Nervous System Flashcards
Consists of the brain and spinal cord, which occupy the dorsal body cavity. The integrating and control center of the nervous system. Interprets sensory input and dictates motor output based on reflexes, current conditions, and past experience.
Central Nervous System (CNS))
Part of the nervous system outside the CNS. Consists mainly of nerves that extend from the brain and spinal cord, and ganglia. Spinal nerves carry impulses to and from the spinal cord, and cranial nerves carry impulses to and from the brain. Serve as communication lines that link all parts of the body to the CNS.
Peripheral Nervous System (PNS)
The nervous system uses these to monitor changes occurring both inside and outside the body.
Sensory Input
The nervous system processes and interprets sensory input and decides what should be done at each moment.
Integration
The nervous system activates effector organs—the muscles and glands—to cause a response.
Motor Output
Promotes maintenance functions and conserves body energy. “Rest and digest” system, keeps body energy use as low as possible, even as it directs vital “housekeeping” activities like digesting food and eliminating feces and urine.
Parasympathetic Division
Mobilizes the body during activity. “Fight-or-flight” system. Evident when individual is excited or in emergency or threatening situations.
Sympathetic Division
Craniosacral; Has long preganglionic and short postganglionic fibers; Located in or near the visceral effector organs; Maintenance functions; conserves and stores energy; “rest and digest”.
Parasympathetic Division
Thoracolumbar; Has the opposite condition—the preganglionic fibers are short and the postganglionic fibers are long; Lie close to the spinal cord; Prepares body for activity; “fight or flight”.
Sympathetic Division
A clear, colorless liquid composed primarily of water that protects the brain and spinal cord from chemical and physical injuries. It forms a liquid cushion that gives buoyancy to CNS structures effectively reducing the brain’s weight by 97%.
Cerebrospinal Fluid
A condition wherein something (such as a tumor) obstructs CSF circulation or drainage, CSF accumulates and exerts pressure on the brain. The head enlarges because the skull bones have not yet fused. This causes damage to the brain because accumulating fluid compresses blood vessels and crushes the soft nervous tissue.
Hydrocephalus
- The choroid plexus of each ventricle produces CSF.
- CSF flows through the ventricles and into the subarachnoid space via the median and
lateral apertures. - CSF flows through the subarachnoid space.
- CSF is absorbed into the dural venous sinuses via the arachnoid granulations.
Location and Circulatory Pattern of Cerebrospinal Fluid
Where is cerebrospinal fluid formed?
Choroid Plexus
Consists of the midbrain, pons, and medulla oblongata. Each roughly an inch long, collectively they account for only 2.5% of total brain mass. Its centers produce the rigidly programmed, automatic behaviors necessary for survival. Positioned between the cerebrum and the spinal cord, it also provides a pathway for fiber tracts running between higher and lower neural centers.
Brain Stem
Located between the diencephalon and pons. Contains visual (superior colliculi) and auditory (inferior colliculi) reflex centers. Contains subcortical motor centers (substantia nigra and red nuclei). Contains nuclei for cranial nerves III and IV.
Midbrain (Mesencephalon)
Bulging brain stem region wedged between the midbrain and the medulla oblongata. Composed of conduction tracts. Contains nuclei of cranial nerves V–VIII.
Pons
Run longitudinally as part of the pathway between higher brain centers and the spinal cord.
Deep Projection Fibers
Form the middle cerebellar peduncles and connect the pons bilaterally with the two sides of the cerebellum dorsally fibers. Issue from numerous pontine nuclei, which relay “conversations” between
the motor cortex and cerebellum.
Superficial Ventral Fibers
Most inferior part of the brain stem that blends imperceptibly into the spinal cord at the level of the foramen magnum of the skull. Contains nuclei of cranial nerves VIII–X and XII. Contains projection fibers. Site of decussation of pyramids.
Medulla Oblongata
Cardiac center which force and rate of heart contraction; Vasomotor center which changes blood vessel diameter to regulate blood pressure.
Cardiovascular Center
Respiratory rhythm and control the rate and depth of breathing.
Respiratory Centers
Located dorsal to the pons and medulla. Accounts for about 11% of total brain mass. Second only to the cerebrum in size, occupies the inferior and posterior aspects of the cranial cavity. Protrudes under the occipital lobes of the cerebral hemispheres, from which it is separated by the transverse cerebral fissure.
Cerebellum
Superior to the brain stem. Forms the central core of the forebrain and surrounded by the cerebral hemispheres.
Diencephalon
Consists of bilateral egg-shaped nuclei, which form the superolateral walls of the third ventricle. Deep, well-hidden brain region that makes up 80% of the diencephalon.
Thalamus
Involved in memory processing. Hypothalamus Merging into the midbrain inferiorly, it extends from the optic chiasma (crossover point of the optic nerves) to the posterior margin of the mammillary bodies. Caps the brain stem and forms the inferolateral walls of the third ventricle.
Cerebellum
Most dorsal portion of the diencephalon. Forms the roof of the third ventricle
Epithalamus
Sensory areas of cerebral cortex are involved in perception of sensory information. Motor areas control execution of voluntary movements. Association areas deal with more complex integrative functions such as memory, personality traits, and intelligence. Basal nuclei help initiate and terminate movements, suppress unwanted movements, and regulate muscle tone. Limbic system promotes range of emotions, including pleasure, pain, docility, affection, fear, and anger.
Cerebrum
Localizes and interprets sensory inputs. Controls voluntary and skilled skeletal muscle activity. Functions in intellectual and emotional processing.
Cortical Gray Matter
Subcortical motor centers. Help control skeletal muscle movements.
Basal Nuclei (Ganglia)
TRANSMIT NERVE
IMPULSES ALONG NERVE FIBERS TO OTHER NEURONS.
Neurons
MADE UP OF BUNDLES OF NERVE FIBERS.
Nerves
CARRY OUT A VARIETY OF FUNCTIONS TO AID AND PROTECT COMPONENTS OF THE NERVOUS SYSTEM.
Neuroglia
Consciously Controlled System
Somatic Nervous System
Unconsciously Controlled System
Autonomic Nervous System
CARRY IMPULSES FROM OTHER NEURONS (OR FROM RECEPTORS) TOWARD THE CELL BODY.
Dendrites
TRANSMITS THE IMPULSE AWAY FROM THE AXONAL HILLOCK OF THE CELL BODY AND MAY GIVE OFF SIDE BRANCHES.
Axon
ENCLOSED BY SHEATHS OF MYELIN PROVIDED BY SCHWANN CELLS AND ARE MYELINATED FIBERS.
Large Axons
The outer layer of myelin.
Neurilemma
NARROW GAPS IN THE MYELIN SHEATH
BETWEEN SCHWANN CELLS.
Nodes of Ranvier
LACK A MYELIN SHEATH AND ARE UNMYELINATED FIBERS.
Small Axons
__________ IN THE CNS IS DUE TO MYELIN SHEATHS IN THIS AREA.
White Matter
UNMYELINATED NERVE TISSUE IN THE CNS APPEARS __________.
Gray Matter
THESE ARE ABLE TO REGENERATE BECAUSE OF THE NEURILEMMA, BUT THE CNS AXONS ARE
MYELINATED BY OLIGODENDROCYTES, THUS LACKING NEURILEMMA, AND USUALLY DO NOT REGENERATE.
Peripheral Neurons
Usually have several dendrites and one axon. Most neurons in the brain and spinal cord are of this
type, as well as all motor neurons.
Multipolar Neurons
Have one main dendrite and one axon. They are found in the retina of the eye, the inner ear, and the olfactory area (olfact = to smell) of the brain.
Bipolar Neurons
Have dendrites and one axon that are fused together to form a continuous process that emerges from the cell body.
Unipolar Neurons
Small cells that phagocytize bacterial cells and cellular debris.
Microglial Cells
Form myelin in the brain and spinal cord.
Oligodendrocytes
Near blood vessels andsupportstructures,aid in metabolism, and respond to brain injury by filling in spaces.
Astrocytes
Cover the inside of ventricles and form choroid plexuses within the ventricles.
Ependyma
The myelin-producing
neuroglia of the peripheral nervous system.
Schwann Cells
Flat cells that surround the cell bodies of neurons of PNS ganglia.
Satellite Cells
Begins at the base of the brain and extends as a slender cord to the level of the intervertebral disk between the first and second lumbar vertebrae.
Spinal Cord
Consisting of the brain, spinal cord, and nerves—constantly receives signals about changes from the external environment and within the body. It then processes the information, decides what action needs to occur, and sends electrical and chemical signals to the cells, enabling proper response. It also powers our ability to learn, feel, create, and experience emotion. It is the most complex of all body systems.
Nervous System
This reward system is attributed to neurons that release the neurotransmitter _________ in areas of the brain called the ventral tegmental area (VTA), the nucleus accumbens, and the amygdala.
Dopamine
Responsible for this “feel good” reward system.
Neurotransmitters
The branch of medical science that deals with the normal functioning and disorders of the nervous system.
Neurology
With a mass of only 2 kg (4.5 lb), about 3% of total body weight.
Nervous System
With sensory (afferent) and motor (efferent) components.
Peripheral Nervous System
Consists of a variety of different receptors as well as sensory neurons.
Sensory System
Conducts nerve impulses from the CNS to muscles and glands.
Motor System
Consists of neurons that conduct impulses from cutaneous and special sense receptors to the CNS, and motor neurons that conduct impulses from the CNS to skeletal muscle tissue.
Somatic Nervous System
Contains sensory neurons from visceral organs and motor neurons that convey impulses from the CNS to smooth muscle tissue, cardiac muscle tissue, and glands. The motor part of the ANS consists of the sympathetic division and the parasympathetic division.
Autonomic Nervous System
Consists of neurons in enteric plexuses that extend the length of the GI tract. Many neurons of the enteric plexuses function independently of the ANS and CNS. Sensory neurons of the ENS monitor chemical changes within the GI tract and stretching of its walls, whereas enteric motor neurons govern contraction of GI tract organs, and activity of the GI tract endocrine cells.
Enteric Nervous System
Cluster of neuronal cell bodies located in the PNS; closely associated with cranial and spinal nerves.
Ganglion
Cluster of neuronal cell bodies located in the CNS.
Nucleus
Bundle of axons that is located in the PNS.
Nerve
Bundle of axons that is located in the CNS.
Tract
Composed primarily of myelinated axons.
White Matter
Contains neuronal cell bodies, dendrites, unmyelinated axons, axon terminals, and neuroglia. It appears grayish, rather than white, because the Nissl bodies impart a gray color and there is little or no myelin in these areas.
Gray Matter
Like muscle fibers, neurons are electrically excitable. Excitable cells communicate with each other by graded potentials or action potentials. Graded potentials allow communication over short distances only whereas action potentials allow communication over long distances. When an action potential occurs in a neuron (nerve cell).
Nerve Action Potential
