NUR 606 Exam 3

Paralysis - -loss of motor function Paresis - -weakness Plegia - -stroke or paralysis Mono- - -one limb Hemi- - -both limbs on one side Di- or para- - -both upper limbs or both lower limbs Quadric- or tetra- - -all four limbs 3 possible problems with the motor unit - - 1. skeletal muscle atrophy/dystrophy 2. neuromuscular junction disorders 3. peripheral nerve injury The motor unit - -alpha motor neuron and the muscle fibers it innervates Most of the diseases of the motor unit cause... - -weakness and wasting of skeletal muscle Components of the motor unit which cause disease when affected - - 1. cell body of the motor neuron 2. the axon of the motor neuron 3. the neuromuscular junction (NMJ) 4. muscle fibers Muscle atrophy - -lack of muscle activity; reduces muscle size, tone, and power Reduction in the diameter of the muscle fibers because of a loss of protein filaments Skeletal Muscle Problems: Disuse Atrophy - -- think of how a leg in a cast gets small and weak - normally innervated muscle is not used for a long period of time - muscle cells shrink in diameter, lose contractile proteins, and become weak (do not die) Skeletal Muscle Problems: Muscular Dystrophy - -- DMD and BMD x-linked recessive NUR 606 NUR 606 NUR 606 - caused by mutations in the dystrophin gene Pathophysiology of muscular dystrophy - -the mutation in the dystrophin gene means that the dystrophin protein is not properly attached to the cell membrane, and the muscle cells do not effectively contract. There is progressive degeneration and eventual necrosis of the muscle tissue. Finally, the muscle is replaced by connective tissue Dystrophin - -Links thin filaments to proteins of sarcolemma Duchene muscular dystrophy (DMD) - -*no dystrophin* most common form of muscular dystrophy; affects primarily boys with onset between the ages of 3 and 5 years; the disorder progresses rapidly so that most of these boys are unable to walk by age 12 and later need a respirator to breathe Becker muscular dystrophy (BMD) - -*some dystrophin* very similar to, but less severe than, Duchenne muscular dystrophy Neuromuscular Junction Problems: Decreased Ach Release - -- botulism - gentamicin Neuromuscular Junction Problems: Decreased Achesterase - -- physostigmine - neostigmine - organophosphates Neuromuscular Junction Problems: Decreased ACh effects on Muscle Cells - -- curare - myasthenia gravis Botulism - -Clostridium botulinum is a rod shaped bacteria found in soil. BLOCKS THE RELEASE OF ACH INTO THE NMJ Gentamicin - -Aminoglycoside antibiotic adverse effect is that is can BLOCK THE RELEASE OF ACH INTO THE NMJ Physostigmine and Neostigmine - -used to treat myasthenia graves INHIBIT ACHESTERASE meaning PREVENTS THE BREAKDOWN OF ACH so ACh stays in the NMJ longer - causes loss of respiratory function organophosphates - -bind to achesterase and prevent them from breacking down ach - cause loss of respiratory function curare - -a drug that blocks nicotinic acetylcholine receptors - ACh cannot bind to the receptors on the muscle cells - it paralyzes the individual, but eventually it wears off - think of poison darts used by indigenous South American people NUR 606 NUR 606 myasthenia gravis - -a chronic autoimmune disease that affects the neuromuscular junction and produces serious weakness of voluntary muscles - the ach receptors don't work, so they are treated with drugs that prevent the breakdown of ACh in the NMJ to make the ACh available for longer Myasthenia Gravis - -- autoimmune disease - gradual destruction of ACh receptors b/c the patient makes autoantibodies for the receptors - gradual development of weakness from proximal to distal (usually starts with drooping eyelid) myasthenia crisis - -respiration compromised True or false? Acetylcholinesterase stimulates the release of acetylcholine (ACh). - -FALSE Acetylcholinesterase breaks down ACh, resulting in relaxation of the skeletal muscle. Peripheral Nerve Injuries - --demyelination -axonal degeneration -mononeuropathies -polyneuropathies demyelination - -Segmental demyelination: this occurs when there is a disorder of schwann cells or damage to the myelin sheath like in guillain barre syndrome. axonal degeneration - -usually due to primary injury to cell body or the axon in the spinal and peripheral nerves Looking at trauma or neuropathy and degenerative changes in the axons Mononeuropathies - -DAMAGE TO ONE NERVE Usually associated with a known peripheral nerve injury, and pain is felt at least partly along the distribution of the damaged nerve. Examples: nerve root compression, nerve entrapment, trigeminal neuralgia, CARPAL TUNNEL Polyneuropathies - -Client feels pain along the distribution of MANY PERIPHERAL NERVES. Examples: diabetic neuropathy, alcohol-nutritional neuropathy, and Guillain-Barré syndrome. Cerebellum Damage - -1. Vestibulocerebellar Damage: difficulty maintaining posture 2. Cerebellar Ataxia: staggering, lurching, uncontrolled gait 3. Cerebellar Tremor: rhythmic back & forth, inability to make smooth corrections in movements NUR 606 Basal Ganglia - -structures in the forebrain that help to control movement basal ganglia diagram - -inhibits and modulates movement patterns that are learned (not innate) ex. Tying your shoe cerebellum diagram - - Basal Ganglia Dysfunction - -Tremors Tics Hypokinetic disorders Hyperkinetic disorders - Chorea: jerky movements - Dystonia: rigidity Which disease is a result of basal ganglia dysfunction? A. Myasthenia gravis B. Multiple sclerosis C. Polio D. Tourette syndrome - -D. Tourette syndrome The tics and hyperkinesia that often accompany Tourette syndrome are typical of basal ganglion dysfunction (the function of the basal ganglia is movement control). Tourette syndrome - -involuntary, spasmodic, twitching movements; uncontrollable vocal sounds; and inappropriate words - manifests around 2-15 y.o. - average age of onset: 6 y.o. males 4x more likely to get it Parkinsonism Characteristics - -- tremor - rigidity - bradykinesia - loss of postural reflexes - autonomic system dysfunction - dementia Parkinson's Disease - -- Dr. Parkinson discovered in 1800s - slow progressive disease - Dopaminergic neurons die in the motor track in the substantia nigra in the basal ganglia -NOT ENOUGH DOPAMINE NUR 606 NUR 606 NUR 606 rest tremor - -Parkinsonian tremor ("pill rolling") Most obvious when the limb is fully supported and at rest amyotrophic lateral sclerosis (ALS) - -condition of progressive deterioration of motor nerve cells resulting in total loss of voluntary muscle control; symptoms advance from muscle weakness in the arms and legs, to the muscles of speech, swallowing, and breathing, to total paralysis and death; also known as Lou Gehrig disease - AFFECTS BOTH UPPER AND LOWER MOTOR NEURONS - Multiple Sclerosis - -- damage to upper motor neurons - Autoimmune destruction of myelin coating on axons - demyelination of white matter in CNS - Body produces autoantibodies that attacks the myelin and causes slow action potentials and eventually conduction block - more women have it than men Which disorder is caused by damage to both upper and lower motor neurons? A. ALS B. MS C. Myasthenia gravis D. Parkinson - -A. ALS Rationale: Also known as Lou Gehrig disease, ALS is the result of damage to both upper and lower motor neurons. Typical S/S include weakness, lack of motor control, denervation atrophy, and hyporeflexia. Spinal Cord Injury: Spinal Shock - -IMMEDIATE RESPONSE to cord injury that occurs 30-60 minutes post injury Temporary or complete loss of function below injury primary neurologic injury - -trauma, laceration, contusion Irreversible damage to neurons from hemorrhage and/or edema Necrosis of neural tissue secondary neurologic injury - -follows with further progressive spread of injury. Spread is usually 2 sections above and below primary injury. - release of vasoactive agents & enzymes, ischemia and edema - Vasospasm from NE, serotonin, histamine - Enzymes breakdown proteins, increase demyelination and necrosis NUR 606 NUR 606 Autonomic Dysreflexia - -patients with spinal cord injuries are at risk for developing autonomic dysreflexia (T-6 or above) can cause stroke, cardiac arrest, retinal hemorrhage Hypertension, bradycardia, constriction of peripheral blood vessels Why does autonomic dysreflexia occur? - -The sympathetic NS responds to stimuli inappropriately because it doesn't have communication with visceral motor nuclei (hypothalamus) to regulate it's function Caused by an irritant (burns, blocked catheter, etc.) below the level of injury Complete Spinal Cord Injury - -injury in which there is complete loss of sensation and muscle control below the level of the injury