2 The Nervous System Free Online FlashCards

What structures make up the CNS and PNS?

The central nervous system (CNS) consists of the brain and spinal cord; the peripheral nervous system (PNS) includes nerves and ganglia outside the CNS.

What are the main parts of a typical neuron and their roles?

Dendrites receive input, the cell body contains the nucleus, and the axon carries signals toward other cells.

How do sensory neurons, interneurons, and motor neurons differ?

Sensory neurons carry information toward the CNS, interneurons connect and process signals within it, and motor neurons carry commands to muscles or glands.

What does myelin do for an axon?

Myelin insulates many axons and helps signals travel rapidly along them.

Which cells produce myelin in the CNS and PNS?

Oligodendrocytes produce myelin in the CNS, while Schwann cells produce it in the PNS.

What triggers an action potential?

When incoming signals bring the axon's trigger zone to threshold, voltage-gated ion channels open and generate an action potential.

How do nodes of Ranvier speed signal conduction?

In myelinated axons, the action potential is regenerated at successive nodes of Ranvier, making conduction faster.

How does a chemical synapse pass a signal to a target cell?

An arriving action potential causes the axon terminal to release neurotransmitters. They cross the synaptic gap and bind to receptors on a target cell, changing its activity.

In which direction does a sensory (afferent) pathway carry information?

A sensory, or afferent, pathway carries information toward the CNS.

In which direction does a motor (efferent) pathway carry commands?

A motor, or efferent, pathway carries commands away from the CNS to muscles or glands.

What makes a reflex a rapid protective response?

A reflex is a rapid protective response in which sensory input is processed through the spinal cord and activates motor output before information is fully processed for conscious perception.

What are two key roles of the spinal cord?

The spinal cord carries signals between the brain and much of the body and organizes many reflexes.