NEU Exam 3 Terms

Afferent Nervous System (Sensory)
- Responsible for conveying sensory information to the central nervous system (CNS).
- Includes Special Senses (e.g., vision, hearing) and General Somatic Senses (e.g., touch, proprioception, pain, temperature).
Efferent Nervous System (Motor)
- Responsible for transmitting motor commands from the CNS to effectors (muscles/glands).

Frontal Lobe
- Involved in decision-making and planning.
Parietal Lobe
- Processes sensory information such as touch, temperature, and pain.
Occipital Lobe
- Responsible for processing visual information.
Temporal Lobe
- Involved in hearing and some aspects of memory.
Cerebellum
- coordinates movement and balance through integration of sensory feedback.
Central Sulcus
- Separates frontal and parietal lobes, with the precentral gyrus (motor area) and postcentral gyrus (sensory area).

The eyes are crucial for vision and forming an internal model of the environment.
Inner Ear Balance Organs: Detect angular and linear accelerations of the head.
Muscles, Joints, Tendons, Skin
- Responsible for self-movement and body position awareness via proprioception and exteroception.
Reactive Postural Response: Adjustments made after detecting balance disturbances.
Anticipatory Postural Adjustments: Pre-planned muscle activations in response to expected disturbances.

Skin Receptors
- Merkel's Disks: Detect pressure and texture.
- Meissner's Corpuscles: Sense light touch and flutter.
- Pacinian Corpuscles: Respond to vibrations.
- Ruffini Endings: Detect stretch.
Muscle and Joint Receptors
- Detect pressure, stretch, and compression relevant for proprioception.
Visceral Receptors
- Detect pressure, temperature, and chemical changes (e.g., pH).
- Pain receptors located throughout the body except for the CNS.

Rapidly adapting receptors: Respond quickly to changes in stimuli (e.g., Meissner's corpuscle).
Slowly adapting receptors: Maintain response during the entire duration of a stimulus (e.g., Merkel's disks).
Receptive Field Sizes: Vary between different receptors, influencing sensitivity and localization accuracy.

Comprised of Gray Matter (cell bodies) and White Matter (axons forming tracts).
Comprises 31 segments, each associated with a pair of spinal nerves (8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal).
Dermatomes: Each spinal nerve corresponds to a specific skin area, involved in sensory information transmission.
Shingles: Reactivation of herpes zoster virus follows dermatome organization causing skin disturbances along affected areas.

Dorsal columns lead to brain regions: dorsal column nuclei, medial lemniscus, thalamus, primary somatosensory cortex (S1).
Somatotopy: Represents a sensory homunculus in the primary somatosensory cortex, mapping different body regions.

Cortical Maps: Plasticity allows for reorganization following injury or experience.
Somatosensory Feedback in Movement: Vital for accurate motor control and posture maintenance, heavily reliant on proprioceptive input.

Proprioception is essential for normal movement, providing sensory feedback for body position and force.
Operates unconsciously and automatically, but can be consciously controlled (as seen in compensatory movements).
Proprioceptors:
- Muscle Spindles: Detect muscle length and stretch velocity.
- Golgi Tendon Organs: Monitor muscle tension and force, conveying feedback to CNS.

Stretch Reflex: Involves a monosynaptic reflex arc, important for maintaining muscle tone and posture.
Reciprocal Inhibition: A process where activation of one muscle inhibits the antagonist, allowing for smooth movement transitions.
Types of Reflex Arcs:
- Monosynaptic: One synapse between sensory and motor neurons (e.g., knee-jerk).
- Disynaptic: Contains an inhibitory interneuron (e.g., withdrawal reflex).
- Polysynaptic: Involves multiple synapses.

Nociception: Objective physiological detection of harmful stimuli; the neural process is distinct from the subjective experience of pain.
Pain Modulation: Influenced by emotional and contextual factors.
Gate Control Theory: Proposes how non-painful input can inhibit pain signaling through excitatory and inhibitory mechanisms in the spinal cord.
Key Signaling Molecules in Pain:
- Prostaglandins: Sensitize nociceptors; targeted by NSAIDs.
- Substance P: Involved in transmitting pain signals; released from nociceptive terminals.

Motor Neurons: Integrate sensory feedback, executing motor commands to muscles.
- Alpha motor neurons: Innervate skeletal muscles to facilitate movement.
Motoneuron Pools: Groups of motoneurons controlling specific muscle groups, allowing for graded control of force.

Motor cortex areas exhibit somatotopic organization to represent different muscle control.
Primary Motor Cortex: Essential for direct voluntary movements.
Premotor Areas: Involved in planning complex movements.
Basal Ganglia: Regulates voluntary movements and posture; its dysfunction can lead to motor disorders like Parkinson's Disease and Huntington's Disease.

Corticospinal Track: Direct pathway for motor commands to spinal cord.
Extrapyramidal Pathways: Modulate and refine motor commands for smooth execution.
Deep Brain Stimulation: A surgical treatment for Parkinson's Disease, stimulating specific brain areas to alleviate symptoms.

Parkinson’s Disease: Features bradykinesia, resting tremor, and muscular rigidity due to dopaminergic neuron degeneration.
Huntington’s Disease: Genetic disorder causing motor control loss and cognitive changes.
Tourette’s Syndrome: Involuntary vocal and motor tics, potentially linked to basal ganglia dysfunction.