Exam 3

Insufficient production of acetylcholine in the synapses of the brain, abnormal tangled neurons, and large deposits of beta-amyloid are problems associated with which one of the following diseases?

Alzheimer's disease

The nervous system is capable of using some neurotransmitters for more than one function. For example, some neurotransmitters may be excitatory in one pathwayyet inhibitory in another. Discuss what accounts for the same neurotransmitter having different functions in alternate pathways.

The answer is the same for neurotransmitters and hormones: cellular receptors. In the case of a neurotransmitter, it is the type of receptor located on the postsynaptic membrane that determines whether the response is excitatory or inhibitory. Similarly, the number of receptors also influences how quickly the postsynaptic cells respond to the message conveyed by the neurotransmitter.

Which one of the following steps occurs during the absolute refractory period?

The neuron cannot generate an action potential.

A student noticed that every time he smelled a certain perfume in the hallway, it reminded him of his mother. This is due largely to the activity of the limbic system. (t/f)

True

Motor neurons of the peripheral nervous system transmit impulses away from the central nervous system. (t/f)

True

Reestablishment of the resting potential in a neuron following an action potential requires the activity of the sodium-potassium pump. (t/f)

True

The absolute refractory period characteristic of neurons is important in ensuring that action potentials travel in only one direction. (t/f)

True

The somatic division of the peripheral nervous system (PNS) controls skeletal muscles. (t/f)

True

There are several toxins that interfere with synaptic transmission. Botulism toxin, for example, interferes with the fusion of acetylcholine-containing vesicles with the membrane of the axon bulb. This would result in which one of the following?

blocking of neurotransmitter release by the presynaptic membrane

Bacterial and viral infections of the brain are rare because the ________ prevents most viruses, proteins, and bacteria from entering the cerebrospinal fluid.

blood-brain barrier

Which one of the following is NOT directly involved in the production of a typical spinal reflex?

brain

The central nervous system is composed of which of the following?

brain and spinal cord

Axons branch into axon terminals, which have ________ located at the terminal ends.

bulbs

When an action potential arrives at the axonal bulb, ________ channels open in the presynaptic membrane, which causes neurotransmitter to be released into the synaptic cleft.

calcium

People who are intoxicated cannot coordinate their movements or walk a straight line because alcohol disrupts the normal function of which region of the brain?

cerebellum

Twelve pairs of ________ nerves carry nerve impulses from the brain to glands, muscles, head, neck, and abdominal and thoracic cavities.

cranial

Recordings of the brain's activities can be made using a(n) ________; this information is used to study the functioning of the brain.

electroencephalogram (EEG)

inflammation of the brain; symptoms include headaches, hallucinations, and disturbances in speech and behavior; often caused by a viral infection

encephalitis

From an evolutionary standpoint, which of the following structures is considered the oldest, most primitive division of the brain?

hindbrain

The sympathetic and parasympathetic divisions of the autonomic division of the peripheral nervous system work antagonistically to maintain ________.

homeostasis

Which one of the following parts of the brain effectively links the nervous system and the endocrine system?

hypothalamus

Regulation of the production of breast milk, carbohydrate metabolism, and temperature control are some of the functions of the

hypothalamus.

Electrical impulses are transmitted between components of the central nervous system via which one of the following?

interneurons

Which of the following parts of the brain is associated with emotions and behavior?

limbic system

Which one of the following divisions of the nervous system predominates during the relaxed state?

parasympathetic division

its effect results in a calm, relaxed state

parasympathetic nervous system

postganglionic neurons secrete acetylcholine

parasympathetic nervous system

A neuron at rest has a charge difference across its cell membrane, with the interior of the cell negative relative to the exterior. This difference in charge across the plasma membrane is referred to as ________ potential.

resting

Because the central nervous system is so important to the proper functioning of the body, the brain is protected by the ________ and the spinal cord is protected by the ________.

skull; vertebrae

When repolarization is occurring during an action potential, ________ channels are closed.

sodium

Which one of the following establishes and maintains the resting potential?

sodium-potassium pump

Transient local changes in the resting potential of a cell are called graded potentials because they can vary in size. In a phenomenon known as ________, many incoming signals produce progressively larger graded potentials in a cell —larger than any single impulse would produce alone.

summation

preganglionic neurons originate in the brain or sacral region of spinal cord

sympathetic nervous system

Saltatory conduction is

the process of conduction leaping along myelinated neurons.

All of the following are functions of the myelin sheath EXCEPT which one?

The myelin sheath plays an important role in synaptic transmission.

On your way to class, you decide to cross a busy street but fail to notice a fast-moving car coming toward you. When you do see the car, your heart rate and breathing increase, and you feel a burst of energy that helps you quickly move to the sidewalk. Describe how your nervous system was able to process the sight of the car with the need to move your legs.

The nervous system relies on a series of sensory neurons to keep you aware of conditions in the external environment. When your eyes saw the car, this stimulus generated an action potential that was sent via sensoryneurons to an integration center that in turn processed the meaning of the signal and produced an appropriate response, or motor output. In this case, the burst of energy suggests that the fight-or-flight response was activated.

Which one of the following occurs with each cycle of the sodium-potassium pump?

The net effect is removal of one osmotic particle and one positive charge from inside the cell.

Given a particular neuron, an action potential either occurs or does notoccur, depending on the strength of the stimulus; therefore, the action potential is described as ________.

all or none

During a brain surgery, a surgeon passes an instrument through the dura mater. Which one of the following does the surgeon pass through next?

arachnoid

Oligodendrocytes are similar to Schwann cells in that they

are a type of neuroglial cell.

Control of smooth muscle and internal organs is the role of the ________ division of the nervous system.

autonomic

Motor neurons carrying information to smooth muscle, cardiac muscle, and all other tissues and organs except skeletal muscle belong to the ________ division of the peripheral nervous system.

autonomic

The region of brain that coordinates antagonistic muscle movements is the

cerebellum.

Conscious thought is associated with which one of the following?

cerebral cortex

Removal of the ________ would prevent any type of decision making.

cerebrum

The left and right cerebral hemispheres are interconnected by a nerve tract network called the ________.

corpus callosum

The left and right sides of the cerebrum are interconnected by which one of the following?

corpus callosum

The first step of an action potential, when the membrane potential of a neuron shifts from negative to positive due to inward movement of sodium ions, is referred to as ________.

depolarization

________ is a type of neural information processing where an action potential is transmitted from one cell to many cells.

divergence

The central nervous system is enclosed by membranes or meninges called the

dura mater, pia mater, and arachnoid.

Which one of the following types of neurotransmitter functions as an inhibitory agent, typically suppressing the sensation of pain?

endorphins

condition characterized by seizures and abnormal periods of brain electrical activity

epilepsy

The three main anatomical and functional divisions of the brain are the

forebrain, midbrain, hindbrain.

Convergence occurs when several presynaptic cells

form a synapse with a single postsynaptic cell.

Which lobe of the cerebral cortex is responsible for speech and conscious thought?

frontal

The ________ controls many functions in the body, including regulating body temperature and hunger drive.

hypothalamus

Which one of the following activities would be facilitated by the sympathetic nervous system?

increased blood pressure

transmit impulses within the central nervous system

interneurons

Short-term memory is associated with the ________, whereas long-term memory is associated with changes in the ________.

limbic system; cerebral cortex

Short-term memory is associated with the ________, whereas long-term memory is associated with the ________.

limbic system; cerebral cortex

Control of respiratory rate, heart rate, and blood pressure is integrated through the

medulla oblongata.

inflammation of the connective tissue layers surrounding the organs of the central nervous system

meningitis

Which component of the nervous system is divided into the somatic and autonomic divisions?

motor

Which one of the following cells transmits impulses away from the central nervous system to the muscles and other organs?

motor neurons

transmit impulses away from the central nervous system

motor neurons

autoimmune disorder that results in damage to the myelin sheaths of CNS neurons; transmission of impulses is subsequently disrupted

multiple sclerosis

Only 20% of cells in the human nervous system are neurons, and the rest are cells that support and protect neurons called ________ cells.

neuroglial

Cells that provide direct protection and physical support to neurons are

neuroglial cells.

Arrival of an action potential at an axon terminal ultimately results in the release of ________ into the synaptic cleft.

neurotransmitters

Cranial nerves and spinal nerves are part of the ________ nervous system.

peripheral

Drugs that cause changes in emotions, consciousness, or behavior are known as ________.

psychoactive drugs

Which one of the following diseases is caused by a virus that is introduced to the body through the skin and travels along sensory neurons to the brain?

rabies

During which one of the following phases of an action potential do the sodium channels close and potassium channels open, releasing potassium from the neuron?

repolarization

Which one of the following provides the central nervous system with information about the outside environment?

sensory division

transmit impulses toward the central nervous system

sensory neurons

Both voluntary and involuntary skeletal muscle movement are controlled through which one of the following divisions of the nervous system?

somatic division

Amyotrophic lateral sclerosis (ALS) is a demyelinating disease that results from nerve damage beginning in the

spinal cord.

Excitatory neurotransmitters encourage the generation of new electrical impulses by which one of the following?

stimulating depolarization of postsynaptic neurons

The ________ reflex, an example being the well-known knee-jerk pathway, plays an important role in maintaining upright posture and movement.

stretch

Preganglionic motor neurons of the ________ division of the nervous system originate in the thoracic and lumbar regions of the spinal cord.

sympathetic

its effect is to prepare the body for emergencies

sympathetic nervous system

postganglionic neurons secrete norepinephrine

sympathetic nervous system

preganglionic motor neurons originate in the thoracic and lumbar regions of the spinal cord

sympathetic nervous system

For an action potential to be generated, a minimum membrane voltage, or a(n) ________, must be reached.

threshold

By which one of the following methods is a stronger stimulus coded by neurons differently from a weaker stimulus?

A stronger stimulus results in more action potentials/unit time.

The phrase all-or-none responsedescribes a neuron-generated action potential. Explain what is meant by this phrase.

Action potentials are produced when the membrane potential (voltage) of the neuron is temporarily reversed by the sudden inward movement of ions from interstitial fluid. The ions can move in only when there is an opening or channel in the membrane. In the case of most neurons, the ion that moves inward via gated channels is sodium. These channels open only when there is a sufficiently strong stimulus; they do not partially open to weaker stimuli. So either the threshold must be reached to achieve an action potential, or the threshold is not reached, and therefore no action potential is generated.

Each of the following statements correctly describes an action potential EXCEPT which one?

Action potentials are propagated by the sodium-potassium pump.

During synaptic transmission, the influx of ________ causes vesicles in the axon bulb to fuse with the cell membrane, releasing ________.

Ca2+; neurotransmitter

Which one of the following events associated with the transmission of an impulse across a synapse occurs last?

Chemically gated channels for sodium open.

An action potential is a long or rapid release of energy, generated by the sodium-potassium pumps of neurons. (t/f)

False

During periodsof stress or increased activity, the parasympathetic division of the autonomic nervous system predominates; during periods of rest, the sympathetic division of the autonomic nervous system predominates. (t/f)

False

Neurotransmitters always cause depolarization of the postsynaptic membrane. (t/f)

False

The functional barrier between blood and the brain is cerebrospinal fluid. (t/f)

False

The repolarization phase of an action potential is dependent on the sodium-potassium pump. (t/f)

False

The strength and duration of a stimulus determine the amplitude of an actionpotential. (t/f)

False

The two major subdivisions of the nervous system are the central nervous system and the limbic nervous system. (t/f)

False

Which one of the following diseases is a progressive degenerative disorder caused by destruction of dopamine-releasing neurons in the brain that coordinate muscle movement?

Parkinson's disease

progressive, degenerative disorder caused by a shortage of dopamine in the brain; symptoms include muscle tremors in hands and feet and an eventual loss of mobility

Parkinson's disease

All of the following statements about psychoactive drugs are TRUE EXCEPT which one?

Psychoactive drugs typically bind to the medulla oblongata.

Which one of the following happens during repolarization of a neuron?

Sodium channels close, and potassium rushes out of the cell to temporarily reestablish the membrane potential.