Organization of the Nervous System, Basic Functions of Synapses, and Neurotransmitters

Question 1

The central nervous system is estimated to contain ____ neurons

Answer 1

80 to 100 billion

Question 2

A special feature of most synapses is that the signal
normally passes only in the ___ direction, from the axon of a preceding neuron to dendrites on cell membranes of subsequent neurons.

Answer 2

forward

Question 3

transmits sensory information from
the receptors of the entire body surface and from some deep structures

Answer 3

somatic portion

Question 4

The most important eventual role of the nervous system is to control the various bodily activities. This task is achieved by controlling:

Answer 4

(1) contraction of appropriate skeletal muscles throughout the body
(2) contraction of smooth muscle in the internal organs
(3) secretion of active chemical substances by both exocrine and endocrine glands

Question 5

that the skeletal muscles can be controlled from many levels of the central nervous system, including

Answer 5

(1) the spinal cord; (2) the reticular substance of the medulla, pons, and mesencephalon; (3) the basal ganglia; (4) the cerebellum; and (5) the motor cortex.

Question 6

The lower regions are concerned primarily with ___, instantaneous muscle responses to sensory stimuli

Answer 6

automatic

Question 7

the higher regions are concerned with deliberate ___ muscle movements controlled by thought processes of the brain

Answer 7

complex

Question 8

More than __% of all sensory information is discarded by the brain as irrelevant and unimportant.

Answer 8

99

Question 9

the junction point from one neuron to the
next

Answer 9

synapse

Question 10

determine the directions that the nervous signals will spread through the nervous system

Answer 10

synapses

Question 11

Most storage occurs in the ___

Answer 11

cerebral cortex

Question 12

The storage of information is the process we call ___

Answer 12

memory

Question 13

Processing of information is the ___ function of the nervous system

Answer 13

integrative

Question 14

MAJOR LEVELS OF CENTRAL NERVOUS
SYSTEM FUNCTION

Answer 14

(1) the spinal cord level
(2) the lower brain or subcortical level
(3) the higher brain or cortical level

Question 15

Many, if not most, of what we call subconscious activities of the body are controlled in the ___ areas of the brain

Answer 15

lower

Question 16

subconscious control of arterial pressure and respiration is achieved mainly in the ___

Answer 16

medulla and pons

Question 17

Control of equilibrium is a combined function of
the older portions of the ___ and the reticular substance of the ___

Answer 17

cerebellum

medulla, pons, and mesencephalon

Question 18

Feeding reflexes, such as salivation and licking the lips in response to the taste of food, are controlled by areas in the ____

Answer 18

medulla, pons, mesencephalon, amygdala, and hypothalamus

Question 19

an extremely large memory storehouse

Answer 19

cerebral cortex

Question 20

T/F the cerebral cortex can function by itself

Answer 20

false

Question 21

Information is transmitted in the central nervous system mainly in the form of nerve action potentials,
called ___

Answer 21

nerve impulses

Question 22

There are two major types of synapses

Answer 22

(1) chemical and (2) electrical

Question 23

they secrete a neurotransmitter that excites the postsynaptic neuron

Answer 23

excitatory

Question 24

they secrete a neurotransmitter that inhibits
the postsynaptic neuron

Answer 24

inhibitory

Question 25

The presynaptic terminal is separated from the postsynaptic neuronal soma by a ____

Answer 25

synaptic cleft

Question 26

The presynaptic terminal has two internal structures important to the excitatory or inhibitory function of the synapse:

Answer 26

transmitter vesicles and the mitochondria

Question 27

The transmitter vesicles contain the ___ that when released into the synaptic cleft, excites or inhibits the postsynaptic neuron.

Answer 27

neurotransmitter

Question 28

provide adenosine triphosphate (ATP), which in turn supplies the energy for synthesizing new transmitter substances

Answer 28

mitochondria

Question 29

When the calcium ions enter the presynaptic terminal, they bind with special protein molecules on the inside surface of the presynaptic membrane, called ___

Answer 29

release sites

Question 30

Receptor activation controls the opening of ion channels in the postsynaptic cell in one of two ways:

Answer 30

(1) by gating ion channels directly and allowing passage of specified types of ions through the membrane;
(2) by activating a “second messenger”

Question 31

cation channels that conduct sodium ions are
lined with ___ charges

Answer 31

negative

Question 32

For the anion channels, when the channel diameters become large enough, ___ pass into the
channels and on through to the opposite side

Answer 32

chloride ions

Question 33

a neurotransmitter that opens cation channels is called an ___

Answer 33

excitatory transmitter

Question 34

opening anion channels allows negative electrical
charges to enter, which inhibits the neuron. Therefore, neurotransmitters that open these channels are called ___

Answer 34

inhibitory transmitters.

Question 35

prolonged postsynaptic neuronal excitation or inhibition is achieved by activating a___ chemical system

Answer 35

second messenger

Question 36

There are several types of second messenger systems. One of the most common types uses a group of proteins called ___

Answer 36

G proteins

Question 37

inactive G protein complex components

Answer 37

GDP
alpha (α)
beta (β)
gamma (γ)

Question 38

As long as the G protein complex is bound to
___, it remains inactive.

Answer 38

GDP

Question 39

a typical small molecule transmitter that obeys the principles of synthesis and release

Answer 39

acetylcholine

Question 40

acetylcholine is synthesized in presynaptic terminal from __ and ___ in the presence of enzyme ___

Answer 40

acetyl coenzyme A & choline

choline acetyltransferase

Question 41

secreted by the terminals of many neurons whose cell bodies are located in the brain stem and hypothalamus.

Answer 41

Norepinephrine

Question 42

Specifically, norepinephrine-secreting neurons located in the ____ in the pons send nerve fibers to widespread areas of the brain to help control overall activity and mood of the mind, such as increasing the level of wakefulness.

Answer 42

locus ceruleus

Question 43

is secreted by neurons that originate in
the substantia nigra

Answer 43

Dopamine

Question 44

The effect of dopamine is usually ___.

Answer 44

inhibition

Question 45

is secreted mainly at synapses in the spinal cord.
It is believed to always act as an inhibitory transmitter.

Answer 45

Glycine

Question 46

secreted by nerve terminals in the spinal cord, cerebellum, basal ganglia, and many areas of the cortex. It is the primary inhibitory neurotransmitter in the adult central nervous system

Answer 46

Gamma-aminobutyric acid (GABA)

Question 47

is secreted by the presynaptic terminals in many of the sensory pathways entering the central nervous system, as well as in many areas of the cerebral cortex.

Answer 47

Glutamate

Question 48

is secreted by nuclei that originate in the median raphe of the brain stem and project to many brain and spinal cord areas, especially to the dorsal horns of the spinal cord and the hypothalamus

Answer 48

Serotonin

Question 49

acts as an inhibitor of pain pathways in the cord; an inhibitor action in the higher regions of the nervous system is believed to help control the mood of the person, perhaps even to cause sleep.

Answer 49

Serotonin

Question 50

is produced by nerve terminals in areas
of the brain responsible for long-term behavior and
memory

Answer 50

Nitric oxide

Question 51

Resting Membrane Potential of the Neuronal Soma

Answer 51

−65 millivolts (mV)

Question 52

three ions that are most important for neuronal function

Answer 52

sodium ions, potassium ions, and chloride ions