NSC - Module Overview
The Nervous System
Introduction
The nervous system is considered the control center for the human body. This system is responsible for coordinating the function of all body systems. The nervous system is highly complex, consisting of more than 100 billion nerve cells. It consists of an impulse transportation system that enables the human body to respond to both internal and external stimuli. This module will explore the structure and function of healthy nerve tissue as well as conditions that may change the normal function of healthy nerve tissue.
Essential Questions
- What are the physical, chemical, and biological properties of the nervous system?
- What is the cellular structure and function of a nerve cell?
- How does the nervous system contribute to the maintenance of homeostasis?
- What body systems depend on the nervous system for function and support?
- How many parts is the nervous system divided into?
- What is the role of the nervous system in the regulation of physiological activities?
- How do the actions of the sympathetic and parasympathetic nervous systems differ?
- What diseases or conditions affect the nervous system?
Key Terms
- Action potential: The change in electrical potential along the membrane of a neuron associated with the passage of an impulse
- Afferent (sensory) nerves: Responsible for relaying sensation from the body to the central nervous system (CNS)
- Autonomic nervous system: A part of the vertebrate nervous system that innervates smooth and cardiac muscle and glandular tissues and governs involuntary actions (as secretion and peristalsis). Consists of the sympathetic nervous system and the parasympathetic nervous system.
- Chemical synapse: Synapse that uses neurotransmitters to transfer signals from one neuron to another
- Central nervous system: The part of the nervous system that includes the brain and spinal cord
- Cerebellum: The back part of the brain that controls balance and the use of muscles
- Cerebrospinal fluid: A colorless liquid, comparable to serum, that is secreted from the blood into the lateral ventricles of the brain. It serves chiefly to maintain uniform pressure within the brain and spinal cord.
- Cerebrum: The front part of the brain that is believed to be where thoughts occur
- Depolarization: The return of a cell's electrical potential to its resting state
- Diencephalon: The posterior subdivision of the forebrain
- Efferent (motor) nerves: Responsible for sending out commands from the CNS to effectors in the body, such as muscles and glands
- Electrical potential: Electrostatic potential energy within a membrane
- Ganglia: Nerve cell clusters
- Gap junction: The channel proteins connecting the pre- and postsynaptic neurons in electrical synapses
- Gray matter: Unmyelinated nervous tissue composed mainly neural cell bodies
- Gyri: Folds in the cerebral cortex (singular: gyrus).
- Hyperpolarize: A reduction in the electrical potential of a cell that inhibits the firing of an action potential
- Hypothalamus: A basal part of the diencephalon that lies beneath the thalamus on each side. It forms the floor of the third ventricle and includes vital autonomic regulatory centers (as for the control of food intake).
- Medulla oblongata: The somewhat pyramidal last part of the vertebrate brain developed from the posterior portion of the hindbrain and continuous posteriorly with the spinal cord. It encloses the fourth ventricle and contains nuclei associated with most of the cranial nerves, major fiber tracts, and decussations that link the spinal cord with higher centers. It mediates the control of involuntary vital functions, such as respiration.
- Meninges: Any of the three membranes that envelop the brain and spinal cord. They include the arachnoid, dura mater, and pia mater.
- Midbrain: The middle division of the three primary divisions of the developing vertebrate brain, or the corresponding part of the adult brain. The midbrain includes a ventral part containing the cerebral peduncles and a dorsal tectum containing the corpora quadrigemina. It surrounds the aqueduct of Sylvius, connecting the third and fourth ventricles.
- Motor reflexes: Quick, unconscious movements controlled by the spinal cord
- Nerves: Any of the filamentous bands of nervous tissue that connect parts of the nervous system with the other organs and conduct nervous impulses. Nerves are made up of axons and dendrites together with protective and supportive structures. Larger nerves have the fibers gathered into funiculi surrounded by a perineurium and the funiculi enclosed in a common epineurium.
- Nervous system: The bodily system in vertebrates that is made up of the brain and spinal cord, nerves, ganglia, and parts of the receptor organs. It receives and interprets stimuli and transmits impulses to the effector organs.
- Neuron: One of the cells that constitute nervous tissue, with the property of transmitting and receiving nervous impulses. Composed of somewhat reddish or grayish protoplasm, they have a large nucleus containing a conspicuous nucleolus, irregular cytoplasmic granules, and cytoplasmic processes which are highly differentiated, frequently as multiple dendrites, or usually as solitary axons. Neurons conduct impulses toward and away from the nerve cell body.
- Neurotransmitters: Chemicals used to send signals from one neuron to another
- Parasympathetic nervous system: The part of the autonomic nervous system that contains chiefly cholinergic fibers. The parasympathetic nervous system tends to induce secretion, increase the tone and contractility of smooth muscle, and slow the heart rate.
- Peripheral nervous system: The part of the nervous system that is outside the central nervous system. It is comprised of the cranial nerves, except the optic nerve, the spinal nerves, and the autonomic nervous system.
- Pons: A broad mass of chiefly transverse nerve fibers in the mammalian brain stem lying ventral to the cerebellum at the anterior end of the medulla oblongata
- Postsynaptic neuron: A neuron that receives messages
- Presynaptic neuron: A signaling neuron
- Resting potential: The resting voltage of a neuron (approximately -70 mV)
- Somatic nervous system: The part of the peripheral nervous system associated with skeletal muscle voluntary control of body movements
- Spinal cord: The large group of nerves that runs through the center of the spine and carries messages between the brain and the rest of the body
- Sulci: Vallies in the cerebral cortex (singular is sulcus)
- Sympathetic nervous system: The part of the autonomic nervous system that contains chiefly adrenergic fibers and tends to depress secretion, decrease the tone and contractility of smooth muscle, and increase heart rate
- Synaptic vesicle: The vesicle in the axon terminal of a neuron that contains neurotransmitters
- Synapse: A minute gap between messaging neurons
- Synaptic cleft: The extracellular space between pre- and postsynaptic neurons.
- Thalamus: The largest subdivision of the diencephalon that consists chiefly of an ovoid mass of nuclei in each lateral wall of the third ventricle and serves chiefly to relay impulses and especially sensory impulses to and from the cerebral cortex
- Voltage-gated ion channels: Ion channels that are activated by changes in the electrical potential of the cell membrane
- Ventricles: The hollow spaces of the brain containing cerebrospinal fluid.
- White matter: Myelinated nervous tissue composed mainly of axons.
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