Case Study of Sarah Kate - Bell's Palsy

Sarah Kate was an active 22 year old in the midst of a pandemic. She went with her friend hiking to get away from the city. About a quarter of a way through a hike, her legs gave out. She thought she was just overheated and tired. Fast forward to a return to school, she found that she could not fo...

Sarah Kate was an active 22 year old in the midst of a pandemic. She went with her friend hiking to get away from the city. About a quarter of a way through a hike, her legs gave out. She thought she was just overheated and tired. Fast forward to a return to school, she found that she could not focus her eyes. She thought she just spent too much time studying and was tired. Case Story - Sarah Kate She woke up the next day discover that the whole side of her face was paralyzed. Notes Handout After she went to the hospital, she was diagnosed with Bell’s Palsy. The doctor’s gave her medication and that relieved the paralysis. She went back to school and was scheduled for a follow-up appointment to get further tests. Then she noticed a weird symptom. When she breathed, she felt a vibration go down her spine. Weird! After having more issues with numbness in her hands and feet, her mother convinced her to go to the ER. There, she saw several neurologists who asked her to perform several tasks such as: touch your nose walk in a straight line read a passage of text An MRI was ordered to scan her brain. What do you notice about this image? Sarah’s next test was a lumbar puncture. A needle is placed between the lumbar and spinal fluid is drawn to check for inflammation and bacterial infection. As the paralysis got worse, Sarah Kate was preparing for the worst. The doctor came in and declared that the MRI showed she had multiple brain lesions. Diagnosis: Multiple Sclerosis A high dose of steroids alleviated some of the paralysis. The main reason the problems were so sudden was the location of the lesions near her spinal cord. The Nervous System - Includes the brain, spinal cord and the nerves Overall function - coordinate the body’s systems by receiving and sending information; maintaining homeostasis Sensory - receives information Integrative - determines where information is sent Motor - responds to signals Two Divisions of the Nervous System Central Nervous System (CNS) Brain and spinal cord Peripheral Nervous System (PNS) Nerves throughout the body  31 /12 Peripheral Nervous System (PNS) 31 pairs of spinal nerves 8 cervical nerve pairs (C1-C8) 12 thoracic nerve pairs (T1- T12) 5 lumbar nerve pairs (L1-L5) 5 sacral (S1-S5) 1 coccygeal nerve pair 12 pairs of cranial nerves What happens when the spinal cord is damaged? Injuries to nerves can result in paralysis. Somatic Nervous System - skeletal - voluntary Autonomic Nervous System - smooth muscles - glands - involuntary Autonomic Nervous System (2 branches) Parasympathetic (rest and digest) Sympathetic (fight or flight) What was going on with Sarah? Why did she have lesions on her brain that caused so many problems? The answer lies within the cells of her nervous system: the NEURONS. Symptoms associated with MS: Sensory loss: numbness in limbs, burning or prickly sensations Spinal cord symptoms (motor): muscle cramping, paralysis Vision problems: blindness or blurred vision Constitutional symptoms: fatigue and dizziness Cognitive difficulties: concentration, memory, and judgment Mental health: depression, bipolar disorder or dementia Neurons = masses of nerve cells that transmit information 1 *functional unit of the nervous system 1. Cell Body - contains the 2 nucleus and other cell organelles 3 2. Dendrites – shorter, more numerous, receive information 3. Axons - single long fibers, conducts information away from the cell Chromatophilic substance (rough ER) - transport system Myelin -insulation surrounding axons Nodes of Ranvier - gaps in the insulation Neuroglial Cells - Support for neurons node of ranvier 1. Microglial Cells - Immune function; digest debris, kills bacteria 2. Oligodendrocytes - make myelin sheath that provides insulation around the axons - central nervous system 3. Astrocytes - -connect blood vessels to neurons -nutrient supply 4. Ependymal Cells - forms membranes around tissue - filters blood to make cerebrospinal fluid 5. Schwann cells: - form the insulating myelin sheath around the neurons in the PNS - axon regeneration - impaired Schwann cells associated with multiple sclerosis (same function as oligodendrocytes, which are found in the CNS)  Which cell…. A 1. Creates myelin sheath 2. Has an immune function 0 3. Forms a membrane 4. Connects to a blood M supply E Practice with neuroglia coloring! Neuron C oloring  Myelin Sheaths - insulate axons - damage interferes with nerve signals - in MS, demyelination causes symptoms What is wrong with Sarah? As the neurons lose their myelin, the nerves are unable to send or receive signals. What aspects of Sarah’s symptoms indicate loss of these signals? PARALYSIS Lesions are evidence of nerve cell damage in your brain or spinal cord. - lesions on the spinal cord may cause motor problems and paralysis - lesions on the cerebellum may cause balance problems Why are the neuron’s in Sarah’s brain demyelinating? Why is this called an AUTOIMMUNE disease? -- immune cells attacking myelin What does “sclerosis” mean? -- scarring Myelinated (white matter) - myelinated axons Unmyelinated (grey matter) - unmyelinated Nerve impulses Dendrites receive signal → signal passes down axon → crosses to the dendrites of a neighboring neuron Nerve Impulse Speed is proportional to the size of the axon greater diameter = faster impulse Myelinated axons conduct impulses faster than unmyelinated one Treatments for MS Most treatments focus on suppressing the immune system so that immune cells do not continue to attack neurons. Corticosteroids: A synthetic adrenal steroid that reduces inflammation and relieves symptoms. Corticosteroids are usually injected into a vein for three to five days. Disease-modifying therapies: Medicines that reduce the number and severity of relapses. Muscle relaxants: Medications that relieve muscle spasms, cramps, or stiffness. Plasma exchange: A treatment similar to dialysis that can speed up recovery from an MS attack. Rehabilitation: Activities that help improve function and mobility, such as exercise, learning to use equipment like canes or walkers, and setting up an exercise program. Nerve Impulses = weak electric current, like a wave ions provide the current (Sodium and Potassium) Communication Between Neurons Synapse = junction between two communicating neurons Nerve pathway - nerve impulse travels from neuron to neuron Dendrite → cell body → along axon -> synapse (gap) → dendrite To complete the signal, a NEUROTRANSMITTER is released at the gap to signal the next neuron. Receptors on the dendrite receive the chemical message Types of Neurotransmitters Excitatory - increase membrane permeability, increases chance for threshold to be achieved Inhibitory - decrease membrane permeability, decrease chance for threshold to be achieved Anatomy of the Synapse A: Neuron (axon) B: Neuron (dendrite) 1. Mitochondria 2. Vesicle 3. Receptor 4. Synapse 5. Receptor 6. Calcium Channel 7. Releases neurotransmitter 8. Re-uptake Examples of Neurotransmitters Acetylcholine - stimulates muscle contraction Dopamine - mood, happiness Serotonin = sleepiness and mood Norepinephrine - fight or flight response Endorphins = pain reduction, mood Agonist = molecule that has the same effect on the neuron as the neurotransmitter itself does. Antagonist = molecule that blocks the effect that the neurotransmitter normally has on the Anatomy of a Nerve Impulse (Coloring) postsynaptic neuron. Antidepressants Zoloft is part of a class of drugs called selective serotonin reuptake inhibitors it inhibits the uptake of serotonin back into the cell, keeping mood elevated for a longer time. Drugs and the Nervous System Cocaine - attaches to the dopamine transporter and blocks the normal recycling process, resulting in a buildup of dopamine in the synapse, which contributes to the pleasurable effects of cocaine. Your neurotransmitters on cocaine Ecstasy (MDMA) The neurotransmitter serotonin is vital in The most common cause of regulating many of our basic functions. Ecstasy-related death is Serotonin is, among other things, the feel overheating (hyperthermia). good neurotransmitter and helps to regulate body temp. Our brain cells are recycle serotonin back into the cells and out of the synapse using serotonin reuptake transporters. Ecstasy essentially takes these upkeep transporters and reverses their roles. This causes a massive flood of serotonin from the brain cells into the synapse. Heroin GABA Activates opiate receptors Blocks release of GABA More dopamine is released DOPAMINE Amphetamines Mimic dopamine - binding to receptors Dopamine does not re-enter the cell, depleting the cell’s supply Disorders Related to Neurons ALS - (Lou Gehrig’s Disease) Amyotrophic Lateral Sclerosis Progressive degeneration of nerve cells in the spinal cord and brain NEURODEGENERATIVE - this means symptoms will get worse over time. - most patients die within 5 years of diagnosis Epilepsy Epileptic seizures are caused by excessive electrical activity within networks of neurons in the brain. If there is too much glutamate, neurons can become hyperexcitable and a seizure may result. Too little GABA (inhibitory) can also result in a seizure. 2 Minute Neuroscience - Epilepsy Myasthenia Gravis autoimmune disorder in which antibodies destroy neuromuscular connections We did a case study on this during the muscle chapter, do you remember it? Poliomyelitis (virus) Polio is an illness caused by a virus that mainly affects nerves in the spinal cord or brain stem. In its most severe form, polio can lead to paralysis. Polio vaccines became available in the 1950’s. Alzheimer’s Disease Brain cell connections and the cells themselves degenerate and die, eventually destroying memory and other important mental functions. See: Case Study - Fading Memories Dendrite Axon terminal Node of Ranvier Cell Body Chromatophilic Substance Schwann’s cells Myelin sheath Nucleus