Chapter 11

Somatic motor fibers carry information from the _______.

CNS to skeletal muscles

Which of the following statements concerning inhibitory synapses (IPSPs) is correct?

The postsynaptic membrane becomes more permeable to potassium and chloride

Saltatory conduction refers to _______.

a conduction process in myelinated axons where the electrical signal appears to jump from gap to gap along the axon

What is the difference between nerves and tracts?

bundles of axons are called tracts in the CNS and nerves in the PNS

The axon hillock of the neuron makes a "decision" to fire an action potential based on the timing and number of pros (in the form of EPSPs) and cons (IPSPs) that weigh into the decision. Given this, which of the following is true?

changes in the concentration of sodium, potassium, or chloride may affect a neuron's ability to make the "decisions" required in conscious thought

A potential of -90 mV is considered __________.

hyperpolarized

Visceral sensory (afferent) fibers carry information from the _______.

organs in the ventral body cavity to the CNS

The movement of which ion through leakage (nongated) channels plays the most important role in generating the resting membrane potential?

potassium

The Nissl bodies seen in the neuron cell body represents which cellular organelle?

rough endoplasmic reticulum

A neuron will not respond to a second stimulus of equal strength to the first stimulus to which it has already responded because __________.

the neuron is in the refractory period

Match the ionic activity associated with the following phase of an action potential: opening of potassium gates and the rushing out of K+.

the repolarization phase in an action potential

Match the term to its correct description: Endorphins __________.

are peptides with inhibitory, opiate like actions

Which of the following neurotransmitters acts as a natural opiate?

endorphins

Which of the following types of glial cells line the central cavities of the brain and spinal cord, where they help to circulate the cerebrospinal fluid?

ependymal cells

Match the term to its correct description: Acetylcholine __________.

excites skeletal muscle

Which of the following events is not involved in the transfer of information across a chemical synapse?

ions flow directly from one neuron to the next

Dopamine __________.

is a "feel good" transmitter; deficient in Parkinson's disease

Match the term to its correct description: Norepinephrine __________.

is a neurotransmitter of postganglionic neurons in the sympathetic nervous system

Match the term to its correct description: GABA __________.

is generally inhibitory; found throughout CNS

Neurons can be classified structurally by the number of processes extending from their cell bodies. Which of the following is the most common neuron type in humans?

multipolar

Match the term to its correct description: Numerous nerve impulses arriving at a synapse at closely timed intervals exert a cumulative effect.

temporal summation

Which of the following divisions of the nervous system is also known as the involuntary nervous system?

the autonomic nervous system

Match the word with its corresponding statement: The all-or-none phenomenon.

An action potential occurring only if enough Na+ enters the cell and threshold is achieved

Match the ionic activity associated with the following phase of an action potential: opening and then closing of the Na+ channels.

Depolarization phase in the generation of an action potential

What is the primary difference between the somatic nervous system and the autonomic nervous system?

The somatic nervous system allows us to consciously control our skeletal muscles, and the autonomic nervous system controls activity that humans cannot consciously control, such as the pumping of the heart and the movement of food through the digestive tract.

In considering the types of neurons and their predominant functions, efferent is to multipolar as __________.

afferent is to unipolar

Which of the following neuroglia is most responsible for helping determine capillary permeability in nervous tissue?

astrocytes

Which of the following types of glial cells are the most abundant and versatile and aid in making exchanges between capillaries and neurons?

astrocytes

Match the system with its correct description: The somatic nervous system __________.

conducts impulses from the CNS to the skeletal muscles

Match the system with its correct description: The central nervous system __________.

consists FROM the brain and spinal cord TO skeletal muscles

Match the system with its correct description: The peripheral nervous system __________.

consists of cranial and spinal nerves carrying impulses to and from the brain and spinal cord

Which type of ion channel opens when a chemical binds to it?

ligand- gated channels

Which of the following is not true of motor (efferent) neurons?

motor (efferent) neurons are bipolar

Spatial summation occurs when __________.

multiple local potentials occur at different places on the same cell at the same time

Which of the following defines integration?

processing and interpretation of sensory input and determining what should be done at each moment in the body

The sodium-potassium ion pump will __________.

pump three sodium ions out of the cell for every two ions of potassium it brings into the cell

Which of the following characteristics is not associated with a myelinated nerve fiber?

slow conduction of nerve impulses

During which phase of an action potential are voltage-gated K+ channels open, while voltage-gated Na+ channels are closed?

repolarizing phase

Which statement is true concerning leakage channels?

Leak channels are found in all parts of the neuron as they contribute to resting membrane potential.

The somatic sensory (afferent) fibers of the peripheral nervous system transmit information from the __________ to the CNS.

skin

Somatic sensory (afferent) fibers carry information from the _______.

skin, skeletal muscles, and joints to the CNS

Calcium has a great many roles in the body from providing structure to bones, stimulating muscle contraction, altering heart rate, influencing heart strength and stimulating hormone release. In a neuron, calcium's main role is __________.

stimulating the release of neurotransmitters

Match the term to its correct description: A stimulus that fails to generate an action potential is a __________.

subthreshold stimulus

Bodily functions that follow "a law unto itself" are controlled by the involuntary nervous system. This system is also termed __________ and functions to __________.

the autonomic nervous system (ANS); conduct impulses from the CNS to cardiac muscle, smooth muscle, and glands

The resting membrane potential of neurons is determined by __________.

the distribution, across the cell membrane, of large anionic cytoplasmic proteins, Na+, K+, and Cl-

Match the ionic activity associated with the following phase of an action potential: excessive potassium efflux as a result of relatively slower closure of the potassium gates.

the phase in an action potential known as the "after hyperpolarization"

Match the ionic activity associated with the following phase of an action potential: All voltage-gated Na+ and K+ channels are closed.

the resting state of a neuron

the voluntary nervous system is to the involuntary nervous system as _________

the somatic nervous system is to the autonomic nervous system

Which of the following is not true of chemical synapses?

they transmit nerve impulses directly from one neuron to another

Match the term to its correct description: Any stimulus above this intensity will result in an action potential in a neuron.

threshold stimulus

Which of the following membrane (ion) channels open and close in response to changes in the membrane potential?

voltage gated channels