Frequently Asked Questions About the Nervous System & The Digestive System: How Your Body Processes Food From Mouth to Intestines

Can the brain regenerate neurons like other body parts heal?

The adult brain has limited but real regenerative capacity. The hippocampus and olfactory bulb generate new neurons throughout life, though at decreasing rates with age. Most brain regions don't generate new neurons but can form new connections and reorganize existing circuits. After injury, surviving neurons can sprout new connections and take over lost functions to some degree. While we can't regrow large brain sections like a lizard regrows its tail, the brain's plasticity enables remarkable recovery through rehabilitation.

Why do we have reflexes, and can we control them?

Reflexes evolved as rapid protective responses bypassing conscious processing. Spinal reflexes like the knee-jerk response or withdrawal from pain occur before the brain perceives the stimulus. This speed advantage prevents injury—you pull your hand from a hot stove before feeling pain. While you can't prevent the initial reflex, you can sometimes override it consciously. With practice, people can suppress some reflexes, but the most protective ones resist conscious control for good evolutionary reasons.

What causes "brain freeze" when eating cold foods?

Brain freeze (sphenopalatine ganglioneuralgia) occurs when cold foods contact the palate, causing rapid blood vessel constriction and dilation. Temperature receptors in the palate send signals via the trigeminal nerve, which also carries facial pain signals. The brain interprets these signals as coming from the forehead, causing referred pain. The pain typically lasts 30-60 seconds until temperature normalizes. Pressing your tongue against the palate or drinking warm water can help by warming the area faster.

Why do we dream, and what happens in the brain during dreams?

Dreams occur primarily during REM (rapid eye movement) sleep when the brain shows activity patterns similar to waking. The visual cortex activates strongly, creating imagery, while the prefrontal cortex responsible for logic and self-awareness decreases activity—explaining dreams' bizarre nature. The emotional centers remain highly active, giving dreams their intense feelings. Current theories suggest dreams help consolidate memories, process emotions, and possibly prepare for future threats through simulation. Everyone dreams multiple times nightly, but memory formation is suppressed, so we forget most dreams unless awakened during them.

Can stress physically damage the brain?

Yes, chronic stress causes measurable brain changes. Prolonged elevation of stress hormones like cortisol damages hippocampal neurons essential for memory formation. The prefrontal cortex shrinks, impairing decision-making and emotional regulation. Meanwhile, the amygdala (fear center) becomes overactive. These changes are partially reversible with stress reduction, exercise, and treatment. Acute stress temporarily impairs function but doesn't cause permanent damage. The key distinction is duration—short-term stress is normal and even beneficial, while chronic stress harms both brain structure and function.

Why do we get dizzy when spinning?

Dizziness from spinning results from fluid movement in the inner ear's semicircular canals. These three fluid-filled loops oriented in different planes detect rotational movement. When you spin, the fluid initially lags behind, bending hair cells that signal rotation to the brain. When you stop, the fluid continues moving, sending false signals that you're spinning in the opposite direction. Your eyes may show nystagmus (rhythmic movements) as the nervous system tries to maintain visual stability. The dizziness subsides as fluid movement stops and signals normalize.

What's the difference between the left and right brain?

While both hemispheres work together for most functions, some specialization exists. The left hemisphere typically specializes in language, logical reasoning, and sequential processing. The right hemisphere excels at spatial processing, pattern recognition, and emotional processing. However, the popular notion of "left-brained" or "right-brained" people is oversimplified. Everyone uses both hemispheres constantly, with the corpus callosum enabling rapid communication. Even specialized functions involve both sides—language comprehension requires left hemisphere grammar processing and right hemisphere interpretation of tone and context.

Can thoughts and emotions affect physical health?

Absolutely. The nervous system's connections to every body system mean mental states profoundly impact physical health. Chronic stress or depression alters immune function, increasing infection susceptibility and slowing wound healing. Anxiety affects digestive function through gut-brain connections. The placebo effect demonstrates how expectations can trigger real physiological changes. Conversely, physical health affects mental state—inflammation influences mood, and gut bacteria produce neurotransmitters. This bidirectional relationship explains why holistic approaches addressing both mental and physical health prove most effective.

Why do we lose consciousness under anesthesia?

General anesthetics work through multiple mechanisms to reversibly shut down consciousness. They enhance inhibitory neurotransmitter (GABA) activity while suppressing excitatory signals. This disrupts the synchronized neural oscillations between the thalamus and cortex necessary for consciousness. Different brain regions shut down in sequence—memory formation stops first, then awareness, and finally basic reflexes. The precise mechanism of consciousness itself remains uncertain, but anesthetics clearly disrupt the integrated information processing required for conscious experience. Modern monitoring ensures the brain maintains vital functions while consciousness is suspended.

Can we improve our memory as we age?

Yes, memory can be maintained and even improved with appropriate strategies. Physical exercise increases BDNF and hippocampal volume. Mental exercises like learning new skills create new neural pathways. Social engagement stimulates multiple brain regions. Memory techniques like association, visualization, and chunking enhance encoding and retrieval. Adequate sleep consolidates memories. Managing cardiovascular risk factors protects brain blood flow. While some age-related changes are inevitable, research shows that active, engaged older adults can maintain excellent memory function and even show improved crystallized intelligence (accumulated knowledge) compared to younger people.

The nervous system represents evolution's most sophisticated achievement—a biological computer capable of consciousness, creativity, and contemplation. From the simplest reflex to the most complex thought, your nervous system orchestrates the symphony of human experience. Understanding this remarkable system empowers you to protect and optimize the very essence of who you are.

Consider this remarkable fact: over your lifetime, your digestive system will process approximately 60 tons of food—equivalent to the weight of 12 elephants! This extraordinary biological factory transforms everything you eat into microscopic nutrients that fuel every cell in your body. The journey from bite to bloodstream involves a precisely choreographed sequence of mechanical grinding, chemical breakdown, and selective absorption that would challenge the world's most sophisticated processing plants. Your digestive system doesn't just break down food; it serves as a critical interface between the outside world and your internal environment, deciding what to absorb and what to reject, defending against pathogens, producing essential vitamins, and even influencing your mood and behavior through the gut-brain axis. Understanding how your digestive system works empowers you to make informed dietary choices, recognize warning signs of digestive problems, and appreciate the incredible complexity hidden behind the simple act of eating a meal.