1. Chapter 19

2.  Sense, interpret & responds to internal & external environmental  Communication & coordination of the body  Seat of intellect & reasoning  Divided into 2 sections Central Peripheral

3.  Most complex but least understood  New discoveries made daily  Millions of nerve cells which exceeds the number of stars in the Milky Way.  In humans, the right side of the brain controls the left side of the body, while the left side of the brain controls the right side.  Inside the womb, neurons grow at the rate of 250,000 neurons per minute.

4.  By the time of it birth, a fetus's brains consists of about 10 million nerve cells.  43 different pairs nerves connect the CNS to our body. Twelve pairs connect to the brain, 31 pairs are connected to the spinal cord.  Average adult males brain is 1375 grams (3 lbs), females is 1275 grams (2 lbs 12 oz).  As we age, the brain loses a gram each year.  Only 4% of the cells in the brain are active, the rest are kept in reserve.  From brain to neuron 224 mph. From neuron to brain 180 mph

7.  Brain & spinal cord  Coordinated full nervous system  Has crucial role of maintaining health, normal functioning body  Meninges-tough membranes surrounding nervous tissue

8.  12 cranial nerves Originate in brain  31 pairs of spinal nerves  Originate from spinal cord  Sensory neurons (afferent) Carry messages from sensory cells to brain  Motor neurons (efferent) Carry messages from brain to body organs or parts

9.  Voluntary  Involuntary-(AKA autonomic) Sympathetic  Fight or flight Parasympathetic  Responds to everyday occurrences

11.  Basic structural unit of nervous system  Bundle of fibers that carry impulses  Nerve fibers functional unit  Types Afferent Efferent Interneuron

12.  Axon-transmits impulses from cell body to dendrite  Cell body-contains nucleus-transmits impulses to the axon  Dendrite-receive impulses & transmit to cell body

14.  Myelin-white, fatty substance  Schwann cells-bundle of myelin  Myelin Sheath-layers of schwann cells  Neurilemma-membrane covering myelin sheath

15.  acts as “glue” supports, binds, repairs, and protects neurons  Estimated 900 billion in body  Types Astrocytes-transfer substances from blood to brain Oligodendroglia-develop myelin sheath Microglia-destroy bacteria & fight infection Ependymal cells-line cavities of nervous system

16.  Space between two neurons  Send messages up to other neurons  Neurotransmitter-impulses transmitted across the synapse Acetylcholine & norepinephrine-most common

17.  Groups of nerve tissue  Located outside CNS  Increased ability to transmit impulses compared with nerve cells due to being clustered together in the ganglion

18.  Plexus 4 major networks of interwoven spinal nerves Provide impulses to specific regions in body  Cervical, brachial, lumbar, sacral  Dermatome Sensations on skin surface controlled by specific spinal nerves

19.  Largest structure of nervous system  Uses about 20% blood flow from heart  Brain cell’s can only survive about 4-6 minutes without oxygen & glucose  Layers Dura mater-leathery outer layer Arachnoid-middle-cerebrospinal fluid Pia mater-innermost-attaches brain & spinal cord

21.  Cerebrum Largest area Divided into two hemispheres  right-controls left side of body  Left-controls right side of body

22.  Diencephalon Contains hypothalamus & thalamus Controls autonomic nervous system, hormone secretion, & appetite. Thalamus controls sensory impulses to the sensory areas of cerebral cortex

23.  Cerebellum Coordination, muscle tone, equilibrium  Brainstem Pons, medulla, midbrain  Heartbeat, respiration, & blood pressure

26.  Evaluation of the nervous system includes assessment of the following: Mental status Cranial nerve function Motor and sensory nerve function Reflexes Coordination Gait (walking) Balance Internal body processes

27.  Electroencephalography (EEG)  Lumbar puncture  Nerve conduction velocity  Computed tomography (CT)  Positron emission tomography (PET)  Magnetic resonance imaging (MRI)  Magnetic resonance angiography (MRA)

28. FIGURE 19-10 Magnetic resonance imagery allows the visualization of the body without use of radiation. (From Elkin MK, et al: Nursing intervention and clinical skills, ed 4, St. Louis, 2008, Mosby.)

29. Alzheimer’s disease  Form of senile dementia  Cause is unknown but has some genetic links.  No cure is known treatment can control symptoms

30.  Cerebrovascular accident (CVA) Commonly called a stroke, it is caused by loss of oxygen to an area of the brain when a clot blocks a vessel or when a vessel breaks. Commonly called a stroke, it is caused by loss of oxygen to an area of the brain when a clot blocks a vessel or when a vessel breaks.  Transient ischemic attack (TIA) Decreased blood supply to an area of the brain resulting from a small clot that temporarily lodges in a vessel Symptoms includes mental and physical dysfunction such as: loss of balance, speech, or thought process. Symptoms includes mental and physical dysfunction such as: loss of balance, speech, or thought process. Treatments Treatments  Anticoagulants, angioplasty, clot-dissolving medications

31.  Encephalitis Inflammation of the brain caused by a viral or bacterial infection or by a chemical agent Inflammation of the brain caused by a viral or bacterial infection or by a chemical agent Acute condition characterized by fever, HA, extreme irritability of the nervous system Acute condition characterized by fever, HA, extreme irritability of the nervous system  Guillain-Barré syndrome Also called infectious polyneuritis, it may appear shortly after a viral immunization or infection Also called infectious polyneuritis, it may appear shortly after a viral immunization or infection Person with this condition experiences muscle weakness that rapidly moves from the legs to face. Person with this condition experiences muscle weakness that rapidly moves from the legs to face. Experience total paralysis of respiratory function Experience total paralysis of respiratory function  Head injury Occurs when the brain impacts the skull as a result of a blow or rapid movement Occurs when the brain impacts the skull as a result of a blow or rapid movement May experience nausea, confusion, increased blood pressure, and drowsiness May experience nausea, confusion, increased blood pressure, and drowsiness

32.  Headache The muscles around the occipital area of the brain constrict the blood flow to the area. The muscles around the occipital area of the brain constrict the blood flow to the area. Tension headaches r/t stress. Tension headaches r/t stress.  Migraine headaches Vascular headaches of unknown cause Vascular headaches of unknown cause Pain results from narrowing of blood vessels in the brain Pain results from narrowing of blood vessels in the brain Can cause gastrointestinal problems such as vomiting. Can cause gastrointestinal problems such as vomiting. May require prescription medication May require prescription medication  Sinus headaches Caused by swelling of the membranes that line the sinus cavities Caused by swelling of the membranes that line the sinus cavities

33.  Meningitis Serious inflammation of the meninges caused by a bacterium, virus, or fungus Serious inflammation of the meninges caused by a bacterium, virus, or fungus Symptoms include: high fever, stiff neck, vomiting, severe HA, and convulsions Symptoms include: high fever, stiff neck, vomiting, severe HA, and convulsions Can lead to blindness, loss of hearing, paralysis, or retardation. Can lead to blindness, loss of hearing, paralysis, or retardation.  Multiple sclerosis Defect in electrical transmission of the neurons caused by degeneration of the myelin sheath Defect in electrical transmission of the neurons caused by degeneration of the myelin sheath Usually appears in adults ages 20-40 Usually appears in adults ages 20-40 Symptoms are progressive loss of muscle control Symptoms are progressive loss of muscle control

34. FIGURE 19-13 The signs of Parkinsonism include rigidity and trembling of the head and extremities. (From Thibodeau GA, Patton KT: Human body in health and disease, ed 4, St Louis, 2005, Mosby.) Parkinson’s disease o Degeneration of certain brain cells o Sometimes called shaking palsy o Caused by a decrease in the secretion of dopamine, a neurotransmitter o Person gradually feels stiffness and tremors, leading to uncontrolled muscle movements and rigidity

35.  Seizure Results from injury, infection, or epilepsy Results from injury, infection, or epilepsy More than 40 types More than 40 types Classified into 2 groups Classified into 2 groups  Partial seizures- involving part of the brain  Generalized- involving the whole brain  Absence seizures-aka petit mal  Febrile & chemical- resulting from medications  Grand mal- a series od distinctive tonic & clonic spasms that last several minutes.  Spinal cord injuries Trauma occurring in the cervical and lumbar area of the spinal column Trauma occurring in the cervical and lumbar area of the spinal column