nervous system IV

Exam and Office Hours

• After receiving exam grades, office hours for spring break will be modified.

• New office hours will provide flexibility over the break.

Written Portion Guidelines

• Emphasis on originality; do not utilize AI for written work.

• AI detection and plagiarism checks will be conducted on submissions.

• Encourage personal contributions and synthesis of accessible information.

Pain Perception

• Pain travels along two pathways in somatic pain:

  • A fibers: Transmit sharp, acute pain; it's easy to pinpoint.

  • C fibers: Transmit chronic, dull pain; harder to localize over time.

• Pain is subjective and influenced by individual experiences.

  • Past experiences shape perceptions of pain severity.

• Example: Perceptions of childbirth pain can be influenced by cultural conditioning.

• The response to pain is also affected by situational reactions (e.g., parental response when children scrape knees).

Types of Pain

• Visceral Pain:

  • Occurs in internal organs and is often poorly localized.

  • Referred pain phenomenon; e.g., heart pain felt in left arm or shoulder, indicative of potential heart attack.

• The brain interprets visceral pain based on spinal cord pathways, sometimes leading to mislocalized pain sensations.

Pain Transmission and Modulation

• Information about pain reaches the brain via spinal pathways.

• Pain perception can be influenced by inhibition of neural transmission.

• Natural opioids (like endorphins and enkephalins) can be released to modulate pain.

• The perception of pain can change based on focus and distraction techniques.

Vision and Light Perception

• Vision is highly utilized but limited; we often do not see well at long distances.

• Light interacts with the eye:

  • Photons reflect off surfaces, allowing us to perceive images.

  • Eye Structure: Comprised of two segments:

    • Posterior Segment: Filled with vitreous humor, stable volume.

    • Anterior Segment: Filled with aqueous humor, constantly renewed.

• The retina is crucial for detecting light and converting it into neural signals.

Eye Function and Disorders

• Common vision issues include:

  • Nearsightedness (Myopia): Image focuses in front of the retina.

  • Farsightedness (Hyperopia): Image focuses behind the retina.

  • Aging Effects: Need for reading glasses due to loss of lens flexibility (presbyopia).

• Cataracts: Opacity of the lens over time, causing hazy vision that typically requires surgery.

• Glaucoma: Increased intraocular pressure can lead to nerve damage and vision loss if untreated.

• Astigmatism: Irregular corneal shape distorts vision.

Sound and Hearing

• Sound transmission involves pressure changes through air, leading to vibrations in the tympanic membrane.

• Inner Ear Functionality:

  • Ossicles amplify sound waves, which then travel through to the cochlea.

  • Hair cells in the cochlea detect specific frequencies of sound, crucial for hearing.

• Deafness can be classified as:

  • Conductive Deafness: Issues in the outer ear to the oval window.

  • Sensorineural Deafness: Problems from the hair cells onward.

  • Central Deafness: Problems in the brain processing pathways.

Equilibrium

• The inner ear has mechanisms for balance:

  • Static Equilibrium: Senses head position changes.

  • Dynamic Equilibrium: Senses movement through semicircular canals.

• Balance is a combined effort where vision, vestibular signals, and proprioception play roles.

Taste and Smell

• Both rely on chemical interactions, requiring substances to be dissolved.

• Taste Map: Identifies sensations such as sweet, sour, salty, and bitter.

• Smell: More complex, with the ability to discern 10,000+ chemical scents.

• Olfactory signals are essential for taste perception; congestion impacts taste ability.