Biological and biochemical
determinants of behavior
Dr. Ahmed Elabwabi
MD. Psychiatry
Assistant professor at Albaha university
The Brain
The
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
Right
side of Brain:
–Positive Emotions
–Creative side of Brain
Left
side of Brain:
–Role in Negative Emotions
–Methodological, systematic side
of Brain
Neurons where the messages
are delivered!
Bio-chemical
electrical
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.
•
Neurotransmitters
The life of
neurotransmitters
In nerve endings there are sacs which contain
neurotransmitter
 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)
– GABA

Biogenic Amines
– Quaternary Amines
 Acetylcholine (Ach)
– Monoamines
 Catecholamines
– Dopamine (DA)
– Norepinephrine (NE)
 Indolamines
– Serotonin (5-HT)
Categories of NTs. cont
Neuropeptides
–Opioid Peptides
Enkephalins
Endorphins
Others.
Neutransmitters and mental
disorders
 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
drugs
• 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 !!
Glutamate
 The principal excitatory NT
 Biosynthesized as byproduct of cell
metabolism
 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.
Glu
Glutamic Acid
Decarboxylase (GAD) and B6
• Removed by reuptake
• Has 2 receptor types
GABA
Drugs that bind to GABA
GABAergic drugs
Benzodiazepine (indirect agonist)
–Probably also site for alcohol
–Endogenous inverse agonist
binds here
Barbiturate (indirect agonist)
THANK YOU