Chapter 16 – Sensory, Motor & Integrative Systems (Principles of Anatomy & Physiology, 14e)

A comprehensive set of question-and-answer flashcards covering key concepts from Chapter 16 on sensory, motor, and integrative systems, including receptor types, sensory and motor pathways, pain, proprioception, sleep, and higher cerebral functions.

What structures make up the central nervous system (CNS)?

The brain and spinal cord.

Which division of the PNS controls voluntary skeletal-muscle movement?

The Somatic Nervous System (SNS).

Which PNS division has sympathetic and parasympathetic branches?

The Autonomic Nervous System (ANS).

What is sensation?

Conscious or subconscious awareness of internal or external changes.

Where must a sensory impulse reach to produce conscious perception?

The cerebral cortex.

Name the three possible destinations of sensory impulses.

Spinal cord (reflexes), lower brain stem (vital reflexes), cerebral cortex (conscious sensations).

Define perception.

The conscious interpretation of sensations, mainly by the cerebral cortex.

What is a sensory modality?

Each distinct type of sensation (e.g., touch, vision, taste).

List the special senses.

Smell, taste, vision, hearing, balance (equilibrium).

What are the two groups of general senses?

Somatic (tactile, thermal, pain, proprioceptive) and visceral (internal organ sensations).

What property allows a receptor to respond strongly to one stimulus type but weakly to others?

Selectivity.

Name the four steps in the process of sensation.

1) Stimulation of receptor, 2) Transduction into graded potential, 3) Generation of nerve impulses, 4) Integration in CNS.

Which microscopic receptor type detects pain, temperature, itch and tickle?

Free nerve endings.

What do encapsulated nerve endings typically detect?

Pressure, vibration and some touch.

Give an example of a specialized receptor cell used in special senses.

Photoreceptors in the retina (others: gustatory cells, hair cells of inner ear).

Where are exteroceptors located and what do they sense?

At/near the body surface; they detect external stimuli such as touch, vision, smell, etc.

Which receptors monitor the body’s internal environment?

Interoreceptors (visceroceptors).

What information do proprioceptors provide?

Body position, muscle length/tension, joint movement.

Name the six receptor classes based on stimulus detected.

Mechanoreceptors, thermoreceptors, nociceptors, photoreceptors, chemoreceptors, osmoreceptors.

What is adaptation in sensory receptors?

A decrease in receptor potential amplitude during a constant stimulus, reducing impulse frequency.

Which receptors adapt rapidly? Give two examples.

Rapidly adapting receptors, e.g., pressure and smell receptors.

Which somatic sensations are considered tactile?

Touch, pressure, vibration, itch, tickle.

What fibers mediate touch, pressure and vibration?

Large-diameter myelinated A fibers connected to encapsulated mechanoreceptors.

Name the two rapidly adapting touch receptors.

Corpuscles of touch (Meissner) and hair root plexuses.

Name the two slowly adapting touch receptors.

Type I tactile (Merkel) discs and Type II Ruffini corpuscles.

Which receptor detects high-frequency vibration?

Lamellated (Pacinian) corpuscle.

Which temperature range primarily activates nociceptors instead of thermoreceptors?

Below 10 °C or above 45 °C.

Differentiate fast and slow pain in terms of fiber type and onset.

Fast pain: sharp, within 0.1 s via myelinated A fibers; Slow pain: burning/aching, ≥1 s via unmyelinated C fibers.

What is referred pain?

Visceral pain perceived in a surface area distant from the affected organ, served by the same spinal segment.

What ability is provided by weight discrimination?

Assessing an object's weight using proprioceptive input.

Which proprioceptor monitors muscle length?

Muscle spindle.

Which proprioceptor protects against tendon overstretch by triggering relaxation?

Tendon organ (Golgi tendon organ).

Which neurons keep muscle spindles taut as muscle length changes?

Gamma motor neurons.

Describe the role of alpha motor neurons in the spindle reflex.

They cause contraction of extrafusal muscle fibers to relieve stretch detected by the spindle.

How many neurons make up a typical pathway to the primary somatosensory cortex?

Three: first-order, second-order, and third-order neurons.

Which pathway carries touch, pressure, vibration and conscious proprioception from the body?

Posterior column–medial lemniscus pathway.

Which pathway conveys pain and temperature sensations?

Anterolateral (spinothalamic) pathway.

Sensations from the face reach the cortex mainly via which pathway?

Trigeminothalamic pathway.

Which tracts carry proprioceptive impulses to the cerebellum?

Anterior and posterior spinocerebellar tracts.

What are lower motor neurons (LMNs)?

Motor neurons that leave the CNS to innervate skeletal muscles via cranial or spinal nerves.

Differentiate direct and indirect motor pathways.

Direct: originate in cerebral cortex for voluntary movement; Indirect: originate in brain-stem nuclei for posture, balance, etc.

Which tract controls precise movements of distal limbs?

Lateral corticospinal tract.

Which direct pathway controls trunk and proximal limb muscles?

Anterior corticospinal tract.

Which tract controls voluntary movements of eyes, face, tongue and neck?

Corticobulbar tract.

What is the primary function of the vestibulospinal tract?

Maintain posture and balance in response to head movements.

Which indirect tract mediates reflex head, eye and trunk movement to visual/auditory stimuli?

Tectospinal tract.

List the four neural circuits that influence LMNs.

Local circuit neurons, upper motor neurons, basal nuclei neurons, cerebellar neurons.

Name two key functions of basal nuclei in movement.

Initiate/terminate movements and suppress unwanted movements; also reduce muscle tone.

State the four-step role of the cerebellum in motor control.

Monitor intentions, monitor actual movement, compare the two, send corrective feedback.

What system maintains cortical arousal and wakefulness?

The reticular activating system (RAS).

Which sensory inputs can activate the RAS?

Pain, touch/pressure, proprioception, bright light, limb movement, loud sounds, etc.

How many stages comprise NREM sleep and which is deepest?

Four stages; Stage 4 is deepest.

During which sleep phase does most dreaming occur?

REM sleep.

Why are most skeletal muscles paralyzed during REM sleep?

Somatic motor neurons (except those for eye & breathing muscles) are inhibited.

Which endogenous chemical promotes sleep by inhibiting the RAS?

Adenosine binding to A1 receptors.

How do caffeine and theophylline promote wakefulness?

They block A1 receptors, preventing adenosine from inhibiting the RAS.

Define immediate, short-term and long-term memory durations.

Immediate: seconds; Short-term: minutes; Long-term: minutes to lifetime.