • The brain and spinal cord are protected by the bones of the skull and vertebral column and by cerebrospinal fluid, a colorless fluid produced by the brain, which cushions the brain and spinal cord within the posterior (dorsal) cavity.

• The Nervous System

  • The space between the arachnoid and pia maters is filled with cerebrospinal fluid (CSF).
  • CSF is produced by a tissue called the choroid plexus in fluid-filled compartments in the CNS called ventricles.

• Fluid Mosaic Model

  • The fluid mosaic model describes the plasma membrane structure as a mosaic of phospholipids, cholesterol, proteins, and carbohydrates.
  • The fluid mosaic model was first proposed by S.J.
  • The fluid mosaic model describes the structure of the plasma membrane as a mosaic of components —including phospholipids, cholesterol, proteins, and carbohydrates—that gives the membrane a fluid character .
  • Therefore, phospholipids form an excellent lipid bilayer cell membrane that separates fluid within the cell from the fluid outside of the cell.
  • The fluid mosaic model of the plasma membrane describes the plasma membrane as a fluid combination of phospholipids, cholesterol, and proteins.

• Introduction to Osmoregulation

  • The intake is balanced by more or less equal excretion of fluids by urination, defecation, sweating, and, to a lesser extent, respiration.
  • The solutes in body fluids are mainly mineral salts and sugars.
  • The body's fluids include blood plasma, the cytosol within cells, and interstitial fluid, the fluid that exists in the spaces between cells and tissues of the body.
  • Mammalian systems have evolved to regulate osmotic pressure by managing concentrations of electrolytes found in the three major fluids: blood plasma, extracellular fluid, and intracellular fluid.
  • Water movement due to osmotic pressure across membranes may change the volume of these fluid compartments.

• Tonicity

  • Three terms—hypotonic, isotonic, and hypertonic—are used to relate the osmolarity of a cell to the osmolarity of the extracellular fluid that contains the cells .
  • In a hypotonic situation, the extracellular fluid has lower osmolarity than the fluid inside the cell, and water enters the cell.
  • (In living systems, the point of reference is always the cytoplasm, so the prefix hypo- means that the extracellular fluid has a lower concentration of solutes, or a lower osmolarity, than the cell cytoplasm. ) It also means that the extracellular fluid has a higher concentration of water in the solution than does the cell.
  • As for a hypertonic solution, the prefix hyper- refers to the extracellular fluid having a higher osmolarity than the cell's cytoplasm; therefore, the fluid contains less water than the cell does.
  • In an isotonic solution, the extracellular fluid has the same osmolarity as the cell.

• Membrane Fluidity

  • First, the mosaic characteristic of the membrane helps the plasma membrane remain fluid.
  • A cold environment tends to compress membranes composed largely of saturated fatty acids, making them less fluid and more susceptible to rupturing.
  • In animals, the third factor that keeps the membrane fluid is cholesterol.
  • Cholesterol extends in both directions the range of temperature in which the membrane is appropriately fluid and, consequently, functional.
  • The plasma membrane is a fluid combination of phospholipids, cholesterol, and proteins.

• Endocytosis

  • This literally means "cell drinking" and was named at a time when the assumption was that the cell was purposefully taking in extracellular fluid.
  • In reality, this is a process that takes in molecules, including water, which the cell needs from the extracellular fluid.
  • If uptake of a compound is dependent on receptor-mediated endocytosis and the process is ineffective, the material will not be removed from the tissue fluids or blood.
  • Instead, it will stay in those fluids and increase in concentration.
  • In pinocytosis, the cell membrane invaginates, surrounds a small volume of fluid, and pinches off.

• Flame Cells of Planaria and Nephridia of Worms

  • The cilia propel waste matter down the tubules and out of the body through excretory pores that open on the body surface; cilia also draw water from the interstitial fluid, allowing for filtration.
  • The ciliated tubules filter fluid from the body cavity and carry waste, including excess ions, through openings called nephrostomes.
  • In (b) annelids, nephridia filter fluid from the body cavity.

• Thyroid Gland

  • These follicles contain a viscous fluid, called colloid, which stores the glycoprotein thyroglobulin.
  • Calcitonin functions to help regulate calcium concentrations in body fluids.
  • The combination of these two events lowers body fluid levels of calcium.