nervous system

• What are the main functions of the nervous system summarized by the acronym CRIME?


  Controlling muscles and glands, Receiving sensory input, Integrating information, Maintaining homeostasis, Establishing and maintaining mental activity
• What is the role of sensory receptors in the nervous system?


  They receive external stimuli from outside the body.
• Where does the integration of information occur in the nervous system?


  In the brain and spinal cord.
• What are the two main divisions of the nervous system?

  Central Nervous System and Peripheral Nervous System.
• What are the components of the Central Nervous System (CNS)?


  • Brain
  • Spinal cord
• What are the components of the Peripheral Nervous System (PNS)?


  • Nerves
  • Ganglia
• What is the function of the sensory division of the Peripheral Nervous System?


  It conducts action potentials from sensory receptors to the CNS.
• What type of neurons transmit action potentials from the periphery to the CNS?


  Sensory neurons.
• What do somatic sensory fibers carry information from?


  Stimuli coming from the skin, skeletal muscles, and joints.
• What do visceral sensory fibers transmit impulses from?


  Visceral organs.
• What is the function of the motor division of the Peripheral Nervous System?


  It conducts action potentials from the CNS to effector organs.
• What is the difference between the somatic motor nervous system and the autonomic motor nervous system?


  The somatic motor nervous system is voluntary, while the autonomic motor nervous system is involuntary.
• What is the sympathetic nervous system responsible for?


  Fight-or-flight responses.
• What is the parasympathetic nervous system responsible for?


  Resting and digesting responses.
• What is unique about the enteric nervous system?


  It contains both sensory and motor neurons within the digestive tract and can function independently.
• What are neurons also called?


  Nerve cells.
• What is the function of dendrites in a neuron?


  They receive information from other neurons and transmit it toward the cell body.
• What is the role of the axon in a neuron?


  It conducts sensory signals to the CNS and transmits action potentials from one part of the brain or spinal cord to another.
• What are neuroglia also known as?


  Glial cells or nerve glue.
• What is the primary function of neuroglia?


  To support neurons and maintain normal conditions within nervous tissue.
• Which type of glial cell is responsible for forming the blood-brain barrier?


  Astrocytes.
• What is the function of ependymal cells?


  They produce cerebrospinal fluid and help move it through the CNS.
• What do microglia act as in the CNS?


  Immune cells that protect the brain by removing bacteria and cell debris.
• What is the role of oligodendrocytes in the CNS?


  They provide insulating material that surrounds axons, known as myelin.
• What do Schwann cells provide in the PNS?


  Myelin to neurons.
• What are the steps involved in neural signaling?


  1. Reception: stimuli received by visual receptors.
  2. Transmission: sensory neurons transmit info to CNS.
  3. Integration: info is interpreted and a response is determined.
  4. Transmission: CNS transmits info to motor neurons.
  5. Actual response: muscles/glands receive info and instructions.
• What is the function of myelin sheaths?


  They prevent almost all ion movement across the cell membrane and increase the speed of action potential generation along axons.
• What happens to action potentials in unmyelinated axons?


  They are conducted slowly as they travel along the entire axon.
• What is multiple sclerosis?


  A disease of the myelin sheath that causes loss of muscle function due to autoimmune attacks on axons.
• What are nodes of Ranvier?


  Gaps in the myelin sheath where ion movement can occur.
• What is the organization of nervous tissue based on?


  • Arrangement and location of neurons and glial cells
  • Presence of myelinated sheaths
• What is gray matter composed of?


  Groups of neuron cell bodies and their dendrites with very little myelin.
• What are leak channels in the membrane?


  Channels that are always open and allow ions to pass through.
• What is the primary function of gated channels?


  They remain closed until opened by specific signals.
• What triggers the opening of chemically gated channels?


  Neurotransmitters binding to receptors.
• What initiates an action potential?


  A change in membrane potential due to the rapid opening of voltage-gated sodium channels.
• What occurs during depolarization?


  The inside of the cell becomes more positive as sodium ions rush in.
• What happens during repolarization?


  Potassium channels open, allowing K⁺ to leave the cell, restoring negativity.
• What is hyperpolarization?


  When the inside of the cell becomes more negative than the resting membrane potential.
• What are the steps of action potential generation and propagation?


  1. Resting State: Leak channels are open; inside is negative.
  2. Stimulus: A neurotransmitter triggers sodium channels to open.
  3. Sodium Influx: Sodium rushes in, causing depolarization.
  4. Repolarization: Sodium channels close; potassium channels open.
  5. Restoration: Sodium-potassium pump restores resting membrane potential.