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A & P MS2 MOD 4
Question | Answer |
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Nervous System | the extensive intricate network of structures that activates, coordinates, and controls all of the functions of the body |
Receives internal and external stimuli through the sensory organs | |
Transmits messages to and from the brain | |
Interprets the transmitted messages, stores any needed information, and coordinates any required responses | |
Responds to internal and external stimuli through the motor organs | |
Stimulus | a change in an organisms external environment or internal conditions that cause a response in one or more of the organisms systems |
Sensory organ | an organ with the primary purpose of monitoring conditions in the environment and within the body in order to provide the brain with information that may require a response |
Motor organ | an organ with the primary function of moving materials within the body or parts of the body itself |
CNS | the part of the nervous system that consists of the brain and spinal cord, to which sensory impulses are transmitted and from which motor impulses pass out; the part of the NS that coordinates the activity of the entire NS |
PNS | the part of the NS that is outside the CNS and consists of 12 pairs of cranial nerves and 31 pairs of spinal nerves that link the various parts of the body to the CNS |
Brain | the portion of the central nervous system contained within the cranium and containing specialized cells that coordinate and regulate the functions of the CNS |
Spinal cord | the cord of nerve tissue that extends from the brain lengthwise along the back in the spinal cord and gives off pairs of spinal nerves, carries impulses to and from the brain, and serves as a center for initiating and coordinating reflex acts |
Spinal Canal | the row of aligned holes in the vertebrae through which the spinal cord passes |
Somatic nervous system | the part of the PNS that connects the CNS to the skin and the skeletal muscles via the cranial and spinal nerves and initiates voluntary responses |
Autonomic NS | the part of the PNS that connects the CNS to the visceral organs via the cranial and spinal nerves and initiates involuntary responses |
Somatic | of, relating to, or affecting the body |
Autonomic | acting or occurring involuntarily |
Sympathetic NS | the part of the ANS that prepares the body to deal with emergencies through the expenditures of energy |
Parasympathetic NS | the part of the ANS that restores homeostatic balance and conserves energy |
Nerve Tissue | tissue consisting of one or more bundles of impulse carrying fibers that connect the brain and the spinal cord and the rest of the body |
Neurons | the basic nerve tissue cells that are capable of transmitting nerve impulses |
Neuralgia | the basic nerve tissue cells that support neurons and play a role when there is injury or infection in the nervous system |
Cell Body | acts as a sending and receiving center, performs metabolic and reproductive functions for the cell, and stores energy |
Dendrite | carries impulses to the cell body |
Axon | carries impulses from the cell body |
Nerve Fiber | an elongated process of a neuron usually the axon concerned primarily with the conduction of impulses |
White Matter | neural tissue that consists largely of myelinated nerve fiber and has a whitish color |
Myelin | A soft white somewhat fatty material that forms a thick sheath about the core of a myelinated nerve fiber |
Myelinated | having myelin sheath |
Axis Cylinder | the central core of a nerve fiber that consists of a jelly like material |
Myelin sheath | the segmented, fatty covering of a nerve fiber that wraps the axons of many nerves and acts as an electrical insulator that reduces the possibility of an impulse stimulating adjacent nerves |
Neurilemma | the layer of cells composed of one or more Schwann cells that enclose the myelin sheath; the cell nucleus is a flattened oval that lies in a small depression in the myelin |
Sensory Neurons | are also called afferent, they receive messages from all parts of the body and transmit them to CNS, and are controlled by the thalamus |
Thalamus | one of a pair of large oval organs in the brain |
Interneurons | are also called central neurons or interneural neurons or connecting neurons; conduct messages or impulses from sensory to motor neurons; are found only in the CNS |
Motor Neurons | also called efferent neurons; transmit messages from the CNS to all parts of the body; are located in the muscles and glands; are controlled by the frontal lobe of the brain |
When the neuron recieves a signal, it sends an impulse to the next neuron across the synapse between an axon and a dendrite | |
Two or more neurons arranged in a chain function to conduct impulses from one place to another | |
Impulses pass only in one direction from a receptor dendrite to the cell body to the axon to a dendrite and so on | |
When a nerve impulse is blocked, the blocking usually takes place at a synapse | |
Synapse | the space between the axon and the dendrites of adjoining neurons through which nerve impulses travel |
A reflex is an involuntary response to a stimulus, such as blinking the eyes when something approaches them, salivating at the sight of appetizing food, and jerking of the knee when a certain spot is tapped | |
Many reflexes do not involve action on part of the brain; instead, the affector/effector circuit is completed by a loop in the spinal cord called a reflex arc | |
A reflex arc consists of an affector that provides a signal through a sensory neuron into a spinal nerve and into the spinal cord | |
The impulse passes through an interneuron in the gray matter of the spinal cord to a motor neuron that connects to an effector | |
Gray matter | nerve tissue that consists of motor neurons and interneurons |
The part of the nerve fiber that is separated by injury or disease from the cell body disintegrates | |
The neurilemma starts to regenerate at the site of the injury; if the cut ends of the nurilemma are not separated by too much distance, the sections grow back together to form a neurilemmar tube | |
The axon stump that is attached to the cell body grows into the nurilemmar tube and the regeneration is complete | |
Oligodendrocytes | form the insulating sheath of myelin on neurons in the central nervous system |
Microglia | move so that they can locate and destroy damaged tissue and invading cells and organisms |
Astrocytes | Prevent harmful chemicals from entering the brain from contaminated blood |
Ependyma | Line the fluid filled cavities in the brain and help to circulate cerebrospinal fluid |
Cerebralspinal Fluid | the tissue fluid that circulates aroung the brain and spinal cord |
Structures of the spinal canal | spinal cord; cerebrospinal fluid; meningies; adipose tissue; blood vessels |
Meninx | any one of the three membranes that envelop the brain and the spinal cord |
The spinal cord is a small cord about 18 inches long in an adult | |
The SC lies within the Spinal canal and is surrounded by the vertebrae | |
The SC acts as the conduction pathway for impulses between the peripheral nerves to an from the brain | |
In cross section the SC exhibits an H shaped area of gray matter surrounded by an outer region of white matter | |
Spinal Nerves emerge from the SC as two short roots the dorsal for the sensory nerves and the ventral for the motor nerves | |
the SC extends from the medulla of the brain to the 1st lumbar vertebra or top of the 2nd lumbar vertebra, where it begins to taper into a horsetail of fibers that finally ends in the coccygeal area | |
Coccygeal | of or relating to the coccyx, the 4 fused vertebrae that form the terminus of the spinal column |
Cerebrospinal fluid | circulates around the brain and spinal cord to maintain an even pressure and act as a cushion or shock absorber |
Components of Cerebrospinal Fluid | water; glucose; sodium chloride; protein; some waste products, such as urea |
Dura mater | the hard, outermost protective layer of the meninges that is composed of connective tissues |
Subdural Space | the cavity beneath the dura mater that is filled with serous fluid |
Arachnoid | the middle layer of the meninges that resembles a spiders web |
Subarachnoid space | the cavity below the arachnoid that is filled with cerebralspinal Fluid and acts as a shock absorber for the spinal cord and the brain |
Pia mater | the soft, innermost layer of the meninges that contain blood vessels that nourish that tissue layers and carry away waste products |
Forebrain | the prosencephalon the anterior division of the brain |
Midbrain | the mesencephalon the middle division of the brain |
Hindbrain | the rhombencephalon the posterior division of the brain |
Major structures of the forebrain | cerebrum, and Diencephalon |
Cerebrum | the telencephalon; the anterior portion of the brain that is considered to be the seat of conscious mental processes |
Diensephalon | the posterior subdivision of the forebrain that includes the thalamus serves as a relay center, functions in the integration of sensory info, hypothalamus which controls body temp, water balance, sleep, appetite, some emotions, and both divisions of ANS |
Major structures of the Hindbrain | Cerebellum, medulla oblongata, and pons |
Cerebellum | the posterior part of the hindbrain that serves to maintain body, balance, equilibrium, coordination, and muscle tone |
Medulla Oblongata | the portion of the hindbrain that is continuous posteriorly with the spinal cord and serves to control vital functions such as breathing, heart rate, blood pressure, swallowing, and coughing |
Pons | the portion of the hindbrain that is at the anterior end of the medulla oblongata and serves to relay impulses between the cerebrum and the cerebellum and the cerebrum and the medulla oblongata |
Hemisphere | one half of a sphere; the lateral half of the cerebrum or cerebellum |
Sulcus | a shallow groove a depression or a furrow on the surface of an organ |
Fissure | a cleft or a groove on the surface of an organ, marking division of the organ into parts |
Lobe | a portion of any organ that is demarcated by sulci |
fissures, or connective tissue | |
Ventricle | a small cavity such as the cavities filled with cerebrospinal fluid in the brain |
Frontal Lobe | the anterior division of each cerebral hemisphere that controls voluntary muscles and judgement |
Parietal Lobe | the middle division of each cerebral hemisphere that controls sensory functions such as pain, touch, and temperature interruption |
Occipital Lobe | the posterior lobe of each cerebral hemisphere that controls vision |
Temporal Lobe | a large lobe of each cerebral hemisphere that is situated in front of the occipital lobe and controls hearing, smell, and taste |
Parietal | of relating to or forming the upper posterior wall of the head |
Occipital | of relating to or located within or near the occiput or occipital bone |
Temporal | of or relating to the temples or the sides of the skull behind the orbits |
Central lobe | one of the lobes consisting each of the cerebral hemispheres and lying hidden in the depths of the lateral sulcus |
Longitudinal fissure | the fissure that divides the cerebrum into two hemispheres |
Central fissures | the fissure that divides the frontal lobe laterally from the parietal lobe |
Lateral Fissures | the fissure that separates the temporal lobe from the parietal lobe |
there are 4 ventricles in the brain; 2 lateral ventricles, and the 3rd and 4th | |
the ventricles | are filled with cerebrospinal fluid |
the ventricles | are continuous with the central canal of the spinal cord |
the lateral ventricles | are located inside the cerebral hemispheres |
each lateral ventricle | possesses a posterior, anterior, and inferior horn |
the posterior horn | of a lateral ventricle extends into the occipital lobe |
the anterior horn | of a lateral ventricle extends into the frontal lobe |
the inferior horn | of a lateral ventricle extends into the temporal lobe |
each lateral ventricle communicates with the third ventricle by way of the interventricle foramen | |
the thrid ventricle | is located in the diencephalon with the thalamus and hypothalamus |
the cerebral aqueduct | connects the third ventricle with the fourth ventricle |
the fourth ventricle | lies between the cerebellum and the pons and the medulla |
the fourth ventricle | communicates with the subarachnoid space of the spinal canal through one medial foramen and two lateral foramina |
inside each ventricle are tiny masses of specialized capillaries called choroid plexuses that secrete cerebrospinal fluid | |
foramen | an opening in a membranous structure |
aqueduct | a canal or passage in a part of organ |
Olfactory | nerve pair I; support the sense of smell |
Optic | nerve pair II; support the sense of sight |
Oculomotor | nerve pair III; control four muscles of the eye |
trochlear | nerve pair IV; control some of the eye muscles |
Trigeminal | nerve pair V; control the muscles of the cornea and conjunctiva, the upper portion of the face, the ear, the lower lip, the teeth, the gums, and the muscles for chewing |
Abducens | nerve pair VI; control the lateral eye movement |
Facial | nerve pair VII; supply the face muscles, the middle ear, and the taste sensors |
Auditory | nerve pair VIII; support the sense of hearing and balance |
Glossopharyngeal | nerve pair IX; support the sense of taste and control swallowing |
Vagus | nerve pair X; control swallowing, hunger, speech, breathing, heary rate, peristalsis, and glands in the stomach and pancreas |
Spinal Accessory | Nerve pair XI; control the muscles of the neck and upper back |
Hypoglossal | nerve pair XII; control the tongue muscles |
Cornea | the transparent part of the coat of the eyeball that covers the iris and pupil and admits light to the interior |
Conjunctiva | the mucous membrane that lines the inner surface of the eyelids and continues over the forepart of the eyeball |
Peristalsis | successive waves of involuntary contractions that pass along the walls of a hollow muscular structure, such as the esophagus or the intestine, and force the contents outward |
Pancreas | a large gland that secretes digestive enzymes and the hormones insulin and glucagon |
Plexus | a network of nerves from several segments of the spinal cord that combine to form nerves to specific parts of the body |
Cervical nerves | the eight pairs of spinal nerves that arise from the neck area of the spinal cord |
thoracic nerves | the 12 pairs of spinal nerves on each side of the thorax, including 11 intercostal nerves and one subcostal nerve |
Lumbar nerves | the 5 pairs of nerves that arise in the lumbar region |
Sacral nerves | the 5 pairs of spinal nerves that arise from the sacral region of the spinal cord |
Coccygeal nerve | the single pair of spinal nerves that arises near the coccygeal region of the spinal cord |
major nerves that arise from the cervical plexus | c 1 through c 4; phrenic |
Phrenic | of or relating to the diaphram |
Major nerves that arise from the brachial plexus | c 5 through c 8; t 1; axillary nerve; radial nerve; median nerve; ulnar nerve |
Axillary | of or pertaining to the axilla, the cavity beneath the junction of the forelimb and the body |
radial | pertaining to the radius, one of the bones of the forearm, lying parallel to the ulna |
Median nerve | the nerve that extends along the radial portions of the forearm and the hand and supplies various muscles and the skin of these parts |
Ulnar nerve | the nerve that supplies the muscles on the ulnar side of the forearm and hand |
Major nerves that arise from the lumbar plexus | L 1 through L 4; femoral nerve |
Femoral | of or pertaining to the femur or thigh |
major nerves that arise from the sacral plexus | l 4 and l 5; s 1 through s 4; sciatic nerve |
Sciatic | near the ischium, the hipbone |
major nerves that arise from the coccygeal plexus | s 4 and s 5; coccygeal nerve |
Multiple sclerosis | a progressive nerve dissorder that leads to degeneration of the myelin sheaths of CNS nerve cells, is marked by patches of hardened tissue in the brain or the spinal cord, and is associated with partial or complete paralysis and jerking muscle tremor |
Sclerosis | any pathological hardening of tissue |
Progressive | becoming more involved |
degenerative | worsening |
Neuroma | the general term for any tumor arising from a nerve and usually consisting of nerve fiber |
Glioma | a generally benign tumor arising from neuralgia |
Astrocytoma | a tumor that occurs in astrocytes |
Ependymoma | a tumor that arises in the lining of a ventricle and may extend to the spinal cord |
Acoustic Neuroma | a tumor that developes from the eighth cranial nerve and grows within the auditory canal |
multiple neurofibromatosis | an inherited disease that produces numerous benign tumors in the Schwann cells of the meninges usually caused by a bacerial infection |
meningiits | an inflammation of the meninges usually caused by a bacterial infection |
Hydrocephalus | an increase in the amount of cerebrospinal fluid in the cranial cavity, resulting in an enlargement of the skull and especially the forehead and atrophy of the brain |
Cerebrovascular accident | a lesion in the brain; a stroke |
Thrombus | a blood clot that obstructs a blood vessel and can thereby prevent the flow of blood to a region of the body |
Aneurism | A weak spot in a blood vessel; generally an artery; that allows a bubble or sac to form in the wall of the vessel |
Cerbral palsy | a disability that results from injury before or during birth that leads to poor muscle coordination and speech disturbances |
Alzheimer's disease | A progressive disease of the central nervous system that results in a loss of memory and reduced intellectual ability and speech and motor control |
Huntington's disease | an inherited disease that leads to involuntary, purposeless movements |
Parkinson's Disease | a degenerative condition in neurons that leads to overstimulation of skeletal muscles, marked by tremor and weakness of resting muscles and by a shuffling gait |
Epilepsy | a condition of recurring of chronic seizures |
Herpes Zoster | a viral infection of the sensory fibers in the skin, causing a painful eruption of red patches |
Trigeminal neuralgia | a condition of recurring pain as a result of disease or injury int the trigeminal (C5) nerve |