Question 1

What connects the upper motor neurons to lower motor neurons?

Accepted Answer

Interneurons connect upper motor neurons to lower motor neurons within the central nervous system, facilitating communication between them.

Question 2

What part of the nervous system integrates and interprets information from PNS sensory neurons?

Accepted Answer

The central nervous system (CNS) is responsible for integrating and interpreting information from PNS sensory neurons.

Question 3

Determine the polysynaptic reflex from this list of examples.

Accepted Answer

The flexion (withdrawal) reflex is a polysynaptic reflex, involving multiple synapses with interneurons in the spinal cord, allowing for a more complex response. The other reflexes listed are monosynaptic.

Question 4

What type of motor neuron stimulates skeletal muscle fibers to contract by the excitation ^-contraction mechanism?

Accepted Answer

Alpha (a) motor neurons are responsible for stimulating skeletal muscle fibers to contract through the excitation-contraction mechanism. They transmit signals from the central nervous system to the muscles, causing them to contract.

Question 5

A test known as two ^-point discrimination threshold measures:

Accepted Answer

The two-point discrimination threshold measures the relative size of receptive fields, as it assesses the ability to distinguish two separate points on the skin, which is influenced by the density and size of receptive fields in that area.

Question 6

Place the following steps in order for motor control. 1. Upper motor neurons stimulate lower motor neurons.
2) Sensory information is relayed back to the cerebellum so movement can be modified if needed.
3) Upper motor neurons in the premotor cortex select a motor program.
4) Lower motor neurons stimulate a skeletal muscle to contract.
5) The basal nuclei enable the thalamus to stimulate upper motor neurons of the primary cortex.

Accepted Answer

The correct order for motor control is: the premotor cortex selects a motor program (3), the basal nuclei enable the thalamus to stimulate upper motor neurons (5), upper motor neurons stimulate lower motor neurons (1), lower motor neurons stimulate a skeletal muscle to contract (4), and sensory information is relayed back to the cerebellum for modification (2).

Question 7

Mechanoreceptors might detect which of the following sensations?

Accepted Answer

Mechanoreceptors are sensory receptors that respond to mechanical pressure or distortion.

Question 8

What type of neuron contacts a muscle fiber and initiates a muscle contraction?

Accepted Answer

Lower motor neurons directly contact muscle fibers at the neuromuscular junction to initiate muscle contraction.

Question 9

Which of the following must occur first in a reflex arc?

Accepted Answer

The reflex arc begins with the detection of a stimulus by a receptor, which then delivers the stimulus to the sensory neurons. This is the first step in the reflex arc process.

Question 10

A reflex with a single synapse between the sensory and motor neurons within the spinal cord is known as a:

Accepted Answer

A reflex with a single synapse between the sensory and motor neurons within the spinal cord is known as a monosynaptic reflex.

Question 11

Ms. Carroll went to her doctor's office with pain in her right shoulder blade and learned she was having a gallbladder attack. You're not surprised to hear about the unusual location of her pain since it is known as:

Accepted Answer

Referred pain is pain that is felt in a part of the body other than the site of the actual injury or disease. In this case, the pain in Ms. Carroll's right shoulder blade is referred pain from her gallbladder attack.

Question 12

Which of the following does NOT characterize a reflex?

Accepted Answer

Neural integration of a reflex usually occurs in the central nervous system (CNS), not the peripheral nervous system (PNS).

Question 13

Regions of skin supplied by a spinal nerve for somatic sensation are known as:

Accepted Answer

Dermatomes are areas of skin that are mainly supplied by a single spinal nerve, and they are important for diagnosing the level of spinal injuries and for understanding referred pain.

Question 14

Visceral pain may be perceived as cutaneous pain, a phenomenon known as:

Accepted Answer

Referred pain occurs when visceral pain is perceived as originating from a different, often cutaneous, location due to the convergence of nerve pathways in the central nervous system.

Question 15

What type of sensory receptors are muscle spindles and Golgi tendon organs?

Accepted Answer

Muscle spindles and Golgi tendon organs are mechanoreceptors as they detect changes in muscle length and tension, respectively.

Question 16

What is NOT true of muscle spindles?

Accepted Answer

Muscle spindles are not found within tendons; they are located within the belly of muscles, embedded among the extrafusal muscle fibers.

Question 17

Motor neurons pools consist of:

Accepted Answer

Motor neuron pools consist of lower motor neurons, which are responsible for directly innervating skeletal muscles and facilitating voluntary movement.

Question 18

What reflex causes muscle relaxation?

Accepted Answer

The Golgi tendon reflex causes muscle relaxation by inhibiting the alpha motor neurons that innervate the muscle. This reflex is activated when the muscle is stretched too far, and it helps to protect the muscle from damage.

Question 19

The speed of nerve impulse transmission through the axon of a sensory neuron will be quickest in:

Accepted Answer

A large-diameter, myelinated axon transmits nerve impulses more quickly due to the presence of myelin, which insulates the axon and allows for faster signal conduction through saltatory conduction.

Question 20

A region of skin has a great number of sensory neurons, and each neuron has a relatively small receptive field. The two ^-point discrimination threshold for this skin region might be:

Accepted Answer

A small receptive field and a high density of sensory neurons allow for better discrimination between two points, resulting in a lower two-point discrimination threshold, such as 5 mm.

Quiz 13: The Peripheral Nervous System