THE NERVOUS SYSTEM Flashcards
1
Q
how many main nervous systems are there
A
2
2
Q
what are the 2 nervous systems we focused on
A
CNS and PNS (central and peripheral)
3
Q
what does the PNS consist of
A
cranial nerves, ganglia outside CNS, and spinal nerves
4
Q
what does the CNS consist of
A
the brain and spinal cord
5
Q
what is the primary function of the CNS
A
the primary function of the CNS is to integrate information
6
Q
what is the process of CNS and PNS
A
the CNS processes sensory information and coordinates an appropriate response through the PNS
7
Q
what are the two main categories of PNS
A
afferent (sensory) and efferent (motor)
8
Q
what are the two main categories of efferent (motor)
A
somatic nervous system (skeletal muscle) and autonomic nervous system (involuntary muscle movements i.e heart: smooth muscle, cardiac + glands)
9
Q
S A M E acronym stands for
A
Sensory - afferent (bring to) and motor - efferent (bring out)
10
Q
what are the parts of a neuron
A
cell body, dendrites, axon hillock, axon, synaptic terminals
11
Q
What are the names of the diff neurons
A
anaxonic neuron, bipolar neuron, unipolar neuron, multipolar neuron
12
Q
properties of anaxonic neurons
A
- small
- many dendrites
- no obvious axon
- brain + special senses
- poorly understood
13
Q
properties of bipolar neurons
A
- one axon + one dendrite (two poles)
- special senses
14
Q
properties of unipolar neurons
A
- single fused process (dendrites and axon with cell body to the side)
- most of the process is the bacon
- most sensory neurons
15
Q
properties of multipolar neurons
A
- 2 or more dentrites and 1 axon
- motor neurons
16
Q
what are the three different neurons and their function
A
sensory neurons - neuron sending sensory into CNS
motor neurons - neurons sending motor info from CNS
interneurons - link sensory + motor neurons (mostly in CNS/ brain + spinal cord)
17
Q
what are neurons supported by
A
glia/neuroglia (glue)
18
Q
True or False? there are different glia in CNS and PNS
A
true
19
Q
what are the names of the Glia in PNS
A
- schwann cells
- satellite cells
20
Q
what are the names of the Glia in CNS
A
- astrocytes
- oligodendrocytes
- ependymal cells
- microglia
21
Q
schwann cells
A
- PNS glia
- function: myelination of PNS axons
- insulation/support of unmyelinated PNS axons
22
Q
satellite cells
A
surround cell bodies of neurons in the PNS with the purpose to regulate exchanges with interstitial fluid
23
Q
astrocytes
A
are most abundant glia cells in CNS and have many cell processes.
they involve in the formation of the BBB and regulate chemical composition of interstitial fluid and structural support
24
Q
oligodendrocytes
A
have many processes and their function is the myelination of CNS axons where each oligodendrocyte myelinates multiple axons which is important as it increases the speed of the AP conduction
25
ependymal cells
epithelial cells that line cavities containing CSF (cerebrospinal fluid) - brain ventricles + spinal cord (central canal) and functions to production + circulation of CSF
26
microglia
least common CNS glia and is a part of the immune system. Phagocytic cells like debris, waste products and pathogens
27
what is myelination
process of wrapping a fatty layer myelin around nerve axons to speed up nerve signal transmission
28
what is myelin
a fatty layer
29
what are bundles of axons called in the PNS
nerves
30
what are bundles of axons called in the CNS
tracts
31
what are clusters of cell bodies called in the PNS
ganglia
32
what are clusters of cell bodies called in the CNS
nuclei
33
function of nerves (PNS)
nerves are bundles of axons in PNS which are most classified as mixed nerves because they contain sensory + motor fibres. Its functions in carrying the action potential which will travel in both sensory and motor directions
34
what are the 3 connective tissues
epineurium (upon) - fibrous outermost layer
perineurium (around) - separates axon bundles into fascicles - blood vessels
endoneurium (within) - wraps around individual axons
35
what are ganglia
ganglia are clusters of cell bodies in the peripheral nervous system that can contain cell bodies from afferent (dorsal root ganglia) and efferent (autonomic nervous system) and are surrounded by epineurium
36
what two colors are associated in the CNS
grey and white matter
37
what is grey matter
grey matter is coloured from cell bodies. It has cell bodies dendrites glia, and unmyelinated axons. It contains nuclei as well
38
what is white matter
white matter is coloured from myelin (fatty substance) and has mostly myelinated axons and tracts
39
what occurs in:
dendrites/cell body
axon hillock
axon
synaptic terminals
graded potentials
AP initiation
AP propagation
Neurotransmitter release
40
list the process of action potentials (graph line)
1) graded potential
2) depolarisation
3) repolarisation
4) hyperpolarisation
41
what are graded potentials?
graded potentials are changes in membrane potential and occur at the dendrites + cell body. They can be excitatory or inhibitory
42
what is an excited neuron
it is closer to threshold + triggers AP by making the membrane potential less negative
43
what is an inhibited neuron
it is further from threshold + inhibits AP by hyperpolarising neurons
44
properties of the spinal cord
- part of the CNS
- conduction pathway to + from brain
- extends from the brain stem
- has 4 vertebral regions: cervical, thoracic, lumbar, sacral
- spinal cord is encased by the vertebral canal
- has white and grey matter
45
what are the 4 vertebral regions
cervical, thoracic, lumbar, sacral
46
what is another name for "horse tail"
cauda equina
47
what is another name for "cauda equina"
horse tail
48
properties of vertebral canal
- roots of spinal nerves emerge from spaces between vertebrae
49
what are meninges and their names
meninges are protective coverings
spinal cord is protected by 3 membranes: spinal meninges are dura mater (outer), arachnoid mater (middle) and pia mater (inner)
50
properties of the pia mater
pia mater is the inner membrane bound to the spinal cord + provides support to blood vessels of spinal cord
51
properties of the dura mater
dura mater is the outer membrane with a tough and fibrous connective tissue layer around the outside
52
properties of the arachnoid mater
arachnoid mater is the middle membrane with a spiderweb like look
53
how many meninges and spaces are in the spinal cord
3 meninges
dura mater
arachnoid mater
pia mater
2 spaces
epidural space
subarachnoid space
54
properties of the epidural space
- between dura mater and vertebrae
- loose connective tissue, blood vessels + adipose tissue (full of fat + connective tissue)
- epidural anesthetic (birth)
55
properties of the subarachnoud space
- between arachnoid mater + pia mater
- contains CSF: shock absorber (helps spinal cord to shift around + move a little) + diffusion medium for gases, nutrients etc
- can also inject spinal anaesthesia here but because it is fluid it is more difficult to localise the anaesthetic so position of the patient helps the spread of CSF of CNS
56
grey matter of spinal cord
- h shape
- organised into horns: dorsal, lateral, ventral
57
white matter of spinal cord
- allows communication within zcns + contains tracts (bundles of axons travelling in CNS)
- ascending and descending tracts
58
properties of the dorsal horn
-sensory neurons enter spinal cord + synapse with cell bodies of interneurons
- posterior
59
properties of the lateral horn
- contains cell bodies of autonomic motor neurons (involuntary control i.e smooth muscle)
- only found in certain areas of spinal cord
- only in T1-L2 and S2-S4
60
properties of the ventral horn
- contains cell bodies of somatic motor neurons (controls skeletal muscle)
61
ascending tracts
take sensory info to the brain
62
descending tracts
send motor commands to the spinal cord
63
spinal roots
- neurons enter + exit spinal cord through roots: dorsal root, dorsal root ganglion and ventral root
- spinal roots contain either afferent or efferent neruons
- each dorsal + ventral root fuses to form a spinal nerve (mixed nerves)
64
dorsal root
afferent axons
65
dorsal root ganglion
sensory neuron cell bodies
66
ventral roots
efferent axons
67
peripheral nerves
- short spinal nerves branch into rami + may converge into nerve plexuses (join back together)
- eventually a peripheral nerve is formed
68
spinal reflexes
- atomatic responses to stimuli
- can be processed in spinal cord (spinal reflexes) or the brain (cranial reflexes)
- can be: monosynaptic or polysynaptic
69
monosynaptic spinal reflex
one synapse between the afferent + efferent neuron
70
polysynaptic spinal reflex
more than one synapse involving interneuron
71
reflex arc order
receptor, afferent neuron, CNS, efferent neuron, effector
72
reflex arc consists of
- receptors that detect sensations
- sensory neurons that send AP to CNS (intergration centre)
- intergration centre which is the CNS (brain or spinal cord)
- motor neuron that stimulates an effector
- effector that could be muscle
73
stretch reflex
- a monosynaptic reflex that allows adjustment to posture by detecting changes in muscle length (stretch) + causes contraction of the same muscle. an example is a patellar reflex
74
how is muscle stretch detected?
-through muscles spindles (sensory receptors for the stretch reflex)
- muscle spindle is a proprioceptor (type of sensory receptor that tells us where muscles + joints are in space)
- muscle spindles have own muscle inside: made of intrafusal muscle fibres with sensory neurons wrapped around it
- surrounded by extrafusal muscle fibres (regular contractile skeletal muscle) that responds to the stretch reflex - e.g quads (when quad stretch muscle spindle also stretches, inc rate of AP in the sensory neurons)
- more AP travel along alpha motor neurons to the quads
75
what do muscle spindles do
muscle spindles detect changes in muscle length
76
polysynaptic reflexees
more complex + longer duration due to more synapses with one or more interneurons
77
what is an interneuron
type of neuron that are located between sensory and motor neurons
78
withdrawal reflex
great for responding to pain
- move away from a stimulus (pain)
- sensory neuron send APs to spinal cord + brain - conscious perception of pain
- synapse with interneurons which can be excitatory or inhibitory
- muscles contract while other muscles relax
- reciprocal inhibition: simultaneous stimulation + inhibition of antagonistic muscles - excited one + inhibit the other
79
crossed extensor reflex
- pairs with withdrawal reflex (i.e one leg withdrawn the other leg is needed)
- injured limb reflexes (bends) and healthy limb extends (straightens)
- contralateral rather than ipsilateral
80
contralateral
motor response on opposite side to stimulus
81
Ipsilateral
motor response on the same side as stimulus (eg stretch + withdrawal reflexes)
82
human brain
-controls emotions, personality, language, motor activity + sensory perception
83
what are the ways the brain is protected
skull
meninges
CSF
BBB - chemical protection
84
what are the cranial meninges
- meninges are protective layers of tissue around the brain and the cranial meninges are continuous with spinal meninges but only diff is with dura mater
85
cranial dura mater
2 layers of blood filled in space between (called dura sinus) + no epidural space (dura mater bound to skull)
86
cranial arachnoid mater
subarachnoid space contains CSF
87
cranial pia mater
sticks to the surface of the brain
88
CSF properties
cushions + nourishes the brain + spinal cord (brain floats in the CSF) + it is produced in the CHOROID PLEXUSES of the ventricles
make CSF from blood which travels through capillaries + ependymal cells decide which component inside the blood want to put into the CSF
89
what is the choroid plexuses
CSF is produced in the choroid plexuses which is an area inside ventricles made up of many capillaries that bring blood supply to the ventricle.
it is also surrounded by ependymal cells to maintain the CSF
90
what are ependymal cells
special transporters that selectively move molecules into CSF
91
what is the flow of CSF
CSF circulates through ventricles of the brain and central canal of the spinal cord then escapes through ventricle openings into the subarachnoid space where it entered venous blood through arachnoid villi
92
blood-brain barrier
is formed by tightly adhered capillary cells which molecules must pass through via diffusion (oxygen, carbon dioxide alcohol or water) or transport proteins (glucose, ions, amino acids)
93
regions of the brain
cerebrum, cerebellum, diencephalon, midbrain, pons, medulla oblongata
94
cerebral cortex lobes
frontal lobe, parietal lobe temporal lobe, occipital lobe
95
cerebrum properties
right + left hemispheres
white + grey matter
surface has undulations: gyrus, sulcus, fissures
memory, thought, skeletal muscle
96
parietal lobe
contains: primary somatosensory cortex allowing perception of general senses - temp, pain, touch, pressure, vibration, proprioception
97
frontal lobe
contains: primary motor cortex which controls skeletal muscle + receives instructions from premotor cortex
98
somatic motor control
cerebral cortex -> spinal cord (ventral horn) -> skeletal muscle
99
prefrontal cortex
lobotomy used to be done
- planning + problem solving
- direction attention
-decision making
-creativity
-personality
100
limbic system
regulate emotion and memory
101
basal nuclei
- motor control
- clusters of gray matter embedded in white matter of cerebrum
- subconscious control of motor activity i.e skeletal muscle tone, pattern + rhythm for movement
- can also fine tune motor commands of upper motor neurons
102
cerebellum
- cooridinator + predictor of movement
- can take in sensory info
- e.g vision - someone throw a ball, sensory info feeds to cerebellum + fine tune motor activity coming from cortex - move hand etc (basically adjust output)
- useful to maintain balance + posture
103
diencephalon
2 components: thalamus and hypothalamus
processing center for sensory information
104
thalamus
controller for sensory information that decides if info needs to go to the consciousness. Motor info from the cerebellum + basal nuclei travels through the thalamus to the cortex
105
hypothalamus
body balancing functions
- homeostatic control
- endorcrine role
-emotional + behavioral drives
- control of autonomic function
106
brain stem
connection spinal cord to rest of brain and has 3 regions - medulla oblongata, pons and midbrain
functions as a highway between spinal cord+ brain structures, autonomic control, alertness, provides attachment for cranial nerves + involved in movement
107
cranial nerves
cranial nerves are PNS nerves that connect to the brain rather than the spinal cord - most are mixed nerves
108
choroid plexus
network of blood vessels in each ventricle of the brain, producing the CSF
109
BBB
selective semi-permeable membrane between the blood and the interstitium of the brain
110
sensory homunculus
goto ipad
111
motor homunculus
goto ipad
112
clusters of neuronal cell bodies in the central nervous system are called
nuclei
113
what is the correct order of a reflex arc
receptor, afferent neuron, CNS, efferent neuron, effector
114
primary somatosensory cortex located in the
parietal lobe
115
autonomic nervous system (ANS)
- is involuntary + controls glands (sweat glands, digestive glands, cardiac muscle, smooth muscle _ adipose tissue)
- maintains homeostasis (blood pressure, body temp, water balance)
- target organs in - thoracic cavities, body wall, abdominopelvic cavities
- has 2 divisions - sympathetic and parasympathetic
116
what is homestasis?
self-regulating process by which biological systems maintain stability while adjusting to changing external conditions
117
sympathetic autonomic nervous system
fight or flight
- preps body to meet challenge
- mental alertness is heightened, metabolic rate is increased, digestive + urinary functions are reduced, energy reserves are activated, respiratory rate increased + airways dilated, heart rate + blood pressure increase, sweat glands activated
118
parasympathetic
resting and digesting
- conserves energy for future use
- decreased metabolic rate
- decreased blood pressure and heart rate
- increased secretion of salivary and digestive glands
- increased motility and blood flow in digestive tract
- stimulation of urination and defecation
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