2: Neuropathology 1 Flashcards
What germ cell layer do neurons and glial cells come from?
Ectoderm
Which germ cell layer do microglia come from?
Mesoderm
Necrosis is ___ death of brain cells and occurs in which brain disease?
rapid
sudden failure e.g stroke
Atrophy is a ___ reduction in brain size.
Is it normal?
slow
Depends - occurs with age, but is accelerated in diseases such as Alzheimer’s
What happens to neurons histologically in acute injury?
Nuclei shrink and angulate
Nucleolus is lost
Cytoplasm turns red
___ neurons are indicative of acute neuronal injury.
Red
Which types of acute injury cause red neuronal death?
Hypoxia
Infarction
What is the role of astrocytes in the CNS?
Support cells
Maintain homeostasis, maintain BBB, role in repair
What is reactive gliosis?
Which cells undergo it?
What does it look like?
Non-specific reaction to CNS injury by glial cells
Glial cells (astrocytes, microglia, ependymal cells, oligodendrocytes)
Hypertrophy and hyperplasia, nucleus enlarges
In demyelinating diseases (e.g MS), the conduction velocity of neurons (increases / decreases).
decreases
What process do astrocytes undergo in response to injury?
Reactive gliosis
like all glial cells
What happens to astrocytes in gliosis?
Hypertrophy
Hyperplasia
Which important processes do
a) neurons
b) glial cells
undergo in response to injury?
a) “Red neuron” reaction
b) Reactive gliosis
What are the role of microglia in the CNS?
Immune surveillance
Phagocytosis
Which immune cell are microglia very similar to?
Macrophages
do the same job i.e phagocytosis, just in the brain
Which state causes acute brain injury and occurs in stroke, trauma and cardiac arrest?
Hypoxia
Which percentage of inhaled oxygen is used by the brain?
20%
Why do neurons depolarise after extended hypoxia?
Which neurotransmitter is released in response to this abnormal depolarisation?
Which ion then enters the neuron
Na/K ATPase stops working - so Na accumulates inside the cell, causing a depolarisation
Glutamate (excitatory)
Ca2+
What is excitotoxicity?
What triggers it?
Process by which neurons are killed by excessive glutamate > Ca2+ release
Extended hypoxia - Na/KATPase fails - Depolarisation - Glutamate release - Ca2+ influx - Release of endotoxins
Various types of swelling, or ___, occur in response to brain injury.
oedema
What is vasogenic oedema?
Breakdown of the BBB in infarcted areas of the brain allows water, ions and protein to filter out, causing swelling
What is cytotoxic oedema?
Hypoxic cells lose function of their sodium-potassium pump
Sodium accumulates in the cell
So water and chloride ions follow down the osmotic gradient
Causing the cell to swell
Protein can also get in through the wrecked cell membrane
Oedema causes ___ of brain tissue.
compression
What can happen to the brain if intracranial pressure increases too much?
Herniation
which tends to be fatal
What is haemorrhagic conversion?
Blood vessels weakened by an ischaemic stroke rupture, causing bleeding
Which three processes cause compression, contributing to complications following a brain injury?
Cytotoxic oedema
Vasogenic oedema
Haemorrhagic conversion
The area of brain affected by a stroke depends on the ___ which are affected.
arteries
What is the average BP of the brain circulation?
20 mmHg
What pathologies of blood vessels cause stroke?
Infarction
Haemorrhage
AVM
Aneurysm
Dissection
What is a cardio risk factor for stroke?
Hypertension
What is
a) global
b) focal
hypoxic ischaemic injury?
a) Widespread brain deperfusion due to shock, hypotension, cardiac arrest, trauma…
b) Damage to one specific area of the brain due to blockage of a specific artery
What MAP is required to perfuse the brain?
60 mmHg and above
What are risk factors for ischaemic stroke?
Hypertension
All the CVD risk factors for atherosclerosis - smoking, diet, HT, age, male diabetes
Congenital heart disease
What colour do neurons turn in acute damage secondary to ischaemic stroke?
Red
Microglia hoover up dead cell debris by ___.
phagocytosis
If an ischaemic stroke turns into a bleed, what is that process called?
Which structure is damaged to cause this?
Haemorrhagic conversion
Blood brain barrier
Which cardio risk factor is a big predictor of stroke?
Hypertension
Which type of infarct affects the basal ganglia?
Lacunar infarction
Haemorrhage
bleeding tissue is damaged by hypoxia
surrounding tissue is damaged by oedema and compression
Which notable type of vascular disease causes subarachnoid haemorrhage?
Berry aneurysm
What are some rarer causes of haemorrhagic stroke?
Amyloid angiopathy
ARTERIOVENOUS malformation
Which circulation is damaged to cause a Berry aneurysm?
Circle of Willis
Which renal disease is associated with Berry aneurysm?
Polycystic kidney disease
Why may haemorrhages secondary to Berry aneurysms cause hydrocephalus?
Blood stops CSF reabsorption in subarachnoid granulations
