Degeneration and recovery Flashcards
Tumor deveopment
- Benign and malignant
- Nerve cells cant divide (proliferate) so don’t become tumorous
Benign tumors
-Does not infiltrate surrounding tissue but causes compression which can destroy brain tissue or cause hydrocephalus which can be life threatening
Malignant tumors
- No defined boarders, can metastasise into the blood stream
- Can cause compression
- Contain cancer stem cells, even if tumour cells are removed, they initiate the growth of new ones (new treatments target these)
Types of brain tumors
- Medulloblastoma - compresses fourth ventricle (hydrocephalus)
- Glioblastoma - glial cells
- Astrocytes - regulates chemicals in extracellular fluid
- Ependymoma - Ependymal cells (line ventricles and produce CSF)
- Oligodendrocytes - Glial cells (myelin sheath)
- Meningioma - meninges
- Pituitary adenoma - pituitary gland
- Neurinoma - schwann cells
- Metastatic carcinoma - secondary tumour
- Angioma - blood vessels
- Pinealoma - pineal gland
Seizures
- Sudden distribution of the brain’s electrical activity (motor neurons) causes convulsion
- Hippocrates was first to suggest seizures are caused by brain damage
Types of seizures
- Partial seizure: Affect localized regions
- Generalized seizure: Affects the whole brain
Causes of seizures
- Scarring from brain injury e.g. stroke or tumour etc.
- High fever
- Alcohol and barbituate withdrawal can cause seizures as they are GABA agonists
- Alcohol and barbiturate withdrawal can cause seizures as they are GABA agonists
- Genetic factors can impact ion channels which can lead to over excitation
- Idiopathic
Damage from seizires
-Damage hippocampus which creates memory problems
Ischaemic strokes
- Cause: Arteries can be blocked by debris such as a blood clot or infection.
- Impacts: Blood flow is obstructed causing damage as oxygen is blocked
- Treatment: Antibiotics rid infection and anticoagulants remove blood clot.
Hemorrhagic stroke
- Cause: blood vessels rupture due to high blood pressure or weak blood vessels which causes blood to leak into the brain.
- Impacts: pressure and subsequent damage due to lack of oxygen
- Treatment: high blood pressure meds or faulty vessels sealed
Stroke damage
- Interruption to blood supply causes oxygen and glucose deprivation
- Attraction of microglia causes phagocytosis so white blood cells rush to the cite causing obstruction of capillaries.
- Sodium potassium transporters stop functioning leading to depolarization and the release of glutamate. Inflow of sodium increases, causing calcium to be absorbed to a toxic level which causes the cell to absorb water and swell and calcium-dependent enzymes are activated which destroy essential molecules e.g. mitochondria which produces free radicals which causes permanent damage (excitotoxic lesions)
Stroke recovery
-Physiotherapy can slowly improve use of limbs impacted by stroke and also shows adjacent cortical areas take on functionality although some damage is permanent
Traumatic brain injury
- Even Mild TBI can lead to neuro-degenerative disorders such as Alzheimer’s and Parkinson’s Diseases.
- Traumatized brain tissue leads to an increased production of glutamate and adenosine which promotes inflammation and causes damage
Fetal alcohol syndrome
- Drinking alcohol during pregnancy is linked to increased risk of miscarriage
- Pregnant women should not drink more than 1-2 UK pints 1-2 times a week
- Exposure to alcohol affects neural plasticity and brain development causing physical and neuropsychological issues e.g. deficits in IQ, attention, coordination, and social interaction
Parkinsons symptoms
-Resting tremor in hands and face, rigidity during volitional movements
Parkinson’s impact on Basal ganglia pathways
-Substantia nigra produces dopamine causing striatum to release GABA
-Parkins stops the production of dopamine so the indirect pathway is excited and the direct is inhibited
Gpi becomes hyperactive causing inhibition in the motor cortex
Treatment
- L-dopa
- deep brain stimulation
- Fetal tissue transplant
L-dopa
- Decreases tremors and increases speed of movements
- Stops working If there are too few dopamine terminals/neurons left and may cause hallucinations instead)
Deep brain stimulation
-Implanted into subthalamic nucleus (Gpi) so patient can electrically stimulate their own brain. This removes some additional excitatory input to Gpi and reduces excessive inhibition to improve motor abilities
Foetal tissue transplant
- Ethically controversial as tissue is obtained from the substantia nigra of aborted fetuses and implanted into the striatum
- Dopaminergic foetal cells are able to grow and secrete dopamine which initially reduces symptoms and can cause painful involuntary movements
- Mutated protein thought to cause dopamine neuron death may transfer to grafted neurons
Multiple sclerosis
-Autoimmune disease in which the immune system attacks the myelin sheaths and creates sclerotic plaques. Interrupts normal transmission of neural messages throughout the spinal cord and brain.
Cause of multiple sclerosis
-Childhood virus may weaken the blood-brain barrier or virus may attach itself to myelin or may be contracted during pregnancy which increases child’s susceptibility
Remitting-relapsing MS treatment
- Interferon is a protein which modulates responsiveness of immune system which has been shown to reduce frequency and severity of attacks
- Glatiramer acetate is a random combination of amino acids found in myelin which may act as a decoy for the immune system
HIV
- Targets and infects astrocytes which leads to apoptosis
- This impacts frontal regions, basal ganglia, hippocampus & white matter
- This can cause dementia, loss of language and movement difficulties
