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05 > Neural Phsyiology and Alteration > Flashcards

Neural Phsyiology and Alteration Flashcards

1
Q

Structure and Function of the Nervous System

A
  • regulated and coordinates the other body system

- transmit signals both chemically and electrically

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2
Q

Cells of the Nervous System

A

Nervous tissue comprises of neurons and neuroglia

  • Neurons transmit and receive electrical and chemical impulses
  • Neuroglia provides supportive functions

Astrocytes provide support and helps maintain blood brain barrier

MS affects myelin coating causing slower neural signals

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3
Q

Organisation of the Nervous System

A

CNS - brain and spinal cord
PNS - cranial and spinal nerves

CNS is composed of two parts

  • Brain - integrates and coordinates body function both consciously and unconsciously - thinking and feeling
  • Spinal cord - conduit for signals from the brain to the body and vice versa, controls simple reflexes with input from the brain

PNS has 2 divisions

  • Sensory (Afferent) - cranial and spinal cerves carry sensory information to the CNS
  • Motor (Efferent) nerves carry messages away from the CNS to target organs or skeletal muscles
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4
Q

Tissues in the CNS

A

Grey matter

  • nerve cell bodies
  • dendrites
  • axons

White matter
- myelin coated axons

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5
Q

Structure of a nerve

A

Cordlike organ of PNS

- bundle of myelinated and unmeylinated peripheral axons enclosed by connective tissue

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6
Q

Classification of nerves

A

Mixture of afferent and efferent fibres, and somatic and autonomic fibres

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7
Q

Pain

A

complex phenomenon

  • involves integration of stimulations of nocioreceptors
  • protective
  • biophyschosocial phenomenon
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8
Q

Nocioreceptors

A

Nocioreceptors or “bare” sensory nerve endings are stimulated by:

  • bradykinin
  • histamine
  • substance P
  • ATP
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9
Q

Transmission of pain impulses

A

Pain impulses travel along fibres of two main types:

  • C fibres - smaller unmyelinated fibres located in skin and deep tissues - slower transmission of impulses
  • A delta fibres - myelinated fibres present in skin and mucous membrane - rapid impulse transmission
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10
Q

Ascending Pain Pathway

A

Carries pain impulse to the brain

  • Information is carried to
  • 1st - dorsal root ganglia
  • 2nd - dorsal horn
  • 3rd - order (thalamus) neurons - with substance P as the principle

Pain fibres cross over at their level of entry to the spinal cord and then from the spinothalamic tract

Interfering with the descending pathway or pain signals can create pain relief

  • opiods
  • local anesthetics
  • alpha 2 agonist
  • anti-inflammatory drugs
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11
Q

Behavioural effects of pain

A
  • Guarding
  • sympathetic discharge - increased HR and BP, RR, O2 consumption
  • Depression
  • Anxiety
  • Muscle spasm
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12
Q

Descending Pathway

A

Nerve fibres from the limbic system and midbrain areas around the cerebral aqueduct

Periaqueductal grey and nucleus raphe magnus travel downwards to the spinal cord where they exert an inhibitory effect on the ascending pain pathway

  • Descending fibres release inhibitory substances such as serotonin and endogenous opoids - endorphins and encephalins
  • which block the pain pathway
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13
Q

Types of pain

A

Acute - rapid onset, well localised, respond to analgesics

Chronic - slowly developing continuous pain, difficult to treat

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14
Q

Homeostatic imbalance

A

long lasting pain leads to hyperglesia (pain amplification), and chronic pain

modulated by NMDA receptors allow spinal cord to “learn” hyperalgesia

early pain management critical to prevent

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15
Q

Visceral and Referred Pain

A

Stimulation of visceral organ receptors

  • felt as vague aching, gnawing, burning
  • activated by tissue stretching ischaemia, chemicals, muscle spasms

Referred pain

  • pain from one body region perceived from different region
  • visceral and somatic pain fibres travel in same nerves; brain assumes stimulus from common (somatic) region

e.g. L) arm pain from HA

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16
Q

Alterations to Cerebral Homeostasis

A
  • Cerebral blood flow accounts from 15-20% of CO
  • ICP - brain tissue, CSF and blood
  • Any change in O2 or CO2 concentration will alter blood vessel diameter and blood flow to the brain
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17
Q

Increased intracranial pressure

A

result from

  • haemorrhage
  • excess CSF
  • tumour growth
  • oedema

When ICP is close or equal to arterial pressure, the patient may experience hypoxia and hypercapnia, which leads to brain injury or death

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18
Q

Alterations to Cognitive Function

A

Consciousness has two components

  • arousal
  • content of thought
  • changes in breathing and level of coma - brain dysfunction
  • pupillary changes - level of brainstem function, drug action and response to hypoxia and ischaemia
  • seizures - sudden discharge in the cerebral neurons
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19
Q

Cerebrovascular Disorders

A

Stroke

Aneurysm

Vascular Malformation

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20
Q

Types of Stroke

A

thrombotic stroke
- blood clot block blood flow in the brain

embolic stroke
- fatty plaque or blood clot breaks away and flows to the brain where it blocks an artery

Cerebral Haemorrhage
- break in blood vessel in brain

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21
Q

Intracranial Aneurysms

A

results from defects in the vascular wall and are classified on the basis of their form and shape

  • Saccular
  • Fusifrom
  • Dissecting
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22
Q

Trauma to the CNS

A

Motor vehicle accidents or sporting injuries

Traumatic brain injuries

  • closed head trauma - blunt - common
  • penetrating head trauma
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23
Q

Degeneration Disorders of the CNS

A

Main degenerative diseases are:

  • alzheimer’s disease
  • parkinson’s disease
  • huntington’s disease
  • MS
  • motor neuron disease (ALS)
24
Q

Alzheimer’s Disease

A
  • decreased brain size
  • loss of neurons
  • decrease in total number of neuronal synapses
  • memory loss very common
25
Q

Parkinson’s Disease

A
  • loss of dopamine secreting neurons hence alterations in muscle functions
26
Q

Clinical Manifestation of Parkinson’s Disease

A
  • tremor at rest
  • rigidity
  • akinesia
  • postural instability
27
Q

Diagnosis of Parkinson’s Disease

A

Difficult to diagnose as usual test such as biochemistry cannot diagnose but rule out causes of symptoms the patient is experiencing

  • Neuroimaging cannot be used
  • diagnosis is made on the basis of clinical picture and neurological and physiological signs and symptoms
28
Q

New research for diagnosing parkinson’s disease

A
  • analysing content of appendixes showed they contain the same toxic protein - called alpha synuclein - that is found in the brains of parkinson’s patients

it has been thought that gut microbiota contributed to neurological diseases such as parkinson’s disease and MS

29
Q

Multiple Sclerosis

A
  • extreme fatigue, memory loss, depression, visual disturbances, loss of coordination and tremor
  • no cure
30
Q

Pathogenesis of MS

A
  • chronic autoimmune, inflammatory disease

- immune cells invade the CNS and demyelinate axon system

31
Q

Huntington’s Disease

A

autosomal dominant genetic disorder involving a mutation resulting in the formation of the protein called huntington

  • this protein miss folding leading to its aggregation in the cells of the brain leading to neuronal cell loss in the basal gangla and cerebral cortex
32
Q

Motor Neuron Disease

A

degeneration of upper and lower motor neurons

axons of the affect nerve degenerate

leads to muscle wasting which begins as weakness and progresses to fatal paralysis

33
Q

Meningitis

A

inflammation of the meninges

  • bacterial - exudate can make CSF flow sluggish and increase ICP
  • patient exhibit symptoms of lower LOC, seizures, muscle weakness, vomiting, and paralysis
34
Q

Encephalitis

A

illness caused by virus affecting the nervous system

caused commonly by herpes simplex or mosquito bourn viruses

  • altered LOC
  • fever
  • delirium
  • confusion
  • seizures
  • abnormal movement
  • increased ICP
35
Q

Brain Abscesses

A

infection that originate outside the CNS

  • infection may travel along the wall of the vein from an adjacent site
  • localised inflammation leads to pus and granular tissue forming in the CNS
  • headache
  • confusion
  • drowsiness
  • sensory or communication deficits
36
Q

Nerve injury and regeneration

A

Nerves can only repair themselves if:

  • the injury occurs in the PNS or
  • occurs near the distal end of the axon
37
Q

Complete and Incomplete spinal cord injuries

A
  • in a complete injury, all function below the area of injury is lost
  • in a incomplete injury, some function is maintain below the site of trauma
38
Q

Location of injuries

A

Cervical - full or partial quadriplegia depending on the site and severity of the trauma

  • C1-3 - loss of breathing and patient would require mechanical ventilation
  • C7-T1 - limited movement of arms

Thoracic - complete injuries will result in paraplegia
- breathing and movement of arms will not be affected

Lumbosacral - decreased control of the anus, bladder, legs, hips and sexual function

39
Q

Incomplete SCI syndromes

A

Central cord syndrome

  • inverse paraplegia
  • legs are functional but arms and hands are paralysed
  • associated with ischaemia and haemorrhage that damages the corticospinal fibres that control arms

Anterior cord syndrome

  • associated with flexion injuries to the cervical spine
  • motor function, pain and temperature sensation are lost below the site of injury however touch, and vibration sensation is maintained

Posterior cord syndrome

  • rare
  • results in a loss of proprioception blow level of injury
  • motor and pain/sensitivity to light touch remains intact
  • doesnt know where the legs are relation to the body

Brown-Sequard Syndrome

  • occurs when the SC is injured on the lateral side or is hemisectioned
  • occurs due to penetrating wounds
  • leads to loss of motor function on the same side of injury and loss of sensation on the opposite side of the SC
40
Q

Define consciousness and state how is it assessed.

A

describes the extent of a person alertness and awareness

it is assess using the glasgow coma scale which measures patient’s responses in terms of how the patients open’s their eyes, verbal responses and motor movement

41
Q

Which part of the brain plays a key role in the control of

consciousness?

A

reticulating activation system (RAS)

- bundle of nerves at our brain stem that filters out unnecessary information so the important stuff

42
Q

Major risk factor for stroke

A

Major risk factors are HTN, diabetes mellitus, hyperlipidaemia, smoking, increased age, family history, alcohol consumption and heart disease

43
Q

State the clinical manifestations of stroke.

A

Problems with motor, speech, sensory, language, and cognitive functions

diagnosis of cause of strokes needs to be identify whether it is haemorrhagic or ischaemic stroke - treating a haemorrhagic stroke with ischaemic treatment can result in death
- CT, MRI and the National Institute of Health stroke scale (NIHSS) may be used for assessment

44
Q

Discuss the difference between the three most clinically important
CNS infections: meningitis, encephalitis and brain abscesses.

A

Meningitis is an infection of the meninges or the membrane of the brain and spinal cord, can be caused by virus and bacteria - streptococcus pneumoniae

Encephalitis is an infection of the brain parenchyma, can be caused by viruses such as herpes simplex

Brain abscesses are accumulations of infective purulent material within the brain or associated with the CNS membrane, mainly caused by strephtococci but can be caused by staphylococci and parasites such as toxoplasma gondii

45
Q

Explain the pathophysiology that causes the symptoms of

Meningococcal disease.

A

Stiff, painful neck, sensitivity to light, vomiting and convulsions
- can cause severe septicaemia

  • leads to localised inflammatory responses, which result in cerebral oedema, raised ICP and vascular thrombosis
  • increased vascular permeability leads to hypotension which is compounded by a loss of vascular tone in the later stages of the illness
  • Myocarditis, and myocardial depression
46
Q

Define what is meant by the term “neurodegenerative disorder”
and outline the common pathophysiological processes implicated in
neurodegeneration.

A

disorders that produce a progressive chronic deterioration of the CNS

leads to changes in the structure and function of the brain and spinal cord

examples include neurodegenerative disorders including alzheimer’s diseases, parkinson’s diseases, huntington’s disease, MND and multiple sclerosis

pathophysiological processes underlying different neurodegenerative disorders have recently been found to have some similarities. it has been proposed that common process include: oxidative stress, intracellular proteins aggregation, mitochondrial dysfunction

47
Q

Describe the clinical manifestations of Parkinson’s disease

A 
tremor at rest
- rigidity
- akinesia (absense of spontaneous movement) or - bradykinesia (slow movement)
- postural instability
TRAP
48
Q

Compare and contrast Huntington’s disease, multiple sclerosis and
motor neuron disease.

A
  • Huntingtons is an autosomal dominant genetic disorder that results in loss of neurons in the basal ganglia nuclei causing a decrease in activity of the inhibitory neurotransmitter GABA
  • MS - autoimmune disorder whereby immune cells destroy CNS myelin sheath leading to plaque formation and causing impairments in motor, sensory, neurological function
  • MND - associated with the degeneration of upper and lower motor neurons, axons of the affected nerve degenerative leading to muscle wasting which begins as weakness and progresses to fatal paralysis
49
Q

Compare and contrast the pathophysiology of primary and secondary
head injury.

A
  • primary head injury immediately from the trauma e.g. contusion, bleeding, axonal shearing
  • secondary head injury occurs from processes initiated by the trauma. occurs days to weeks after the injury and plays a major role in the brain injury and death of a patients following a TBI. may be from ischaemia, increased ICP, cerebral oedema.
50
Q

Outline what are the possible causes of seizures and describe the
different types of seizure.

A

auses of seizures include: abnormal levels of glucose or sodium, brain infection, brain injury, drug, epilepsy, extremely high BP

  • primary generalized seizure begin with widespread electrical discharges across both sides of the brain, e.g. generalised tonic clonic seizures - characterised by stiffening and jerking movements and absence seizures - patient stares into space
  • partial seizures begin with an electrical discharge in one part of the brain e.g. simple or complexpartial seizures and secondarily generalised seizures
51
Q

Discuss the different types of pain.

A

Somatogenic pain - due to recognisable physical cause e.g. burns, fracture, incision

Psychogenic pain - on obvious physical cause, however, still real pain in terms of measurable electrical pain

Somatic pain - well localised pain from skin, muscles or joints, responds well to simple analgesics

Visceral pain - poorly localised pain from organs in thoracic and abdominal cavity

Referred - visceral pain which is perceived as somatic pain in an area with the same innervation

52
Q

How might the body inhibit the ascending pain pathway?

A

y the descending pathway

  • fibres release inhibitory substances such as serotonin and endogenous opioid - endorphins
53
Q

Describe the pathogenesis and common complications of spinal cord
injury of spinal cord injury.

A

primary phase - neurological deficits are present - spinal cord disrupting axons, blood vessels, and cell membrane

Secondary phase - leads to tissue destruction and involves inflammation, oedema dysfunction, ischaemia, excitotoxicity and delayed apoptotic cell death

54
Q

Who does people experience sweating and nausea from a SCI

A

they experience a sympathetic stress response

- the by products of damaged cells are also stimulating the chemoreceptor trigger zone

55
Q

Explain how both sensory and motor function could be affected on one
side only

A

spinal cord is probably more damaged on the R than on the L hemisection

  • motor function is affected on the same side as the injury because of damage to the corticospinal tract (descending pathway)

05 (20 decks)

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