Assignment 13: Neuron Structure and Resting Membrane Potential

What division of the nervous system is most specifically responsible for voluntary motor control?

somatic nervous system

Nerve impulses leading to the brain carry information about cool temperatures on the skin. The nerve fibers sending these signals will most likely belong to which division of the nervous system?

sensory (afferent) division

Nerve impulses leading to the skeletal muscle carry information to direct movement. The nerve fibers sending these signals will most likely belong to which division of the nervous system?

somatic nervous system

Cranial nerve II, the optic nerve, sends nerve impulses to the brain carrying information about the things we see. These nerve fibers most likely belong to which division of the nervous system?

sensory (afferent) division

Which of the choices below describes the ANS?

motor fibers that conduct nerve impulses from the CNS to smooth muscle, cardiac muscle, and glands

Which of the following describes the nervous system integrative function?

analyzes sensory information, stores information, makes decisions

Which of the following is NOT a characteristic of neurons?

They are mitotic.

Which of the following is NOT a function of the autonomic nervous system?

innervation of skeletal muscle

The term central nervous system refers to the ____.

brain and spinal cord

Which of the following peripheral nervous system (PNS) neuroglia form the myelin sheaths around larger nerve fibers in the PNS? 

Schwann cells

Schwann cells are functional similar to _____.

oligodendrocytes

What is the structure is A?

dendrites

Which of these materials or structures would be found in greatest amounts or numbers at E?

vesicles containing neurotransmitter

In which area of the neuron is an action potential initially generated?

C

Which is the main receptive portion of the neuron

the dendrite

In myelinated axons the voltage-regulated sodium channels are concentrated at the myelin sheath gap ( nodes of Ranvier) 

True

In the motor division of the PNS, the effector organs consist of the three types of muscle tissue and glands. Which of these effectors organs would be under voluntary control and thereby fall into the somatic nervous system?

Skeletal Muscle

Which of the following statements in correct regarding the polarization of a neuronal membrane and the formation of a resting membrane potential? 

Sodium/Potassium pumps maintain concentration gradients; sodium and potassium move down their concentration gradients through leakage channels

   More Na⁺ than K⁺ leaks through neuron membranes because of the properties of the non-gated leak channels.   

False

The interior surface of a neuron's plasma membrane at resting membrane potential will have a ________.

negative charge and contains less sodium than outside of the cell 

Ions are unequally distributed across the plasma membrane of all cells. This ion distribution creates an electrical potential difference across the membrane. What is the name given to this potential difference?

Resting membrane potential (RMP)

Sodium and potassium ions can diffuse across the plasma membranes of all cells because of the presence of what type of channel?

Leak channels 

On average, the resting membrane potential is -70 mV. What does the sign and magnitude of this value tell you?

The inside surface of the plasma membrane is much more negatively charged than the outside surface.

The plasma membrane is much more permeable to K⁺ than to Na⁺. Why?

There are many more K⁺ leak channels than Na⁺ leak channels in the plasma membrane.

What prevents the Na⁺ and K⁺ gradients from dissipating?

Na⁺-K⁺ ATPase