Santhakumar Raja

Neurohumoral transmission involves the following four steps (figure) Step 1: Initiation of an Action Potential and Axonal Conduction During resting conditions, the membrane potential inside a typical axon is −70mV with respect to exterior of axon. A high concentration of K+ and low levels of Na+ and Cl– (K+ 140mM, Na+ 10- 15mM ) within the cell cause this difference in

Autonomic Nervous System has the following functions : Reflex Activities : The ANS is involved in complex reflex activities that depend on sensory input to the CNS and on motor output. Reflex actions are rapid and are coordinated subconsciously in the brain, i.e., below the level of the cerebrum. Deals with Excitation and Stressed Conditions

The differences between sympathetic and parasympathetic nervous system according to their origin, character and effect on respective organs are listed in table. Sympathetic Parasympathetic Origin From all thoracic and upper 3 lumbar segments. From cranial 3, 7, 9, 10 and sacral 2, 3, 4 segments. Character Short preganglionic and long post-ganglionic fibres. Long preganglionic and

The preganglionic fibres of the parasympathetic nervous system arise from the cell bodies of the CNS. The preganglionic fibres originate from the nuclei of the third, seventh, ninth and tenth cranial nerves (CN III, VII, IX, and X), and, the fourth sacral segments (S2 to S4) of the spinal cord. The parasympathetic nervous system has

The preganglionic fibres of the sympathetic nervous system arise from the cell bodies spanning from the Thoracic (T1) to the Lumbar (L2) part of the spinal cord. The Sympathetic Nervous System is made up of the following parts: Sympathetic Trunks : These represent a pair of long cords located on either side of the vertebral column. They extend from

These receptors possess a subunit along with enzymatic property or bind a JAK (Janus Kinase) enzyme on activation. The outer face of plasma membrane carry binding site for agonist and the inner face has catalytic site (figure). A single transmembrane stretch of peptide chain interconnects these two domains. The two primary subgroups of these receptors

These receptors belong to a large family of cell membrane receptors. These receptors are bonded with effector (enzyme/channel/carrier protein) by one or more GTO-activated protein (G-protein) to give effective response. The structural organisation of all such receptors is common. GTP carrying α-subunit dissociated from the other two subunits can either inhibit or activate the effector. The β and γ

The drug receptor interaction may be affected by : Isosterism : Isosteres are groups of atoms having identical physical or chemical properties of a molecule due to resemblance in size, electronegativity, or stereochemistry, and presence of these groups in molecules is known as isosterism. For example, N2 and CO, both have 14 total electrons and no charges

In molecular terms, the activity of drugs is initiated by their atomic level interaction with a receptor. Since the association of small molecules (e.g., drugs) with macromolecules (e.g., receptors) is promoted and stabilised by intermolecular interactions, an understanding of the nature of chemical bonds and intermolecular interactions is of great interest to the medicinal chemist.