ch. 48 part 1 Flashcards
1
Q
two divisions of nervous system
A
- CNS
- PNS
2
Q
central nervous system
A
brain and nerve cord
- spinal cord in vertebrates
3
Q
peripheral nervous system
A
all neurons and projections of their plasma membranes that are outside of the CNS
4
Q
neurons
A
cells that send and receive electrical and chemical signals to and from other neurons or other cells throughout the body
5
Q
which animal does not have neurons
A
sponges
6
Q
structure of the neuron
A
- soma/cell body
- dendrites
- axons
7
Q
cell body or soma
A
- contains nucleus and organelles
8
Q
dendrites
A
- extensions of plasma membrane
- single or branching
- incoming singals
9
Q
axons
A
- extension of plasma membrane (neurolemma)
- typically single
- sending signals
- axon hillock near cell body
- axon terminals
10
Q
axon terminals
A
convey electrical or chemical message to other cells
11
Q
neurolemma
A
outer portion of myelin sheath created by Schwann cells
12
Q
glia cells
A
- perform various functions
- many times more numerous than neurons
- can function as stem cells to produce more glial cells and neurons
13
Q
types of glia cells in CNS
A
- astrocytes
- microglia
- ependymal cells
- oligodendrocytes
14
Q
astrocytes (star cell)
A
- metabolic support
- maintain blood-brain barrier
provide structural support - regulate ion, nutrient, and dissolved gas concentrations
- absorb and recycle neurotransmitters
- form scar tissue after injury
15
Q
microglia (little glue)
A
- remove cellular debris, wastes, and pathogens by phagocytosis
16
Q
what is the myelin sheath interrupted by
A
nodes of Ranvier
17
Q
what produces the nodes of Ranvier
A
oligodendrocytes (CNS) and Schwann cells (PNS)
18
Q
dendro
A
tree
19
Q
oligo
A
few or little
20
Q
cyte
A
cells
21
Q
types of glia cells in the PNS
A
- Schwann cells
- satellite cells
22
Q
ependymal cells
A
- line ventricles (brain) and central canal (spinal cord)
- assist in producing, circulating, and monitoring of cerebrospinal fluid
23
Q
oligodendrocytes
A
- myeline CNS axons
- provide structural framework
24
Q
Schwann cells
A
- surround axons in PNS
- are responsible for myelination of peripheral axons
- participate in repair process after injury
25
satellite cells
- surround neuron cell bodies in ganglia
- regulate O2, CO2, nutrient, and neurotransmitter levels around neurons in ganglia
26
synapse
junction between an axon and another cell
27
chemical messengers released from synaptic terminal at synapses
neurotransmitters
28
process of releasing neurotransmitters
1. action potential travels down axon to terminal
2. Ca2+ channel increases Ca2+ channel in presynaptic neuron
3. binds to vesicle filled with Ca2+
4. exocytosis of vesicle, neurotransmitters travel across synaptic cleft
5. neurotransmitters bind to receptors on postsynaptic membrane
29
presynaptic cell at synapse
neuron
30
postsynaptic cell at synapse
neuron, muscle, or gland cell
31
3 main types of neurons
1. sensory neurons (afferent)
2. motor neurons (efferent)
3. interneurons
32
sensory/afferent neurons
- detect information form outside world/internal body conditions
- transmit to CNS
33
afferent
bring to or lead toward
34
motor/efferent neurons
- send signals away from CNS to elicit response
35
efferent
conduct away or carry off
36
interneurons (association neurons)
form interconnections between other neurons in the CNS
37
inter
between
38
telodendria
synaptic knobs
39
reflex arc
stimulus from sensory neurons sent to CNS (dorsal root ganglion), little/no interpretation (few/no interneurons), signal transmitted to motor neurons to elicit response
- quick/automatic response
40
potential =
voltage
41
membrane potential
difference in charge inside and outside the cell
- polarized
42
what separates charges in and out of the cell?
plasma membrane barrier
43
resting membrane potential
when neurons not sending signals
44
what axons are used to read voltage measurements
squid giant axons
45
voltmeter function
records voltage difference between the microelectrodes inside and outside the neuron
- measure of membrane potential
- measurement made as a function of time
46
what are plasma membranes not very permeable to
cations and anions
- separates charge by keeping different ions largely inside or outside cell
47
resting potential value inside cell
-70 mv
48
is the interior or exterior of the cell more negative at rest
interior
49
what are negative ions within the cell drawn to
positive ions arrayed on the outer surface
50
3 factors contributing to resting potential
1. Na+/K+ -ATPase (sodium-potassium pump)
2. ion specific channels allow passive movement of ions
3. negatively charged molecules such as proteins more abundant inside cell
51
Na/K pump
transports 3 Na+ out for every 2 K+ moved in
52
are there more ungated K+ or Na+ channels
K+
53
is the membrane more permeable to K+ or Na+ at rest
K+
54
where are negatively charged molecules more abundant at rest
inside the cell
55
equilibrium potential
opposing forces of chemical and electrical gradients can create an equilibrium where there is no net movement
56
what do all cells have?
a membrane potential
57
what cells are excitable
neurons and muscle cells
58
excitable
capacity to generate electrical signals
59
3 types of gated ion channels
1. voltage-gated
2. ligand-gated
3. mechanically-gated
60
voltage-gated
open and close in response to voltage changes
61
ligand-gated
open and close in response to ligands or chemicals
62
mechanically-gated
open due to distortions in the cell membrane (touch)
63
polarization
changes in membrane potential
64
depolarization
cell membrane is less polarized, less negative relative to surrounding solution
- gated channels open allowing Na+ to flow in and membrane potential becomes more positive (less negative)
65
hyperpolarization
cell membrane more polarized, more negative
- K+ moves out of the cell making the cell membrane less positive (more negative)
66
graded potentials
- depolarization or hyperpolarization
- varies depending on strength of stimulus
- occur locally and dendrites or cell body
- spreads short distance and dies out
- act as triggers for action potential
