the neuron Flashcards
(20 cards)
Q: Why do complex organisms need a nervous system?
A: To coordinate specialized cells living in different environments and enable cooperation for survival.
Q: What’s the difference between the endocrine and nervous systems in coordination?
A: The endocrine system provides slow, broad coordination via hormones; the nervous system provides fast, precise coordination via electrical impulses.
Q: What are the three main functions of neurons?
A: Transmit electrical impulses, target specific cells, and integrate signals from different sources.
Q: Why do neurons need a constant supply of glucose and oxygen?
A: Because they cannot store energy and stop functioning within seconds without it.
Q: Can neurons regenerate after death?
A: No; neurogenesis is mostly complete by 5 months after conception.
Q: What are glial cells, and what do they do?
A: Cells that support and protect neurons by providing nutrients, waste removal, insulation, and immune defense.
Q: What is the function of astrocytes?
A: Provide physical and nutritional support, transport nutrients, remove waste, and participate in neural signaling.
Q: What do microglia do?
A: Defend the brain, repair neurons, and remove dead cells through phagocytosis.
Q: What is the role of oligodendroglia?
A: Insulate axons by forming the myelin sheath, speeding up electrical transmission.
Q: What maintains the resting membrane potential in neurons?
A: The sodium-potassium pump and selective ion channels in the membrane.
Q: What happens if only passive ion channels were present in the neuron membrane?
A: The membrane would depolarize and electrical activity would stop.
Q: What is depolarization?
A: When positive ions enter (or negative leave) the neuron, making the inside more positive.
Q: What is an action potential?
A: A self-replicating electrical signal that travels along the axon with constant strength.
Q: What triggers an action potential?
A: Depolarization beyond the threshold of -50 mV at the axon hillock.
Q: What is the Hodgkin-Huxley cycle?
A: A cycle of Na+ influx causing further depolarization and opening of more Na+ channels, triggering an action potential.
Q: Why does the action potential not travel backwards?
A: The previous segment is hyperpolarized and harder to depolarize, preventing reverse transmission.
Q: What is saltatory conduction?
A: Action potentials “jump” between nodes of Ranvier in myelinated axons, speeding up transmission.
Q: What determines how a signal is interpreted in the brain (qualitative coding)?
A: The location where the signal is received in the brain.
Q: What is quantitative coding of neural signals?
A: The strength of the input is reflected in the neuron’s firing rate—stronger input = faster firing.
Q: What does it mean that neurons transmit signals but also receive from many sources?
A: Neurons integrate and modify input, so signals are never passed on unaltered.
