Nervous system longer version

• What are the two types of cells in nervous tissue?

  Neurons and neuroglia
• What is the primary function of neurons?

  To provide most functions of the nervous system, including sensing and controlling muscle activity
• Can most neurons undergo mitotic division?

  No, most cannot undergo mitotic division
• How do neuroglia differ from neurons in terms of their quantity?

  Neuroglia outnumber neurons by approximately 25 times
• What are the functions of neuroglia?

  Support, nourish, and protect neurons
• What is the ability of neurons to respond to stimuli called?

  Electrical excitability
• What is an action potential?

  An electrical signal that propagates along the surface of the neuron membrane
• What are the three parts of a neuron?

  Cell body, dendrites, and axons
• What is the function of the cell body of a neuron?

  Contains the nucleus and typical cellular organelles
• What are Nissl bodies?

  Sites of protein synthesis in the neuron
• What is the role of neurofibrils in neurons?

  Provide shape and support to the neuron
• What is the function of dendrites?

  Receiving or input portion of the neuron
• How do dendritic spines function?

  They serve as receptor sites for chemical messengers from other neurons
• How many axons do neurons typically have?

  One axon
• What is the axon hillock?

  The cone-shaped junction of the cell body and axon
• What is the function of axon terminals?

  They are fine divisions of the axons that communicate with other neurons or effector cells
• What is a synapse?

  Communication between two neurons or a neuron and an effector cell
• What are synaptic vesicles?

  Membrane-enclosed sacs that contain neurotransmitters
• What is the difference between slow and fast axonal transport?

  Slow transport moves materials at 1-5 mm per day, while fast transport moves materials at 200-400 mm per day
• What are the three types of structural classification of neurons?

  Multipolar, bipolar, and pseudounipolar neurons
• Where are multipolar neurons primarily found?

  In the brain and spinal cord
• What is the function of sensory neurons?

  To carry nerve impulses from sensory receptors to the CNS
• What are gliomas?

  Brain tumors derived from glia
• What is the role of astrocytes in the CNS?

  Support neurons and maintain the blood-brain barrier
• What do oligodendrocytes do?

  Form myelin sheaths around CNS axons
• What is the function of Schwann cells?

  Form the myelin sheath around axons in the PNS
• What is myelination?

  The process of forming a myelin sheath around axons
• How does myelination affect nerve impulse conduction?

  It electrically insulates the axon, increasing the speed of conduction
• What are graded potentials?

  Short distance electrical signals that can vary in amplitude
• What is the resting membrane potential (RMP)?

  The electrical potential difference across the plasma membrane of a resting neuron
• What factors determine the resting membrane potential?

  Unequal distribution of ions, inability of ions to leave the cell, and the Na+/K+ ATPase activity
• What is the all-or-none principle in action potentials?

  An action potential occurs completely or not at all in response to a stimulus
• What is the refractory period?

  The time during which a second nerve impulse cannot be initiated
• How does saltatory conduction differ from continuous conduction?

  Saltatory conduction occurs in myelinated axons and is faster than continuous conduction in unmyelinated axons
• What factors affect the speed of action potential propagation?

  Amount of myelination, axon diameter, and temperature
• What are the key differences between graded potentials and action potentials?

  Graded Potentials:

  • Arise mainly at dendrites and cell bodies
  • Decremental conduction
  • Amplitude varies with stimulus strength
  • No refractory period

  
  

  Action Potentials:

  • Arise at trigger zones and propagate along axons
  • Non-decremental conduction
  • Consistent amplitude
  • Present refractory period
• What are the functions of the different types of neuroglia in the CNS?

  • Astrocytes: Support neurons, maintain blood-brain barrier
  • Oligodendrocytes: Form myelin sheaths around axons
  • Microglial cells: Act as phagocytes to remove debris
  • Ependymal cells: Produce cerebrospinal fluid
• What are the functions of the different types of neurons?

  • Sensory neurons: Carry impulses to the CNS
  • Motor neurons: Carry impulses away from the CNS to effectors
  • Interneurons: Process information within the CNS
• What is the process of myelination in the PNS and CNS?

  PNS:

  • Schwann cells form myelin sheath around single axons
  • Can surround multiple nonmyelinated axons

  
  

  CNS:

  • Oligodendrocytes myelinate multiple axons
  • Myelin sheath gaps present
• What are the phases of an action potential?

  1. Depolarizing phase: Membrane potential becomes less negative
  2. Repolarizing phase: Membrane potential returns to resting state
  3. After-hyperpolarizing phase: Membrane potential becomes more negative than resting level