Drugs And Disease

Question 1

What is the blood-brain barrier

Answer 1

Separation of circulating blood and brain extracellular fluid in CNS

Question 2

Cause of Parkinson’s disease

Answer 2

Neurones in the parts of the brain that control movement are destroyed
-normally produce dopamine so losing them causes a lack of dopamine as less dopamine released into synaptic clefts so less available to bind to the receptors on post synaptic membranes meaning fewer sodium ion channels open and post synaptic cell less likely to depolarise= fewer APs produced

Question 3

Symptoms of Parkinson’s disease

Answer 3

Affects motor skills so tremors, slow movement and stiffness within muscles

Question 4

Treatment for Parkinson’s disease and how it works

Answer 4

L-dopa, has very similar structure to dopamine
-when drug given it’s absorbed into the brain and converted into dopamine by enzyme dopa-carboxylase (dopamine can’t be given to treat Parkinson’s as it can’t enter the brain) so increases levels of dopamine in brain
-means more nerve impulses transmitted across synapses in parts of the brain that control movement so more control over movement

Question 5

Cause of depression

Answer 5

Believed to be linked to low level of serotonin which transmits nerve impulses across synapses in the parts of the brain that control mood

Question 6

Treatments for depression

Answer 6

Antidepressants to increase level of serotonin in brain
-SSRIs increase serotonin levels by preventing its reuptake at synapses by inhibiting the re uptake transporter eg Prozac is SSRI

Question 7

Affect of MDMA on the brain

Answer 7

Increases level of serotonin in the brain by inhibiting the reuptake of serotonin into the presynaptic neurones which it does by binding to and blocking the reuptake proteins on the presynaptic membrane (usually serotonin taken back into presynaptic neurone after triggering an AP, to be used again)
-also triggers release of serotonin from presynaptic neurones
-means serotonin levels stay high in the synapse and cause depolarisation of the post synaptic neurones in parts of the brain that control mood

Question 8

Effect of MDMA

Answer 8

Mood elevation

Question 9

Cause of schizophrenia

Answer 9

Excess dopamine

Question 10

Why do some drugs used to treat SZ lead some patients to experience symptoms similar to those of Parkinson’s

Answer 10

Drugs for SZ decrease dopamine levels in brain by blocking dopamine binding to its receptor on post synaptic membrane (but don’t activate post synaptic membrane as similar in shape but not identical) so no change in permeability to sodium ions and no depolarisation so fewer action potentials generated but Parkinson’s caused by low levels of dopamine which these drugs cause

Question 11

What is serotonin secreted by

Answer 11

Neurones in the brain stem, their axons extend to many areas of brain including cerebral cortex, cerebellum and spinal cord

Question 12

Why can MDMA use cause depression

Answer 12

Causes depletion in serotonin, post synaptic membrane less responsible to serotonin and low serotonin levels associated with depression