Neurotransmitters Flashcards
Acetylcholine
Low in Alzheimers - memory function
Dopamine
V levels in basal ganglia - Parkinsons
Schizophrenia
Adrenaline and noradrenaine
V in depression
Serotonin
V in depression
GABA
V in epilepsy
V in Huntingtons
Glutamine
From damage in stroke
Stroke
Ischaemic
•Obstruction of blood supply to a region of the brain
–Thrombosis (causes?)
–Atheroma (causes?)
–Tumour?
–Embolus (causes: atrial fibrillation, DVT, tumour fragment, infective endocarditis)
Stroke and Brain Damage
REMEMBER if motor or sensory cortex has the lesion, the opposite side of the body is affected! – “Decussation” or crossing over of fibers.
FAST
Face/Arms/Speech/Time
TIA = transient ischaemic attack
Temporarily blocked arteries
Cells weakened but don’t die
Stroke Risk Factors
- Age (more in older age group)
- Gender (more in males)
- Ethnicity (more in non-Europeans)
- Heredity (family history present)
- Excessive alcohol and cigarette consumption
- High blood cholesterol levels
- Diabetes mellitus
- Hypercoagulability
- Hypertension
Aneurysm
•An aneurysm is an abnormal dilation of the artery wall…bursting leads to a brain bleed
•The artery wall may be weakened by:
–Atheroma
–Destruction of elastin by proteolytic enzymes
–Continued high pressure on the collagen matrix due to hypertension
–Marfan’s syndrome
Treatment
- metal clip or wrapped
Head trauma
Glasgow coma scale
Vital signs
Blunt force
Coup/contrecoup
Concussion
- Signs are a brief disruption in level of consciousness and amnesia. Full recovery is expected.
- Recurrent concussions can cause permanent damage.
Contusion
- Bruising of the brain.
- Brain cells will die and effects vary according to area impacted.
- Full recovery may not occur
What changes would you notice with increased intracranial pressure for:
- blood pressure ^
- heart rate/pulse
- temperature
- pupils - fixed dilated
- level of consciousness v
Treatment Mannitol
Diuretic
Tentorial Herniation (Coning)
- The tentorium is a fold in the dura mater which separates the cerebrum and cerebellum. The upper brain stem passes through an opening in the tentorium.
- With herniation, increased pressure above the tentorium forces part of the temporal lobe thru an opening, which squeezes the brain stem and damages its blood supply
- This affects the reticular formation and results in coma.
- Nerve III (oculomotor nerve) may be damaged due to increased pressure resulting in a fixed and dilated pupil, first on the side of herniation and then later on the other side as well
- Permanent ischemic damage occurs if herniation reduces oxygenated blood below a critical threshold for more than a few minutes (especially if there is a reduction in blood pressure as well)
Alzheimer’s Disease
Impact
•Progressive, degenerative
•Diffuse atrophy of the cortex
•Widespread loss of cholinergic neurons Hippocampus – impaired memory, learning Amygdala – inappropriate emotions/ anxiety Frontal lobe – impaired speech, reasoning, personality (can be agitated, aggressive)
Alzheimer’s - Pathophysiology
•Neuritic/senile plaques
•Neurofibrillary tangles
•Loss of up to 95% of cholinergic innervation in the cortex
•Plus – decline of enzyme that produces acetylcholine
Alzheimer’s - Treatment
Cholinesterase inhibitor
Parkinson’s Disease
•Progressive degeneration of dopaminergic neurons from substantia nigra
•Leads to reduction in dopamine activity in basal ganglia affecting:
–Learned, automatic movement
–Monitoring and smoothing of voluntary movements initiated by motor cortex
–Inhibition of antagonistic or unnecessary movements
Tremor
Unilateral, pill rolling hand tremor.
May affect other limbs and head. - at rest
Rigidity
1st general slowing and stiffness - leadpipe
Expressionless face
v swallowing
Bradykinesia
Slowness of movement
slow speech - quieter/monotonous
less spontaneous
shuffling walk
Huntingtons disease
- Autosomal dominant
- Progressive loss of neurons in the basal ganglia
- Get increased motor output – “choreiform movements”
- Usually presents 20-50 y
- Personality and cognitive changes in later stages
Multiple Sclerosis
- Autoimmune, progressive, demyelination
- Get neurodegeneration in later stages
- Diagnosis usually 20-40y, more in females
- Symptoms: Motor (limb weakness, loss of bladder/bowel control, speech), Sensory (numbness, pain), Visual (double vision, loss of vision), Cognitive (thinking)
Epilepsy
- Different types
- Tonic/clonic
- Grand mal
- Petit mal
- Temporal lobe
- Common features – uncontrolled firing of a group of neurons; symptoms/presentation depend on location and extent of spread
- Neurons – lowered seizure threshold or hypersensitive to hypoglycemia, hypernatremia, repeated sensory stimulation, fatigue, etc.
- Drugs used to treat epilepsy increase levels of GABA (inhibitory neurotransmitter)
Unipolar Depression
Along with decreased levels of noradrenaline and serotonin….
•Depressed may show dysfunction in limbic and frontal areas
•Chronic stress, with persistent high levels of corticotropin-releasing factor and cortisol leads to: insomnia, low appetite, decreased reproductive function, etc.
Aim to reduce chronic stress. DRUGS USED TO TREAT DEPRESSION:
SSRIS- block re-uptake of serotonin selectively MAOIs- non-selective- block noradrenaline breakdown TCAs- non-selective- block re-uptake
Selective serotonin reuptake inhibitor Monoamine oxidase inhibitor Tricyclic antidepressants
