A&P - Sensory Pathways & The Somatic Nervous System

What does the afferent division of the nervous system do?

It carries sensory information to the CNS.

What does the efferent division of the nervous system do?

It carries motor commands from the CNS.

What system provides voluntary control of skeletal muscles?

The somatic nervous system (SNS).

What system provides involuntary control of visceral effectors?

The autonomic nervous system (ANS).

What are sensory receptors?

Specialized cells that monitor internal or external conditions.

What happens when a sensory receptor is stimulated?

It generates action potentials along sensory pathways.

What are general senses?

Temperature pain touch pressure vibration and proprioception.

What are special senses?

Smell taste vision equilibrium and hearing.

What is a receptive field?

Area monitored by a single sensory receptor.

How does receptive field size affect localization?

Larger fields reduce precision smaller fields increase precision.

What are tonic receptors?

Receptors that are always active.

What are phasic receptors?

Receptors that activate in bursts when stimulated.

What is adaptation?

Reduced sensitivity during constant stimulation.

What is peripheral adaptation?

When receptor activity decreases in the PNS.

What is central adaptation?

When the CNS reduces the amount of sensory information reaching the cortex.

What do exteroceptors detect?

External environment conditions.

What do proprioceptors detect?

Body position and movement of joints and muscles.

What do interoceptors detect?

Internal organ conditions.

What do nociceptors sense?

Pain.

What do thermoreceptors sense?

Temperature changes.

What do mechanoreceptors sense?

Touch pressure and vibration.

What do baroreceptors detect?

Pressure changes in organs.

What do chemoreceptors detect?

Chemical concentrations like pH O2 and CO2.

What is a first order neuron?

A sensory neuron delivering information to the CNS.

Where do first order neurons synapse?

On second order neurons in the spinal cord or brainstem.

What is a second order neuron?

An interneuron that receives sensory input and crosses over.

Where do second order neurons synapse?

On third order neurons in the thalamus.

What is a third order neuron?

An interneuron that sends information to the somatosensory cortex.

What are the three somatic sensory pathways?

Spinothalamic posterior column and spinocerebellar.

What does the spinothalamic pathway carry?

Crude touch pain pressure and temperature.

What does the posterior column pathway carry?

Fine touch vibration pressure and proprioception.

What is a sensory homunculus?

A map showing where sensations are processed in the cortex.

What does the spinocerebellar pathway carry?

Proprioceptive info from muscles and joints.

Does the spinocerebellar pathway reach awareness?

No it does not reach conscious awareness.

What do visceral sensory pathways carry?

Information from interoceptors in organs.

Where does visceral sensory information go?

To the medulla oblongata.

What do somatic motor pathways do?

Carry motor commands to skeletal muscles.

What is an upper motor neuron?

A CNS neuron that controls lower motor neurons.

What is a lower motor neuron?

A neuron that directly activates skeletal muscles.

What does the corticospinal pathway control?

Voluntary movement of skeletal muscles.