Chapter 9 The nervous system

What are the primary functions of the nervous system?

Maintains body homeostasis, provides sensation, supports mental functioning, emotional response, and activates muscles and glands.

What are the two main divisions of the nervous system?

Central Nervous System (CNS) and Peripheral Nervous System (PNS).

What structures make up the Central Nervous System?

The brain and spinal cord.

What are the two functional divisions of the Autonomic Nervous System?

Sympathetic and Parasympathetic.

What does the sympathetic nervous system do during stress?

Prepares the body for fight or flight, increasing heart rate and blood flow to muscles while inhibiting digestion.

What is the primary role of the parasympathetic nervous system?

Calms the body down, promoting relaxation, digestion, and conserving energy.

How do sensory (afferent) neurons function?

They convey impulses to the CNS from sensory receptors throughout the body.

What is the function of motor (efferent) neurons?

They carry impulses from the CNS to effector organs such as muscles and glands.

What are neurons?

Specialized cells that are the functional units of the nervous system.

What are the two types of fibers that extend from a neuron?

Dendrites and axons.

What do dendrites do?

Conduct impulses toward the cell body of the neuron.

What do axons do?

Conduct impulses away from the cell body of the neuron.

What are glial cells?

Supporting cells in the CNS and PNS that do not transmit electrical signals.

What is the function of astrocytes?

They maintain the blood-brain barrier.

What is myelin?

A whitish fatty substance that insulates and protects axons, increasing the transmission rate of nerve impulses.

What cells produce myelin in the CNS?

Oligodendrocytes.

What are the gaps in myelinated nerve fibers called?

Nodes of Ranvier.

What is a synapse?

The junction point for transmitting nerve impulses from one neuron to another.

What occurs during depolarization?

The membrane becomes less negative, approaching a positive potential.

What is the role of neurotransmitters?

They transmit signals across the synaptic cleft and can influence the chance of action potentials in the postsynaptic neuron.

What are spinal nerves?

Mixed nerves that carry sensory and motor information to and from the spinal cord.

How many pairs of spinal nerves are there?

31 pairs.

What distinguishes sensory neurons located in the dorsal root?

They contain cell bodies of sensory neurons.

What is a reflex arc?

A neural pathway that controls a reflex action, involving a receptor, sensory neuron, CNS, motor neuron, and effector.

What is multiple sclerosis?

An autoimmune disease that causes destruction of the myelin sheath.

What is the definition of paraplegia?

Paralysis of both lower limbs.

What causes Guillain-Barré syndrome?

It is an autoimmune disorder that attacks peripheral nerves.