Anatomy and Physiology - Problem Drill 13: The Peripheral Nervous System

Transcription

1 Anatomy and Physiology - Problem Drill 13: The Peripheral Nervous System No. 1 of What part of the neuron is specifically designed for propagating a signal? (A) Terminal Branches (B) Axon (C) Dendrites (D) Synapses Terminal branches are the structures that release neurotransmitters into the synapse. B. Correct! Electrical impulses initiated in the dendrites are propagated down the axon to the terminal branches. C. Incorrect! Dendrites bind neurotransmitter released into the synapses by the terminal branches of an excited neuron. Synapses are the spaces between the terminal branches of one neuron and the dendrites of another. Excited neurons release neurotransmitters into synapses, which are the small spaces between the terminal branches of the excited neuron and the dendrites of the receiving neuron. The receiving end of this pathway is the dendrites of the second neuron. A threshold excitation of the dendrites results in an action potential being propagated down the axon.

2 No. 2 of What cell type is responsible for sensory information transmission? (A) Oligodendrocytes (B) Bipolar neurons (C) Unipolar neurons (D) Satellite cells Oligodendrocytes are central nervous system glial cells. Bipolar neurons are seen in specialized sensory organs. C. Correct! Afferent sensory neurons are neurons with a single dendritic-axon process with cell bodies off to one side. Groups of cell bodies for the dorsal root ganglia. Satellite cells are PNS glial cells that surround the cell bodies in the dorsal root ganglia. There are several structural classes of neurons in the nervous system: anaxonic neurons are small neurons that don t seem to have an axon, bipolar neurons are small neurons with two distinct processes, a dendritic process and an axon extending from the cell body, unipolar neurons which are large neurons that have a cell body lying to one side of the axonal-dendritic process, and multipolar neurons which many dendritic process off the cell body and also have a single axon extending from the cell body that can split into several axonal processes. In the Peripheral Nervous System the two anatomical types of neurons present are the unipolar neuron, or the afferent sensory neuron, and the multipolar neuron or motor efferent neuron.

3 No. 3 of When you move your hand away from a painful stimulus, like a hot kettle, what is the neural pathway that is involved? (A) Sensory receptor, afferent neuron, interneuron, efferent neuron, motor response. (B) Sensory receptor, efferent neuron, interneuron, afferent neuron, motor response. (C) Sensory receptor, efferent neuron, cerebellum, afferent neuron, motor response. (D) Sensory receptor, afferent neuron, cerebrum, efferent neuron, motor response. A. Correct! This is a reflexive response and signals through a simple reflex arc. Sensory information from the periphery is brought to the CNS via afferent neurons, not efferent neurons. C. Incorrect! Reflexes do not require the input of the CNS. Reflexes do not require the input of the CNS. A painful stimulus is detected by nocireceptors in the skin which send an efferent signal to the spinal cord. A simple reflex arc then bypasses the CNS and directly signals via an efferent neuron to you re your hand out of the way.

4 No. 4 of Schwann cells in the PNS are similar to what cells in the CNS? I. Anaxonic neurons II. Oligodendrocytes III. Astrocytes IV. Microglia (A) I and II (B) III only (C) II and IV (D) I and III Although oligodendrocytes are correct, schwann cells are not neurons. Astrocytes are one of the glial cells that schwann cells do not resemble. C. Correct! Schwann cells myelinate peripheral neurons similar to oligodendrocytes and scavenge debris like microglia. Schwann cells are not like astrocytes or neurons. Schwann cells myelinate peripheral neurons like it s CNS counterpart, the oligodendrocyte, and they also scavenge debris similar to microglia in the CNS.

5 No. 5 of The Peripheral nervous system consists of the. (A) Spinal cord and the brain (B) Autonomic and somatic systems (C) Sensory and motor systems (D) Sympathetic and parasympathetic systems The spinal cord and the brain are part of the central nervous system. The autonomic and somatic systems are part of the motor system. C. Correct! The peripheral nervous system consists of the sensory and motor systems. The sympathetic and parasympathetic systems are part of the autonomic system. The central nervous system is made up of the brain and the spinal cord - which is the portal to the peripheral nervous system. The peripheral nervous system is made up of motor neurons which provide locomotion to our bodies, and the sensory system. The Motor system can be divided into the somatic (referring to the body or voluntary muscular system) and the autonomic (the automatic muscular systems) system which is further divided into the sympathetic and parasympathetic systems which work in opposition to each other.

6 No. 6 of Pupil dilation is regulated by. (A) Visual sensory system (B) Inputs from the cerebellum (C) Sympathetic nervous system (D) Autonomic system The visual sensory system includes the retina, and the photoreceptors there, not the workings at the opening of the eyes. The cerebellum coordinates voluntary movement, and pupil dilation is not a voluntary action. C. Correct! The sympathetic system controls increases in involuntary movements, and pupil dilation is one of those actions. Although the autonomic system controls pupil size, dilation is under the control of the sympathetic system. Pupil size is under involuntary muscle control and therefore under the control of the autonomic nervous system, however, the dilation of the pupils is an increase in the size of the pupil and increases in the automatic systems are under the control of the sympathetic nervous system.

7 No. 7 of The part of the nervous system usually considered to be voluntary is. (A) Autonomic (B) Sensory (C) Peripheral (D) Somatic The autonomic system controls involuntary movements. The sensory system is the part of the peripheral nervous system that processes sensory inputs that contribute to initiating voluntary movements. C. Incorrect! Although the peripheral system includes the system that controls voluntary movement, it also contains the system that controls involuntary movements. D. Correct! The somatic motor system is the part of the nervous system that controls voluntary movement. Voluntary movements are controlled by the somatic motor system, which is part of the peripheral nervous system.

8 No. 8 of Which statement about the sensory nervous system is not true? (A) There are five senses in the system. (B) Inputs from these senses can modulate the somatic systems. (C) Inputs from these senses can modulate the autonomic systems. (D) Not all of the inputs pass through the brainstem. A. Correct! Including sight, smell, taste, hearing, touch and proprioception, there are at least 6 senses in this system. The somatic system controls voluntary movements, which are often modulated by our senses. C. Incorrect! Often something we experience through our senses regulates the involuntary effects in our bodies (i.e. seeing someone we love, can make your heart race and your breath quicken). Inputs from the peripheral nervous system such as touch and proprioception will pass through the brain stem, but not every sensory input does. The sensory nervous system initiates at sensory organs that send signals to the brain. The skin detects temperature, touch and painful stimuli. The nose and tongue detect aromatic chemicals. The ears detect pressure waves that are transformed into sound signals. The eyes detect photons of light. We also can detect where our body is in space. This sense is called proprioception. Often the information from our senses influences both our voluntary movements (walking around a hole you see in your path) and our involuntary functions (increases in your breath and heart rate when you hear someone scream).

9 No. 9 of Neurons that conduct impulses to the Central Nervous System are called. (A) Afferent neurons (B) Effector neurons (C) Efferent neurons (D) Interneurons A. Correct! Neurons carrying information to the spinal cord or brain stem are called Afferent neurons. The effector is the response that occurs in response to the sensory information that is sent to the brain. C. Incorrect! Neurons carrying information from the brain are called Efferent neurons. Interneurons are small neurons contained entirely inside the spinal cord. Neurons carrying impulses to the CNS are called afferent neurons and neurons carrying information away from the nervous system are called efferent neurons.

10 No. 10 of Sympathetic ganglia are. (A) Enlargement in the Dorsal Root nerve containing neuronal cell bodies (B) Enlargement in the Ventral root nerve containing neuronal synapses (C) Chain of enlarged nerves ventral to the spinal cord containing neuronal synapses (D) Efferent sympathetic neurons synapsing on the effector organs Dorsal root ganglia contain afferent sensory neuronal cell bodies. The ventral root does not have an enlarged region. C. Correct! The sympathetic ganglia are enlarged nerves containing the synapses of the two neurons involved in autonomic sympathetic signaling. Ganglia are not neurons although they contain neuronal synapses or cell bodies. Sympathetic ganglia are a chain of enlarged nerves ventral to the spinal cord that contain synapses from spinal neurons onto efferent neurons.