the nevous system Flashcards
1
Q
what is the role of the endocrine system
A
it transmits chemical signals called hormones to receptive cells
2
Q
are hormones generally slow or fast acting. can they affect more than one region throughout the body
A
relatively slow acting
they can affect one or more regions of the boy
3
Q
name some of the simplest animals with nervous systems
A
hydras, jellies and other cnidarians
4
Q
what features of an animal mean that it has a more specialised nervous system
A
elongated, bilaterally symmetrical bodies
5
Q
what is cephalization
A
clustering of sensory neurons and interneurons at the anterior (front) end of the body. nerves that extend towards the posterior (rear) end enable these anterior neurons to communicate with cells elsewhere in the body
6
Q
neurons that carry out integration form which type of nervous system
A
the central nervous system
7
Q
neurons that carry information in and out of the CNS form what type of nervous system
A
the peripheral nervous system
8
Q
what are ganglia
A
segmentally arranged clusters of neurons that act as relay points in transmitting information
9
Q
what forms the CNS
A
the brain and the spinal chord
10
Q
what forms the PNS
A
nerves (spinal nerves and cranial nerve) and ganglia
11
Q
what are the two components of nervous tissue
A
neurons - transmit nerve impulses glia - nourish, insulate and replenish neurons
12
Q
give an example of a glial cell and its function
A
schwann cells - produce myelin sheaths surrounding axons in the PNS and oligodendrocyte, their counterparts of the CNS
13
Q
how are the simplest nervous systems arranged
A
in nerve nets (a series of interconnected neurons)
14
Q
What does the PNS do
A
transmits information to and from the CNS
it regulates movement and the internal environment by nerves and glia
15
Q
in the PNS ………… neurons transmit information to the CNS
A
afferent (sensory)
16
Q
in the PNS ……….. neurons transmit information away form the CNS
A
efferent (motor/autonomic)
17
Q
what are the 5 major glial cells in the nervous system
A
CNS - oligodendrocytes - astrocytes - microglia - ependymal cells PNS - schwann cells
18
Q
during development, where does the central nervous system develop from
A
the dorsal nerve chord
19
Q
the cavity of the dorsal nerve cord gives rise to the narrow………….. of the spinal cord and the ………. of the brain
A
central canal
ventricles
20
Q
the canal and ventricles of the brain are filled with what
A
cerebrospinal fluid
21
Q
how is cerebrospinal fluid made
A
in the brain by filtering arterial blood
22
Q
what is the role of cerebrospinal fluid
A
it supplies the CNS with nutrients and hormones and carries away waste. it drains into the veins
23
Q
what is a reflex
A
a rapid involuntary response to a particular stimulus
24
Q
why are reflexes rapid
A
sensory information activates neurons without having to travel from the spinal cord to the brain and back
25
what are the 2 efferent components of the PNS
motor system and the autonomic nervous system
26
what do the neurons of the motor system do
carry signals to skeletal muscles
27
is motor control voluntary or involuntary
can be either
| e.g. raising your hand is voluntary but the knee jerk reflex is controlled by the spinal chord
28
what do the neurons of the autonomic nervous system do
carry signals to smooth and cardiac muscle
29
is the autonomic nervous system voluntary or involuntary
involuntary
30
what are the 2 divisions of the autonomic nervous system
sympathetic and parasympathetic
31
what organ systems does the autonomic nervous system regulate
digestive, cardiovascular, excretory and endocrine
32
what is the enteric/intrinsic nervous system
network of neurons that exerts direct and partially independent control of the digestive tract, pancreas and gallbladder
33
what does activation of the sympathetic nervous system result in
```
arousal and energy generation
e.g.
the heart beats faster
digestion is inhibited
the liver converts glycogen to glucose
adrenal medulla increases secretion of epinephrine
```
34
what does activation of the parasympathetic nervous system result in
```
promote calming and a return to self maintenance functions "rest and digest"
e.g.
heat rate decreases
digestion id enhanced
glycogen production increases
```
35
in which process does the parasympathetic nervous system complement the sympathetic nervous system rather than antagonizing it
regulation of reproductive activity
36
how do the parasympathetic and sympathetic nervous systems differ in organization and signals released
parasympathetic nerves exit the CNS at the base of the brain or the spinal cord and form synapses in ganglia near or within an internal organ
sympathetic nerves typically exit the CNS midway along the spinal cord and form synapses in ganglia located just outside the spinal cord
37
what are preganglionic neurons
they release acetyl choline as a neurotransmitter
38
what are postganglionic neurons
parasympathetic division - release acetyl choline
| sympathetic division - release nor epinephrine
39
what is it that enables the sympathetic and parasympathetic divisions to bring about posit e effects in organs
the difference in neurotransmitters
40
what are the 3 major regions of the vertebrate brain
forebrain, midbrain and hindbrain
41
what are the components and function of the forebrain
olfactory bulb, cerebrum, thalamus and hypothalamus
| functions - smell, regulation of sleep, learning ad any complex processing
42
what is the function of the midbrain
coordinates routing of sensory input
43
what are the components and function of the hindbrain
```
cerebellum
function - controls involuntary activities, such as blood circulation and coordinates motor activities such as locomotion
```
44
which part of the brain generally increases in size with evolution of the brain
the cerebrum (forebrain)
45
what is the role of the cerebrum
controls skeletal muscle contraction and is the centre for emotion, learning, memory and perception
46
what is the outer layer of the cerebrum called and what are its functions
cerebral cortex
function - perception, voluntary movement and learning
left side controls the right side of the body and voice versa
47
what does the cerebellum coordinate
coordinates movement and balance and helps in learning and remembering motor skills
48
generation and experience of emotions involve the brain structures grouped as what system
the limbic (reward) system - contains the amygdala, olfactory bulb, nucleus accumbens hippocampus and parts of the thalamus
49
what is the function of the amygdala
storage and recall of emotional memory
50
what are the 4 lobes of the cerebral cortex
frontal
parietal
temporal
occipital
51
what are the functions of the frontal lobe of the cerebral cortex
decision making, planning, control of skeletal muscles, forming speech
52
what are the functions of the parietal lobe of the cerebral cortex
sense of touch, integration of sensory information
53
what are the functions of the occipital lobe of the cerebral cortex
processing visual stimuli and pattern recognition, combining images and object recognition
54
what are the functions of the temporal lobe of the cerebral cortex
hearing
55
what are neurons
nerve cells that transfer information within the body
56
most of a neurons organelles, including its nucleus are located where
in the cell body
57
the cells body of a neuron is studded with dendrites. what are dendrites
highly branched extensions that receive signals form other neurons
58
as neuron has a single axon. what is an axon
an extension that transmits signal to other cells
59
which is longer, axons or dendrites
axons
| e.g. those that reach from the spinal cord in the giraffe to the muscle cells in its feet
60
the junction at the end of the axon that branches to the receiving cell is called what
the synapse
61
the part of the axon branch that forms the synapse is called what
synaptic terminal
62
what are neurotransmitters
chemical messengers
63
what do neurotransmitters do
pass information from the transmitting neuron to the receiving cell
64
in describing a synapse what is the transmitting neuron referred to as
presynaptic cell
65
in describing a synapse what is the receiving cell (neuron, muscle gland cell etc) referred to as
post synaptic cell
66
what are neuron supporting cells called
glia
67
what are the 3 stages of information processing by a nervous system
sensory input, integration ad motor output
68
what are sensory neurons
transmit information about external stimuli e.g. light, touch or smell
or internal conditions such as blood pressure or muscle tension
69
what are interneurons
they form the local circuits connecting neurons in the brain or ganglia
they are responsible for integration (analysis and interpretation) of sensory input
70
what are motor neurons
they transmit signals to muscle cells, causing them to contract
71
what happens at the synapse
the electrical signal is converted into a chemical signal
72
what is resting potential
the membrane potential characteristic of a non conducting excitable cell, with the inside of the cell more negative than the outside - imbalance in charge
73
what is action potential
an electrical signal that propagates (travels) along the membrane of a neuron or other excitable cell as a non graded (all-or-one) depolarization.
74
what is the membrane potential
the voltage (difference in electrical charge) across the plasma membrane
75
in most neurons the concentration of ………….. is higher inside the cell and the concentration of ………… is higher outside the cell
potassium
| sodium
76
what maintains the sodium and potassium gradient of a neuron
the sodium potassium pump
77
how does the sodium potassium pump maintain the ion gradient
```
3 sodium ions bind
pump hydrolyses ATP
phosphorylation
conformation change
sodium ions released
2 potassium ions bind
dephosphorylation
conformation change
potassium ions released
cycle repeats
```
78
how many potassium ions are pumped into the cell
2
79
how many sodium ions are pumped out of the cell
3
80
what is a gated channel
a channel that opens or closes in response to a stimulus
| e.g. voltage change or ligand binding/unbinding
81
what is hyperpolarization
increase in the magnitude of the membrane potential, making the inside of the cell even more negative
82
what is depolarization
reduction in the magnitude of the membrane potential the inside of the cell gets less negative
83
if hyperpolarization or depolarization only causes a shift in the membrane potential what is this known as
graded potential - they decay with time and distance from their source
84
action potential
if a depolarization shifts the membrane potential sufficiently the result is a massive change in membrane voltage
85
how are action potentials different to graded potentials
action potentials have a constant magnitude and can regenerate in adjacent regions of the membrane
action potentials can therefore spread along axons, making them well suited for transmitting
86
if a depolarization increases the membrane potential to a level called ………… the voltage gated sodium channels open
threshold
87
describe the steps in generation of action potential
1: the gated sodium and potassium channels are closed. ungated channels maintain the resting potential
2: a stimulus opens some sodium channels. Sodium inflow depolarizes the membrane
3: depolarization opens most sodium channels while the potassium channels remain closed. sodium influx makes the inside of the membrane positive with respect to the outside
4: most sodium channels become inactivated blocking sodium inflow. most potassium channels open permitting potassium outflow which makes the inside of the cell negative again
5: the sodium channels close but some potassium channels are still open. as these potassium channels close and the sodium channels become unblocked (though still closed) the membrane returns to its resting state.
88
what are the 5 steps in generation of action potential
```
resting state
depolarisation
rising phase of the action potential
falling phase of the action potential
undershoot
```
89
describe the resting state in generation of an action potential
the membrane of the axon is a at resting potential most voltage gated channels are closed. some potassium channels are open
90
describe depolarization in generation of an action potential
```
a stimulus (neurotransmitter) depolarizes the membrane. sodium channels open allowing an influx of sodium into the cell.
if the stimulus is sufficiently strong to reach the threshold then sodium inflow persists causing further depolarisation
this opens more gated sodium channels allowing even more sodium influx
```
91
describe the rising phase of the action potential
once the threshold is crossed, the positive feedback cycle rapidly increases the membrane potential
92
describe the falling phase of the action potential
voltage gated sodium channels inactivate stopping the influx into the cell
voltage gated potassium channels open causing rapid outflow of potassium
this rapidly decreases the membrane potential
93
describe the undershoot
the membrane's permeability to potassium is higher than at rest
gated potassium channels close
membrane returns to resting potential
94
what is the refractory period
the downtime when a second action potential cannot be initiated due to inactivation of sodium gated channels at the end of the previous action potential cycle
95
is the magnitude and duration of the action potential the same along the entire axon
yes - because an action potential is an all or none event
96
where does a nerve impulse start and finish
```
cell body (axon hillock)
synaptic terminal
```
97
why don't action potentials ever travel back towards the cell body
the area behind the travelling zone of depolarization has its sodium channels inactivated and is in the refractory period so can't respond to further input
98
the rate of action potential production is proportional to what
signal strength
99
a wide axon provides ……… resistance to the current associated with action potential
less
100
vertebrates have narrow axons but are insulated which increases the rate of action potential. what is the layer of insulation called
myelin sheath
101
what are myelin sheaths produced by
glia:
oligodendrocytes in the CNS
Schwann cells in the PNS
the myelin sheaths are mainly made from lipids which are poor conductor, so good insulators
102
which disease is caused by destruction of myelin sheaths
multiple sclerosis
103
what are the gaps in the myelin sheath called
nodes of ranvier - voltage gated sodium channels are restricted to these
104
what is saltatory conduction
rapid transmission of a nerve impulse resulting from action potential jumping from one node of ranvier to another, skipping the myelin sheathed regions of the membrane
105
what carries information across a synapse
neurotransmitters
106
Near the synapse the action potential activates voltage-gated...………... channels
calcium channels
107
calcium ions enter through the membrane and cause what
synaptic vesicles to fuse with the synaptic membrane releasing the neurotransmitters
