Spinal Cord Reflexes

These flashcards cover key concepts and details related to spinal cord reflexes, including definitions, functions, and examples.

What is a reflex?

An involuntary, automatic motor response to a sensory stimulus.

What are examples of simple human reflexes?

Touching a hot object and jerking the hand away; stepping on a tack and lifting the injured foot.

When do reflex activities appear in humans?

About five months before birth.

What is a receptor in the context of a reflex pathway?

A specialized structure at the beginning of a sensory neuron that receives the stimulus.

What are afferent neurons?

Sensory neurons that relay sensory information from the receptor to the brain or spinal cord.

What is the CNS center in reflex pathways?

A center in the brain or spinal cord where information is relayed across one or more synapses from sensory neurons to motor neurons.

What characterizes monosynaptic reflexes?

Sensory neurons directly synapse with motor neurons.

What is an efferent neuron?

The motor neuron that transmits information out of the brain or spinal cord to an effector.

Define an effector in reflex pathways.

Smooth muscle cell, cardiac muscle cell, secretory cell, or skeletal muscle cell that provides the reflex response.

What is a myotatic reflex?

An ipsilateral monosynaptic reflex tested at various locations where a skeletal muscle can be stretched.

What is the patellar reflex commonly known as?

The knee-jerk reflex.

What is the purpose of the Jendrassik maneuver?

To heighten the patellar reflex by countering some normal descending inhibitory inputs.

What effect does conscious attention have on reflex response?

It normally dampens the reflex response.

What is hyperreflexia?

Exaggerated reflexes due to decreased normal inhibitory influences.

What happens when a muscle is activated in a reflex?

The opposing muscles are inhibited to allow for smooth movement.

What do alpha motor neurons do?

They synapse with skeletal muscle fibers and are always excitatory.

Where do brainstem reflexes typically occur?

In the brainstem, and they include responses such as lens accommodation and pupil constriction.

What is the Achilles tendon reflex?

A myotatic reflex tested by tapping the Achilles tendon to elicit gastrocnemius contraction.