Central Nervous System
The central nervous system (CNS) consists of what two components?
Brain and Spinal Cord
non-neuronal cells in the central nervous system
Neuroglia or glial cells
What are the left and right hemispheres of the brain typically responsible for?
Left: Language, Intellect, Logical thinking
Right: visual-spatial skills, emotion, artistic/musical skills
During repolarization, what flows out of the cell to restore the negative charge inside the membrane?
Potassium ions
What is the function of the central nervous system?
Responsible for almost everything we do, think, and feel.
Oligodendrocyte
Explain the concept of Contralateral Control
Each hemisphere controls the opposite side of the body.
What actively pumps three sodium ions out of the cell for every two potassium ions it pumps in?
The sodium-potassium pump
Name the four major regions of the brain
Cerebrum, Diencephalon, Brain Stem, Cerebellum.
Long extension or fiber that transmits electrical impulses away from the cell body to other cells
Axon
Explain the functions of the four lobes of the brain
Frontal: Voluntary movement, planning, decision-making, consciousness & personality
Parietal: Sensation, temperature, touch, pain, spatial perception
Temporal: Hearing, smell, memory
Occipital: Vision, vision association
The all-or-nothing threshold for an action potential to occur is approximately what?
-55 mV
Given that white matter contains more myelinated axons than gray matter, what is white matter optimized for in the central nervous system?
Transferring signals rapidly throughout the CNS.
Which cells are the main source of immune defense against invading microorganisms in the CNS?
Microglial cells
Prefrontal: intellect, cognition, reasoning, planning, personality
Broca's Area: Speech production
Wernicke's Area: Language comprehension
A patient experiences a mutation that results in malfunctioning voltage-gated sodium channels, preventing them from opening properly. How would this affect the generation of an action potential, and what symptoms might the patient experience?
Since voltage-gated sodium channels fail to open, depolarization would not occur, preventing the neuron from reaching the threshold and firing an action potential. This could lead to neuromuscular impairments, such as muscle weakness, paralysis, or sensory deficits, depending on the affected neurons.
A patient suffers a traumatic injury that severs several myelinated axons in the white matter of their spinal cord. Explain how this might affect the speed and coordination of signal transmission in their central nervous system and suggest one potential treatment or strategy to promote recovery.
The injury would slow down or block signals in the central nervous system, affecting movement, sensation, or other body functions depending on where it happened. Recovery could involve physical therapy to help retrain the body or treatments like stem cells to repair the damaged myelin.
A person experiences delayed reflexes and muscle weakness due to damage that slows the transmission of nerve signals. This damage most likely affects which part of the neuron, and what structural component is involved?
The axon and the myelin sheath.
A bilingual patient who recently suffered a brain injury can still speak their first language fluently but struggles with grammar and syntax in their second language. Which region of the cerebrum is most likely affected, and why might this deficit be specific to the second language?
Broca's area. This region is critical for language production, and the second language often relies more heavily on explicit grammatical processing, which is mediated by Broca's area and can be more vulnerable to damage.
A person is exposed to a toxin that blocks the sodium-potassium pump. Over time, how would this affect neuronal action potentials, and what physiological consequences might occur?
The sodium-potassium pump is essential for maintaining the resting membrane potential by actively transporting sodium out and potassium into the cell. If this pump is blocked, sodium would gradually accumulate inside the neuron, and potassium would leak out, causing the resting membrane potential to become less negative (closer to zero).
Over time, this would make it harder for neurons to repolarize after firing, leading to neuronal dysfunction. Consequences might include muscle paralysis, cognitive impairment, cardiac arrhythmias, and potentially fatal nervous system failure due to the loss of proper electrical signaling.
A patient suffers a traumatic brain injury that damages the brainstem, specifically the medulla oblongata. What vital functions might be affected, and why could this type of injury be life-threatening?
The medulla oblongata controls autonomic functions such as breathing, heart rate, and blood pressure regulation. Damage to this region could result in respiratory failure, cardiovascular instability, and loss of reflexes like swallowing and gag reflex, potentially leading to death without medical intervention.
A new experimental drug is designed to target microglia and reduce their activity. While this might help in reducing neuroinflammation, what unintended consequences could this have on overall brain function?
Microglia are the brain's immune cells, responsible for removing pathogens, dead neurons, and toxic waste. If microglial activity is suppressed, the brain might become vulnerable to infections, buildup of cellular debris, and neurodegenerative diseases like Alzheimer’s or Parkinson’s. Additionally, impaired microglial function might weaken synaptic pruning, which is essential for learning and memory.
A stroke patient has difficulty recognizing familiar faces but can still identify objects and people by their voice. Based on this symptom, which lobe of the cerebrum is most likely damaged, and what specific brain region is involved?
The temporal lobe, specifically the fusiform gyrus (fusiform face area - FFA), is responsible for facial recognition.
A neuroscientist is studying a rare neurological disorder where neurons exhibit prolonged depolarization and delayed repolarization. Genetic testing reveals a mutation in a specific ion channel. Based on your knowledge of neuronal action potentials, which ion channel is most likely affected, how does this mutation alter neuronal function, and what potential symptoms could result?
The most likely affected ion channel is the voltage-gated potassium channel, which is responsible for repolarization by allowing potassium ions to exit the neuron. If this channel is mutated or dysfunctional, potassium would not leave the cell as efficiently, leading to prolonged depolarization and delayed repolarization.
This could cause neuronal hyperexcitability because the neuron remains depolarized longer, making it easier to fire repeated action potentials. Potential symptoms might include muscle spasms, seizures, heightened pain sensitivity, or irregular heart rhythms (if cardiac neurons are affected) due to the excessive neuronal firing.