Sensory Pathways & Somatic Nervous System

What does the peripheral nervous system link?

It links the central nervous system (CNS) to the outside world.

What are sensory receptors responsible for?

They respond to changes in the environment (stimuli), both internal and external.

What is the difference between sensation and perception?

Sensation is the awareness of stimuli, while perception is the interpretation of the meaning of stimuli.

How can sensory receptors be classified structurally?

They can be classified as simple (general senses) or complex (sense organs like vision and hearing).

What is adaptation in sensory receptors?

Adaptation is the reduction in sensitivity in the presence of constant stimuli.

What is peripheral adaptation?

It occurs when sensory receptors become less responsive over time to an unchanging stimulus.

What is central adaptation?

It is when conscious awareness of a stimulus disappears, reducing the information reaching the CNS.

What are tonic receptors?

Tonic receptors are always active and change the rate of action potential generation based on stimulus changes.

What are phasic receptors?

Phasic receptors are normally inactive but become active with changes in conditions; they adapt quickly.

What type of sensory receptor detects touch, pressure, and vibration?

Mechanoreceptors.

What are the three classes of mechanoreceptors?

Tactile receptors, baroreceptors, and proprioceptors.

What do nociceptors sense?

They cause the sensation of pain.

What are exteroceptors?

Exteroceptors receive stimuli from outside the body, including touch, pressure, temperature, and pain.

What are interoceptors?

Interoceptors respond to stimuli from inside the body, such as chemical changes and stretch.

What is the function of the first order neuron in somatic sensory pathways?

It carries impulses to the CNS and has its cell body in the dorsal root ganglion or cranial nerve ganglion.

What is the role of the second order neuron?

It is located in the spinal cord or brain stem and synapses with the first order neuron, often crossing over to the opposite side.

What is the function of the third order neuron?

It is located in the thalamus and synapses with the second order neuron.

What are ascending tracts responsible for?

They conduct sensory impulses from peripheral nerves to the brain.

What does the lateral spinothalamic tract transmit?

It transmits pain and temperature sensations.

What does the anterior spinothalamic tract transmit?

It transmits crude touch and pressure sensations.

What is the corticospinal pathway responsible for?

It controls voluntary motor functions and consists of upper and lower motor neurons.

What is the function of the basal nuclei?

They adjust the activity of upper motor neurons and are important in starting, stopping, and monitoring movements.

What is the motor homunculus?

It is a graphical representation of motor areas of the brain, showing disproportionate areas for different body parts.

What is the sensory homunculus?

It is a graphical representation of sensory processing areas in the brain, also showing disproportionate areas for different body parts.