Overview of Nervous System Functions and Sensory Pathways

Afferent Division

Brings sensory info TO the CNS from receptors.

Efferent Division

Sends motor commands FROM the CNS to muscles/glands.

Somatic Nervous System (SNS)

Controls voluntary movements of skeletal muscle.

Autonomic Nervous System (ANS)

Controls involuntary actions like heart rate and digestion.

Receptor Specificity

Receptors only respond to one kind of stimulus.

Receptive Field

Area a receptor monitors; smaller field = more sensitive.

Adaptation

When receptors stop responding to constant stimuli.

Tonic Receptors

Always active; adapt slowly (ex: pain receptors).

Phasic Receptors

Active briefly when stimulus changes; adapt fast.

General Senses

Touch, pain, pressure, temp, proprioception.

Special Senses

Vision, hearing, balance, taste, smell.

Sensation

Raw signal detected by a receptor.

Perception

Brain's conscious interpretation of a sensation.

Spinothalamic Tract

Carries pain/temp info to thalamus -> cortex.

Posterior Column Pathway

Carries fine touch and proprioception to cortex.

Spinocerebellar Tract

Sends proprioception info to cerebellum.

Visceral Sensory Pathway

Senses from organs to brainstem (unconscious).

Referred Pain

Pain felt in skin but comes from internal organs.

Phantom Pain

Feeling pain in an amputated limb.

Corticospinal Pathway

Voluntary muscle control from cortex to body.

Corticobulbar Tract

Controls face/head muscles via cranial nerves.

Vestibulospinal Tract

Helps maintain balance and posture.

Tectospinal Tract

Reflexive head/neck movement to sounds or sights.

Reticulospinal Tract

Controls reflexes and muscle tone.

Motor Homunculus

Body map in motor cortex showing control areas.

Sensory Homunculus

Body map in sensory cortex showing sensation areas.

Basal Nuclei

Help start and stop voluntary movements.

Cerebellum

Fine-tunes movements and maintains posture.

Nociceptors

Sense pain from tissue damage; found everywhere.

Thermoreceptors

Detect heat/cold; skin and hypothalamus.

Chemoreceptors

Detect chemicals (pH, solutes); tongue, nose, tissues.

Photoreceptors

Sense light; located in the retina.

Proprioceptors

Sense joint position and movement.

Baroreceptors

Detect pressure changes in blood vessels, bladder.

Free Nerve Endings

Detect pain, temp, and touch in skin.

Root Hair Plexus

Senses hair movement.

Tactile Discs

Detect fine touch in the skin.

Tactile Corpuscles

Sense light touch in the dermis.

Lamellated Corpuscles

Detect vibrations; found deep in dermis.

Ruffini Corpuscles

Sense skin stretch and force direction.