The Central Nervous System
The Central Nervous System is the complex of nerve tissues that controls the activities of the body. In vertebrates it comprises the brain and spinal cord.
The Peripheral Nervous System
The Peripheral Nervous System the nervous system outside the brain and spinal cord. The PNS consists of the nerves and ganglia outside of the brain and spinal cord.
The Somatic Nervous System
The Somatic Nervous System is the part of the peripheral nervous system associated with skeletal muscle voluntary control of body movements. The SNS consists of afferent nerves or sensory nerves, and efferent nerves or motor nerves.
The Autonomic Nervous System
The Autonomic Nervous System is the part of the nervous system responsible for control of the bodily functions not consciously directed, such as breathing, the heartbeat, and digestive processes.
The Parasympathetic Nervous System
The parasympathetic nervous system is one of the extensions of the ANS. It conserves energy as it slows the heart rate, increases intestinal and gland activity, and relaxes sphincter muscles in the gastrointestinal tract.
The Sympathetic Nervous System
This is another part of the ANS. It depresses secretion, decreases the tone and contractility of smooth muscle, and increases heart rate.
Sensory neurons are nerve cells within the nervous system responsible for converting external stimuli from the organism's environment into internal electrical impulses.
An interneuron a neuron that transmits impulses between other neurons, especially as part of a reflex arc.
A motor neuron is a nerve cell forming part of a pathway along which impulses pass from the brain or spinal cord to a muscle or gland.
A neuromuscular junction 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—a chemical released by nerve cells to send signals to other cells
Norepinephrine and Epinephrine
Epinephrine and norepinephrine are released by the adrenal medulla and nervous system respectively. They are the flight/fight hormones that are released when the body is under extreme stress. During stress, much of the body's energy is used to combat imminent danger.
A synapse is a junction between two nerve cells, consisting of a minute gap across which impulses pass by diffusion of a neurotransmitter.
White matter is composed of bundles of myelinated nerve cell projections, which connect various gray matter areas of the brain to each other, and carry nerve impulses between neurons.
Grey matter is a major component of the central nervous system, consisting of neuronal cell bodies, neuropil, glial cells, synapses, and capillaries.
The cerebral cortex is the outer layer of the cerebrum composed of folded gray matter and playing an important role in consciousness.
The Lobes of the Brain
The Limbic System
The limbic system is a complex system of nerves and networks in the brain, involving several areas near the edge of the cortex concerned with instinct and mood. It controls the basic emotions (fear, pleasure, anger) and drives (hunger, sex, dominance, care of offspring).