Chapter 29 By Andrey Mychajlyszyn

Central Nervous System

The central nervous system (CNS) is the part of the nervous system consisting of the brain and spinal cord. It receives information from and sends information to the peripheral nervous system.

Peripheral Nervous System

The peripheral nervous system refers to parts of the nervous system outside the brain and spinal cord. It includes the cranial nerves, spinal nerves and their roots and branches, peripheral nerves, and neuromuscular junctions. bundles of nerve fibers or axons conduct information to and from the central nervous system.

Somatic Nervous System

It is the part of the peripheral nervous system associated with skeletal muscle voluntary control of body movements. The system is responsible for nearly all voluntary muscle movements as well as for processing sensory information that arrives via external stimuli including hearing, touch, and sight.

Autonomic Nervous System

It is a division of the peripheral nervous system that supplies smooth muscle and glands, and thus influences the function of internal organs. This system works automatically, without a person’s conscious effort.

Parasympathetic Nervous System

The parasympathetic nervous system (PNS) controls homeostasis and the body at rest and is responsible for the body's "rest and digest" function. It conserves energy as it slows the heart rate, increases intestinal and gland activity, and relaxes sphincter muscles in the gastrointestinal tract.

Sympathetic Nervous System

The sympathetic nervous system (SNS) controls the body's responses to a perceived threat and is responsible for the "fight or flight" response. It is one of the two main divisions of the autonomic nervous system, the other being the parasympathetic nervous system.

Sensory Neuron

Sensory neurons are nerve cells within the nervous system responsible for converting external stimuli from the organism's environment into internal electrical impulses.


Interneurons are types of nerve cells, typically found in integrative areas of the central nervous system, whose axons (and dendrites) are limited to a single brain area. Interneurons create neural circuits, enabling communication between sensory or motor neurons and the central nervous system.

Motor Neuron

They are efferent neurons that originate in the spinal cord and synapse with muscle fibers to facilitate muscle contraction and with muscle spindles to modify proprioceptive sensitivity.

Neuromuscular Junction

It is a chemical synapse formed by the contact between a motor neuron and a muscle fiber. It is at the neuromuscular junction that a motor neuron is able to transmit a signal to the muscle fiber, causing muscle contraction.


Acetylcholine is an organic chemical that functions in the brain and body of many types of animals, including humans, as a neurotransmitter, which is a chemical released by nerve cells to send signals to other cells. In the peripheral nervous system acetylcholine plays a role in skeletal muscle movement, as well as in the regulation of smooth muscle and cardiac muscle. In the central nervous system acetylcholine is believed to be involved in learning, memory, and mood.

Norepinephrine and Epinephrine

Norepinephrine is an organic chemical in the catecholamine family that functions in the brain and body as a hormone and neurotransmitter. Epinephrine also known as adrenalin or adrenaline, is a hormone, neurotransmitter and medication. Epinephrine is normally produced by both the adrenal glands and certain neurons. It plays an important role in the fight-or-flight response by increasing blood flow to muscles.


It is found in the nervous system, and synapse is a structure that permits a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron. They allow the nervous system to connect to and control other systems of the body.

White Matter

White matter is found in the deeper tissues of the brain (subcortical). It contains nerve fibers (axons), which are extensions of nerve cells (neurons). Many of these nerve fibers are surrounded by a type of sheath or covering called myelin. Myelin gives the white matter its color. It also protects the nerve fibers from injury and improves the speed and transmission of electrical nerve signals.

Gray Matter

The grey matter is mainly composed of neuronal cell bodies and unmyelinated axons. Axons are the processes that extend from neuronal cell bodies, carrying signals between those bodies. In the grey matter, these axons are mainly unmyelinated, meaning they are not covered by a whitish-colored, fatty protein called myelin. The grey matter serves to process information in the brain.

Cerebral Cortex

The cerebral cortex is the outer layer of neural tissue of the cerebrum of the brain, in humans and other mammals. The cerebral cortex plays a key role in memory, attention, perception, awareness, thought, language, and consciousness.

Lobes of the Brain

The lobes of the brain have been shown also to be related to different brain functions. The cerebrum, the largest portion of the human brain, is divided into lobes, but so is the cerebellum. The lobes of the brain are the frontal lobe, the parietal lobe, occipital lobe, and the temporal lobe.

Limbic System

The limbic system is a set of brain structures located on both sides of the thalamus, immediately beneath the cerebrum. It is not only responsible for our emotional lives but also many higher mental functions, such as learning and formation of memories.

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