block D - CNS Flashcards
(110 cards)
1
Q
what are the functions of the CNS?
A
they’re the primary unit of integration
- help to keep the body environment constant (homeostasis),
- helps with the bodies perception (sight, taste, smell and hearing),
- movement and coordination, intellect and emotions
2
Q
what are the cellular components of the CNS?
A
neurons, glia and blood supply
3
Q
what are glia?
A
theyre cells that are ‘others’
helper cells
4
Q
what are myelinated axon bundles?
A
they wrap the cell body to protect it
5
Q
what are astrocytes?
A
they connect with neurons and blood cells
they keep the junctions between endothelial cells tight in central arterioles
they also make sure that nothing that’s not allowed into the arterioles get in
6
Q
what are olgiodendrocytes?
A
theyre myelin sheaths in the CNS
they help to more effectively transmit electrical impulses
7
Q
what are microglia?
A
theyre cells like phagocytes and scavengers
8
Q
what are ependymal cells?
A
they’re line ventricles, spinal canal and CSF circulation
9
Q
what are the major subdivisions of the brain?
A
forebrain
midbrain
hindbrain
10
Q
what are the two main parts of the forebrain and what do they consist of?
A
outer- cerebrum, corpus striatum and hippocampus
inner- thalamus and hypothalamus
11
Q
what sections make up the midbrian?
A
basal ganglia including substantia nigra
12
Q
what parts make up the hindbrain?
A
cerebellum, medulla oblongata, pons and reticular formation
13
Q
why is the brain wrinkled?
A
it increases surface area
14
Q
what is the hippocampus important for?
A
memories and emotions
15
Q
what is grey matter made of?
A
cell bodies
16
Q
what is white matter made up of?
A
its made up of mostly cell axons
17
Q
what are the 4 lobes of the outer forebrain?
A
frontal lobe
parietal lobe
temporal lobe
occipital lobe
18
Q
what does the central sulcus help to do?
A
it helps us discriminate different parts of the brain
19
Q
what is the occipital lobe important for?
A
vision
20
Q
what is the corpus striatum?
A
its part of basal ganglia and it coordinates body movements
21
Q
what system is the hippocampus part of? and what is it important for?
A
limbic system and its important in pleasure, hostility, anger and instincts, its also involved in memory
22
Q
what does the thalamus do?
A
it is the relay center and receives all sensory input, which gives it to the cerebrum and relays cerebrum motor output to other areas
23
Q
what does the hypothalamus do?
A
it regulated autonomic and endocrine systems
these are essential for hunger, thurst, osmotic balance, body temperature and metabolic rate
24
Q
what is the subratntia nigra?
A
its part of the basal ganglia and coordinates body movements
25
what does the hindbrain do?
it is a continuation of the spinal cord and has acending and decending nerves from the forebrain, its in control of veceral refelexes like heart rate, digestion and breathing
26
what happens if the hindbrain is damaged?
DEATH
27
what is the brain stem reticulum formation?
its within the brainstem and it modulates levels of wakefulness and sleep
28
what is the 2nd biggest structure in the brain?
the cerebellum
29
what does the cerebellum control?
fine coordinated movemets
30
what is the spinal cord surrounded by?
ascending and decending nerve tracts
31
what is the Ventral root?
motor/efferent nerves leaVing cord and innerVate effectors (innervate = supply)
32
what is the dorsal root?
its sensory and efferent nerves entering the cord
33
what is the dorsal root ganglion?
its a cluster of nerves coming out of the dorsal root
the nerves are sensory nerve cell bodies
34
what is the blood brain barrier between?
it is between the blood vessels and cerebral ventricles, these are around the brain and brainstem
and between the blood vessels and the interstitial fluid adjacent to neurons
35
what is the CSF-ISF interface?
its where there is some movement of fluid because of a permeable interface between the cerebrospinal fluid and the interstitial fluid (between the brain and the spinal cord)
36
what does the fluid which is separate from the blood do?
supplies metabolites
physically protects the brain
provides appropriate chemical environment for neuronal function
removes waste
37
how much of your energy does your brain burn?
1/5
38
how does the CNS get energy?
it relies on blood glucose and O2 supply to function, it receives 15% of all the blood pumped by the heart and 20% of the body's total O2 usage
39
what is the difference between a central areteriole and a peripheral arteriole?
central arterioles have astrocytes to keep them together so nothing unwanted can get into them as they go up to the brain buit peripheral arterioles dont have these astrocytes to keep them together so theyve got tiny pores that allow things into them
40
what are the structural specialisations of central arterioles?
- tight junctions between endothelial cells
- astorcytes - 2nd barrier
41
what do central arterioles let into them and what do they stop from getting in?
they allow small ionised lipid-soluble compounds like O2, CO2 and hormones, they also allow in substrates for specific transporters e.g. glucose, essential amino acids and ions
they block the entry of proteins, substances bound to plasma proteins, toxins, pathogens and most drugs
42
what does BBB stand for?
Blood-Brain Barrier
43
what causes injury and inflammation like meningitus?
BBB breakdown and when the CNS is exposed to harmful substances
44
what does the cerebrospinal fluid fill?
4 chambers
2x layteral, 3rd and 4th ventricles and spinal cord canal
45
what is the point of cerebral spinal fulid?
it cushions the brain and spinal cord from physical forces and it aids the removal of waste to the venous system
46
can cerebral spinal fluid flow anywhere it wants to in the brain?
no, it follows a specific path through the brain and it only flows in one direction
it flows from ventricles to surround brain and spinal cord and a small amount goes into the spinal cord canal and then exits through one-way valves to veins
47
how is cerebral spinal fluid produced?
by choroid plexus (ependymal cells + capillary bed)
it produces ~20ml CSF/hr for physical support and buffer
the ependymal cells actively secrete Na+ into ventricle and Cl- follows passively, this increases the osmotoc pressure which drives into venticle
48
what does the cerebral spinal fluid carry?
glucose transporters have low efficiency so CSF glucose is about 66% of blood glucose and it has less K+ than blood (a net reverse transport of K+)
49
what are chemical messengers?
theyre general properties of neurotransmission and you get non-peptide ones and peptide ones
50
what are non-peptide neurotransmitters involved in?
they're involved of synthesis, storage, release, mimicry, antagonists and inactivation
they're also involved in pathways and are the main CNS types
51
what are the structural properties of neurotransmitters?
they have a presynaptic axon, post-synaptoc cell body and post-synaptic recpetors
52
what does calcium do at the synapse?
it activates and changes some of the vesicles and then they fuse and dump out neurotransmitter into the synapse for it to then bind to the post synaptic membrane
53
what are examples of monoamines?
noradrenaline,
dopamine,
5-hydroxytryptamine (5HT/ serotonin),
histamine
54
what are some examples of amino acid non-peptide neurotransmitters?
GABA, glutamate and glycine
55
what are some other non-peptide neurotransmitters?
acetylcholine, ATP and nitric oxide
56
what is the criteria for identification of a neurotransmitter? (theres 6)
1. synthesised within the neuron
2. stored in nerve terminal
3. released by nerve stimulation in Ca2+ dependant manner
4. specific mechanisms exist for inactivation
5. exogenously applied substances mimic endogenous response to neurotransmitter
6. antagonist inhibits both neurotransmitter and exogenously applied substance
57
what are the steps of dopamine as a neurotransmitter?
1. its synthesised within the neuron
2. its stored in the nerve terminal
3. its released by nerve stimulation in Ca2+ - dependant matter
4. specific mechanisms
5. mimicry
6. inhibition by antagonist
58
what happens to dopamine after its caused a spike of neurotransmitter?
its rapidly degraded, if its not you would just be hyper all the time
59
what happens in 'mimicry' of dopamine as a neurotransmitter?
cAMP is measures in straitum after nerve stimulation or adding dopamine
60
how is noradrenaline distributed in the brain?
its distributed from the brain stem to the cortex, then to the libic system, cerebellum and brain stem
61
what are the physiological functions of noradrenaline?
its part of the reward system and mood, state of arousal (alertedness) and blood pressure regulation
62
how is dopamine distributed in the brain?
SN to basal ganglia then to VTA to limbic system and cortical forebrain hypothalamus and then finally to pituritary
63
what are the physiological functions of dopamine?
motor control
reward system
mood
motivation
prolactin secretion
64
how is 5-HT distruibuted around the brain?
from brain stem to cortex to limbic system, thalamus, hypothalamus and cerebellum
65
what are the physiological functions of 5-HT?
sleep
wakefulness
temperature regulation
mood
66
what is the physiological functions of acetylcholine and how is it distributed?
arousal, learning and motor control
distribution - long and short projections from basal forebrain, interneurons in basal ganglia
67
how is glutamate distributed in the brain and that are the physiological functions of it?
functions- memory, epilepsy, relay of sensory information
distribution - widespread, mainly present as interneurons
68
how is GABA distributed in the brain and that are the physiological functions of it?
functions-epilepsy and anxiety
distribution - widespread, mainly present as interneurons
69
how is glycine distributed in the brain and that are the physiological functions of it?
distribution - spinal cord interneurons, modulates NMDA receptors
function- epilepsy (not all forms)
70
what are neuropeptides?
they're 5->30 amino acids
they have many different function's from classical neurotransmitters
71
what are the similarities between classical neurotransmitters and neuropeptides?
- stored in vesicles, in specific regions
- Ca2+ dependant release
- effect > 2nd messengers / change in ion channel activity`
72
what are the differences between neuropeptides Vs classical neurotransmitters ?
- synthesised in cell body, part of large precursor protein
- transported to terminal
- processed to active peptide
- released at lower concentrations
- mechanism of inactivation unclear
- removed slowly from synaptic cleft
- longer action
73
what what is involved in indirect, slow neurotransmission?
its via G-proteins and cytoplasmic 2nd messengers
74
what are some examples of ligands of GCPR?
dopamine, NA, 5HT, aCh- musccarenic, clutamate metatrophic
75
how fast is 'slow neurotransmission'?
secs to mins
76
how fast is 'fast neurotransmission'?
10's of miliseconds
77
what is direct, fast neurotransmisson via?
receptor-operated ion channels
78
what are some examples of receptor-operated ion channels?
nicotinic ACh receptors
glumate ionotropic receptors
P2X receptors
79
what causes inhibitory post-synaptoc potential (IPSP) and what causes exitatory post-synaptic potential (EPSP)?
IPSP- Cl-
EPSP-Na+ and K+
80
if theres not enough stimulation to hit the neurotransmission threshold, what happens?
nothing. it just fizzles out and doesnt lead to anything
81
how do pre-synaptic inhibition by fast neurotransmitters work?
the inhibitory neuron is the one affecting the pre-synaptic synapse
82
what senses are sensed by the sensory reception?
vision
somatic sensory/ touch
gustatory / taste
olfaction / smell
auditory / hearing
balance /movement propricoception
83
why is sensory reception important?
it maintains homeostasis
detects and reacts to changes in environment
protects the body from noxious (damaging) stimuli
84
what are the different types of sensory receptors?
1. cuteneous receptors - touch, pressure, temperature and pain
2. proprioceptors - body position
3. special senses- sight, hearign, taste and smell
85
what do sensory afferent nerves sense?
they only sense their own one specific stimulus
86
what do free nerve endings sense?
pain and temperature
87
do the same receptors sense hot and cold?
no, theres 2 different neurons that are sensitive to the different temperatures
88
how does skin sense pressure?
theres is lots of different nerve endings to sense different pressures and theyre all covered in connective tissue layers
89
what are some names of nerve endings that detect touch?
merkel's disk
meissner's corpuscle
Ruffini's ending
90
what happens if the stimulus strength is: sub-threshold; moderate; strong?
sub-thershold- no action potentials are produced
moderate - a few action potentials are generated
strong- lots of action potentials are generated
91
what happens if there's a strong continuous signal created?
they start ignoring the information sent because they've already detected it and created a response
92
give examples of 1st, 2nd and 3rd order neurons?
1st - goes from the stimulus to the spinal cord
2nd- goes from spinal cord to thalamus
3rd - goes from thalamus to cortex
93
do 2 signals coming from the same place to the same place have to follow the same pathway?
no, there can be 2 different pathways for the same pathway
94
what does the dorsal column system palthway transmit signals for?
fine touch
pressure
propriception
95
what does the spinothalamic system transmit signals for?
pain
temperature
coarse touch
96
what does decussation mean?
it means pathways that have to cross to the other side of the brain- thus sensory info is processed on the other side of the brain
97
where do the signals continuously sensed go to in the brain?
they go to the post centural gyrus
98
what are the two types of nociceptor fibres and what do they sense?
Aδ- these sense fast, sharp pain myelinated
C fibres- slow, dull aching pain unmyelinated
99
what are the characteristics of thermoreceptors?
theyre activated by extreme temperatures (>45 degrees, <15 degrees) theyre found at Aδ fibresq
100
what are the characteristics of mechanireceptors?
theyre activated by intense pressure and are found at Aδ fibres
101
what are the characteristics of polymodal nociceptors?
theyre activated by high intensity mechanical, chemical and thermal (both hot and cold) stimuli
102
what is referred pain?
its pain perceived to come form one part of the body but it actually comes from another part
103
how does spinal cord modulation of pain carried by C fibres?
interneurons that release enkaphalins on either descending stimuli from CNS or localised 5HT to activate pre- and post-synaptic opiate receptors at spinal sensory synapse; GPCRs coupled to Gi leading to decreased cAMP, reduced PKA activity, modulation of K+ conductance thus decreasing neuronal excitability
its part of the spinothalamic pathway
104
what is the gate control theory of pain?
its where theres a dampening down of the pain signals and the C fibre can turn off the neurons so strong signals dont go to the thalamus
105
how is pain carried by Aδ fibres modulated?
Aδ fibres synapse in different area of spinal cord
No interneurons that release enkephalins
No opiate receptors morphine ineffective
Sharp pain harder to treat
106
how is the sense of pain different for everyone?
the more your exposed to continuous stress, the less you may feel pain
its modulated by previous experiences
107
what are some non-steroidal anti-inflammatory drugs and what do they do?
they block COX-1 and COX-2 which block inflammation
- aspirin, ibuprofen
108
what does lidocane block?
the generation of action potentials
109
how do local anasthetics work?
they're injected locally and block Voltage-dependant Na+ channels to block action potentials
110
how do opiods treat pain?
they bypass the primary nociceptive afferent pathway and inhibits discharge of 1 degree
