Nervous system Flashcards
0
Q
function of astrocyte?
A
regulate extracellular composition of brain fluid via BLOOD BRAIN BARRIER
form a support framework for the CNS
1
Q
what are nissl bodies?
A
cluster of ribosomes and rough ER within nerve cell body cytoplasm
2
Q
function of oligodendrocyte?
A
production of myelin
3
Q
function of myelin?
A
insulates nerve fibre from surrounding extracellular fluid, speeds up action potential conduction
4
Q
function of Microglial cell
A
phagacytic cells that remove dead nervous tissue, micro-organisms and other foreign material
5
Q
which neuroglial cell would you expect to be most common in grey matter?
A
astrocytes
6
Q
why is there so little myelin present in grey matter?
A
as myelin is not present near cell bodies and grey matter is full of nerve cell bodies
7
Q
where are ependymal cells located?
A
edge of CNS tissue,
lining the ventricles of the brain and central canal of the spinal cord
8
Q
function of ependymal cells
A
ependymal cells (+ blood vessels) form the choroid plexuses within the ventricles of the brain...this secretes cerebrospinal fluid the free surface of ependymal cells has patches of cilia that help move fluid around the brain and spinal cord
9
Q
what are the sulcus?
A
grooves(vallys) of the surface of the brain
10
Q
what are gyrus?
A
hills or folds of the cortext of cerebellum/cerebrum
11
Q
what is the function of the precentral gyrus?
A
primary motor area - controls voluntary movements
12
Q
function of post central gyrus?
A
primary sensory - conscious perception, localisation and identification of stimulus
13
Q
function of occipital lobe?
A
vision!
14
Q
function of the thalamus?
A
considered the sensory relay station of the brain.
auditory, visual, sensory input eg. pain, temp, touch all pass through thalamus
15
Q
function of hypothalamus?
A
1) autonomic nervous system eg. heart rate
2) endocrine system(hormones -> pituitary gland eg. metabolism
3) limbic system - rage, fear, sexual feelings
4) basic body functions eg. body temp control
16
Q
what vertebra marks the inferior end of the spinal cord?
A
T12 - L1
17
Q
how do we check for an infection in the brain?
A
lumbar puncture
18
Q
where is the needle in a lumbar puncture inserted?
A
the subarachnoid space at either T3-T4 or T4-T5
19
Q
why are cervical and lumbar parts of the spinal cord enlarged?
A
more nerves exit spinal cord at these regions to supply arms and legs respectively
20
Q
what is the meninges?
A
protective layers of tissue surrounding the brain and spinal cord
21
Q
name the meninges from the outer most to the inner most
A
dura mater
arachnoid mater
pia mater
22
Q
what is the function of the dura mater?
A
tough, thick, outer layer of meninges
made of dense irregular connective tissue protects the CNS tissue
23
Q
function of the arachnoid mater
A
very thin, spider like, that connects to pia mater
space contains cerebrospinal fluid which protects and cusions the CNS + provides nutrients
24
why is dura mater white in colour?
as its dense irregular connective tissue, hence containing a lot of COLLAGEN
25
what is the space called between the dura and skull/vertebral bones?
epidural space!
26
what is normally located in the epidural space?
adipose tissue, blood vessels and nerves
27
describe movement of CSF:
flows from lateral ventricle -> 3rd ventricle -> 4th ventricle
then exits ventricle and enters subarachnoid & central canal of spinal cord. flows up & down vertebral column then resorbed in arachnoid villi
28
what makes CSF circulate
itself...driven by its own pressure + rhythmic pulsations of the brain produced by heart beating
29
where is CSF formed?
choroid plexus of each lateral ventricle
30
how can you tell which side of spine is dorsal and ventral?
presence of dorsal grey horn and ventral median fissure
31
where is grey matter located in the brain?
edge of cerebrum/cerebellum?
32
what are ganglia?
cell bodies of neurons in the PNS
33
where is grey matter located in the spinal cord
it forms a H/butterfly in the centre of spinal cord
34
where are the cell bodies of motor neurons of the PNS located?
within the grey matter of the spinal cord
35
name the protective layers of a peripheral spinal nerve from outer most to inner most
epineurium, perineurium, endoneurium
36
describe refractory period:
period of depolarisation of the neuron during which it cannot respond to a second stimulus
37
describe depolarisation:
state in which the resting potential is reversed as sodium ions rush into the neuron
38
describe polarised:
electronic condition of the plasma membrane of a resting neuron
39
describe repolarisation:
period in which potassium ions diffuse out of the neuron
40
describe action potential:
transmission of the depolarisation wave along the neurons membrane(axon)
41
describe potassium ions:
chief positive intracellular ion in a resting potential
42
describe sodium-potassium pump
process by which ATP is used to move sodium ions out of the cell and potassium ions back into the cell; completely restores the resting conditions of the neutron
43
describe the events that occur at a chemical synapse between 2 neurons
1) neurotransmitters diffuse from presynapic terminal across the synaptic cleft (2) calcium ions diffuse into the cell and cause synaptic vesicles to release neurotransmitters (3) neurotransmitters combine with their receptor sites and cause ligand-gated ion channels to open. Ions diffuse into/out of the cell and cause a change in membrane potential. (4) action potentials arriving at the presynaptic terminal cause voltage-gated Ca2+ channels to open
44
name the parts of the neuron that can conduct and action potential
axon and just before the synaptic terminals
45
composition of corpus callosum:
primarily composed of over 200 million axons, called commissural fibres
46
function of corpus callosum?
axons(commissural fibres) interconnect allowing communication between left & right cerebral hemispheres
transfer of motor, sensory and cognitive info between hemispheres
47
components of brain stem:
midbrain
pons
medulla oblogata
48
function of axon
conduction of action potential away from cell body
49
function of dendrites
receive synaptic input from other cells or sensory stimuli that generate local electrical responses (graded potential) that conducts towards cell body
50
what do nodes of ranvier allow?
propagation of action potential in myelinated neurons
| or SALTATORY conduction - allowing potential to jump from one node to another making it much faster
51
function of grey matter
site of synapse formation
| Integration of sensory inputs and neuronal computation
52
site of integration of sensory inputs and neuronal computation
grey matter
53
function of white matter?
site of axons and tracts of neurons that link different parts of the CNS
54
why is white matter white?
myelin
55
function of microglia
act as macrophages in the brain and spinal cord
| main form of active immune defense in the CNS
56
function of Astroglia
- biochemical support of ependymal cells
- provision of nutrients to neurons
- maintenance of extracellular ions
- repair
57
define continuous propagaion:
entire axon contains voltage gated ion channels, action potential gradually conducts along the length
58
define saltatory propagation:
voltage gated channels only at nodes of ranvier so action potential is regenerated at each node by current conducting axially (along the length), fast!
59
what tissues react during reflexes?
muscles or glands
60
what does the typical reflex involving muscle require?
```
sensory receptor(in muscle)
sensory neuron(receptor to spinal cord)
integrating centre(within spinal cord, determines magnitude of respons
motor neuron(motor neuron to skeletal muscle)
```
61
what does the term monosynaptic reflex ARC mean?
| mono = one | synaptic = synapse |
| sensory neuron synapses directly with motor neuron in the grey matter of spinal cord (no interneuron)
62
what type reflex is the platella reflex an example of?
postural reflex
63
so what movement of the arm does the bowler in cricket do?
circumduction
64
describe location of nuclei in skeletal muscle?
they're peripherally located
65
what is the synaptic delay?
time between arrival of action potential at axon terminal and action at synapse
66
describe what happens after neurotransmitter release?
binds to receptors on post-synaptic
destroyed by enzymes (prevents neurons becoming too excited)
reuptake by presynaptic terminal - recycling
diffuse away(move away from synapse)
reuptake into glia eg. astrocytes
67
types of neurotransmitters
ionotropic - directly bind to and open ion channels
| metabotropic - act via second messengers
68
what do the names of neurotransmitters end in?
"ine"
69
what is serotonin?
"feel good" moon neurotransmitters
90% in intestine
lower levels of serotonin are found in patients with depression
70
what happens with the parasympathetic activity?
Salivation
Lacrimation (tears)
Urination
Defecation
rest and digest
71
cut the brain in left and right sides
sagittal
72
cuts the brain in top and bottom
axial
| horizontal
73
cuts brain in front and back
coronal
74
left hemisphere
spoken written language
numeric and scientific skills
reasoning
ability to use sign language
75
right hemisphere
```
"Creative side"
musical and artistic awareness
spatial and pattern awareness
recognition of faces
emotional content of language
```
76
what matter is the cortex made of?
grey matter!
77
primary function of motor cortex
Maps out/plans behaviours leading to skeletal muscle contraction
78
primary function of sensory cortex
Interprets incoming information
| Makes information identifiable and useful
79
What is the main function of the basal ganglia?
```
Voluntary motor control
habits
Eye movements
Cognitive functions
Emotional functions
```
80
state the sequence of events in an action potential:
```
resting
threshold -50mv reached
depolarisation
repolarisation
hyperopolarisation
resting
```
81
state the activity of gates during resting of an action potential
Na+/K+ ATpase
| Na+ gated channels closed
82
state the activity of gates during threshold
Na+ gated channels open
83
state the activity of gates during depolarisation
Na+ channels open
84
state the activity of gates during repolarisation
Na+ gated channels close
| K+ gated channels open
85
state the activity of gates during hyperopolarisation
Na+/K+ ATpase active
86
what is the action potential threshold?
-50mv
87
what stimulates vesicles to fuse with membrane?
Ca2+
| action potential triggers influx of Ca2+
88
what is exocytosis?
release of contents from cell into the extracellular space, in this case it is released into synapse
89
what does the binding of neurotransmitters to receptors on post-synaptic neuron do?
stimulate post-synaptic potential
| change in membrane potential
90
what is graded potential?
summation of individual actions of the ligand-gated ion channel proteins
91
why are neurotrasmitters reabsorbed?
saves energy as pre-synaptic cell doesn't need to make new neurotransmitters from scratch
92
why are some neurotransmitters pumped back into glia?
to avoid overstimulation of the post-synaptic neuron
93
what is electrical synapse?
direct neural connection through gap junctions
94
3 groups of neurotransmitters
amino acids
classical neurotransmitters
neuropeptides
95
how do anti-depressant drugs work at serotonin synapses
Selective Seretonin Reuptake Inhibitors, inhibit the reuptake of serotonin at the synapse, continues to stimulate post-synaptic cell, prolongs effect
96
why is too much Glutamate bad for the brain?
overestimates the brain and spinal cord -> seizures
| excitotoxcity -> cell death
97
what are the 2 main second messengers?
Cyclic AMP
| Inositiol triophosphate
98
briefly describe how second messager cyclic AMP (cAMP) works to transmit signal in post-synaptic cell
activates membrane potential G PROTEIN
ATD -> cAMP
impacts membrane permeability, metabolic pathways, protein synthesis
99
briefly describe second messenger Inositol Triphosphate
activates G PROTEIN and PHOSPHOIL[pase
| IP3 -> diacylglycerol (DAG)
100
what is an IPSP
inhibitory post-synaptic potential
| synaptic potential that makes post synaptic neuron LESS likely to generate and action potential
101
what is an EPSP
excitatory post synaptic potential
MORE likely to generate an action potential in post synaptic neuron
ESPS's summate when there are enough synapses close together
102
when there is enough synapses close together what is it called?
spatial summation
103
what happens with EPSP's when post synaptic membrane is depolarised in rapid succession?
EPSP's provide temporal summation
104
what is contained in the brain stem
midbrain, pons, medulla
105
what region of the brain is responsible for maintenance of body temperature
hypothalamus
106
what part of part of the brain contributes to coordination, precision and accurate timing?
cerebellum
107
function of pons?
basically to replay signals from forebrain to cerebellum
108
what do the signals that pass through pons control?
respiration, sleep, swallowing, bladder control, hearing, taste, facial exression/sensation
109
why is the medulla so important?
controls cardiac(heart rate)
respiratory centers(breathing)
Vasomotor (blood pressure)
vomiting
110
what does the medulla contain?
nuclei concerned with Vital Visceral functions
111
what dural fold separates left and right hemispheres
falx cerebri
112
what dural fold separates left and right lobes of the cerebellum?
falx cerebelli
113
what dural fold separates the cerebral hemispheres from the cerebellum?
tentorium cerebelli
114
whats the little pocket of fluid below protective layers of the skull
superior sagittal sinus
115
where is CSF reabsorbed?
```
arachnoid villi
(finger like projections of arachnoid membrane that project fluid into superior sagittal sinus)
```
