Somatic Sensory Nervous System
How many neurons do both the medial leminscal pathway and the lateral spinothalamic pathway involve?
3 neurons in relay (up and across)
What is the lateral spinothalamic pathway?
A pathway sending pain and temperature signals to the brain
What is the sensory stimulus converted into?
Action potentials
What is a withdrawal reflex?
An involuntary process that causes a part of the body to automatically pull away from something that is causing pain
What is the medial leminscal pathway?
Ascending spinal tract from body heading up to brain (carrying sensory info.)
What is the integration centre of the somatic sensory system?
Cerebral cortex
What type of touch does Ruffini's corpuscle detect?
Crude and persistent
What does continuous stimulation result in? (in regard to receptor potential over time)
Decreased receptors potential (over time)
What type of touch does Pacini's corpuscle detect?
Deep pressure and vibration
What does duration refer to?
Duration of action potential firing in afferent neuron
What does stimulus intensity refer to?
Frequency of action potential firing in afferent neuron
In muscle tension receptors: ... ... organ senses muscle tension and protects the muscle from ... by causing ... before the muscle tension becomes too great and causes damage.
Golgi tendon, tearing, relaxation
Small receptive fields lead to...
Good discrimination
What does the basal ganglia do?
Helps to select an appropriate movement for a given situation (based on past actions)What does the cerebellum do?
What does increasing a stimulus intensity do in regard to AP frequency?
Increase in AP frequency
What type of touch does Merkel's disc detect?
Light pressure
What does location refer to?
Location of sensory receptors activated/mapped in the brain
What type of touch does Meissner's corpuscle detect?
Low frequency vibration
Motor cortex signals to ... motor neurons via ... .At the same time the motor cortex signals to the .... . The .... compares the actual movement with the intended movement and signals adjustment to ... and ... . Sensory signals ... to cerebellum
Lower, thalamus, cerebellum, cerebellum, cortex, muscle, feedback
What does the cerebellum do?
Monitors what is happening with what was planned and moves action to correspond with what was planned
How can movements have more force?
More motor neurons recruited
What controls movement of skeletal muscle?
Motor cortex
What does the motor cortex generate?
Motor neurons
In muscle length receptors: .... .... sense length and ... change of muscle length and cause muscle .... (... reflex) to keep you upright/ keep your ...
Muscle spindles, change, shortening, stretch, posture
If the AP is below the threshold, is there a response in the afferent neuron?
No
What do free nerve endings detect?
Pain
How do withdrawal reflexes work?
Pain receptors are stimulated, AP's are generated and transmitted, sensory neurons synapse with excitatory interneurons, these synapse with motor neurons to stimulate muscles and move the limb away from the pain source
Where is the sensation signal (what and where) interpreted in the somatosensory cortex?
Primary region of cortex
What are areas of skin on which neurons detect sensory information known as?
Receptive fields
Where is perception (interpretation of signal) interpreted in the somatosensory cortex?
Secondary (association) region of cortex
Where does the neural circuit take place?
Spinal cord
How does the stretch reflex work?
Stretch activates the muscle spindle. Sensory neurons synapse directly with motor neurons in the spinal cord.
What type pf touch does Krause's end bulb detect?
Textural sensation
What is the corticospinal pathway?
The main tract for nearly all the voluntary muscle activity
What is the reflex arc?
The nerve pathway involved in a reflex action, between afferent neuron and afferent neuron with a synapse between.
What also happens during a withdrawal reflex?
The other limb is stabilized to maintain posture
Krause's end bulb, Pacini's corpuscle, Merkel's disc, Meissner's corpuscle and Ruffini's corpuscle all detect what?
Touch
What do somatic sensations refer to? (4)
Touch, pain, warm/cold, body position
What does modality refer to?
Type of sensory receptor activated
How does the corticospinal pathway work?
Upper motor neurons at the primary motor cortex synapse onto lower motor neurons to carry voluntary impulses from the brain to skeletal muscles
What do special senses refer to? (5)
Vision, hearing, taste, small and balance
What is somatic control?
Voluntary control of skeletal muscle
The basal ganglia interacts with the motor cortex: At rest, basal ganglia ... the motor cortex. Upon deciding to move, the cortex ... with the basal ganlia. Inhibition of inhibition allows .. .. ....
inhibit, checks, us to move
Areas of the cortex correspond to different areas of the body. Densely ... areas of the body occupy ... regions of the cortex. eg. ... and ...
innervated, large, lips, thumb
Chronic pain has a ... receptive field, ... small ..myelinated axons and is ...
large, small un, visceral
Acute pain has a ... receptive field, ... myelinated axons and is ...
small, large, somatic
