Uploaded by Hibatalla Ahmed

biological and biochemical determinants of behavior

Biological and biochemical
determinants of behavior
Dr. Ahmed Elabwabi
MD. Psychiatry
Assistant professor at Albaha university
The Brain
mind is considered a
functional correlate of brain.
Brain reaches its maximum
number of synaptic
connections and its greatest
metabolic activity around age
3 or 4
Brain Hemispheric Hypothesis
side of Brain:
–Positive Emotions
–Creative side of Brain
side of Brain:
–Role in Negative Emotions
–Methodological, systematic side
of Brain
Neurons where the messages
are delivered!
impulses create a cascade
of effects based on the
message sent to various
organ receptors of the body
The role biochemical factors
The role biochemical composition
and reactions in humwn behavior
• Mainly:
• Genetics
• Neurotransmitters.
The life of
In nerve endings there are sacs which contain
 Neurotransmitter are automatically released when
the electric signal reach the nerve ending.
 Neurotransmitter are the means of chemicals
transmission between neurons.
 Once the chemical message is delvered one of two
fates happen to neurotransmitters:
– Degradation by monoamine oxidase enzyme
– Reuptake to the presynaptic neurone to reture to its sacs.
Categories of NTs
Amino Acids
– Glutamate (Glu)
Biogenic Amines
– Quaternary Amines
 Acetylcholine (Ach)
– Monoamines
 Catecholamines
– Dopamine (DA)
– Norepinephrine (NE)
 Indolamines
– Serotonin (5-HT)
Categories of NTs. cont
–Opioid Peptides
Neutransmitters and mental
 Dopamine:
when is in excess is related
to psychosis e.g. schizophrenia
 Acetylecholine: is deficient is related to
amnesia and dementia
 Norarnaline is related to depression
 Serotonin is related to depression
Neurotransmitters and their correlation with some
• Dopamine - amphetamines, cocaine, ETOH
• Serotonin - LSD, ETOH
• Endorphins - opioids, ETOH
• GABA - benzodiazepines, ETOH
• Glutamate –ETOH
• Acetylcholine - nicotine, ETOH
 Anandamide – Marijuana
GABA and glutamate : The
engine and the brake !!
 The principal excitatory NT
 Biosynthesized as byproduct of cell
 Removed by reuptake
 Elevated levels  neurotoxic
 4 receptor types
GABA (Gamma Aminobutyric Acid)
• Principal Inhibitory neurotranmitter.
• Biosynthesis: GAB is composed by biochemical
changes to glutamate.
Glutamic Acid
Decarboxylase (GAD) and B6
• Removed by reuptake
• Has 2 receptor types
Drugs that bind to GABA
GABAergic drugs
Benzodiazepine (indirect agonist)
–Probably also site for alcohol
–Endogenous inverse agonist
binds here
Barbiturate (indirect agonist)