Medical Pharmacology – Chapter 9 – nervous system and
neurotransmission
The effects of drugs in the body are due to influence on the
nervous system.
To understand these effects, we need to know:
1. Know which various neurotransmission processes are
affected by a drug
2. Understand the functional morphology and innervation
patterns of the nervous system and the neurotransmitters
Via afferent (sensory) nerve fibers to CNS.
Sight senses
Hearing senses
Smell senses
Enteroceptive receptors; register physical and chemical changes within body
o Mechanoreceptors (respond to stretching or pressure changes)
o Thermoreceptors (involved in temperature)
o Chemoreceptors (involved in smell, taste)
o Nociceptors (register pain after stimulation)
Via CNS to efferent (motor) nerve fibers
Stimulus transfer
Nerve cell has cell body, dendrites and axon. The axon can
vary in length
Axon hillock: location where axon leaves the cell body.
Here action potentials can be produced
Axon tip; close to the effector cell, but make no electrical
contact
Synapse; makes the electrical contact with the effector cell
Presynaptic element; represented as button shaped thickening of the axon tip
Postsynaptic element; formed by membrane of the effector cell
Synaptic cleft; is in open connection with other intercellular spaces
Neurotransmitter is released caused by depolarization.
When neurotransmitter bind to receptors it can initiate processes that lead to a
biological effect (e.g. contraction of muscle cells, induction of new action potential
etc.)
When synaptic cleft is larger or when there is no synaptic organisation the process of
stimulus transfer need more time.
Major classes of neurotransmitter substance:
1. Acetylcholine
2. Monamines (biogenic amines); noradrenaline, dopamine, serotonin. Modified
amino acids
3. Aminoacids; gluatminic acid, gamma-amino-butyric acid (GABA)
4. Peptides (neuropeptides); vasopressin and endorphin. These are larger
molecules consist of 3-30 amino acids
neurotransmission
The effects of drugs in the body are due to influence on the
nervous system.
To understand these effects, we need to know:
1. Know which various neurotransmission processes are
affected by a drug
2. Understand the functional morphology and innervation
patterns of the nervous system and the neurotransmitters
Via afferent (sensory) nerve fibers to CNS.
Sight senses
Hearing senses
Smell senses
Enteroceptive receptors; register physical and chemical changes within body
o Mechanoreceptors (respond to stretching or pressure changes)
o Thermoreceptors (involved in temperature)
o Chemoreceptors (involved in smell, taste)
o Nociceptors (register pain after stimulation)
Via CNS to efferent (motor) nerve fibers
Stimulus transfer
Nerve cell has cell body, dendrites and axon. The axon can
vary in length
Axon hillock: location where axon leaves the cell body.
Here action potentials can be produced
Axon tip; close to the effector cell, but make no electrical
contact
Synapse; makes the electrical contact with the effector cell
Presynaptic element; represented as button shaped thickening of the axon tip
Postsynaptic element; formed by membrane of the effector cell
Synaptic cleft; is in open connection with other intercellular spaces
Neurotransmitter is released caused by depolarization.
When neurotransmitter bind to receptors it can initiate processes that lead to a
biological effect (e.g. contraction of muscle cells, induction of new action potential
etc.)
When synaptic cleft is larger or when there is no synaptic organisation the process of
stimulus transfer need more time.
Major classes of neurotransmitter substance:
1. Acetylcholine
2. Monamines (biogenic amines); noradrenaline, dopamine, serotonin. Modified
amino acids
3. Aminoacids; gluatminic acid, gamma-amino-butyric acid (GABA)
4. Peptides (neuropeptides); vasopressin and endorphin. These are larger
molecules consist of 3-30 amino acids
