Chapter 15: Sensory Pathways and the Somatic Nervous System

Flashcards covering major concepts in sensory pathways and the somatic nervous system for exam preparation.

What are the two divisions of the nervous system based on function?

Afferent (sensory) and efferent (motor) divisions.

What does the somatic nervous system control?

Contractions of skeletal muscles.

What is the primary function of sensory pathways?

To relay sensory information from receptors to the central nervous system (CNS).

What are sensory receptors?

Specialized cells or processes that monitor specific conditions in the body or external environment.

What is an action potential?

A graded change in membrane potential generated by sensory receptors in response to stimuli.

What are the components of the afferent division of the nervous system?

Somatic and visceral sensory pathways.

What is the role of the efferent division?

To carry out somatic motor commands that control peripheral effectors.

What types of senses do general sensory receptors provide?

Temperature, pain, touch, pressure, vibration, and proprioception.

What is the difference between sensation and perception?

Sensation is arriving information; perception is the conscious awareness of that sensation.

What do tonic receptors do?

They are always active and provide continuous information about presence of a stimulus.

What do phasic receptors do?

They are normally inactive and provide information about intensity and rate of change of a stimulus.

What are mechano-receptors sensitive to?

Physical stimuli that distort their plasma membranes.

What are the four types of general sensory receptors based on the nature of stimulus?

Nociceptors, thermoreceptors, mechanoreceptors, chemoreceptors.

What is the primary characteristic of nociceptors?

They are pain receptors with large receptive fields.

Where are thermoreceptors primarily located?

In the dermis, skeletal muscles, liver, and hypothalamus.

What do proprioceptors monitor?

Positions of joints and skeletal muscles.

What type of sensory information do baroreceptors provide?

Information about pressure changes in blood vessels.

What are tactile receptors responsible for?

Providing sensations of touch, pressure, and vibration.

What is the role of the first-order neuron in sensory pathways?

To deliver sensations to the CNS.

What is the role of the second-order neuron in sensory pathways?

An interneuron in the spinal cord or brainstem that receives information from the first-order neuron.

What function do third-order neurons serve?

They relay sensory information from the thalamus to the primary somatosensory cortex.

What are interoceptors?

Sensory receptors that monitor visceral tissues and organs.

What cranial nerves are involved in visceral sensory pathways?

Cranial nerves V, VII, IX, and X.

What does the solitary nucleus do?

It is a major processing and sorting center for visceral sensory information.

What types of motor neurons are involved in somatic motor pathways?

Upper motor neuron and lower motor neuron.

Where is the cell body of the upper motor neuron located?

In a CNS processing center.

What is the function of the basal nuclei?

To provide background patterns of movement involved in voluntary motor activities.

What is the cerebellum responsible for in motor control?

It monitors proprioceptive, visual, and vestibular sensations to fine-tune movements.

How do phasic receptors adapt to stimuli?

They respond to a change in stimulus conditions but quickly decrease activity.

What happens during peripheral adaptation?

Receptor sensitivity decreases in response to constant stimulus.

What is meant by 'receptive field'?

The area monitored by a single receptor cell.

What types of stimuli do free nerve endings respond to?

Touch, pressure, pain, and temperature.

What is the significance of labeled lines in sensory processing?

They carry information about one modality or type of stimulus to the cortex.

What is adaptation in the context of sensory receptors?

The reduction of receptor sensitivity in the presence of a constant stimulus.

What do mechanoreceptors include?

Tactile receptors, baroreceptors, and proprioceptors.

How do the nervous system pathways process the information from sensory receptors?

Through relay synapses where information is processed and relayed to higher centers.

What do stimulus frequency and patterns inform about?

Strength, duration, and variation of a sensation.

What determines the localization of a stimulus?

The size of the receptive field; smaller fields allow for better localization.

What functional role do the primary somatosensory cortex serve?

It is where sensations are relayed and consciously perceived.

What is the role of lower motor neurons?

To carry out commands from upper motor neurons to muscle fibers.

Why do nociceptors convey both fast and slow pain?

Different types of nerve fibers (A fibers for fast pain and C fibers for slow pain) are responsible for each.

Where are chemoreceptors primarily located?

In the carotid bodies and aortic bodies.