NERVOUS SYSTEM Flashcards
1
Q
what are the functions of the nervous system
A
receiving sensory input
integrating information
controlling muscles and glands
maintaining homeostasis
establishing and maintaining mental activity
2
Q
two major divisions of the nervous system
A
central nervous system (CNS)
peripheral nervous system (PNS)
3
Q
consists of the brain and spinal cord
A
CNS
4
Q
consists of all the nervous tissue outside CNS including nerves and ganglia
A
PNS
5
Q
the communication link between CNS and the various parts of the body ; carries information about the different tissues of the body to the CNS and delivers commands
A
PNS
6
Q
PNS can be divided into 2 parts
A
sensory division or afferent (toward)
motor division or efferent (away)
7
Q
conducts action potentials from sensory receptors to the CNS
A
sensory division
8
Q
conducts action potentials from the CNS to effector organs such as muscles and glands
A
motor division
9
Q
the neurons that transmit action potentials from the CNS toward the periphery are called the
A
motor neurons
10
Q
the effectors controlled by motor division include
A
muscle tissue and glands
11
Q
components of motor division
A
somatic nervous system
autonomic nervous system
12
Q
transmits action potentials from the CNS to skeletal muscles
A
somatic nervous system
13
Q
transmits action potentials from the CNS to cardiac muscle, smooth muscle, and glands
A
autonomic nervous system
14
Q
divisions of autonomic nervous sytem
A
sympathetic divison
parasympathetic division
15
Q
a unique part of the peripheral nervous system ; has both sensory and motor neurons contained wholly within the digestive tract
A
enteric nervous system (ENS)
16
Q
two types of cells that make up the nervous system
A
neurons
glial cells
17
Q
type of cell that receives stimuli, conduct action potentials, and transmit signals to other neurons or effector organs
A
neurons or nerve cells
18
Q
3 parts of a neuron
A
cell body
dendrites and axons (2 types of processes)
19
Q
contains a single nucleus
A
cell body
20
Q
each neuron has an _, a single long cell process extending from the neuron cell body
A
axon
21
Q
the area where the axon leaves the neuron cell body is called the
A
axon hillock
22
Q
an axon may remain unbranched or may branch to form
A
collateral axons
23
Q
axons can be surrounded by a highly specialized insulating layer of cells called the
A
myelin sheaths
24
Q
axons of __ conduct action potentials towards the CNS
A
sensory neurons
25
axons of __ conduct action potentials away from the CNS
motor neurons
26
3 categories of neurons based on the arrangement of their processes
multipolar neurons
bipolar neurons
pseudo-unipolar neurons
27
have many dendrites and a single axon
multipolar neurons
28
has two processes-- one dendrite and one axon ; located in some sensory organs such as the retina of the eye and nasal cavity
bipolar neurons
29
have a single process extending from the cell body ; this process divides into two extensions a short distance from the cell body
psuedo-unipolar neurons
30
are the supportive cells of the CNS and PNS, meaning these cells do not conduct action potentials instead carry out different activities that enhance neuron function and maintain normal conditions within nervous tissue
glial cells or neuroglia
31
4 types of glial cells in the CNS
astrocytes
ependymal cells
microglia
oligodendrocytes
32
2 types of glial cells in the PNS
schwann cells
satellite cells
33
type of glial cells in the CNS that serve as the major supporting cells ; can stimulate or inhibit the signaling activity of nearby neurons ;
astrocytes
34
astrocytes participate with blood vessel endothelium to form a permeability barrier called the __ between the blood and the CNS
blood-brain barrier
35
type of glial cells in the CNS that line the fluid-filled cavities (ventricles and canals) ; some produce cerebrospinal fluid or help move the fluid
ependymal cells
36
type of glial cells in the CNS that acts as immune cells ; they help protect the brain by removing bacteria and cell debris
microglia
37
type of glial cells in the CNS that provide insulating material that surrounds axons
oligodendrocytes
38
type of glial cells in the PNS that provide insulating material around axons
schwann cells
39
type of glial cells in the PNS that are found around the cell bodies of certain neurons of the PNS ; these cells provide support and nutrition to the neurons from heavy-metal poisons such as lead and mercury
satellite cells
40
are specialized layers that wrap around the axons of some neurons ; formed by the processes of oligodendrocytes in the CNS and schwann cells in the PNS
myelin sheaths
41
axons with these myelin sheaths are called
myelinated axons
42
gaps in the myelin sheath are called __ that occur about every millimeter between the myelinated areas
nodes of ranvier
43
nervous tissues exist as what colors
gray and white matter
44
this type of matter consists of groups of neuron cell bodies and their dendrites where there is little myeline
gray matter
45
in the CNS, gray matter on the surface of the brain is called the
cortex
46
in the CNS, clusters of gray matter located deeper within the brain are called
nuclei
47
in the PNS, a cluster of neuron cell bodies is called a
ganglion
48
type of matter that consists of parallel axon with their myelin sheath which are whitish in color
white matter
49
white matter of the CNS forms _ which propagate action potentials from one area of the CNS to another
nerve tracts of conduction pathways
50
white matter of the PNS consists of bundles of axons and associated connective tissue that form
nerves
51
two basic types of ion channels
leak channels
gated channels
52
are always open ; ions can leak across the membrane down their concentration gradient
leak channels
53
are closed until opened by specific signals
gated channels
54
are opened by specific chemicals
chemically gated channels
55
are opened by a change in the electrical property of the cell membrane
voltage-gated channels
56
inside of most cell membrane is _ charged while the outside is _ charged
negatively:positively
57
this uneven charge distribution across the cell membrane means that the membrane is
polarized
58
in an unstimulated cell, we refer to this as the
resting membrane potential
59
in neuron communication, these changes can lead to _ which are electrical signals that are conducted along the cell membrane from one region of the cell to another
action potentials
60
on stimulation, chemically gated channels are opened and initiate
local potentials
61
if sufficiently strong, the local potentials activate voltage gated channels to initiate an _ potential
action
62
action potentials occur in an
all-or-none fashion
63
the pattern of action potential conduction along a neuron cell membrane may occur in one of two ways
continuous conduction
saltatory conduction
64
in unmyelinated axons, _ conduction occurs ; action potential in one part of a cell membrane stimulates local currents in adjacent parts of the cell membrane
continuous
65
in myelinated axons, _ conduction occurs ; action potential at one node of ranvier causes a local current to flow through the surrounding extracellular fluid and through the cytoplasm of the axon to the next node
saltatory
66
is a junction where the axon of one neuron interacts with another neuron or with cells of an effector organs such as a muscle or gland
synapse
67
3 major components of synapse
presynaptic terminal
postsynaptic terminal
synaptic cleft
68
the end of axon forms __
presynaptic terminal
69
the membrane of dendrite or effector cell is the
postsynaptic membrane
70
the space separating the presynaptic and postsynaptic is the
synaptic cleft
71
chemical substances called __ act as chemical signals
neurotransmitters
72
neurotransmitters are stored in __ in the presynaptic terminal
synaptic vesicles
73
if K+ or Cl- channels open, the inside of the postsynaptic cells tend to become more negative or __ and an action potential is inhibited from occurring
hyperpolarized
74
of the many neurotransmitters or suspected neurotransmitter substances, the best known are
acetylcholine and norepinephrine
75
in synapses where the acetylcholine is the neurotransmitter, such as in the neuromuscular junction, an enzyme called __ breaks down the acetylcholine
acetylcholinesterase
76
the two simplest pathways in the CNS are
converging pathway
diverging pathway
77
in this pathway, two or more neurons synapse with the same postsynaptic neuron ; allows information transmitted in more than one neuronal pathway to converge into a single pathway
converging pathway
78
in this pathway, the axon from one neuron divides and synapses with more than one other postsynaptic neuron ; this allows information transmitted in one neuronal pathway to diverge into two or more pathways
diverging pathway
79
many presynaptic action potentials are needed in a process called __ ; allows integration of multiple subthreshold local potentials
summation
80
two types of summation
spatial summation
temporal summation
81
type of summation that occurs when the local potentials originate from different locations on the postsynaptic neuron
spatial summation
82
type of summation that occurs when local potentials overlap in time ; can occur from a single output rapidly which allows the resulting local potentials to overlap briefly
temporal summation
83
the nerves of the PNS can be divided into how many groups
2 groups: 12 pairs of cranial nerves and 31 pairs of spinal nerves
84
collects information from numerous sources both inside and on the surface of the body and relays it by way of sensory neurons to the CNS
PNS
85
extends from the foramen magnum at the base of the skull to the second lumbar vertebra ; communicate between the spinal cord and the body
spinal cord
86
the inferior end of the spinal cord and the spinal nerves exiting there resemble a horse's tail and are collectively called
cauda equina
87
the white matter consists of
myelinated axons
88
the gray matter consists of a
collection of neuron cell bodies
89
the white matter in each half of the spinal cord is organized into three columns
dorsal column
ventral column
lateral column
90
consists of axons that conduct action potentials toward the brain
ascending tracts
91
consists of axons that conduct action potentials away from the brain
descending tracts
92
the gray matter is shaped like a letter
H
93
components of gray matter
dorsal horns and ventral horns
94
exist in the levels of the spinal cord associated with the autonomic nervous system
small lateral horns
95
the ventral rootlets combine to form a
ventral root
96
is a fluid filled space in the center of the spinal cord
central canal
97
dorsal roots combine to form
dorsal root
98
it contains the cell bodies of pseudo-unipolar sensory regions
dorsal root ganglion
99
an involuntary reaction in response to a stimulus applied to the periphery and transmitted to the CNS
relfex
100
is the neuronal pathway by which a reflex occurs ; the basic functional unit of the nervous system
reflex arc
101
the simplest reflex is the __ ; is a classic example of the stretch reflex involving the spinal cord
knee-jerk reflex or patellar reflex
102
type of reflex that involves removing a limb or another body part from painful stimulus ; sensory receptors are pain receptors
withdrawal reflex
