Introduction to Nervous System Flashcards
how can you divide the NS?
Central NS: Brain, Spinal Cord
Peripheral NS: Somatic NS (skeletal muscle), Autonomous NS (glands, BV internal organs. a) Sympathetic NS (fight or flight) b) Parasympathetic NS (rest and digest))
How is the periphral system linked to the CNS?
-
Receptors - in the Peripheral NS
a) Visceral sensory receptors (internal organs)
b) Somatic sensory receptors (postion, touch, pressure, pain, temp.)
c) Special sensory receptors (smell, taste, vision, balance and hearing)
2. Information porcessing: via Peripheral NS into CNS (spinal cord or brain)
- *3. Motor division** (PNS):
a) somatic NSS - skeletal muscle (effectors)
b) autonomic NSS - smooth muscle, cardiac muscle, glands (effectors)
Which NS are sensory, interneurons and motor neurons found in ?
Sensory neuron: PNS into CNS. connects to intermeuron.
Intermeuron: relays info from sensory neuron to motor neuron. CNS.
Motor Neuron: leaves CNS into PNS.
what are the majority of cells in NS?
glial cells
what are the glial cells in CNS / PNS?
CNS:
- astrocytes
- oligodendrocytes:
- ependymal cells:
- macroglia cells
PNS
- Schwann cells
- Satelitte Cells
what do glia cells in CNS do?
CNS
- astrocytes: main cell type. star like process. control environment around neurons. form blood brain barrier: prevents substances entering and damaging cells.
- oligodendrocytes: cells put out processes that wrap around neighbouring axons. can myelinate multiple axons
- ependymal cells: lining cells of ventricular system. they are epithelial boundary that regulate the movement of cerebral spinal fluid in/out brain tissue and ventricle system.
- macroglia cells - only active when pathogens come into brain - turn into macrophages
what do glial cells do in PNS?
PNS
- Schwann cells: myelinate one axon
- Satelitte Cells: (similar role as astrocytes) - modulate environment around neuronal cell body
difference between oligodendrocytes or schwann cell
oligodendrocytes: myelinate mutliple axons or sections of an axon
schwann cell: only myelinates one axon at one point: multiple schwann cells required
what makes cerebral spinal fluid and what is function?
cerebral spinal fluid:
produced by: blood plasma
function:
- provides bouyancy
- protection for the brain and CNS
- modulates temperature and external env
what are the meninges?
meninges: three layers of tissue
- outer protective sheeth: dura mater (2 layers: dura mater outer and inner layers). connective tissue. attached to bone.
2. delicate thinner layer: arachnoid: covers surface of brain. keeps arteries and veins on the surface of cerebral cortex
3. thinner layer. firmly attached to surface: pia. helps supply of nutrients to brain by keeping BV in place.
arachnoid:
what are the arterires like in the brain?
- arteries are thinner walled - less smooth muscle.
- can be distended
which type of cell is this?
- role?
astrocyte
blood brain barrier!
which is this?
role?
where?
ependymal cells
- function: ciliated. move cerebral spinal fluid (CFS) around CNS.
- located: lining central canal of spinal cord and ventricular system
what is this cell (the blue one?)
function?
oligodendroncyte
- myelinate lots of axons
- myelinate lots of sections of same axons
what are the higher functions of the CNS? where each once associated with?
- memory: hippocampus
- emotion: frontal lobe
- coordination of complex movement: cerebellum
4. language comprehension and production: auditory area: temporal lobe. speeach production: frontal lobe
5. processing of multisensory information: primary somatosensory cortex
- detection of visual stimuli: occipital lobe
what does brain stem do?
part of which NS?
connects brain and CNS together.
autonomic NS : breathing, body temp, digestion, alertness
whats in the grey matter of the cerebral cortex?
where found?
Cerebral cortex
grey matter:
location: outer layer
made from: cell bodies (no myelin)
white matter:
located: underneath
made from: myelinated axons (by oligoden)
whats in the middle of the cerebral cortex?
older part of brain
- thalamus: relay stations for information going to or from cortex. response to pain
what connects the left and right side of brain?
corpus collosum: lots of axons that conveys info between left and right side.
where does the brain end and spinal cord start?
hard to say: they merge into each other / continuation of same structure.
what are these arrows pointing to?
right arrow: corpus callosum
left arrow: cerebellum
where is the starting point of cranial nerves?
how many pairs of cranial nerves are there?
which cranial nerves exit and enter the answer to 1.? what are there functions?
- brainstem!!
2. 12 pairs of cranial nerves -
- cranial nerves III - XII -> provide main motor and sensory innervation to face and neck
what is the reticular formation?
where?
location: brain stem
function: bit of brain that decides whats important / wake up bc of fire engines
what do the conductive functions do?
send info up and down brain to spinal cord and periphery
which cranial nerves DONT come from brain stem?
Cranial Nerve 1: Olfactory Nerve
Cranial Nerve 2: Optic Nerve
what does each do?
- CN III
- CN VII
- CN IX
- CN X
Parasympathetic Nervous System
- CN III: pupil size and lens focusing
- CN VII: saliva focusing, tear production
- CN IX: saliva production
- CN X: everything else (90% of parasympathetic nervous system)
where does brain stem end / spinal cord start?
where does spinal cord end?
whats after spinal cord?
-brain stem continues till about C2/C3.
- here it turns into spinal cord: goes till to L1 vert.
- then forms cauda equina. typically L1-L5
in the spinal cord: where is the grey / white matter?
how does the spinal cord anatomically connect to the peripheral NS?
grey matter: inside
white matter: outside
connection:
- dorsal root: sensory neuron cell bodies. goes into the spinal cord - synapse
- exit the spinal cord through the ventral root: turns into motor neuron
what direction is info flow from sensory -> motor nerves in spinal cord?
what is key to note?
information flow:
- dorsal / posterior rootlets: sensory nerves. into CNS
- anterior / ventral rootlets: motor nerves. FROM CNS
BUT KEY TO NOTE:
both above flow into same peripheral nerve!
peripheral nerve: mixed with both sensory and motor axons
describe what white matter tracts are like in spinal cord
ascending tracts:
- sensory: periphery to CNS (goes up to brain).
-
located on outside
a) pain, temp, position,
descending tracts:
- motor - comes down from brain
- further in
what are peripheral nerves like?
whats difference in speed of AP between smaller and bigger axons?
what produces myelin in peripheral nerves?
wha are the Nodes of Ranvier?
- peripheral nerves = have both motor and sensory axons
- = small axons: slower conveying of AP. bigger axons: quicker conveying of AP
- = myelin is produced by schwann cells
- Nodes of Ranvier: gap between the schwann cells, where AP occurs.
what are plexi - why need them?
what are the 4 major plexi?
plexi: multiple spinal nerves, from different levels.
Allows more complex movement and control - why you have many more dermatomes on arms / legs compare to the trunk
4 major: cervical, brachial, lumbar, and sacral
compare the number of spinal nerves in the trunk (body) compared to the limbs
Trunk: one spinal nerve
Limbs: multiple spinal nerves (plexi)
whats a dermatome?
an area of skin innervated by axons from single spinal nerve root (sensory)
what happens to pupils in para and symp nerves?
para: constrict, symp: dilate
what is the parasympathetic system aka?
which is the main nerve of the para? - what does it control?
craniosacral outflow
vagus nerve controls (goes everywhere)
- heart
- lungs
- liver
- pancreas
- kidneys
- GI
- genetilia and sexual reproduction
- (more)
(see earlier slide on other cranial nerve functions)
what is sympathetic NS aka?
where does sympathetic start? describe its structure
- describe sympathetic outflow
- sympathetic aka thoracolumbar
- no cranial nerves
- from T1-L2: sympathetic chain ganglia: one on each side
- sympathetic outflow: spinal cord -> sympathetic chain -> decides where to go -> can make up to 20 different decisions for where synapses = global effect / less precise activation - activates multiple organ systems.
what are four Fs of autonomic nervous system?
- is para / symp switched on/off ? or what?
Fight, Flight, Feeding & Sex
para and sympathetic systems are both active all the time:
- effect is controlled by which is most active
which of autonomic system is for stress? which is for calm?
stress: sympathetic
calm: parasympathetic
which of para and sym has longer / shorter preganglionic bits?
preganglionic of parasympathetic: very long
preganglionic of sympathetic: very short (only going to sympathetic chain ganglia)
