4. motor systems and 5. other sensory systems

Muscle Fiber Innervation by Motor Neuron Axons

• Each motor neuron controls multiple muscle fibers; together they form a motor unit.

Neuromuscular Junction

• Synapse between motor neuron and muscle fiber; neurotransmitter is acetylcholine (ACh).

Antagonistic Muscles

• Opposing muscle pairs (e.g., biceps/triceps) enabling smooth movement.

Proprioceptors

• Receptors that detect body position and movement. • Includes muscle spindles (detect stretch) and Golgi tendon organs (detect tension).

Stretch Reflex

• Automatic contraction in response to muscle stretch; mediated by the spinal cord.

Motor Program

• Pre-set sequence of movements; can be learned or innate.

Reflexes (Spinal) vs. Voluntary Movement (Cortex)

• Reflexes: automatic, consistent responses via spinal cord. • Voluntary: planned and controlled by the cerebral cortex.

Basal Ganglia & Action Selection

• Group of subcortical structures involved in initiating and inhibiting movements.

Parkinson’s Disease

• Caused by loss of dopamine-producing neurons in the substantia nigra. • Symptoms: tremors, rigidity, slow movement.

Adequate Stimulus

• Type of energy a sensory receptor is specialized to detect.

Anatomy of the Ear

• Outer ear: collects sound waves. • Middle ear: ossicles (malleus, incus, stapes) transmit vibrations. • Inner ear: cochlea with hair cells (mechanical receptors) transduces sound.

Theories of Pitch Perception

• Place theory: specific areas of basilar membrane respond to different frequencies (high). • Frequency theory: whole membrane vibrates in sync with sound (low). • Combination explains full hearing range.

Tinnitus

• Perceived ringing due to cochlear or auditory nerve damage.

Vestibular Sensation

• Detects head position and movement via semicircular canals and otolith organs; critical for balance.

Pheromones

• Chemical signals influencing behavior or physiology, including attraction and mating.

Taste and Smell Axons Converge = Flavor

• Integration of gustatory and olfactory input creates perception of flavor.

Five Basic Tastes

• Sweet, sour, salty, bitter, umami. • Different receptors activate ion channels or G-protein pathways.

Dermatome

• Skin area innervated by a single spinal nerve.

Somatosensory Cortex

• Receives and processes touch and body position information; organized somatotopically.

Substance P

• Neurotransmitter involved in transmitting pain signals to the brain.