neuroscience

• What are neurons considered in the nervous system?

  Fundamental building blocks
• What do neurons transmit?

  Nerve impulses or action potential

  
• How does the action potential flow in a neuron?

  From the dendrites, through the cell body, to the axon

  
• What is the action potential in neurons?

  A rapid, temporary electrical signal

  
• What is the fundamental mechanism by which neurons communicate?

  The action potential

  
• What provides a boundary between a cell's internal environment and the outside world?

  The cell membrane
• What are the main components of a cell membrane?

  Phospholipids and proteins
• What is the structure of a phospholipid molecule?

  A hydrophilic head and two hydrophobic tails

  
• What role do proteins play in the cell membrane?

  They allow certain molecules to pass through
• What is membrane potential?

  The difference in electrical charge between the inside and outside of the cell
• What happens to the membrane potential when neurons are stimulated?

  It can change and become more or less negative

  
• What is the resting membrane potential in neurons?

  Approximately -70 millivolts (mV)

  
• What does it mean when a neuron is said to be polarized?

  It has a resting membrane potential

  
• What can a change in membrane potential generate?

  An electrical current or voltage
• What is depolarization in neurons?

  The process by which the membrane potential becomes less negative

  
• What occurs during hyperpolarization?

  The inside of the membrane becomes even more negative than usual

  
• Why is the rapid depolarization and hyperpolarization of the neuronal membrane important?

  It is essential during an action potential

  
• What is diffusion?

  The random movement of particles from high to low concentration

  
• What is dynamic equilibrium in diffusion?

  When molecules are evenly distributed but continue to move randomly
• What makes atoms electrically neutral?

  Equal numbers of protons and electrons
• What happens when an atom loses or gains an electron?

  It becomes an ion with a positive or negative charge

  
• What do charged particles (ions) generate?

  Electrostatic forces
• What is an electrical gradient?

  A gradient where ions are attracted to a region of opposite charge
• What are the Latin names for sodium and potassium?

  Natrium (Na+) and Kalium (K+)
• What is the resting membrane potential mainly due to?

  The movement of potassium ions (K+) out of the cell

  
• What is the nerve impulse (or action potential) mainly due to?

  The movement of sodium ions (Na+) into the cell

  
• What are semi-permeable membranes?

  Membranes that allow some ions to pass through but not others
• What happens if the membrane is permeable to certain ions?

  Those ions will move from high concentration to low concentration

  
• What do ionic gradients depend on in neurons?

  The sodium and potassium gradients

  
• What is the sodium concentration outside the cell compared to inside?

  10 times higher outside the cell
• What is the potassium concentration inside the cell compared to outside?

  40 times higher inside the cell

  
• What drives the diffusion gradient for sodium (Na+) inside the cell?

  The diffusion gradient outside the cell

  
• What drives the diffusion gradient for potassium (K+) outside the cell?

  The diffusion gradient inside the cell

  
• What regulates the influx of ions in neurons?

  Ion channels
• What happens when diffusion gradients and electrical gradients work in opposite directions?

  An ion may leave the cell down its diffusion gradient but be attracted back in by the electrical gradient

  
• What happens to potassium ions when the membrane is permeable to them?

  They will leak outside the cells due to the diffusion gradient

  
• What occurs as potassium ions diffuse out of the cell?

  The inside of the cell builds up a slight excess of negative charge

  
• What is the equilibrium potential for potassium (K+)?

  • 90 millivolts (mV)

  
• What happens when the membrane is only permeable to sodium (Na+)?

  Sodium will enter the cell down its diffusion gradient

  
• What occurs as sodium ions enter the cell?

  The inside of the membrane builds up a slight excess of positive charge