pt 2

• What are the two kinds of cells in the human nervous system?

  • Neurons
  • Glia
• Approximately how many individual neurons are in the human brain?

  100 billion
• What does behavior depend upon in the nervous system?

  Communication between neurons
• What are the three basic subdivisions of neurons?

  1. Dendrites: Gather information from other neurons
  2. Cell Body or Soma: Integrates the information
  3. Axon: Carries information to be passed on to other cells
• What type of neurons bring information to the central nervous system?

  Sensory neurons
• What is the role of interneurons in the central nervous system?

  Associate sensory and motor activity
• What do motor neurons do?

  Send signals from the brain and spinal cord to muscles
• How does the appearance of a neuron relate to its connections?

  • Neurons with large cell bodies have long extensions
  • Neurons with small cell bodies have short extensions
• What do neurons receive every second?

  Thousands of excitatory and inhibitory signals
• How do neurons respond to the signals they receive?

  They sum the signals and decide to send a message or not
• What is the significance of the "1-0" language of neurons?

  • "1": Sending a message to downstream neurons
  • "0": Not sending any message downstream
  • Enables enormous possibilities for behavior
• What is the resting membrane potential?

  The electrical charge across the cell membrane in the absence of stimulation
• What is the resting membrane potential value relative to the extracellular side?

  −70 millivolts
• Which charged particles contribute to the resting membrane potential?

  • Sodium (Na⁺): Higher concentration outside cell
  • Chloride (Cl⁻): Higher concentration outside cell
  • Potassium (K⁺): Higher concentration inside cell
  • Large proteins (A⁻): Higher concentration inside cell
• What happens to voltage-gated Na⁺ channels at -70 mV?

  They are closed
• What do passive K⁺ channels allow?

  K⁺ to move into and out of the cell more freely
• What is hyperpolarization?

  An increase in electrical charge across a membrane (more negative)
• What is depolarization?

  A decrease in electrical charge across a membrane (more positive)
• What is the difference between graded potential and action potential?

  • Graded Potential: Varies in magnitude, can be hyperpolarizing or depolarizing
  • Action Potential: Large, brief reversal in polarity, all-or-none response
• What happens during an action potential?

  The voltage across the membrane suddenly reverses
• What is the threshold potential for triggering an action potential?

  Approximately −40 mV
• What is the purpose of the Na⁺–K⁺ pump?

  To maintain the Na⁺/K⁺ gradient
• What are the phases of an action potential?

  1. Na⁺ entry makes intracellular side positive
  2. K⁺ exit restores resting potential
• What is the distinction between inside and outside the cell regarding ion concentrations?

  • Inside: Higher concentration of K⁺ and large proteins (A⁻)
  • Outside: Higher concentration of Na⁺ and Cl⁻
• What are the key concepts to remember about resting membrane potential and graded potentials?

  • Resting Membrane Potential: Na⁺ outside, K⁺ inside
  • Graded Potential: Preparation for action potential, can be hyperpolarizing or depolarizing
  • Action Potential: All-or-none response
• What are the important concepts to learn regarding ion movement?

  • Ion movement at resting membrane potential (RMP)
  • Ion movement for changes in membrane potential
  • Differences between graded potential and action potential
  • Mechanisms of ligand-gated vs. voltage-gated channels
• What are the differences between passive ion channels, ligand-gated channels, and voltage-gated channels?

  • Passive Ion Channels: Allow free movement of ions
  • Ligand-Gated Channels: Open in response to specific chemicals
  • Voltage-Gated Channels: Open in response to changes in membrane potential