Introduction to Nervous System

Question 1

how can you divide the NS?

Answer 1

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))

Question 2

How is the periphral system linked to the CNS?

Answer 2

1. 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)

Question 3

Which NS are sensory, interneurons and motor neurons found in ?

Answer 3

Sensory neuron: PNS into CNS. connects to intermeuron.

Intermeuron: relays info from sensory neuron to motor neuron. CNS.

Motor Neuron: leaves CNS into PNS.

Question 4

what are the majority of cells in NS?

Answer 4

glial cells

Question 5

what are the glial cells in CNS / PNS?

Answer 5

CNS:

• astrocytes
• oligodendrocytes:

- ependymal cells​:

- macroglia cells

PNS

• Schwann cells
• Satelitte Cells

Question 6

what do glia cells in CNS do?

Answer 6

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

Question 7

what do glial cells do in PNS?

Answer 7

PNS

- Schwann cells: myelinate one axon

• Satelitte Cells: (similar role as astrocytes) - modulate environment around neuronal cell body

Question 8

difference between oligodendrocytes or schwann cell

Answer 8

oligodendrocytes: myelinate mutliple axons or sections of an axon

schwann cell: only myelinates one axon at one point: multiple schwann cells required

Question 9

what makes cerebral spinal fluid and what is function?

Answer 9

cerebral spinal fluid:

produced by: blood plasma

function:

• provides bouyancy
• protection for the brain and CNS
• modulates temperature and external env

Question 10

what are the meninges?

Answer 10

meninges: three layers of tissue

1. 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.

Answer 11

arachnoid:

Question 12

what are the arterires like in the brain?

Answer 12

• arteries are thinner walled - less smooth muscle.
• can be distended (swollen due to pressure from inside; bloated)

Question 13

which type of cell is this?

• role?

Answer 13

astrocyte

blood brain barrier!

Question 14

which is this?

role?

where?

Answer 14

ependymal cells

- function: ciliated. move cerebral spinal fluid (CFS) around CNS.

• located: lining central canal of spinal cord and ventricular system

Question 15

what is this cell (the blue one?)

function?

Answer 15

oligodendroncyte

• myelinate lots of axons
• myelinate lots of sections of same axons

Question 16

which parts of the brain code for the following?

1. memory:
2. emotion:
3. coordination of complex movement:
4. language comprehension and production:
5. processing of multisensory information:
6. detection of visual stimuli:

Answer 16

1. memory: hippocampus
2. emotion: frontal lobe
3. 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

6. detection of visual stimuli: occipital lobe

Question 17

what does brain stem do?

part of which NS?

Answer 17

connects brain and CNS together.

autonomic NS : breathing, body temp, digestion, alertness

Question 18

whats in the grey matter of the cerebral cortex?

where found?

Answer 18

Cerebral cortex

grey matter:

location: outer layer

made from: cell bodies (no myelin)

white matter:

located: underneath

made from: myelinated axons (by oligoden)

Question 19

whats in the middle of the cerebral cortex?

Answer 19

older part of brain

• thalamus: relay stations for information going to or from cortex. response to pain

Question 20

what connects the left and right side of brain?

Answer 20

corpus collosum: lots of axons that conveys info between left and right side.

Question 21

where does the brain end and spinal cord start?

Answer 21

hard to say: they merge into each other / continuation of same structure.

Question 22

what are these arrows pointing to?

Answer 22

right arrow: corpus callosum

left arrow: cerebellum

Question 23

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?

Answer 23

1. brainstem!!

2. 12 pairs of cranial nerves -

3. cranial nerves III - XII -> provide main motor and sensory innervation to face and neck

Question 24

what is the reticular formation?

where?

Answer 24

location: brain stem

function: bit of brain that decides whats important / wake up bc of fire engines

Question 27

what do the conductive functions do?

Answer 27

send info up and down brain to spinal cord and periphery

Question 28

which cranial nerves DONT come from brain stem?

Answer 28

Cranial Nerve 1: **Olfactory Nerve** Cranial Nerve 2: **Optic Nerve**

Question 29

what does each do? ## Footnote **- CN III** - **CN VII** **- CN IX** - **CN X**

Answer 29

**_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)

Question 30

where does brain stem end / spinal cord start? where does spinal cord end? whats after spinal cord?

Answer 30

**-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**

Question 32

in the spinal cord: where is the grey / white matter? how does the spinal cord anatomically connect to the peripheral NS?

Answer 32

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**

Question 33

what direction is info flow from sensory -\> motor nerves in spinal cord? what is key to note?

Answer 33

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**

Question 34

describe what white matter tracts are like in spinal cord

Answer 34

_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

Question 35

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?

Answer 35

1. peripheral nerves = have **both motor and sensory axons** 2. = small axons: slower conveying of AP. bigger axons: quicker conveying of AP 3. = myelin is produced by schwann cells 4. Nodes of Ranvier: gap between the schwann cells, where AP occurs.

Question 36

what are plexi - why need them? what are the 4 major plexi?

Answer 36

**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

Question 37

compare the number of spinal nerves in the trunk (body) compared to the limbs

Answer 37

Trunk: one spinal nerve Limbs: multiple spinal nerves (plexi)

Question 38

whats a dermatome?

Answer 38

an area of skin innervated by axons from single spinal nerve root **(sensory)**

Question 39

what happens to pupils in para and symp nerves?

Answer 39

para: constrict, symp: dilate

Question 40

what is the parasympathetic system aka? which is the main nerve of the para? - what does it control?

Answer 40

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)

Question 41

what is sympathetic NS aka? where does sympathetic start? describe its structure - describe sympathetic outflow

Answer 41

- 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.**

Question 43

what are four Fs of autonomic nervous system? - is para / symp switched on/off ? or what?

Answer 43

**F**ight, **F**light, **F**eeding & **S**ex **para and sympathetic systems are both active all the time:** - effect is controlled by which is most active

Question 44

which of autonomic system is for stress? which is for calm?

Answer 44

stress: sympathetic calm: parasympathetic

Question 45

which of para and sym has longer / shorter preganglionic bits?

Answer 45

**preganglionic of parasympathetic:** very long **preganglionic of sympathetic:** very short (only going to sympathetic chain ganglia)