Nervous System Honor

Science & Health

Requirements

  1. Make a diagram or model of a human brain, including the following parts: medulla, pons, cerebellum, thalamus, hypothalamus, pituitary gland and cerebrum. Describe the basic function of each one.

    Answer: The brain (encephalon) is the central nervous system. Medulla oblongata: controls vital functions (breathing, heart rate, swallowing). Pons: connects the cerebrum/cerebellum, processes sleep. Cerebellum: 'little brain', fine balance. Thalamus: sensory relay station (all senses except smell). Hypothalamus: temperature, hunger, thirst, sleep. Pituitary gland: commands other glands (thyroid, adrenal, gonads). Cerebrum: 4 lobes (frontal, parietal, temporal, occipital) with distinct functions. A three-dimensional diagram aids visualization.

  2. What is a neuron? Draw a neuron and identify its parts. Where does information enter the neuron and where does it leave? What is a synapse?

    Answer: Neuron: a nerve cell that transmits impulses. Parts: dendrites (receive), cell body, axon (sends), terminals. Information enters through the dendrites and leaves through the axon. Synapse: the connection between neurons with neurotransmitters transferring the signal across the actual existing synaptic cleft. — The neuron is the basic unit of the nervous system. The brain has ~86 billion. Dendrites: short branches that capture signals. Cell body (soma): has the nucleus and maintains metabolism. Axon: a long extension that conducts the action potential at 50-120 m/s. The myelin sheath (oligodendrocytes in the CNS, Schwann cells in the PNS) accelerates conduction. Axon terminals (synaptic boutons) release neurotransmitters. Synapse: chemical (most) or electrical (rare). Synaptic cleft ~20 nm. Neurotransmitters: dopamine (pleasure), GABA (inhibitory), glutamate (excitatory).

  3. What are the organs and structures that make up the nervous system?

    Answer: CNS: brain and spinal cord, protected by meninges, cerebrospinal fluid and bones. PNS: cranial nerves (12 pairs) and spinal nerves (31 pairs), ganglia. It subdivides into somatic (voluntary) and autonomic (involuntary, sympathetic/parasympathetic). The system is the anatomical and functional basis of the organism. — The nervous system is an anatomical and functional organization. CNS: brain (~1.4 kg in adults) and spinal cord (~45 cm). Triple protection: meninges (dura mater, arachnoid, pia mater), cerebrospinal fluid (cushions) and bones. PNS: 12 pairs of cranial nerves (from the trigeminal to the hypoglossal) and 31 spinal pairs (cervical, thoracic, lumbar, sacral, coccygeal). Somatic: voluntary control, sensation. Autonomic: viscera, glands. Common disorders: stroke (CNS), diabetic neuropathy (PNS). The system is the basis for all body functions.

  4. Differentiate between the Sympathetic Autonomic Nervous System and the Parasympathetic Autonomic Nervous System, describing the main activities related to each of them.

    Answer: Sympathetic: fight or flight, accelerates the heart, dilates the pupils, adrenaline, inhibits digestion. Parasympathetic: rest and digest, slows the heart, contracts the pupils, activates digestion, conserves energy. Both are complementary and balance the body's involuntary functions according to the actual moment. — The autonomic system is divided into two antagonistic branches. Sympathetic ('fight or flight'): originates in the thoracic and lumbar spinal cord; uses noradrenaline; accelerates heart rate, dilates bronchioles, releases glucose, dilates pupils, inhibits peristalsis. Active during stress, exercise, fright. Parasympathetic ('rest and digest'): originates in the brainstem and sacral spinal cord; uses acetylcholine; reduces heart rate, activates digestion, contracts pupils, conserves energy. Active during rest, sleep, calm eating. The balance between the two maintains homeostasis.

  5. Explain how drugs affect the function of neurons, especially the synapse. Make a commitment to never use drugs.

    Answer: Drugs alter neurotransmitters: cocaine blocks dopamine; alcohol potentiates GABA; nicotine activates acetylcholine; marijuana mimics endocannabinoids. It causes dependence and cognitive loss. A personal commitment to never use them protects the health of the Christian Adventist Pathfinder. — Drugs affect synapses through neurotransmitters. Cocaine: artificially increases synaptic dopamine, causing addiction. Alcohol: GABAergic (depressant); damages neurons with chronic use. Nicotine: nicotinic receptors activate dopamine; high dependence (>50% of users). Marijuana: THC activates CB1 receptors; reduces memory, motivation. LSD: blocks serotonin. Heroin: cerebral opioids. Consequences: dependence, neurodegenerative diseases, depression, suicide. Christian commitment (1 Cor 6:19): the body is the temple of the Spirit.

  6. What is a reflex? Perform the patellar reflex test on someone. (Instructions: ask someone to sit with their feet not touching the floor. Gently give a small tap just below the knee). Explain why this reflex occurs (use the following terms in your report: sensory neuron, motor neuron, spinal cord). Why do doctors use this test in a physical exam?

    Answer: A reflex is an automatic response to a stimulus, without conscious decision. Patellar: the tendon below the knee is tapped; the stretch activates a sensory neuron → spinal cord → motor neuron → contraction of the quadriceps (the leg kicks). Doctors test it to assess the integrity of the reflex arc, identify spinal cord injuries or neurological diseases such as multiple sclerosis and neuropathies. — The reflex is the basis of the nervous system. Simple reflex arc: receptor → sensory neuron → spinal cord → motor neuron → effector. Patellar reflex (stretch reflex): tests spinal segment L2-L4. Time: <50ms. Doctors test it for: integrity of the pathway, comparison between sides (asymmetry suggests injury), exclusion of diseases (multiple sclerosis, herniated disc). Other reflexes: Achilles (heel), biceps (biceps), Babinski (sole of the foot). Diminished or absent: injury; increased: pyramidal lesion. A universal basic neurological exam.

  7. What is a sensory neuron? What is adaptation? Demonstrate what adaptation is by doing the following:
    • Rest your arm on a table and place a lid (or something very light) on top of it. Note what you are feeling at that moment and one minute later, without moving your arm.
    • Place a finger from one hand in a bowl of cold water and a finger from the other hand in one with warm water. After 30 seconds, place both fingers in a bowl of room-temperature water. What did you feel in each finger?
    • What spiritual lesson can you draw from the concept of adaptation?

    Answer: A sensory neuron (afferent) is the nerve cell that captures stimuli from the environment or from the body itself (touch, temperature, pressure, pain, light, sound) and conducts this information from the receptors to the central nervous system. Sensory adaptation is the gradual reduction of a receptor's response to a constant and prolonged stimulus — this is why we stop feeling the clothes on our body, the smell of an environment after a few minutes, or the water that seemed cold and soon feels warm. 1) When resting your arm on the table with a lid (or something very light) on top of it, at the first moment you clearly feel the weight and the contact of the object on your skin. After about a minute, without moving your arm, this sensation greatly diminishes or almost completely disappears: the pressure receptors of the skin have adapted to the constant stimulus and stopped warning the brain about it. 2) After keeping one finger in cold water and another in warm water for 30 seconds, when placing both in room-temperature water each finger feels something different: the finger that was in cold water perceives the room-temperature water as hot (warm), and the finger that was in warm water perceives the same room-temperature water as cold. This happens because each receptor adapted to the previous temperature and begins to judge the new temperature in relation to it. 3) Spiritual lesson: just as the senses adapt and stop perceiving a constant stimulus, the heart can 'adapt' to sin and gradually harden over time, ceasing to feel what once bothered it. Hebrews 3:13 warns us: 'But exhort one another daily... lest any of you be hardened through the deceitfulness of sin'. We need to keep our spiritual sensitivity alive, seeking God daily. — Sensory neurons (afferent) carry information from the sensory organs to the CNS. Sensory adaptation: receptors reduce firing when a stimulus is constant (energy efficiency). Arm example: constant pressure ceases to be perceived. Temperature: relative comparison fools absolute perception. Lesson: spiritual adaptation to sin is dangerous — it starts small (a white lie), becomes routine (no longer perceiving the seriousness), hardens the heart. Solution: daily contact with the Word (Heb 4:12), prayer and fraternal exhortation keep spiritual sensitivity alive.

  8. What are the flavors perceived by taste? Draw a map of your tongue, showing which parts of it respond to the following flavors: sweet, sour, bitter and salty. Instructions: dip a cotton swab in one of the following: sugar water (for sweet), lemon juice (for sour), broth of jiló or guariroba (for bitter) and salt water (for salty). Then, lightly touch different parts of your tongue. Note which areas of your tongue taste the solution. Rinse with pure water and use a new cotton swab with another substance.

    Answer: Four basic flavors: sweet, salty, sour, bitter. Fifth: umami (glutamate). The old map (sweet at the tip, bitter at the back) has been refuted: all taste buds detect all flavors at different intensities. The symbolic map is still used in textbooks for an introduction. — Taste has 4 classic flavors + umami. Sweet: sugar, fruits. Salty: table salt (NaCl). Sour (acidic): lemon, vinegar. Bitter: coffee, jiló, plain tea. Umami: discovered by Ikeda (1908), monosodium glutamate, found in cheeses, meats. The old map (1901, Hänig): refuted by Pardo et al. (1974) — all areas detect all flavors. Approximately 10,000 taste buds with receptor cells renewed every 10 days. Smell complements: 80% of 'taste' comes from smell.

  9. Make a diagram of an eye (model, drawing, etc.), identifying the following parts: pupil, iris, cornea, sclera, lens, aqueous humor, vitreous humor, retina, optic nerve. Explain the function of each of them. Why do you have a blind spot? Find your blind spot. Instructions: place a very small black dot in the center of a white sheet. Close one of your eyes and look straight ahead. Hold the paper and move it until the black dot disappears (this usually happens when the dot is a little below eye level — this is important).

    Answer: Pupil: regulates light. Iris: colored, controls the pupil. Cornea: external lens. Sclera: white, protective. Lens: adjustable internal lens. Aqueous/vitreous humor: fluids. Retina: photoreceptors. Optic nerve: carries the signal to the brain. Blind spot: the location on the retina where the optic nerve exits. — Ocular anatomy is complex. Pupil: adjustable opening (2-8mm). Iris: pigmentation determines eye color (blue, green, brown). Cornea: 2/3 of ocular refraction. Sclera: white, hard, protective. Lens: biconvex lens, adjusts focus (accommodation). Aqueous humor: nourishes the cornea/lens. Vitreous humor: 80% of the ocular volume. Retina: cones (color) and rods (low light). Optic nerve: ~1 million axons. Blind spot (optic disc): no photoreceptors where the nerve exits; the brain 'fills in' the gap. Each one has ~6 degrees of visual angle.

  10. Make a diagram of an ear (model, drawing, etc.), identifying the following parts: auricle, external auditory meatus (or canal), eardrum, malleus, incus, stapes, auditory tube, cochlea and semicircular canals. Explain the function of each of them. Identify the three parts of the ear. Explain why the following activities can be harmful to your hearing:
    • Listening to something on headphones
    • Putting an object in the ear / using cotton swabs
    • Going to a concert / performances with loud music
    • Not treating an ear infection properly

    Answer: Outer: auricle and meatus. Middle: eardrum, malleus, incus, stapes, tube. Inner: cochlea, semicircular canals. Dangers: loud headphones damage the cochlea, cotton swabs puncture the eardrum, concerts and infections cause permanent deafness. Care protects the Pathfinder's hearing. — The ear has 3 parts. Outer: captures sound. The auricle (outer ear) directs it; the meatus carries the sound to the eardrum. Middle: the eardrum vibrates; the malleus, incus, stapes (ossicles) amplify it 22x; the auditory tube (Eustachian) equalizes pressure. Inner: the cochlea (snail-shaped) with hair cells converts vibration into a nerve signal; the semicircular canals maintain balance. Dangers: >85dB for 8h+ damages hair cells (they do not regenerate). In-ear headphones are worse than over-ear. Cotton swab: pushes wax toward the eardrum. Concert: up to 110dB. Infections: otitis media.

  11. Do one or more of the following activities (some of them may need to be planned with a doctor or dentist or together with a college or university):
    • Observe an electroencephalogram and explain its function.
    • Observe a magnetic resonance imaging scan or a computed tomography scan and explain its function.
    • Observe someone being anesthetized and explain how anesthesia works.

    Answer: EEG: records brain electrical activity via electrodes. MRI/CT: imaging exams showing brain structures. Anesthesia: blocks consciousness or pain by acting on synapses. Observing requires medical authorization and a supervised visit to a hospital or clinic by the Pathfinder. — Practical activities integrate theory and actual visualization. EEG (Electroencephalogram): invented by Hans Berger in 1924; electrodes capture alpha, beta, theta, delta waves. MRI: magnetic field + radiofrequency; no ionizing radiation. CT: X-rays in slices. Anesthesia: general (propofol, sevoflurane), regional (spinal anesthesia), local (lidocaine). Observation requires formal hospital/medical authorization — Brazilian laws (CFM Resolution) protect patient privacy. Agreements with Adventist hospitals (Adventist Hospital of São Paulo) facilitate educational visits.

  12. List at least five things you can do to protect your brain from damage.

    Answer: 1) Helmet when cycling. 2) Seat belt. 3) No drugs. 4) Healthy eating. 5) Adequate sleep. 6) Regular exercise. 7) Stimulate the mind. 8) Avoid falls. Each habit reduces the risk of stroke, dementia, head trauma and actual existing neurodegenerative diseases. — The brain is vulnerable to damage. Helmet: reduces brain injuries in cyclists by 70%. Seat belt: 45% fewer deaths. Drugs: cocaine, alcohol, ecstasy damage neurons. Diet: omega-3 (fish), antioxidants (fruits), vegetables reduce inflammation. Sleep: consolidates memory, clears toxins (glymphatic system). Exercise: increases BDNF (neurotrophic factor). Mental stimulation: cognitive reserve against Alzheimer's. Falls: 30% cause of stroke in the elderly. Care accumulates: good habits early in life = a healthy brain at 80 years old.

  13. Do one of the following:
    • Visit and help someone (a minimum of 2 hours) who has a cognitive or nervous system disease and describe what special care is needed.
    • Briefly describe the following nervous system disorders: Alzheimer's disease, multiple sclerosis, epilepsy, depression, Down syndrome, Huntington's disease, quadriplegia, and paraplegia.

    Answer: Option 1: a 2h+ visit to someone with a neurological disease requiring special care. Option 2: describe Alzheimer's (memory), multiple sclerosis (myelin), epilepsy (discharges), depression, Down syndrome (trisomy 21), Huntington's, quadriplegia/paraplegia (spinal). Each one requires real medical knowledge. — Practical and theoretical knowledge. Alzheimer's: a degenerative brain disease, 70% of dementia cases, symptoms: forgetting recent events, disorientation, personality changes. Multiple sclerosis: the immune system attacks the myelin sheath, causing weakness, double vision. Epilepsy: seizures; treatment with anticonvulsants. Depression: low serotonin; treatment with antidepressants + therapy. Down syndrome: an extra chromosome 21. Huntington's: hereditary, involuntary movements. Quadriplegia: cervical spinal cord injury (4 limbs); paraplegia: lumbar (legs). The visit teaches compassion.

  14. Find at least three Bible verses that refer to the nervous system or to the decision-making process.

    Answer: 1) Proverbs 4:23: 'Keep thy heart with all diligence; for out of it are the issues of life'. 2) Romans 12:2: 'be ye transformed by the renewing of your mind'. 3) Philippians 4:8: 'whatsoever things are true... think on these things'. They show that the mind, heart and thought are central to the Christian life, regulating emotions, decisions and character. — The Bible repeatedly mentions the mind and heart (the decision-making center). Prov 4:23: the heart as the source of life. Rom 12:2: mental renewal against conformity to the world. Phil 4:8: filtering thoughts by virtue. Others: 1 Cor 2:16 'we have the mind of Christ'; 2 Tim 1:7 'spirit of power, and of love, and of a sound mind'; Ps 19:14 'the meditation of my heart'. Modern neuroscience confirms neuroplasticity — repeated thoughts form neural pathways. The Bible and science converge: mastering thoughts transforms the Pathfinder's character, decisions and well-being.