- What are the 3 layers of the meninges?

- Dura mater periosteal - layer of periosteum meningeal - durable, dense fibrous membrane - Arachnoid mater thin, transparent, fibrous membrane - Pia mater thin, translucent and mesh-like 2 cells thick

CNS and ANS Flashcards by Chloe Tan

What 4 main lobes are the cerebral hemispheres split into and what are their functions?

Frontal - regulating and initiating motor function, language, cognitive functions, attention, memory

Parietal - sensation (touch, pain), sensory aspects of language, spatial orientation and self-perception 

Temporal - processing auditory information, contains structures such as hippocampus, wernickes, amygdala 

Occipital - processing visual information

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What structures does the limbic lobe include?

Amygdala - processing fearful and threatening stimuli

Hippocampus - short term memory

Mamillary body - recollective memory

Cingulate gyrus - processing emotions and behaviour regulation

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Where can you find the insular cortex (lobe)?

- What functions is the insular cortex concerned with?

Deep inside the lateral fissure

Visceral sensation, autonomic control and interoception, auditory processing, visual vestibular integration

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What are the 3 layers of the meninges?

Dura mater

  periosteal - layer of periosteum 

  meningeal - durable, dense fibrous membrane

Arachnoid mater
```
thin, transparent, fibrous membrane 
```
- Pia materthin, translucent and mesh-like2 cells thick

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Where is cerebrospinal fluid (CSF) produced?
What does the CSF occupy?
How much CSF is produced each day?

Choroid plexus of lateral, 3rd and 4th ventricles

Ventricular system and sub-arachnoid space

500ml

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What are the functions of cerebrosinal fluid?

- What are the differences between CSF and plasma?

Protection of CNS/brain
Mechanical support for CNS/brain
Transport of biochemical compounds/nutrients

CSF has a lower pH, less glucose, protein and potassium than plasma 

Same concentration of sodium

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What is the spinal cord composed of?

Composed of segments - each giving rise to a pair of mixed spinal nerves:

Cervical (8)

Thoracic (12)

Lumbar (5)

Sacral (5)

Coccygeal (1)

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What do the spinal nerves emerge through?
Which spinal nerves emerge above vertebrae?
Which spinal nerves emerge below the vertebrae?

Intervertebral foramina

Nerves C1-C7

C8 - Co1

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Why is the cervical enlargement increased?

- Why is the lumbar enlargement increased?

Huge amount of extra innervation coming in from and going out to the upper limbs

Due to an increase in innervation coming from and going out to the lower limbs

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What is the major descending pathway for voluntary movement?
where are its upper and lower motor neurones?

– What structure forms as the tracts descend?

Corticospinal tract

composed of upper motor neurones in the primary motor cortex and lower motor neurones in brainstem and spinal cord

Internal capsule

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What are the major ascending pathways for sensation and what does each one sense ?

Dorsal (posterior) column pathway - for fine touch, pressure, vibration and proprioception (position) from the skin and joints

Spinothalamic pathway - pain, temperature (lateral) and crude touch (ventral) from the skin

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What sulcus is found between the pre-central gyrus and post-central gyrus?
Where is the primary motor cortex found?

Central sulcus

Pre-central gyrus

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Where are the upper and lower motor neurons for the corticospinal tract found?
Where do fibres of the corticospincal tract decussate?

Upper motor neurons - Primary Motor Cortex

Lower motor neurons - Brainstem and Spinal Cord

At the Medulla

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What percentage of the corticospial tract neurons decussate and what do these neurons form?
What does the lateral corticospinal tract supply in general?

85%
Lateral

Limb muscles

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What does the anterior corticospinal tract supply?
What pathways go from the primary motor cortex to the muscles of the face?
Where are the upper and lower motor neurones of the pathways that go from the primary motor cortex to the muscles of the face located?

Trunk muscles

Corticobulbar tract 

Upper motor neurones > primary motor cortex 

Lower motor neurones > within the cranial cavity, in the brain stem in nuclei of cranial nerves

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Which muscles are motor nuclei of cranial nerves 3,4,5,6,7 and 12 responsible for moving, respectively?

CN3 (oculumotor) - extraocular muscles

CN4 (trochlear) - extraocular muscles 

CN5 (trigeminal) - muslces of mastication 

CN6 (abducens) - extraocular muscles 

CN7 (facial) - muscles of facial expression

CN12 (hyoglossal) - muscles of the tongue

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What does the vestibulospinal tract do?
What does the tectospinal tract do?
What does the reticulospinal tract do?
What does the rubrospinal tract do?

Provides information about head movement and position and mediates postural adjustments

Orientation of the head and neck during eye movements

Control of breathing and emotional motor function 

Innervate lower motor neurons of the upper limb

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Outline the dorsal column pathway

Fibres enter via the dorsal horn and enter the ascending dorsal column pathways

Information conveyed from lower limbs and body (below T6) travel ipsilaterally along the gracile tract 

Information conveyed from upper limbs and body (above T6) travel ipsilaterally along the cuneate tract

Synapse at medulla and then cross to the other side and ascend on the opposite side of the body up to the thalamus 

Synapses onto a third neurone at the thalamus, which then projects up to relevant part of the sensory cortex

Where does the cuneate tract synapse?
Where does the gracile tracts synapse?
What is a fasciculus?

neurone in the Cuneate Nucleus in Medulla

neurone in the
Gracile Nucleus in Medulla

Fibre Bundle

Where do the second order neurons of the dorsal tract decussate?
What tract do these second order neurons then form once they have crossed?

Caudal medulla

Contralateral medial lemniscus tract

Outline the pathways of the anterior and lateral spinothalamic tracts

Primary afferent axons terminate upon entering the spinal cord

Second order neurons decussate immediately in the spinal cord and form the spinothalamic tract

2nd order neurons terminate in the thalamus

3rd order neurons from the thalamus project to the somatosensory cortex

Which part of the spinothalamic tract takes information about pain and temperature?
Which part of the spinothalamic tract takes information about crude touch?

Lateral

Anterior

What non-skeletal peripheral functions does the ANS control?

Cardiac muscle

Internal organs

Smooth muscle 

Skin

What are the 2 afferent neurones of the sensory division?

- What sort of stimuli does the Somatic sensory neurone deal with?

Somatic sensory
Visceral sensory

External stimuli

- What effect does the PNS have on the Lungs, Liver and Bladder?

Lungs - Constriction Liver - Increased bile release Bladder - Contraction

- What effect does the SNS have on the Lungs, Liver and Bladder?

Lungs - Dilation Liver - Increased glucose release Bladder - Relaxation

- Which of the PNS and SNS controls the majority of the blood vessels? - If there is a high blood pressure, how is this information relayed to the relevant visceral motors and which of the PNS and SNS are switched on?

SNS Visceral sensory - baroreceptors detect increase in pressure Signal sent to the PNS to be sent to CNS Signal sent from CNS to PNS to visceral motors Parasympathetic nervous system switched on to reduce blood flow Sympathetic nervous system switched off to prevent further increase in blood flow

- Where is the autonomic sensory (afferent) information relayed to? - Where do visceral motor nuclei originate?

Hypothalamus Hypothalamus

- What do autonomic neurons generally consist of? - In the PNS, is the pre-ganglionic fibre longer or shorter than the post-ganglionic fibres? - In the SNS, is the pre-ganglionic fibre longer or shorter than the post-ganglionic fibres?

Two neurons - pre-ganglionic and post-ganglionic neuron Ganglion - nerve cell cluster or group of nerve cell bodies outside of CNS Longer Shorter

- What is meant by a sympathetic (paravertebral) trunk?

Long chains running parallel to the spinal cord, with lots of sympathetic nerves coming out of the spinal cord will synapse within those sympathetic chains Allows for mass activation, so lots of sympathetic neurons can be activated at the same time Allows coordinated responses for flight or fight

- What is the exception to the two neuron arrangement in the ANS? - What neurotransmitter does the Adrenal gland release?

Adrenal gland Single sympathetic nerve that innervates the adrenal gland Does not release neurotransmitter Instead secretes hormone, Adrenaline (and some noradrenaline) Into bloodstream

- Which neurotransmitters do pre-ganglionic nerves release? - In PNS, what neurotransmitter is released from the post-ganglionic nerve? - In SNS, what neurotransmitter is released from the post-ganglionic nerve?

Acetylcholine (ACh) ACh Noradrenaline (NA)

Which receptors are present for the sympathetic nervous system? Which receptors are present for the parasympathetic nervous system?

Nicotinic for pre ganglionic and Adrenergic for post ganglionic Nicotinic for Pre ganglionic and Muscarinic for post ganglionic

- What is the name of the complex neural network within the gut? - Are there sympathetic neurons in the lung? - How does sympathetic control occur in the lungs to initiate bronchodilation?

Enteric nervous system - largely responds to gut function and stimuli received within the gut without engaging the brain No Adrenaline released from adrenal gland travels in the bloodstream and diffuses into the lung to cause bronchodilation that way

- Describe the micturition reflex

Bladder slowly fills and moderate pressure in the bladder, SNS is in charge at this point Internal sphincter controlled by SNS is closed off to prevent urine leaving the bladder Once pressure gets to certain point, sensory information is relayed to the brain PNS switched on and SNS is switched off PNS contracts detrusor muscle to squeeze bladder and force urine out Internal Sphincter is relaxed as SNS is turned off so urine can leave the bladder

- How does somatic motor efference play a part in the passing of urine?

Gives voluntary level of control of when urine exits the bladder

- What type of receptor is required at all autonomic ganglia?

Cholinergic (nicotinic acetylcholine) receptors e.g, Ion channel receptors as they mediate all fast excitatory and inhibitory transmission

- At the nerve innervating the Adrenal gland in the SNS, what receptor is found? - In the heart, what are the muscarinic and adrenergic receptors responsible for respectively?

Nicotinic Acetylcholine (nACh) ion channel receptors Muscarinic - slowing down Adrenergic - speeding up

- Describe the action of Noradrenaline at a synapse?

Tyrosine converted to DOPA by tyrosine hydroxylase This DOPA then converted to dopamine by DOPA decarboxylase Dopamine packaged into vesicles with dopamine Beta hydroxylase and Noradrenaline is the product Action potential causes Ca2+ influx and exocytosis Exocytosis and neurotransmitter release Receptor activation (Adrenergic) Removal of neurotransmitter from synapse via uptake into pre-synaptic terminal or glial cell; can be metabolised in the synapse prior to uptake

- Describe the action of Adrenaline in the nerve innervating the Adrenal gland

Tyrosine converted to DOPA by tyrosine hydroxylase and DOPA converted to dopamine by DOPA decarboxylase Dopamine packaged into vesicles with dopamine Beta hydroxylase, Noradrenaline is the product Noradrenaline converted to adrenaline in the cytoplasm by phenylethanol methyltransferase Action potential causes Ca2+ influx & Exocytosis Exocytosis & Neurotransmitter release Adrenaline diffuses into capillaries and is transported to tissues in the blood

- What are the 2 enzymes that metabolise noradrenaline?

Monoamine oxidase A within pre-synaptic terminal Catechol-O-methyltransferase (COMT) in glial cells

- If you take an opioid, what will happen to your pupils and why?

Constrict Parasympathetic nervous system activated

Describe the action of Ach at a synapse

Choline and acetyl co A enzymatically converted by choline acetyl transferase into acetylcholine packaged into vesicles AP causes calcium influx and exocytosis NT release receptor activation acetylcholine rapidly degraded by acetylcholinesterase in synapse or uptaken by choline uptake protein