Sensory System Recording (W2025)

Overview of the Sensory System

• The sensory system is not included in the current exam but will be on the second exam.

• Reminder: Reach out via personal email for questions over the weekend.

Central Nervous System Clinical Questions

Brain Injuries Comparison

• Frontal Lobe vs. Parietal Lobe

  • Similarity: Both involve areas related to speech.

  • Difference:

    • Frontal lobe: Associated with conscious thought, memory, and emotions.

    • Parietal lobe: Involved in processing sensory information (temperature, pain).

• Temporal Lobe vs. Occipital Lobe

  • Similarity: Both interpret sensations.

  • Difference:

    • Temporal lobe: Primarily processes hearing and sound.

    • Occipital lobe: Primarily processes vision.

• Thalamus vs. Hypothalamus

  • Similarity: Both are involved in reactions or emotional responses.

  • Difference:

    • Thalamus: Sends sensory messages across the cerebrum; coordinates muscle movement.

    • Hypothalamus: Regulates hormones and homeostasis (hunger, thirst, body temperature).

Clinical Scenarios

1. Molly R. (2-month-old)

   • Without shunt for cerebrospinal fluid, may cause brain damage due to excess fluid pressure.

2. Mr. B (87 years old)

   • Unable to speak due to frontal lobe damage.

   • Experienced right-side paralysis due to cerebrum damage.

   • Facial drooping points to damage in cranial nerve VII controlling facial muscles.

   • Ruptured blood vessel located in the left hemisphere.

3. Sally (bicycle accident)

   • With cerebellum injury: Potential difficulties with fine motor skills like tying shoes or playing piano.

Sensory System Overview

Sensory Receptors and Stimuli

• Stimulus: Change in the environment prompting a response.

• Receptors: Specialized nerve endings detecting various stimuli (temperature, pain, touch).

• Sensation: Awareness of stimuli; requires a minimum intensity to initiate a nerve impulse.

Types of Receptors

• Thermoreceptors: Detect temperature changes (hot/cold).

• Photoreceptors: Respond to light (mainly in the eyes).

• Chemoreceptors: Detect chemical changes (smell and taste).

• Mechanoreceptors: Respond to mechanical stimuli (pressure, sound, balance).

  • Found in skin, muscles, and joints.

Pain Receptors

• Nociceptors: Detect damage leading to pain, stimulated by chemical signals from damaged cells.

  • Differentiate between:

    • Somatic Pain: From skin and deeper tissues.

    • Visceral Pain: From internal organs.

    • Acute Pain: Sharp, quick, often short-lived.

    • Chronic Pain: Persistent, duller discomfort.

Referred Pain

• Pain felt in areas not directly affected, due to shared sensory pathways (e.g., heart attack pain felt in the arm).

Proprioception

• Awareness of body position and movement; helps maintain balance and spatial awareness.

• Example: Affects motion perception when spinning.

General and Special Senses

General Senses

• Found throughout the body, include touch, pressure, temperature, and pain receptors.

Special Senses

• Vision

  • Eye Structure: Fibrous tunic (sclera, cornea), vascular tunic (iris, pupil), and nervous tunic (retina).

  • Light pathway: Cornea ➔ aqueous humor ➔ lens ➔ vitreous humor ➔ retina.

  • Rods (sensitive to light) vs. Cones (color detection).

• Hearing

  • Ear Structure: External (auricle), middle (ossicles), and inner ear (cochlea).

  • Sound pathway: Tympanic membrane ➔ ossicles ➔ oval window ➔ cochlea.

  • Hair cell movement in the cochlea converts sound waves into neural signals.

• Balance

  • Functions of inner ear structures: Vestibule for static equilibrium and semicircular canals for dynamic equilibrium.

• Taste (Gestation)

  • Taste buds detect flavors influenced by chemoreception; requires moisture to taste.

  • Taste sensations vary (sweet, sour, bitter, salty, umami).

• Smell (Olfaction)

  • Olfactory cells detect 10,000 odors; closely related to emotional responses and memory.

  • Requires odor molecules to be dissolved in moisture to stimulate olfactory hairs.

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Summary of Exam Preparation

• For the upcoming exam, focus on understanding the components and functions of the sensory system discussed above.

• Remember to clarify any doubts via email before the weekend.