Neurology Flashcards
1
Q
What are the two parts of the PNS?
A
Somatic PNS
Autonomic Nervous System
2
Q
What is controlled by the somatic PNS?
A
Motor and sensory function for the body wall
3
Q
What is controlled by the autonomic nervous system?
A
Regulates function of the viscera: internal organs, smooth muscle, pupils, sweating, blood vessels, bladder, intestine, glands and heart contraction rate
4
Q
What are the three parts of the autonomic nervous system?
A
Sympathetic
Parasympathetic
Enteric
5
Q
What direction do afferent axons send information?
A
Towards the brain and spinal cord from the PNS
6
Q
What direction do efferent axons send information?
A
From the brain and spinal cord to the periphery
7
Q
What are interneurones?
A
CNS neurons that synapse with other CNS neurons within the brain or spinal cord
8
Q
What is the structure of the cerebral cortex?
A
Two hemispheres made up to Frontal lobe, Temporal lobe, Parietal lobe and Occipital lobe
In general, each received sensory information from and controls movement on opposite side of the body
9
Q
What is controlled by the cerebellum?
A
Coordinates movement
Involved in learning motor skills
10
Q
What is the main function of the brain stem?
A
Densely packed fibres. Controls vital functions (e.g. consciousness, breathing).
Cranial nerves provide sensory and motor innervation to the head.
Ascending and descending pathways connect the spinal cord with the forebrain
Damage here is serious, can be fatal
11
Q
The dorsal and ventral roots that emerge from the spinal cord are part of what nervous system?
A
PNS
12
Q
Give an example of an unmyelinated neuron
A
Nociceptors (pain)
13
Q
What is the structure of a spinal nerve?
A
Contains both afferent and efferent axons bundled into fascicles surrounded by perineurium. The whole nerve is in a tough epineurium capsule
14
Q
Axons in which nerves are able to regenerate after injury?
A
In peripheral nerves
15
Q
What is found in white and grey matter?
A
Neuronal cell bodies are in grey matter
White matter comprises ascending and descending axon tracts to and from the brain
16
Q
For a reflex response what inputs and outputs are required?
A
Somatic sensory inputs to the spinal cord
Interneurons and motor outputs from the spinal cord
17
Q
What inputs and outputs are required for conscious registering and voluntary movement?
A
Sensory inputs activate sensory neurons in the spinal cord, grey matter transmits action potential upward to the sensory cortex of the brain.
Neurons in the motor cortex of the brain extend axons downward to synapse with the spinal motor neurons and transmit action potentials for voluntary movement
18
Q
In the white matter of the spinal cord are the sensory and motor axons ascending or descending?
A
Sensory axon tracts: Ascending to the brain
Motor axon tracts: Descending to spinal cord
19
Q
A 72 year-old patient has lost voluntary movement and sensation in his left arm, but the muscles still show reflex activity. His right arm and both legs function normally. Where would this injury occur in the nervous system?
A
Injury must be in the right hemisphere containing both motor and sensory neurons/axons- but only for the arm.
No peripheral nerve injury as reflex activity is intact.
Not spinal cord as only one arm affected and legs are fine
As 72 years old could be a stroke
20
Q
A 19 year old patient has lost voluntary movement and sensation in her left arm. The muscles do not show reflex activity. Her right arm and both legs function normally. Where would this injury occur in the nervous system?
A
Likely to be a peripheral nerve injury to the left arm/shoulder since there is no reflex activity. Unlikely to be spinal cord as right arm is fine.
21
Q
A 49 year-old patient has lost voluntary movement and sensation in his left arm and leg but the muscles still show reflex activity. His right arm and leg function normally. Where would this injury occur in the nervous system?
A
Injury not peripheral as reflex activity intact, plus both arm and leg affected.
Unlikely to be spinal cord as only one side affected
Injury likely to be in the right brain sensorimotor cortex as only left limbs affected, but spread across regions for both arm and leg
Possibly brain tumour or a stroke
22
Q
A 50 year-old man who smokes and has high blood pressure collapses at work. He is unable to speak or move the right side of his face and he is unable to move his right arm or leg. Where is the problem and what is a likely diagnosis?
A
In the brain
Stroke
23
Q
What are the main causes of stroke? What part of the brian does it affect? What part of the body if affected as a result?
A
80% are infarct (blockage of a vessel)
20% haemorrhage
Can affect any part of the brain (including brain stem)
Tends to cause a problem on the other side to the brain lesion
24
Q
What is contralateral brain damage?
A
Injury that causes a problem on the opposite side of the body to the damage
25
On what side of the brain would a stroke cause aphasia, and what is it?
Left side of the brain responsible for language so a stroke on the left side would cause aphasia (problems with communication)
26
What would a stroke affecting the middle cerebral artery cause?
Often results in weakness and loss of sensation on the other side
27
What would a stroke affecting the posterior cerebral artery cause?
Often affect the occipital lobe- result in visual loss on the contralateral side
28
What would a stroke affecting the anterior cerebral artery cause?
Often cause contralateral leg weakness
29
What would a stroke affecting the brain stem cause?
May cause problems with balance, eye movements, speech and swallowing (cranial nerves) and breathing
30
What are the types of acute stroke treatment? (2)
```
Intravenous thrombolysis (dissolve the clot)
Intra-arterial thrombectomy (remove clot)
```
31
What are the methods used to prevent further stroke? (3)
Thin blood with aspirin
Treat diabetes and high cholesterol
Treat dangerously narrow carotid arteries
32
What techniques are used to diagnose neurological problems in the examination? (3)
Cognitive/ thinking abilities: 'mini mental state examination'
Cranial Nerves: Smell, vision, eye movements, facial sensation and movements
Limbs: Power, coordination, reflexes and sensation
33
What is involved in a mini mental state examination? (5)
1) Orientation: What is the year, season, date, day, month? Where are we? (city, house number, street)
2) Registration: Name three objects, repeat three objects, remember three objects, count number of trials
3) Trials: Serial 7s (100-7-7etc) alternatively spell 'world' backwards
4) Recall: Three objects from 2
5) Language: Name a pencil and a watch, Repeat "no ifs, ands or buts", follow a three-stage command, read and obey "close your eyes, write a sentence, copy a design"
34
What are the symptoms of Parkinson's disease normally present on examination?
Slow, shuffling gait, stooped, loss of arm swing, pill-rolling tremor at rest, increased tone and cogwheeling, bradykinesia (slowed finger movements), micrographia (small writing)
35
What is Parkinson's disease?
A slowly progressive degenerative disease affecting the basal ganglia.
The main clinical features are rigidity (stiffness), tremor (shaking) and bradykinesia (reduced movement)
There is a loss of neurones from the substantia nigra to the caudate and putamen (parts of the basal ganglia)
36
What is the neurotransmitter associated with Parkinson's disease?
Dopamine
37
What are patients with Parkinson's disease treated with? How does this work?
Levodopa
| Able to cross the blood brain barrier, unlike dopamine, and is then converted to dopamine
38
What are the causes of stiffness and weakness in the lower limbs with brisk reflexes?
Spinal cord
- Spastic paraparesis
- Multiple myeloma
39
What are the causes of spastic paraparesis? (7)
1) Trauma
2) Inflammatory/ autoimmune (e.g. MS)
3) Neoplastic (e.g. spinal cord tumour, metastatic tumour)
4) Degenerative (motor neurone disease)
5) Vitamin Deficiency (B12)
6) Infection (e.g. syphilis, viral)
7) Vascular (Anterior Spinal Artery Thrombosis)
40
What is a multiple myeloma? How is it treated?
Tumour of plasma cells
| Treated with radiotherapy and chemotherapy
41
What symptoms would be present in an examination of a patient with a peripheral nerve disorder?
Normal cognition
Normal cranial nerves
Normal upper limbs except for loss of sensation in a glove formation
Lower limbs very weak (worse distally) and floppy (decreased tone) with absent reflexes (Lower Motor Neurone)
Sensory loss in the legs in a stocking distribution
42
What are the causes of acute polyneuropathy? (4)
1) Infections (e.g. diphtheria)
2) Autoimmune (e.g. Guillain-Barre Syndrome or Acute Inflammatory Demyelinating Polyneuropathy)
3) Drugs (Chemotherapy)
4) Exposure to toxins (organophosphate insecticides)
43
What are the symptoms of GBS/AIDP? (Guillain-Barre syndrome or Acute Inflammatory Demyelinating Polyneuropathy)
Common cause of acute neuromuscular weakness
Clinical diagnosis
Progressive ascending sensorimotor paralysis with areflexia, affecting 1 or more limbs ad reaching nadir within 4 weeks
Patients may progress to almost complete paralysis and require ventilation
44
What is the mechanism of auto-immune acute polyneuropathy?
Unidentified antigens bind to myelin on an axon
Activate MAC (membrane attack complex) complement
Causes injury to the nerve
Macrophages bind to and break down myelin (macrophage scavenging)
45
What treatment is used for GBS/AIDP (Guillain-Barre syndrome or Acute Inflammatory Demyelinating Polyneuropathy)? (4)
1) 'Immunotherapy'- Plasma exchange or intravenous immunoglobulin
2) Supportive including ventilation if necessary
3) Cardiac monitoring
4) Anticoagulation to prevent leg clots (and subsequent pulmonary emboli)
46
What investigations are conducted to diagnose neurological problems? (5)
1) Brain scans: CT and MRI
2) Cerebrospinal fluid (CSF): Lumbar puncture
3) Nerve conduction studies and electromyography (EMG)
4) Electroencephalogram (EEG) and evoked potentials
5) Brain pathology: damage to cells or larger structures
47
What forms of syndromic formulations are used for diagnosing neurological problems? (5)
1) Clinical facts: history and examination
2) Interpretation in terms of physiology/anatomy
3) Syndromic formulation and lesion localisation
4) Anatomic diagnosis + mode of onset
5) Use investigations to confirm or refute clinical judgement
48
What is a neuron? What are it's main features?
A neuron is a highly organised, metabolically very active secretory cell that is the basic structural and functional unit of the nervous system
- Large, prominent nucleus
- Abundant rough ER
- Well developed Golgi
- Abundant mitochondria
- Highly organised cytoskeleton
49
What are dendrites?
The major area of reception of incoming information on a neuron. Spreads from cell body and branches frequently, greatly increasing the surface area of the neuron.
Often covered in protrusions called spines which receive the majority of synapses
50
What part of a dendrite receive the majority of synapses?
Spines
51
Where are Purkinje neurons located?
In the cerebellum
52
What are axons? Where do they emerge from? How many per cell? What are the prominent features?
Conduct impulses away from cell body. They emerge from the axon hillock. Usually only one per cell but may branch after leaving the cell body, and at target. Has prominent microtubules and neurofilaments (intermediate filaments)
53
What are the two types of axon terminal?
Boutons
| Varicosities
54
What type of transport shops synaptic vesicles from the Golgi in a synapse?
Anterograde transport
55
What happens to competing inputs in a postsynaptic neuron?
(Neuronal) integration
56
What are the types of synapse and their action? (3)
1) Axo-dendritic (often excitatory)
2) Axo-somatic (often inhibitory)
3) Axo-axonic (often modulatory)
57
What types of protein filament make up the cytoskeleton of neurons?
Microfilaments, intermediate filaments and microtubules
Neurofilaments play a critical role in determining axon caliber
Mircotubules are very abundant in the nervous system
58
What is a pseudounipolar neuron?
A sensory neuron with two fused processes which are axonal in structure
59
What is a bipolar neuron?
An neuron with two axonal processes
60
What is a Golgi type I multipolar neuron? Give 4 examples of where these axons are found
A neuron with highly branched dendritic trees and axons that extend long distances
e.g. pyramidal cells of the cerebral cortex, Purkinje cells of the cerebellum, anterior horn cells of the spinal cord and retinal ganglion cells
61
What is a Golgi type II multipolar neuron? Give 2 examples of where these axons are found
A neuron with highly branched dendritic trees and short axons
e.g. axons that terminate quite close to cell body of origin and stellate cells of the cerebral cortex and cerebellum
62
What are the three types of neuron?
1) Sensory neurons
2) Motor neurons
3) Interneurons
63
What are interneurons?
Responsible for modification, coordination, integration, facilitation and inhibition of sensory input
64
What are neuroglia?
The support cells of the nervous system with many and varied function, essential for the correct functioning of neurons
65
What are the types of neuroglia? ( 7)
1) Astroglia
2) Oligodendroglia
3) Microglia
4) Immature progenitors
5) Ependymal cells
6) Schwann cells
7) Satellite glia
66
What are astroglia?
A multi-processed star-like shape cell, the most numerous type of neuroglia. Gap junctions suggest astroglia-astroglia signalling
Contains numerous intermediate filament bundles in the cytoplasm of fibrous astroglia (GFAP)
67
What are the functions of astroglia? (9)
1) Scaffold for neuronal migration and axon growth during development
2) Formation of blood-brain barrier
3) Transport of substances from blood to neurons
4) Segregation of neuronal processed (synapses)
5) Removal of neurotransmitters
6) Synthesis of neurotrophic factors
7) Neuronal-glial and glial-neuronal signalling
8) Potassium ion buffering
9) Glial scar formation
68
What is an oligodendroglia? What are their characteristic features?
The myelin-forming cells of the CNS
| Small spherical nuclei with a few thin processes. Prominent ER and Golgi and metabolically highly active
69
What are the two types of oligodendroglia?
Interfasicular oligodendroglia
| Perineuronal oligodendroglia
70
What is the main function of oligodendroglia?
Production and maintenance of multiple (1-40) myelin sheaths
71
What is myelin?
A lipid-rich insulating membrane made up of up to 50 lamellae
Dark and light bands visible at EM level
72
Give two examples of diseases associated with myelin
Multiple sclerosis
| Adrenoleucodystrophy
73
What are microglia? What are their main functions?
Resident macrophage population of the CNS involved in immune surveillance. They present antigens to invading immune cells and are the first cells to react to infection or damage. They have a role in tissue remodelling and synaptic stripping
74
What are the peripheral glial cells?
Schwann cells
75
What are Schwann cells?
Myelin-producing cells of the PNS. Each Schwann cell only produces one myelin sheath. they surround unmyelinated axons and promote axon regeneration
76
What is flux?
The number of molecules that cross a unit of area per unit of time
77
What are the unit of measurement of:
1) Voltage
2) Current
3) Resistance?
1) Volts
2) Amps
3) Ohms
78
What is membrane potential? What is a normal value?
The voltage difference on the inside of the cell compared to the outside
-70mV
79
At rest is Na+ or K+ permeability greater?
K+>>Na+
80
What is the Nernst equation used to calculate?
Equilibrium potential
81
What is the Goldman- Hodgkin- Katz (GHK) equation used to calculate?
The resting membrane potential while considering the permeability of the membrane to each ion
82
What is a graded potential? Where is it strongest?
They occur at synapses and sensory receptors. They contribute to initiating or preventing action potentials and are strongest at the stimulation site
83
Give three examples of where an action potential will occur.
In a neuron
In a muscle cell initiating contraction
In pancreatic β-cells, provoking the release of insulin
84
What are the phases of an action potential?
1) Resting membrane potential
2) Depolarising stimulus
3) Upstroke (Depolarisation)
4) Repolarisation
5) After Hyperpolarisation
85
Where does the upstroke phase of an action potential start? (voltage)
At the threshold (∼-55mV)
86
At what voltage does repolarisation begin?
+30mV
87
What is the absolute refractory period? What channel causes this? In what phase of an action potential does it occur?
The period in which a new action potential cannot be triggered, even with a very strong stimulus
Occurs in repolarisation
At the start of repolarisation Na+ inactivation gate is closed- Na+ activation gate is open however later in repolarisation both gates are closed
88
What is the relative refractory period? What channel is involved in this? In what phase of an action potential does it occur?
Where a stronger than normal stimulus is required to trigger an action potential
Occurs in after-hyperpolarisation
Na+ activation gate is closed- Na+ inactivation gate is open
89
What affects the conduction velocity? How does it affect it?
Axon diameter: ↑ with axon diameter- less resistance to current flow inside a large diameter axon
Myelination: Higher in myelinated than non-myelinated axons of the same diameter- action potentials only occur at nodes of Ranvier
90
What slows conduction velocity?
Reduced axon diameter (i.e. regrowth after injury)
Reduced myelination (i.e. multiple sclerosis and diphtheria)
Cold, anoxia, compression and drugs (some anaesthetics)
91
How big is the gap between presynaptic nerve ending and postsynaptic region?
20-100nm
92
What part of a neuron is the postsynaptic region?
Dendrite of cell soma
93
What are the three stages of synaptic transmission?
1) Biosynthesis, packaging and release of neurotransmitter
2) Receptor action
3) Inactivation
94
What is required for transmitter release in synaptic transmission?
An increase in intracellular calcium
95
What is the process of synaptic transmission starting with membrane depolarisation?
1) Membrane depolarisation
2) Ca2+ channels open
3) Ca2+ influx
4) Vesicle fusion
5) Vesicle exocytosis
6) Transmitter release
96
What mechanism ensures rapid release of neurotransmitters occurs?
1) Synaptic vesicles are filled with neurotransmitter and docked in the synaptic zone "primed"
2) Ca2+ entry activates a Ca2+ sensor in the protein complex
3) Interaction between synaptic vesicles and synaptic membrane proteins allows rapid response
97
Give 4 examples of neurotoxin and their mechanism of action
1) Tetanus toxin: C. tetani causes paralysis
2) Zn2+-dependent endopeptideases: inhibit transmitter release
3) Botulinum toxin: C.botulinum causes flacid paralysis
4) α-Latrotoxin (black widow spider): stimulates transmitter release to depletion
98
What neurotransmitter receptors transmit fast and slow action?
Fast: Ion channel receptor- mediates all fast excitatory and inhibitory transmission
Slow: G-protein coupled receptor- effectors may be enzymes (adenyl cyclase, phospholipase C, cGMP-PDE) or channels (e.g. Ca2+ or K+)
99
Give examples of ion channel receptors in the CNS.
Glutamate
| GABA (Gamma amino butyric acid)
100
Give examples of ion channel receptors in the NMJ.
Acetylcholine (ACh) at nicotinic receptors
101
Give examples of G-protein coupled receptors in the CNS and PNS.
Acetylcholine (ACh) at muscarinic receptors, dopamine (DA), noradrenaline (NA), 5-hydroxytryptamine (5HT) and neuropeptides (e.g. enkephalin)
102
Considering glutamate and GABA are they excitatory or inhibitory?
Glutamate: excitatory
GABA: inhibitory
103
What glutamate receptor is involved in the majority of fast excitatory synapses?
AMPA receptors
(α-amino-3-hydroxy-5-methyl-4-isoxazole propanoic acid)
Majority of fast excitatory synapses. Rapid onset, offset and desensitisation
104
What glutamate receptor is the slow component of excitatory transmission?
NMDA receptors
(N-methyl-D aspartate)
Serve as coincidence detectors which underlie learning mechanisms
105
How is glutmate recycled after binding it's receptor?
Glutamate→Glutamine (Glutamine synthetase) in glial cells
106
Abnormal cell firing leads to seizures associated with excess what in the synapse?
Glutamate
107
Abnormal neuronal excitability causes what condition?
Epilepsy
108
Hw is GABA recycled after binding it's receptor
GABA→Succinate semialdehyde (GABA transaminase GABA-T)
109
What drugs facilitate GABA transmission? (4)
Antiepileptic
Anxiolytic
Sedative
Muscle relaxant
110
What is the focus of epilepsy treatment?
Dampening down excitatory activity by facilitating inhibitory transmission
111
What is a seizure?
A transient alteration of behaviour due to the disordered, synchronous and rhythmic firing of populations of brain neurones
112
Where do seizures arise? What is the difference between partial seizures and generalised seizures?
Seizures arise from the cerebral cortex
Partial seizures: beginning focally at a cortical site
Generalised seizures: involve both hemispheres widely from the outset
113
How would a seizure involving the motor cortex present?
Associated with clonic jerkig of the body part controlled by this region of the cortex
114
How does a simple partial seizure present?
Associated with preservation or consciousness
115
How does a complex partial seizure present?
Associated with preservation of consciousness
116
What are the types of generalised seizure?
Absence
Myoclonic
Tonic-colonic
117
What causes seizures? (neurotransmitters)
Decrease in GABA-mediated inhibition
| Increase in glutamate-mediated excitation in the brain
118
What is the cellular mechanism and main uses of valproate?
Mechanism: Weak effect on GABA transaminase and on Na+ channels
Uses: Most types, especially absence seizures
119
What is the cellular mechanism and main uses of phenobarbital?
Mechanism: Enhanced GABA action. Inhibition of synaptic excitation
Uses: All types except absence seizures
120
What is the cellular mechanism and main uses of benzodiazepines? Give examples of these
Mechanism: Enhanced GABA action
Uses: All types. Diazepam used i.v. to control status epilepticus
e.g. clonazepam, clobazam, diazepam
121
What is the cellular mechanism and main uses of vigabatrin?
Mechanism: Inhibits GABA transaminase
Uses: All types. Appears to be effective in patients resistant to other drugs
122
What are the functions of the diencephalon?
Contains several nuclei with different function:
Thalamus acts as a relay station for the cerebral cortex
Hypothalamus coordinates homeostatic mechanisms
123
What are the functions of the cerebral hemispheres?
Basal ganglia: involved in control of movement
Cerebral cortex: involved in all functions
Corpus callosum: interconnects corresponding parts of 2 hemispheres across midline
124
What does the central sulcus divide?
Frontal and parietal lobe
125
What does the lateral sulcus divide?
Frontal and temporal lobe
126
What divides the frontal and parietal lobe?
Cental sulcus
127
What divides the frontal and temporal lobe?
Lateral sulcus
128
What divides the parietal and occipital lobe>
Parieto-occipital sulcus
129
Where is the primary auditory cortex?
Just inferior to the medial end of the lateral sulcus
130
Where is the visual cortex?
Posterior part of the occipital lobe
131
What is the most superior ventricle of the ventricular system?
The lateral ventricle
132
What is the most inferior ventricle of the ventricular system?
The fourth ventricle
133
What ventricle is connected to the lateral ventricle?
The third ventricle
134
What connects the third and fourth ventricle?
Aqueduct
135
Where is CSF secreted?
By choroid plexus in ventricles
136
Where is CSF reabsorbed?
Into the venous sinuses via arachnoid villi
137
Where does CSF circulate around the brain?
Through ventricular system and subarachnoid space between the meninges
138
What neurons are found in the dorsal horn?
Interneurons which receive sensory information from the body
139
What neurons are found in the ventral horn?
Notorneuron cell bodies
140
Describe the process of degeneration and regeneration of an axon
1) After nerve section, the distal part of the axon degenerates and Schwann cells proliferate
2) Sprouts grow out from the proximal stump of the axon, guided by Schwann cells
3) The first sprout to connect with the target organ becomes myelinated; the other sprouts regress
4) Th regenerated axon forms, usually with slightly shorter internodes
141
Which part of the brain lies in the anterior cranial fossa?
Frontal lobe of cerebral hemisphere
142
Which part of the brain lies in the middle cranial fossa?
Temporal lobe of cerebral hemisphere
143
Which part of the brain lies in the posterior cranial fossa?
Cerebellum
144
Which part of the brain lies directly above the body of the sphenoid bone?
Hypothalamus
145
Which part of the brain passes through the foramen magnum?
Medulla
146
What is the corpus callosum?
The fibres joining together the two hemispheres of the brain
147
What is the infundibulum?
The stalk of the pituitary
148
Which part of the ventricular system relates to the cerebral hemisphere?
The lateral ventricle
149
Which part of the ventricular system relates to the diencephalon?
The third ventricle
150
Which part of the ventricular system relates to the midbrain?
The aqueduct
151
Which part of the ventricular system relates to the pons and medulla?
The fourth ventricle
152
What is the basal ganglia?
A group of structures linked to the thalamus in the base of the brain involved in coordination and movement
153
What are the parts of the spine? How many vertebrae in each?
```
Cervical: 7
Thoracic: 12
Lumbar: 5
Sacral: 5
Coccyx: 1 fused (or up to 4 unfused)
```
154
How many vertebrae in the spine?
30
155
How many nerves are there in each section of the spine?
```
Cervical: 8
Thoracic: 12
Lumbar: 5
Sacral: 5
Coccyx: 1
```
156
Where are the spinal nerves in relation to the vertebrae in each section of the spine?
```
Cervical: All above except for C8
Thoracic: All below
Lumbar: All below
Sacral: All below
Coccyx: Below (or between if unfused)
```
157
Between which vertebrae would you insert a needle to safely sample CSF when performing a lumbar puncture?
Below the spinal cord, usually between L3 and L4 or L4 and L5
158
How does the composition of CSF differ from blood?
Normally contains few cells
Much less protein
Reduced concentration of potassium and calcium ions
Higher concentration or magnesium and chloride ions
159
What is the normal volume and flow rate of CSF?
150ml
| Approximately 500ml/day
160
What is hydrocephalus?
A build-up of fluid on the brain causing an increase in pressure
161
What are the two types of hydrocephalus?
Communicating (all 4 ventricles)
| Non-communicating (not all ventricles enlarged)
162
What are the main causes of communicating hydrocephalus?
Block in CSF absorption or CSF flow over brain surface caused by:
- Meningitis
- Head injury
- Congenital
- Haemorrhage (sub-arachnoid)
163
What are the main causes of non-communicating hydrocephalus?
Block in ventricular system caused by:
- Aqueduct stenosis
- Ventricular tumours
- Paraventricular tumours
164
What are the main signs and symptoms of hydrocephalus?
```
Headache
Drowsiness
Blackouts
Raised intracranial pressure
Increased head circumference (in child)
```
165
How may hydrocephalus be treated?
```
Remove cause (e.g. papilloma)
Divert CSF (e.g. shunt)
Open alternate pathway (e.g. ventriculostomy)
```
166
Where does an epidural/ extradural haemorrhage occur and in what vessel?
Usually due to a damaged meningeal artery between the skull and the dura after head trauma
167
Where does a subdural haemorrhage occur and in what vessel?
Usually due to a damaged vein between the dura and arachnoid membrane
168
How might you distinguish between an epidural and subdural haemorrhage?
The first symptoms (headache, drowsiness, vomitting, seizures) are likely to arise promptly after arterial bleeding in an epidural haemorrhage whereas symptoms may be delayed by hours or days after venous bleeding in a subdural haemorrhage.
Can be confirmed with imaging
169
What structures are usually infected in meningitis?
Pia mater
Subarachnoid space
Some spread to the upper layers of the cortex in severe cases
170
Analysis of a sample of CSF should distinguish between bacterial and viral meningitis. What would you look for?
Bacterial infection: High white cell count with neutrophils predominating. Protein concentration is increased and glucose concentration is decreased. Bacteria may be identifiable
Viral infection: Any increase in white cells is predominantly lymphocytes. Protein and glucose levels of the CSF are usually normal. Virus identification is unlikely
171
What components make up the CNS?
Brain
| Spinal cord
172
What structure joins the spinal cord to the brain?
Medulla
173
Where are the motor neuron somas located?
In the grey matter in the spinal cord
174
What components make up the PNS?
Peripheral nerves
| Ganglia
175
What are the three types of neuron in the peripheral nervous system?
1) Somatic motor neuron
2) Autonomic motor neuron
3) Sensory neuron
176
Describe a somatic motor neuron
Soma IN the CNS, axon extends to target then synapses with skeletal muscle
177
Describe an autonomic motor neuron
Soma in CNS of preganglionic neuron. Synapses with autonomic ganglion. Postganglionic neuron synapses with blood vessels, glands, viscera etc
178
Describe a sensory neuron
Stimulus from skin, joint receptors, viscera etc. Ganglion (soma)
179
What is a plexus?
Where spinal nerves combine to form peripheral nerves
180
Which spinal nerves innervate the arm?
C5, C6, C7, C8 and T1
181
Which peripheral nerves innervate the arm?
```
Axillary nerve
Radial nerve
Musculocutaneous nerve
Median nerve
Medial cutaneous nerve of the arm
Medial cutaneous nerve of the forearm
Ulnar nerve
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182
What is a peripheral neuropathy? What causes it? What does it affect?
Progressive degeneration of nerves. Usually distal to proximal.
Causes may be metabolic, infectious or hereditary
Affects sensory and/or motor axons. May initially affect myelin or axon
183
What diagnostic techniques are used to diagnose peripheral neuropathy?
Conduction velocity
| Nerve biopsy
184
What is a neuromuscular junction?
A specialised synapse between a motor neuron and a muscle fibre
185
What is the gap between a presynaptic neuron and a postsynaptic neuron called?
Synaptic cleft
186
What is the neurotransmitter for voluntary striated muscle?
Acetylcholine
187
What does the NMJ initiate?
Muscle contraction
188
What is the mechanism whereby muscle contraction is initiated from a NMJ?
1) Action potential opens voltage-gated Ca2+ channels
2) Ca2+ enters
3) Ca2+ triggers exocytosis of vesicles
4) Acetylcholine diffuses in cleft
5) Acetylcholine binds to receptor-cation channel and opens channel
6) Local currents flow from depolarised region and adjacent region; action potential triggered and spreads along surface membrane
7) Acetylcholine broke down by acetylcholine esterase. Muscle fibre response to that molecule of acetyl choline ceases
189
What is the structure of skeletal muscle?
Muscle made up of muscle fascicles bounded by perimysium
Muscle fascicles made up of muscle fibres surrounded by endomysium
Muscle fibres made up of myofibrils
Myofibrils made up of myofilaments
190
What are the characteristic features of myofibres?
Covered by sarcolemma (plasma membrane)
T-tubules tunnel into centre
Cytoplasm called sarcoplasm with myoglobin and mitochondria present
Network of fluid filled tubules- sarcoplasmic reticulum
Composed of myofibrils
191
What are myofibrils? What is their composition? How much of the myofibre contains myofibrils?
1-2μm in diameter
Extend along entire length of myofibres
Composed of actin and myosin
192
What are myofilaments? What is their arrangement in a myofibre? How much of the myofibre contains myofilaments?
Light and dark bands give muscle striated appearance
Do not extend along length of myofibre
Overlap and are arranged in compartments called sarcomeres
Dense protein Z-discs separate sarcomeres
Dark bands (A-band) have thick myosin
Light bands (I-bands) have thin actin
Myosin and actin filaments overlap
193
What happens to components of the sarcomere during contraction in the sliding filament theory?
During contraction I band became shorter
A-band remained the same length
H-zone narrowed or disappeared
194
What is the process of activation and relaxation in myofilaments?
1) Action potential propagates along surface membrane and into T-tubules
2) DHP receptor in T-tubule membrane: senses AP and changes shape of the protein link to ryanodine receptor, opens ryanodine receptor Ca2+ channel in the sarcoplasmic reticulum into space around the filaments
3) Ca2+ binds to troponin and tropomyosin moves
4) Cross-bridges attach to actin
5) Ca2+ is actively transported into the SR continuously which action potentials continue. ATP-driven pump (uptake
195
Give examples of disorders affecting the NMJ
1) Botulism: Botulinum toxim produces an irreversible disruption in stimulation-induced acetylcholine release by the presynaptic nerve terminal
2) Myastenia gravis (MG): Autoimmune disease caused by antibodies against acetyl choline receptor
3) Lambert-Eaton myastenic syndrome (LEMS): associated with lung cancer, but an autoimmune disease caused by antibodies directed against the voltage-gated calcium channels (VGCC)
196
What is an electromyography?
Recording the action potentials occurring in skeletal muscle fibres
197
What is an electrocardiogram?
Recording action potentials of the heart
198
What is an electroencephalogram?
Recording action potentials from the brain
199
What nerves are found in the arm?
Radial nerve
Medial nerve
Ulna nerve
200
What type of response is triggered by the sympathetic and parasympathetic nervous system?
Sympathetic: Fight or flight
Parasympathetic: Rest and digest
201
What effect do the sympathetic and parasympathetic nervous system have on the heart?
Sympathetic: Increases heart rate
Parasympathetic: Decreases heart rate
202
What effect do the sympathetic and parasympathetic nervous system have on the small intestine?
Parasympathetic: Stimulates motility
Sympathetic: Slows down
203
What effect do the sympathetic and parasympathetic nervous system have on the pupil?
Sympathetic: Dilates pupils
Parasympathetic: Narrows pupils
204
Which nervous system stimulates saliva? Sympathetic or Parasympathetic?
Both
Sympathetic: Thick, viscous secretions
Parasympathetic: Copious, watery secretions
205
What effect does the sympathetic nervous system have on blood vessels?
Dilates skeletal muscle
| Constricts the skin, mucous membranes and splanchnic area§
206
Where does the parasympathetic nervous system originate in the spine?
The CRANIAL and sacral part of the spine
207
What is the neurotransmitter associated with the parasympathetic nervous system?
Acetylcholine
208
Where does the sympathetic nervous system originate in the spine? Where does it go once the nerves leave the spine?
T1 to L1/2
| Once leaving the spine it forms the sympathetic trunk
209
What neurotransmitters are associated with the sympathetic nervous system when it synapses directly with the effector organ?
Acetylcholine
| Noradrenaline
210
What neurotransmitters are associated with the sympathetic nervous system when it stimulates the adrenal medulla?
Acetylcholine
| Adrenaline (and noradrenaline)
211
What is stimulated by the sympathetic nervous system when the only neurotransmitter is acetylcholine?
Effector organs e.g. sweat glands
212
Explain the response from sympathetic and parasympathetic nervous systems following an increase in blood pressure
1) Blood pressure increases
2) Sensed by arterial baroreceptors
3) Causes large stimulation along afferent nerve to the CNS
4) Stimulates parasympathetic nerve which inhibits heart rate
5) Inhibits sympathetic nerves reducing arterioles and vein contraction and effect on heart rate
213
What does sympathetic stimulation of the heart cause?
Increased force of contraction of cardiac muscle (inotropic effect)- increased SV
Increased heart rate (chronotropic effect)
This increases cardiac output
(Also sympathetic-mediated vasoconstriction which increased TPR)
↑↑BP=↑COx↑TPR
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What are the exceptions to vasoconstriction caused by sympathetic nervous system? (3)
1) Skeletal muscle= dilation (either cholinergic fibres or have adrenergic β-receptors)
2) Local vasodilators (e.g. CO2, increased [H+], nitric oxide, histamine etc)
3) Increased parasympathetic stimulation to certain blood vessels to discrete glands, organs (e.g. penis)
215
What effect does the sympathetic nervous system have on the gastro-intestinal system? (Parasympathetic has reverse effect) (3)
1) Generally decreases motility and tone
2) Usually stimulates contraction of sphincters
3) Generally inhibits secretory activity
216
How does the sympathetic nervous system increase oxygen delivery to the lungs? What is the neurotransmitter?
Via noradrenaline/adrenaline from the adrenals.
Neurotransmitter: Acetylcholine
Parasympathetic nerve projects down into the bronchioles and releases Ach causing bronchoconstriction
217
What nervous system causes constriction and dilation of the pupils in the eye? What happens to the muscles? What is the neurotransmitter?
Parasympathetic: Circular muscles contract, pupil constrict (Neurotransmitter= Ach)
Sympathetic: Dilates pupil- Radial muscles contract (Neurotransmitter= Ach and NA)
218
What nervous system has long pre-ganglionic neurons and a short post-ganglionic neuron?
Parasympathetic nervous system
219
With regard to the bladder what is the role of each nervous system?
Parasympathetic: Contracts the Detrussor muscle to empty the bladder (MAIN INFLUENCE)
Sympathetic: Contracts the Internal sphincter to stop urination
ALSO MOTOR NERVES: Contract external sphincter for voluntary control
220
Describe the process of urination with regard to the role of nerves
1) Micturition reflex- pressure in bladder relays sensory information to the spinal cord
2) Spinal cord uses parasympathetic ganglion to contract Detrussor muscle (contract bladder)
3) Sympathetic influence stops- internal sphincter relaxes
4) Motor nerves exercise voluntary control- relax external sphincter
221
What two molecules form acetylcholine?
Acetic acid + choline
222
What are the three types of catecholamine?
Noradrenaline
Adrenaline
Dopamine
223
What are the three types of sympathetic nerve stimulation?
1) Acetylcholine released from preganglionic fibre then noradrenaline released from postganglionic fibre stimulating the effector organ
2) Acetylcholine released from preganglionic fibre stimulating the adrenal medulla to release adrenaline and noradrenaline into the bloodstream which stimulates the target organ
3) Acetylcholine released from preganglionic fibre and postganglionic fibre in sweat glands
224
What are the two exceptions to acetylcholine stimulating the release of noradrenaline in the sympathetic nervous system?
Adrenal glands
| Sweat glands
225
If you could block Ach action in autonomic ganglia, what effect would this have on the heart?
Diminished parasympathetic and sympathetic- action would depend on which system was dominant at the time
If sat down- Increase heart rate
If exercising- Decrease heart rate
226
What are the two types of acetylcholine receptor int he parasympathetic nervous system?
Muscarinic
| Nicotinic
227
Where are muscarinic receptors found in the parasympathetic nervous system?
Within effector organs
228
Where are nicotinic receptors found in the parasympathetic nervous system?
Within autonomic ganglia
229
What stimulates and blocks nicotinic receptors?
Stimulated by nicotine and acetylcholine
| Blocked by hexamethonium
230
What type of receptor is a nicotinic receptor?
Ionotropic (ligand-binding) receptor
231
What stimulates and blocks muscarinic receptors found in the parasympathetic nervous system?
Stimulated by muscarine and acetylcholine
| Blocked by atropine
232
What type of receptor is a muscarinic receptor?
G-protein coupled receptor
233
Which receptor is faster? Nicotinic or muscarinic?
Nicotinic
234
What are the different types of adrenoceptor?
α1
α2
β1
β2
235
What receptor does ventolin (asthma inhaler) bind to?
β2 adrenoceptor
236
What type of receptor are adrenoceptors?
G-protein coupled receptor
237
Where are adrenoceptors found in the sympathetic nervous system?
At effector organs innervated by post-ganglionic fibres
238
What are adrenoceptors stimulated by?
Noradrenaline and adrenaline
239
What type of receptor for sweat glands have?
Muscarinic receptors
240
What type of receptor do effector organs stimulated by the adrenal medulla in the sympathetic nervous system have?
Adrenoceptors
241
Describe the process of synthesis, release and metabolism of amine transmitters
1) Precursor is enzymatically converted to neurotransmitter
2) Transmitter contained in vesicles
3) Action potential travels across membrane and causes influx of Ca2+
4) Vesicle fuses and neurotransmitter released
5) Neurotransmitter enters and crosses the synaptic cleft
6) Neurotransmitter binds to receptor and stimulates response
7) Neurotransmitter is removed from cleft and degraded
8) Neurotransmitter is recylced back into the presynaptic neurone
242
What is the function of acetylcholinesterase?
Metabolises Ach and breaks down products to be resorbed into the neurone
243
What enzyme converts choline into acetylcholine?
Choline acetyl transferse
244
What would happen if you blocked acetylcholinesterase?
Prevent Ach from being broken down in the synapse so it will build up and give a massive, exaggerated response
245
Describe the synthesis, release and metabolism of acetylcholine
1) Acetyl CoA is converted to choline
2) Choline is converted into Acetylcholine + CoA by choline acetyl transferase
3) Acetylcholine stored in a vesicle
4) Action potential propagates to the end of the presynaptic neuron and causes influx of Ca2+
5) Acetylcholine is released and travels across the synaptic cleft
6) Acetylcholine binds to it's receptor
7) Acetylcholinesterase breaks down Ach into Choline and acetate which is taken up into the neurone to be reused
246
Describe the synthesis, release, reuptake and metabolism of noradrenaline
1) Tyrosine is converted to DOPA by tyrosine hydroxylase
2) DOPA is converted to Dopamine by DOPA decarboxylase
3) Dopamine stored in vesicle
4) In vesicle dopamine is converted to noradrenaline by Dopamine β hydroxylase
5) Action potential propagates down the neurone and causes a mass influx of Ca2+
6) Ca2+ causes noradrenaline vesicle to fuse to membrane and be released into synaptic cleft
7) Noradrenaline binds to adrenoceptor
8) Protein transports NA back into presynaptic neurone where it is metabolised by monoamine oxidase A (MAO-A)
OR
8) Protein transports NA into tissue for degradation by COMT
NORADRENALINE IS NOT METABOLISED IN THE SYNAPSE. IT IS REMOVED PRIOR TO METABOLISM
247
Where in the body is noradrenaline released from? What cells?
The adrenal medulla
| Chromaffine cells
248
What percentage adrenaline and noradrenaline are produced in chromaffine cells?
80% adrenaline
| 20% noradrenaline
249
Descrine the process of adrenaline release from the adrenal medulla
1) Tyrosine is converted into DOPA by tyrosine hydroxylase
2) DOPA is converted into dopamine by DOPA decarboxylase
3) Dopamine is stored in vesicles
4) In vesicle dopamine is converted into noradrenaline by dopamine β hydroxylase
5) Dopamine release from vesicle (still within presynaptic neurone)
6) Noradrenaline converted into adrenaline by Phenylethanloamine methyl transferase
7) Adrenaline stored in vesicles
8) Action potential propagates along neurone and causes mass influx of calcium
9) Adrenaline released into interstitial space
10) Adrenaline enters the blood stream
250
What enzyme converts dopamine to noradrenaline?
Dopamine β hydroxylase
251
What enzyme converts noradrenaline to adrenaline?
Phenylethanolamine Methyl transferase (PNMT)
252
How does cortisol affect the release of adrenaline?
Cortisol enhances the effect of PNMT whick upregulates the production of adrenaline
253
Which nervous system stimulates individual target tissues?
Parasympathetic nervous system
254
What does the autonomic nervous system stimulate in the fight or flight response? (5)
1) Heart: Increases cardiac output
2) Brain: More alert
3) Dilation of blood vessels: in brain and muscle
4) Constriction of blood vessels: in skin and kidneys
5) Stimulate glycogenolysis
255
How does the HPA system contribute to fight or flight?
Produces cortisol
256
How does cortisol contribute to the fight or flight response? (4)
1) Mobilises fat
2) Stimulates amino acid transport into cells: nutrients for respiration and gluconeogenesis
3) Reduces inflammation
4) Inhibits allergic reactions
257
How are mean arterial blood pressure (MABP) and total peripheral resistance (TPR) used to calculate cardiac output?
CO=MABP/TPR
258
How are stroke volume and heart rate used to calculate cardiac output?
CO=SVxHR
259
What effects does sympathetic stimulation of the heart have?
Inotropic effect
| Chronotropic effect
260
What is an inotropic effect?
Increase in stroke volume
261
What is a chronotropic effect?
Increase in heart rate
262
What increases the total peripheral resistance?
Increased sympathetic activity- vasoconstriction
263
What two types of receptor detect lower blood pressure?
Baroreceptors
| Cardiopulmonary volume receptors
264
Where are the baroreceptors located?
Carotid sinus
| Aortic arch
265
What does stimulation of baroreceptors cause?
Inhibition of the sympathetic nervous system
266
What is the mechanism of the baroreceptor reflex if you have decreased blood pressure?
1) Stretch receptors decrease
2) Decrease firing sent to brain
3) Decreased inhibition of sympathetic nervous system
4) Signal to sympathetic ganglia and adrenal medulla= increased activation of sympathetic nervous system
5) Release of catecholamines from adrenal medulla
6) Constriction of blood vessel and increased activation of the heart (increased heart rate)
267
What is the baroreceptor reflex if you have increased arterial blood pressure?
1) Stimulates baroreceptors
2) Increased afferent nerve activity
3) Decreased sympathetic nerve activity
4a) Decreased vasomotor tone
4b) Decreased heart rate and force of contraction
4c) Also increased vagal tone
5) Decreased arterial blood pressure
268
What is the cardiovascular response to gaining an upright position?
1) Pooling of blood in lower limbs
2) Reduced venous return
3) Decreased cardiac output
4) Decreased arterial blood pressure
5) Decreased stimulation of baroreceptors and cardiopulmonary receptors
6a) Decreased vagal tone to heart
6b) Increased sympathetic nerve activity
7a) Increased cardiac output
7b) Increased total peripheral resistance
8) Increased arterial blood pressure
269
What impacts the effectiveness of the cardiovascular response to gaining an upright position?
Puberty
| Old age
270
What is postural hypotension?
An acute reduced sympathetic nerve response when transitioning from sitting to standing. Blood flow to the brain is impaired.
Results in fainting
271
What is the mechanism for postural hypotension?
1) Pooling of blood in lower limbs
2) Reduced venous return
3) Decreased cardiac output
4) Decreased arterial blood pressure
5) Decreased stimulation of baroreceptors and cardiopulmonary receptors
6a) Decreased vagal tone to heart
6b) IMPAIRED sympathetic nerve response
7a) LITTLE CHANGE to cardiac output
7b) NO INCREASE in total peripheral resistance
8) Arterial blood pressure NOT maintained
9) Decreased cerebral blood flow
10) FAINT
272
What disease is associated with postural hypotension?
Parkinson's disease
273
Which nervous system increases pupil diameter?
Sympathetic
274
Which nervous system decreases pupil diameter?
Parasympathetic
275
What is miosis (eye)?
Constriction of the pupil
276
What is mydriasis (eye)?
Dilation of the pupil
277
What is the mechanism of the pupillary light reflex?
1) Light enters the pupil and is detected on the retina
2) Optic nerve (cranial II sensory) relays signal to the brain
3) Neurone then activates the parasympathetic nerve
4) Oculomotor nerve (preganglionic) relays signal to postganglionic nerve
5) Ciliary ganglion (postganglionic) relays signal to eye
6) Increases pupillary constriction
278
Where does the parasympathetic nerve that stimulates the pupillary light reflex originate?
Edinger-Westphal nucleus
279
What is the consensual reflex?
When you shine light in one eye it will effect both pupils
280
What allows the consensual reflex to occur?
Parasympathetic nerve response originates at the same Pretectal nucleus for both eyes, therefore only one stimulus is needed
281
Which nervous system produces localised reponses that conserve body energy?
Parasympathetic
282
Which nervous system produces mass responses to mobilise body energy for increased activity?
Sympathetic
283
What are the inputs for changes in the hypothalamus?
Homeostatic changes
| Higher brain centres (Cortex: what makes you human, previous life experiences, memory)
284
Where does the hypothalamus project to?
Medulla
285
What are the outputs from the medulla?
Sympathetic or parasympathetic activity
286
Where are the preganglionic neurons found?
In the CNS (in spinal cord)
287
What is a ganglion?
A collection of cell bodies sitting in the periphery
288
Where are the ganglia found in the sympathetic nervous system?
In the sympathetic trunk
289
Where are the ganglia found in the parasympathetic nervous system?
Close to (or even in) the viscera they innervate
290
What is the largest division of the autonomic nervous system?
Sympathetic nervous system
291
How do neurons pass from the ventral ramus to a ganglion in the synaptic trunk?
Through the white rami commuicans
292
How does postganglionic fibres pass to the effector organ from the synaptic trunk?
Through grey rami communicans
293
Where is the sympathetic trunk found?
From the base of the skull to the coccyx
294
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How many ganglia are found in each region of the sympathetic trunk?
Cervical region:
Thoracic region:
Lumbar region:
Pelvis:
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Cervical region: 3 ganglia
Thoracic region: 11/12 ganglia
Lumbar region: 4/5 ganglia
Pelvis: 4/5 ganglia
295
What is the cervical plexus around?
The pharynx
296
What are the types of cervical plexus? (3)
Cardiac plexus
Thyroid plexus
Pulmonary plexus
297
What is the thoracic plexus around?
Thoracic aorta
298
What thoracic nerves pass through the diaphragm to innervate the contents of the abdomen?
Splanchnic nerves
299
What nerves in the lumbar region takes part in all plexi of sympathetic nerves in abdominal and pelvic regions
Lumbar splanchnic nerves
300
What is secretomotor sympathetic action?
Stimulation of the sweat glands
301
Where do the parasympathetic fibres leave the sacrum?
Anterior rami of S2-4
302
What fibres originate at the pelvic splanchnic nerve? (5)
1) Motor fibres to rectum
2) Motor fibres to bladder wall
3) Inhibitory fibres to bladder sphincter
4) Vasodilator fibres for erection of penis/clitoris
5) Visceromotor innervation of large part of the gut (pass superiorly)
303
What nerves originates at the cranial region in the parasympathetic nervous system?
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Oculomotor nerve (CN III)
Facial nerve (CN VII)
Glossopharyngeal nerve (CN IX)
Vagus nerve (CN X)
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304
What ganglion does the oculomotor nerve synapse with? What is the general function?
Ciliary ganglion: pupil movement in the eye
305
What ganglion does the facial nerve synapse with? What is the general function?
Submandibular ganglion: muscles of facial expression and salivary glands
Pterygopalatine ganglion: paranasal sinuses and lacrimal glands (tear ducts)
306
What ganglion does the glossopharyngeal nerve synapse with? What is the general function?
Otic ganglion: parotid gland (major salivary gland)
307
How does the vagus nerve enter the neck and thorax?
Via carotid sheath
308
What does the vagus nerve branch to? (5)
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Lungs
Heart
Oesophagus
Stomach
Intestines
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309
Where is the enteric nervous system found?
In the walls of the alimentary system
310
What is the function of the sensory part of the enteric system?
Monitors mechanical, chemical and hormonal activity of the gut
311
What is the function of the motor part of the enteric system?
Gut motility, secretion and vessel tone
312
In the periphery what neurotransmitter is always released from post ganglionic fibres?
Noradrenaline
