Transcript 29.5 Brain Function and Chemistry

29.5 Brain Function and Chemistry
KEY CONCEPT
Scientists study the functions and chemistry of the
brain.
29.5 Brain Function and Chemistry
New techniques improve our understanding of the brain.
• Today, scientists study the brain without surgery.
29.5 Brain Function and Chemistry
• There are three common technologies.
– CT (computerized tomography)uses x-rays to view
structure.
– MRI (magnetic resonance imaging) uses magnetic fields
and radio waves to view structure.
– PET detects activity, uses radioactive glucose
29.5 Brain Function and Chemistry
What alters brain chemistry? Drugs and Illness
• Different neurotransmitters relate to different functions.
synapse
Normal
receptor
neurotransmitter
– some stimulate impulses
– some prevent impulses
29.5 Brain Function and Chemistry
• Abnormal levels of neurotransmitter can cause illness.
– Schizophrenia, Parkinson’s, Alzheimer's disease
– depression
Normal
Schizophrenic
Depressed
29.5 Brain Function and Chemistry
Drugs alter brain chemistry.
• Addiction is the physiological need for
a substance.
• Tolerance occurs when more drug is
needed to produce an effect.
• Drugs might cause desensitization or
sensitization.
– desensitization: more
neurotransmitter leads to fewer
receptors
– sensitization: less neurotransmitter
leads to more receptors.
When the amount of neurotransmitter
becomes abnormal, the adjacent
neuron adapts.
29.5 Brain Function and Chemistry
• Stimulants cause more action potentials
– may increase neurotransmitter in synapse
– may decrease removal of neurotransmitter in synapse
cocaine
neurotransmitter
synapse
29.5 Brain Function and Chemistry
• Depressants cause fewer action potentials.
– may produce neurotransmitter that prevent impulses
– may slow release of neurotransmitter that generates
impulses
29.5 Brain Function and Chemistry
Stimulants:
29.5 Brain Function and Chemistry
Open books to page 891
Define the terms
Answer this questions also
Make a list of the five neurotransmitters on page 892
and describe each function.