Mass Stimulation of Sympathetic/ Parasympathetic Systems

• The autonomic nervous system is the portion of the nervous system that controls most visceral functions of the body. This system helps to control arterial pressure, gastrointestinal motility, gastrointestinal secretion, urinary bladder emptying, sweating, body temperature, and many other activities.
• • About 75% of all parasympathetic nerve fibers are present in the vagus nerves, which supply parasympathetic innervation to the heart, lungs, esophagus, stomach, small intestine, colon, liver, gallbladder, pancreas, kidneys, and upper portions of the ureters.
• • In some cases, almost all portions of the sympathetic nervous system discharges simultaneously as a complete unit, a phenomenon called mass discharge.
• • This frequently occurs when the hypothalamus is activated by fright or severe pain. The result is a widespread reaction throughout the body called the alarm or stress response, which is discussed shortly.
• 1. During the process of heat regulation, the sympathetics control sweating and blood flow in the skin without affecting other organs innervated by the sympathetics.
• 1. For example, heating a skin area causes local vasodilation and enhanced local sweating, whereas cooling causes opposite effects.
• The parasympathetic system is responsible for "rest and digest" functions in the body.
• parasympathetic system is often highly specific.

  • Cardiovascular Reflexes:
  • Mouth Glands:
  • Stomach Glands:
  • Rectal Emptying Reflex:
• • Cardiovascular Reflexes:Acts on the heart to change its rate of beating, not its force of contraction
• • Mouth Glands: It can make the glands in your mouth produce saliva
• • Stomach Glands:It can influence the secretion of digestive juices, like stomach acid and pancreatic enzymes
• • Rectal Emptying Reflex:

  The parasympathetic system can trigger the emptying of the rectum (going to the bathroom), and sometimes, it can also lead to the emptying of the bladder.
• When large portions of the sympathetic nervous system discharge at the same time-that is, a mass discharge
• it is frequently said that the purpose of the sympathetic system is to provide extra activation of the body in states of stress, which is called the sympathetic stress response.
• signals are transmitted downward through the reticular formation of the brain stem and into the spinal cord to cause massive sympathetic discharge; most aforementioned sympathetic events ensue immediately. This is called the sympathetic alarm reaction. It is also called the fight-or-flight reaction.
• Medullary

  • Located at the base of the brain stem, it regulates vital functions like cardiovascular control and respiratory control.
• Pons

  Located above the medulla in the brain stem, is involved in coordinating breathing patterns.
• Midbrain

  • The mesencephalon, also known as the midbrain, is located at the top of the brain stem, functions are more closely related to sensory and motor coordination, particularly for vision- related activities and also reflexes.
• Higher Brain Control

  • Hypothalamus and Cerebrum
• Brain Stem as a relay station

  • taking messages from higher brain areas and sending them to the right parts of the body.
• Pharmacology of Autonomic Nervous System

  • Therapeutic Index
  • Drug Absorption
• Pharmacology of Autonomic Nervous System

  • Therapeutic Index
  • Drug Absorption
• Pharmacology of Autonomic Nervous System

  • Therapeutic Index
  • Drug Absorption
• Therapeutic Index is a ratio that expresses the relationship between the dose expected to elicit some adverse effect and the dose needed to elicit therapeutic effects
• Plasma concentration: derived by collecting a blood sample at any time after drug administration and measuring the amount of a drug in a given volume of blood plasma of the sample.
• Sub therapeutic: involving or relating to drug dosages administered at too low a level to produce a therapeutic effect.
• therapeutic window describes the dosage range between a minimum effective therapeutic concentration, and the minimum toxic concentration. (ex: minimum 10 mg/L and toxic effect occurs at 20 mg/L then the window would be 10-20 mg/L).
• Adverse response: (harmful or unfavorable) the toxic effect.
• Peak of effect : Dosage wherein it shows maximum effect.
• the TI can be calculated as the lethal dose of a drug for 50 % of the population
• The higher the therapeutic index, the lower the chance of the drug producing any toxic side effects.
• Drug Absorption

  Absorption is the process that brings a drug from the administration, example, tablet or capsule, into the systemic circulation. Absorption affects the speed and concentration at which a drug may arrive at its desired location of effect.
• A pill is usually absorbed into the blood through the stomach walls after it is swallowed – these can become active in a few minutes but usually take an hour or two to reach the highest concentration in the blood.
• IV drugs are injected directly into the blood work much faster – sometimes in seconds or minutes.
• • Sympathomimetic drugs are stimulant compounds which mimic the effects of endogenous agonists of the sympathetic nervous system.
• an endogenous agonist for a particular receptor is a compound naturally produced by the body which binds to and activates that receptor
• Sympathomimetic Drugs

  • Norepinephrine
  • Epinephrine
  • Methoxamine
• 1. Norepinephrine – 1-2 minutes - is used to increase and maintain blood pressure in limited, short-term serious health situations.
• 1. Epinephrine – 1-2 minutes (adrenaline – fight or flight response) – for people undergoing cardiac arrest.
• • Methoxamine treatment of hypotension, or low blood pressure