Nervous System: Vocabulary: Videos & Practice Problems

Understanding nervous system disorders involves recognizing conditions like Bell's palsy, cerebral palsy, Huntington's chorea, Guillain-Barré syndrome, multiple sclerosis, Parkinson's disease, Alzheimer's disease, and spina bifida. Diagnostic procedures include Babinski's sign, deep tendon reflex, Romberg test, and imaging like PET scans. Neurotransmitters such as acetylcholine, endorphins, and dopamine play key roles in muscle communication, pain reduction, and mood regulation. Treatments like anticonvulsants and levodopa address seizures and dopamine deficiencies, highlighting the integration of physiology and pharmacology in managing neurological health.

Nervous System Disorders Concept 1

Medical terminology related to nervous system disorders encompasses a variety of conditions characterized by distinct symptoms and underlying causes. Bell's palsy is identified by sudden, temporary unilateral facial paralysis, causing one side of the face to droop or become immobile. This condition is reversible and often linked to nerve inflammation or viral infections. In contrast, cerebral palsy results from brain damage affecting motor control, typically occurring during childbirth, leading to lifelong motor impairments. The term "palsy" in both conditions refers to paralysis or weakness.

Huntington's chorea is a fatal hereditary disorder marked by involuntary, jerky movements resembling uncoordinated dancing. This neurodegenerative disease progressively impairs motor function and cognitive abilities. Guillain-Barré syndrome (GBS) is an acute autoimmune disorder where the immune system attacks the myelin sheath—the fatty insulation surrounding nerve axons—resulting in muscle weakness, sensory disturbances, and potentially breathing difficulties. Unlike GBS, multiple sclerosis (MS) is a chronic autoimmune disease also targeting the myelin sheath, causing long-term neurological symptoms due to disrupted nerve signal transmission.

Parkinson's disease is a progressive neurological disorder characterized by the degeneration of dopamine-producing neurons in the brain, leading to motor symptoms such as tremors, rigidity, and bradykinesia. Dopamine is a critical neurotransmitter for coordinating movement, and its deficiency underlies the hallmark symptoms of Parkinson's. Alzheimer's disease involves chronic neurodegeneration with widespread neuron death, resulting in dementia and memory loss, predominantly affecting older adults.

Reye syndrome is a rare but serious condition triggered by viral infections combined with aspirin use in children, leading to brain and liver damage. Awareness of this syndrome is crucial in pediatric care to prevent exacerbation of symptoms. Sciatica refers to pain, numbness, or tingling radiating along the sciatic nerve down the leg, often caused by nerve compression or injury.

Spina bifida is a congenital defect where the spinal cord fails to close completely during fetal development, resulting in a gap or bulge in the spine. This malformation can cause varying degrees of neurological impairment depending on severity. Lastly, akathisia is a movement disorder characterized by an inability to remain still, often manifesting as restlessness or constant motion, and can be a side effect of certain medications or neurological conditions.

Understanding these neurological disorders involves recognizing their distinct pathophysiology, symptoms, and progression. Key concepts include the role of the myelin sheath in nerve conduction, the impact of neurotransmitter deficits such as dopamine in Parkinson's disease, and the importance of early detection and management to mitigate long-term effects. These terms and their associated clinical features form a foundational vocabulary for studying nervous system pathologies.

Nervous System Disorders Example 1

A 32-year-old woman presenting with progressive memory loss, concentration difficulties, vertigo, hearing loss, muscle spasms, and walking problems, along with MRI evidence of brain demyelination, is likely experiencing multiple sclerosis (MS). Demyelination refers to the destruction of the myelin sheath, which insulates nerve fibers and facilitates rapid nerve signal transmission. Two primary conditions involving demyelination are Guillain-Barré syndrome and multiple sclerosis. Guillain-Barré syndrome is characterized by acute onset and rapid progression, often affecting the peripheral nervous system, whereas multiple sclerosis is a chronic, progressive disease affecting the central nervous system. The chronic nature of symptoms and brain involvement in this case strongly indicate multiple sclerosis as the diagnosis. Understanding the distinction between acute and chronic demyelinating diseases is crucial for accurate diagnosis and treatment planning.

A lumbar puncture was done on a patient suffering from bradykinesia, tremors, long bouts of depression and fatigue. The cerebrospinal fluid collected shows a decrease in white blood cell count and a significantly reduced dopamine level. Based on their analysis the patient suffers from which of the following disorders? 

• A. MS
• B. Cerebral Palsy
• C. Parkinson’s Disease
• D. Bipolar Disorder
• E. Bell’s Palsy 

Answer: (C)

Medical Procedures Concept 2

Understanding key medical terms related to the nervous system is essential for recognizing and diagnosing neurological disorders. One important reflex is the Babinski's sign, which involves stroking the side of the foot to observe the movement of the big toe. In infants under two years old, a positive Babinski's sign is when the big toe moves upward while the other toes point downward, indicating normal neurological development. However, in individuals older than two, this same response may suggest damage to the brain or spinal cord, as the expected reaction is the big toe moving downward with the other toes fanning upward.

The deep tendon reflex is another critical neurological test, commonly assessed by tapping the knee with a reflex hammer. This action causes a muscle contraction, such as the leg kicking forward, which helps evaluate the integrity of the nervous system pathways.

Balance and coordination are evaluated using the Romberg test, which measures a person's ability to maintain physical stability by standing still with eyes closed or on one leg. This test helps identify issues with proprioception or vestibular function.

Spasticity refers to an abnormal increase in muscle tone, resulting in tight, stiff muscles that can fatigue easily due to constant contraction. This condition often arises from neurological damage affecting motor control.

Tremors are involuntary, repetitive oscillating movements, commonly described as shaking or trembling, which can be symptomatic of various neurological disorders.

Before seizures or migraines, some individuals experience an aura, which includes unusual sensory perceptions such as visual disturbances or strange smells. This phenomenon acts as a warning sign of an impending neurological event.

Syncope is the medical term for fainting, typically caused by a temporary drop in cranial blood pressure, leading to a brief loss of consciousness.

In surgical contexts, burr holes are small openings drilled into the skull to relieve intracranial pressure by allowing fluid drainage. This procedure is crucial in managing conditions that cause increased pressure within the brain.

A hydrocephalus shunt is a flexible tube surgically implanted to drain excess cerebrospinal fluid from the brain, preventing fluid accumulation. The term breaks down into "hydro" meaning water, "cephalo" meaning head, and "shunt" meaning to bypass, illustrating its function as a bypass for excess fluid.

Imaging techniques such as positron emission tomography (PET) scans utilize radioactive glucose to visualize metabolic activity in the brain. Since glucose is a primary energy source for brain cells, PET scans help detect abnormalities by highlighting areas of altered glucose uptake.

Familiarity with these neurological terms and procedures enhances understanding of nervous system function and aids in the diagnosis and treatment of neurological disorders.

Medical Procedures Example 2

Spasticity is a form of hypertonia characterized by an abnormal increase in muscle tone, leading to excessive tightness in the muscles. This heightened muscle tone is not just a temporary state; it can cause muscle fatigue and weakness over time due to the constant strain on the muscles. Understanding spasticity is crucial because it highlights how sustained muscle tightness can impair muscle function and endurance.

Deep tendon reflexes are involuntary responses that involve both the central nervous system (CNS) and the peripheral nervous system (PNS). When a tendon is tapped, sensory signals travel through the PNS to the CNS, which processes the information and sends a motor response back through the PNS to the muscle, causing it to contract. This reflex arc demonstrates the integrated function of both nervous system components rather than being limited to the CNS alone.

Hydrocephalus shunts are medical devices implanted to drain excess cerebrospinal fluid and relieve pressure in the brain. Although these shunts integrate with the body to some extent, they are mechanical devices that may require replacement, especially as a patient grows or if the device malfunctions. This adaptability is important for long-term management of hydrocephalus, emphasizing that such shunts are not permanent, irreplaceable implants.

Syncope refers to a temporary loss of consciousness caused by a transient decrease in cranial blood flow, commonly known as fainting. It is important to distinguish syncope from permanent loss of consciousness or coma, as syncope is reversible and typically brief. This distinction is vital for accurate diagnosis and treatment of conditions affecting cerebral perfusion.

In summary, spasticity is a type of hypertonia that can lead to muscle fatigue and weakness due to sustained muscle tightness. Deep tendon reflexes involve both the central and peripheral nervous systems, hydrocephalus shunts can be replaced as needed, and syncope is a temporary, not permanent, loss of consciousness. These concepts are fundamental in understanding neuromuscular function and neurological disorders.

Which of the following would not be a reasonable use for burr holes? 

• A. Taking a biopsy of brain matter.  
• B. Implementation of a medical device such as a shunt. 
• C. Removal of a solid clot.  
• D. Treatment of hydrocephalus. 

Answer: (C)

Physiology & Pharmacology Concept 3

Understanding the physiology and pharmacology of neurotransmitters and drugs is essential for grasping how the nervous system functions and responds to treatment. Acetylcholine (ACh) is a key neurotransmitter that facilitates communication between neurons and muscle cells, playing a crucial role in muscle contraction and memory processes. This connection highlights how signals from neurons stimulate muscle fibers to contract, enabling movement and coordination.

Endorphins are another important class of neurotransmitters that act as natural painkillers by reducing pain perception and promoting feelings of well-being. Their ability to modulate pain makes them vital in managing stress and discomfort within the nervous system.

Dopamine is a neurotransmitter deeply involved in regulating movement, mood, and motivation. Often referred to as the "feel-good" hormone, dopamine influences emotional responses and motor control, making it central to both psychological and physical health.

In pharmacology, anticonvulsants are medications designed to prevent or control seizures by stabilizing neural activity and reducing excessive electrical discharges in the brain. These drugs are critical in managing conditions like epilepsy, where uncontrolled neuronal firing leads to convulsions.

Levodopa is a pharmacological agent used to treat dopamine deficiency, particularly in disorders such as Parkinson's disease. By acting as a precursor to dopamine, levodopa helps restore dopamine levels in the brain, improving motor function and alleviating symptoms related to dopamine loss.

Overall, the interplay between neurotransmitters like acetylcholine, endorphins, and dopamine, along with pharmacological agents such as anticonvulsants and levodopa, illustrates the complex mechanisms underlying nervous system physiology and therapeutic interventions.

Physiology & Pharmacology Example 3

Levodopa primarily influences mood by acting on the central nervous system rather than the peripheral nervous system, as mood regulation is controlled centrally. Acetylcholine plays a crucial role in promoting muscle contraction while simultaneously inhibiting muscle relaxation, highlighting its dual function in neuromuscular activity. When acetylcholine levels increase, muscle contraction is enhanced, which naturally suppresses muscle relaxation.

Endorphins are neurotransmitters that elevate the pain threshold, helping to reduce the perception of pain, but they do not render a person completely immune to pain sensations. Instead, they modulate pain by providing analgesic effects, allowing for better pain management rather than total elimination.

Dopamine is a key neurotransmitter involved in regulating mood, motivation, and motor control, often referred to as the "feel-good" hormone. However, it does not play a significant role in thermoregulation, which is the body's process of maintaining its internal temperature.

Understanding these neurotransmitters and their functions is essential for grasping how the nervous system controls both physical and emotional responses. Acetylcholine's role in muscle contraction and relaxation, endorphins' modulation of pain, and dopamine's influence on mood and motivation illustrate the complex interplay within the central nervous system.

What is the primary role of endorphins in the human body? 

• A. Regulate the circadian rhythm when it comes to our sleep-wake cycles.  
• B. Stimulate muscle contraction in voluntary movements.  
• C. Act as the body’s natural pain relievers and to enhance feelings of pleasure.  
• D. Regulate our fight-or-flight response to an external stressor.  

Answer: (C)

Here’s what students ask on this topic:

What are the main differences between Bell's palsy and cerebral palsy?

Bell's palsy is a sudden, temporary unilateral facial paralysis causing one side of the face to droop or become frozen. It is often temporary and can be remembered as "Bell's pausing." In contrast, cerebral palsy is a brain damage condition affecting the motor control center, typically occurring during childbirth. It results in long-term motor impairments and is remembered as "cerebrum pausing." While Bell's palsy affects facial muscles temporarily, cerebral palsy involves permanent motor control issues due to brain injury.

How do Guillain-Barré syndrome and multiple sclerosis differ in terms of their impact on the nervous system?

Guillain-Barré syndrome (GBS) is an acute autoimmune disorder that causes destruction of the myelin sheath around peripheral nerves, leading to rapid onset of weakness, breathing problems, and sensory disturbances. It is considered a short-term condition. Multiple sclerosis (MS), on the other hand, is a chronic autoimmune disorder that also destroys myelin sheaths but primarily affects the central nervous system over a long period. MS symptoms progress slowly and involve scrambled nerve signals, remembered as "my sheets are scrambled." The key difference is that GBS is acute and peripheral, while MS is chronic and central.

What is the significance of the Babinski's sign in neurological examinations?

Babinski's sign is a neurological test where the side of the foot is stroked with an object to observe the big toe's movement. In infants under two years old, a positive Babinski's sign is normal, where the big toe moves upward and other toes fan out. However, in individuals older than two, this response indicates possible brain or spinal cord damage if the big toe moves upward instead of downward. Thus, Babinski's sign helps assess the integrity of the central nervous system and detect neurological abnormalities.

What roles do neurotransmitters like acetylcholine, endorphins, and dopamine play in the nervous system?

Acetylcholine (ACH) is a neurotransmitter that facilitates communication between neurons and muscle cells, essential for muscle contraction and memory functions. Endorphins act as natural painkillers by reducing pain sensations and promoting feelings of well-being, often called "end pain." Dopamine is crucial for regulating movement, mood, and motivation, often referred to as the "feel-good hormone." These neurotransmitters are vital for normal nervous system function, influencing muscle activity, emotional states, and pain management.

How do anticonvulsants and levodopa function in treating nervous system disorders?

Anticonvulsants are medications used to prevent or control seizures by stabilizing nerve activity and reducing abnormal electrical impulses in the brain. They are often described as "anti-commotion" drugs because they stop the shaking associated with seizures. Levodopa is a drug that treats dopamine deficiency, especially in Parkinson's disease, by acting as a precursor to dopamine and increasing its levels in the brain. This helps improve movement and motor control in patients with dopamine-related disorders.

What is the purpose of a hydrocephalus shunt and how does it work?

A hydrocephalus shunt is a flexible tube surgically placed in the brain to drain excess cerebrospinal fluid, preventing increased intracranial pressure. The term "hydrocephalus" means "water on the brain," and the shunt acts as a bypass to redirect fluid from the brain to another part of the body where it can be absorbed. This procedure helps relieve symptoms caused by fluid buildup, such as headaches and brain swelling, and is critical in managing hydrocephalus, especially in infants.