Propagation of Action Potentials
Sodium Channels: New sodium channels open in the neuron.
Potassium Channels: After sodium channels, new potassium channels open followed by the closing of sodium channels.
Function: This process propagates the action potential along the axon to transmit information effectively to another cell.
Example: This process helps athletes, like baseball players, to react quickly, allowing for split-second reaction times.
Speed of Nerve Impulses
Nerve impulses can travel quickly across nerve fibers due to the action potentials.
Sodium-Potassium Pump: An essential factor, this pump restores resting potential by maintaining the balance of sodium and potassium ions.
ATP Consumption: The nervous system uses a significant amount of ATP to maintain this balance, more than any other organ.
Nervous System Functionality
Neurons are always prepared to send signals; maintaining a positive charge outside the cell and a negative charge inside is crucial.
Implications of Imbalance: Any imbalance in ion concentrations could lead to severe consequences for nerve function.
Endocytosis
Definition: A process where cells bring substances into the cytoplasm.
Types of Endocytosis:
Phagocytosis: The process of engulfing large particles such as bacteria or debris into a vesicle.
White blood cells utilize this to consume invading bacteria and dead cells.
Pinocytosis: The process of engulfing small particles, fluids, and molecules.
When cells encounter a large concentration of molecules, the membrane folds inward to form a vesicle with these substances.
Exocytosis
Definition: The process by which cells expel materials from the cytoplasm outside the cell.
Process: Expulsion of substances such as certain hormones (e.g., estrogen, ADH) through vesicles merging with the membrane.
Goblet Cells
Function: Produces mucus which is made of mucin and attracts water to create a viscous substance.
Mucus Composition: It is a protein suspended in water that plays essential roles in protection and lubrication in various tissues.
Examples: Dry nasal mucus (boogers) is the result of water evaporation from the mucus.