Special pathology - neurology Flashcards
Neuropathophysiology refers to
pathophysiological conditions that affect the nervous system
groups of neuronal cell bodies in the peripheral nervous system are called?
while those in the CNS are called?
ganglia
in the central nervouse system, they’re called nuclei
describe an Axon (3)
one long nerve fibre
enclosed in a myelin sheath (lipoprotein)
carries nerve impulses away from the cell body
describe Dendrites (2)
multiple branched protoplasmic extensions of a nerve cell
carry impulses to the cell body
Action potentials are (3)
-described and measured as an electrical parameter
-evoked in nerve and muscle cells in response to stimulation
-associated with the cellular and cellular membrane metabolism (membrane potential)
2 fundamental activities of neurons
- modulate and effectively transmit chemical and electric signals from one neuron to another via synapses in the CNS
- or from one neuron to a muscle cell via junctional complexes, myoneural junctions, or motor end plates in the PNS
what are glial cells
supportive cells of the nervous system
name 4 macroglial cells
Astrocytes
Oligodendrocytes
Shwann cells
Ependymal cells
what are Microglial cells
resident phagocytic cells of the nervous system that regulate brain development, maintenance of neuronal networks, and injury repair.
principal manifestation of the activity of the central nervous system is the
reflex
function of astrocytes
Astrocytes regulate synaptic transmission and plasticity, protect neurons against toxic compounds, and support metabolically to ensure their optimal functioning.
function of oligodendrocytes
are highly specialized neural cells whose function is to myelinate central nervous system axons.
Myelin sheaths are extraordinarily large extensions of the oligodendrocyte cell membrane
function of schwann cells
play a vital role in maintaining the peripheral nervous system, and come in two types either myelinating or non-myelinating Schwann cells.
Both play a pivotal role in the maintenance and regeneration of axons of the neurons in the PNS.
function of ependymal cells
play a critical role in cerebrospinal fluid (CSF) homeostasis, brain metabolism, and the clearance of waste from the brain
Immuno-privilege of the CNS means?
adaptive immunity and inflammation are highly controlled
Central nervous system (CNS) immune privilege is an experimentally defined phenomenon. Tissues that are rapidly rejected by the immune system when grafted in sites, such as the skin, show prolonged survival when grafted into the CNS.
haematoencephalic barrier =
Blood-brain barrier is between endothelial cells of capillaries and astrocytes.
purpose is to protect against toxic substances in the blood, supplies brain tissues with vital nutrients, and filters harmful compounds from the brain back to the bloodstream.
hemato-liquor barrier =
Blood-CSF barrier of the CNS is formed by tight junctions between neighboring choroid plexus epithelial cells
to preserve homeostasis within the cerebral compartment so that the complex neural integrative functions of the CNS can operate optimally.
Cerebrospinal fluid originates
in the ventricles of the brain
-fills and surrounds the brain and the spinal cord
-provides a mechanical barrier/buffer against physical damage
-nutrient delivery and waste removal system for the brain
- the fluid is constantly flowing/circulating and renewing itself
Encephalitis
inflammation of the brain
Encephalopathy
(degenerative) disease process of the brain
(syndrome)
Myelitis
Inflammation of the spinal cord
Myelopathy
(degenerative) disease process of the spinal cord
Neuropathy
disease process of the nerve
Myopathy
disease process of the muscles
upper motor neuron
Motor neurons with axons residing solely in the CNS that control lower motor neurons.
lower motor neuron
Large multipolar neurons in the brainstem and ventral horns of the spinal cord with axons extending into the PNS.
difference between upper and lower motor neurons
The upper motor neurons originate in the cerebral cortex and travel down to the brain stem or spinal cord, while the lower motor neurons begin in the spinal cord and go on to innervate muscles and glands throughout the body.
which cells of the CNS are most sensitive to injury
Neurons are the most sensitive to injury, whereas glial and other cells are more resistant to injury.
Neurons with the highest metabolic rate, such as some neurons in the cerebral cortex, will die 6 to 10 minutes after the cessation of blood flow after cardiac arrest.
neurons > oligodendroglia > astrocytes > microglia > blood vessels
why are neurons so vulnerable?
- small energy stores, depend heavily on an intact blood flow to supply oxygen and nutrients
- neurons do not have regeneration
If nerve fibers in the CNS are cut by transection of the cord, what is the result?
no or little regeneration of nerve fibers results:
- paralysis
- neurologic deficit
If fibers in the PNS are cut, what is the result?
they can regenerate under certain circumstances.
Healing in the CNS is different than in the rest of the body. wounds deep in the CNS heal by
proliferation of astrocyte processes
CNS has the ability to resist infection and injury but—-
once the CNS is infected, it has a low degree of resistance when compared with other tissues of the body.
8 Major disease categories
Anomaly
Degenerative
Ideopathic
Inflammatory
Metabolic - toxic
Neoplastic
Trauma
Vascular
___
Vascular
Ideopathic
Trauma
Anomaly
Metabolic - toxic
Inflammatory
Neoplastic
Degenerative
Acute neuronal necrosis or?
is what?
or ischemic necrosis
common response to a variety of CNS injuries,
cerebral ischemia caused by:
e.g.
blood loss and hypovolemic shock vascular thrombosis
cardiac failure
inflammatory mediators
bacterial toxins
thermal injury
heavy metals
nutritional deficiencies, such as thiamine deficiency
trauma
Brain edema
Increase in tissue water within the brain, results in an increase in brain volume.
The fluid may be present in the intracellular or extracellular compartments or both.
The term is also used to include the accumulation of plasma, especially in association with severe injury to the vasculature.
Brain swelling
marked, rapidly developing
sometimes unexplained increase in cerebral blood volume and brain volume
can be because of relaxation (dilation) of the arterioles that occurs after brain injury
laesio cerebri
Traumatic brain injury (TBI),
any damage to the brain from an applied force
countercoup injury
refers to two separate brain injuries sustained during the same incident.
As the brain jolts backward, it can hit the skull on the opposite side and cause a bruise called a contrecoup lesion.
Secondary brain damage
24-72 after the trauma
lacerated capillaries
decreased perfusion (O2, glucose deficit)
cell damage
cell edema
increased intracranial pressure
necrosis , apoptosis
Cerebral circulatory disorders (3)
- Transient cerebral ischemia /transient ischemic attack
- (Cerebral) Stroke
- Hypertensive encephalopathy
3 types of Stroke
Cerebral ischemic stroke/infarction
Hemorrhagic stroke:
Intracerebral
Subarachnoid
Cerebral circulatory disorders can be classified as (2)
Organic (hemorrhages, embolic thrombosis)
Functional (cerebral ischemia, hyperemia)
Severe organic brain damage is usually caused by
ischemia:
– Systemic circulatory failure – hypovolemic shock, severe heart failure
– Local impaired blood flow – atherosclerosis of cerebral vessels, embolic thrombosis, decreased perfusion resulting from increased intracranial pressure
The severity of the damage caused by cerebrral ischemia depends on whether the ischemia is
focal or complete.
Symptoms of cerebral ischemia appear only in case of a significant decrease in
perfusion pressure.
A critical decrease in cerebral oxygen consumption occurs in case the cerebral volumetric blood flow rate is decreased by
half.
hemorrhagic stroke is when
bleeding occurs directly into the brain parenchyma (intraparenchymal hemorrhage)
hemorrhagic stroke is Usually accompanied by
secondary haemorrhages – bleeding extends from the parenchyma into the ventricular chambers and subarachnoid space.
Secondary spinal cord injury examples
(24 – 72 h after trauma)
ischemia, oedema, free radicals
Pathogenesis of acute spinal trauma
contusion/compression leads to
release of vasoactive substances which leads to
damage to microvasculature
can lead to:
hemorrhage
ischemia
edema
necrosis
name 2 inherited Bleeding disorders:
von Willebrand’s disease (Doberman),
hemophilia
name 2 aquired Bleeding disorders:
rodenticide toxicity,
infectious/inflammatory diseases (DIC,
angiostrongylus)
angiostrongylus
Angiostrongylus cantonensis is a parasitic nematode (roundworm) that causes angiostrongyliasis, the most common cause of eosinophilic meningitis.
what is Common to find at the site of
acute intervertebral disc herniations, vertebral fractures or luxation, due to disruption of the venous sinuses?
extensive extradural hemorrhage
Peripheral nervous system can be divided into: (3)
sensorimotor division
autonomic division
enteric division
Pathophysiology of peripheral nerve trauma (3)
- Primary damage of myelin sheath
- Primary axonal degeneration
- Combination of them
Neurotoxicity may result from
myriad agents, including metals, pesticides, solvents and other chemicals, and bacterial, animal, and plant-derived toxins, as well as therapeutic agents.
Drug-induced toxicity may be caused by (3)
overdosage
undesirable side effects
accidental exposure (usually ingestion).
signs of neurotoxicity
excitation, depression,
tremors, seizures,
hyperactivity, ataxia,
circling, salivation,
hyperthermia, coma
what is a polyneuropathy
Polyneuropathy means that many nerves in different parts of the body are involved. (sort of like it being systemic but applied to the nerves)
Seizure
sudden, transient, abnormal phenomenon of a motor, sensory, autonomic, or psychic nature resulting from a transient dysfunction of part or all of the brain
Epilepsy is
s a disorder of the brain that is characterized by
recurring, unpredictable seizures.
Epileptic seizure types can be classified into two major categories:
partial
generalised
The presence of epileptic seizures implies a
forebrain disorder.
seizures may originate :
outside (extracranial)
inside (intracranial)
Seizures can be characterized as (3)
functional or idiopathic disorders
(where no gross structural changes are evident in the brain)
structural disorders
(where there is a gross structural cause within the brain, brain tumour or hydrocephalus)
Paralyses
loss of movement
Paresis
mplying weakness or incomplete loss of muscle function
Monoparesis or monoplegia
denotes partial or complete loss of voluntary motor function in one limb, resulting from a neurologic lesion.
Hemiparesis or hemiplegia
refers to motor dysfunction of two limbs on the same side
Diparesis or diplegia or paraparesis or paraplegia
both front (upper) or rear (lower) limbs, ie bilateral motor dysfunction
Tetraparesis or tetraplegia or quadriparesis or quadriplegia
refers to partial (-paresis) or complete (-plegia) loss of voluntary motor function in all limbs
Bradykinesia or hypokinesis or hypokinesia
slow movement and an impaired ability to move the body swiftly on command
Hyperkinesis or hyperkinesia
an increase in muscular activity that can result in excessive abnormal movements, excessive normal movements, or a combination of both
Dyskinesia
involuntary muscle movements
Akinesia
the state of being without movement
