The Sensory System

• The body’s sensory system is made up of nerves conducting chemical and electrical transmissions from the internal and peripheral body through the spinal column to the brain and back again. The pulses carry information from the brain to keep the entire body functioning.
• There are four main types of nerve fibres. They include the A-alpha, B-alpha, D-alpha and C fibres. The A-alpha nerve cells are covered in a myelin sheath promoting signal conduction. They also have the largest diameter meaning that a signal will travel quickly through them. Sharp, fast messages travel with speed from the source of the threat to the brain where it is perceived as painful and elicits a response. In contrast The C nerve diameter is the narrowest, leaving it to be the nerve fibre through which dull, prolonged pain is felt. (**1)
• Between nerve fibres are nerve synapses. It is in these synapses that the chemical neurotransmitters occur, converting the electrical messages that travel along the nerve axon into chemical messages between fibres and back to electrical message in the next. These messages include signals which register pain, inflammation and anxiety in the brain.
• The body’s physiological response to a sensation which may be harmful or potentially harmful is known as a Nociception response. When a chemical, thermal or mechanical sensation is perceived, a message is sent via the nerve fibres to the brain. The brain then initiates an appropriate physical and chemical response to protect the body and to deal with the pain sensation. (**2)
  • Video: YouTube – Nociceptors – an introduction to pain/Phases of Nociceptive pain     

• The endogenous cannabinoid system was first discovered in the 1990’s. Four types of cannabinoid receptors. The receptors are found on cell membranes in the central nervous system (brain and spine), peripheral nervous system (spine and body), in endothelial cells of organs which include the uterus and in keratinocytes which are present in the immune system. (**3)
• High levels of receptors are found in the thalamus, amygdala, midbrain, medulla oblongata and spinal cord, all of which are responsible for both flight and fight responses as well as bridges to long term memory association and storage in the brain. (**3)
• In 2006, Manzanares, Julian and Carrascosa found nerve cannabinoid receptors along the myelinated A-fibres and even along the C fibres which indicated that the “distribution of the receptors is consistent with the function of modulating pain perception at both the peripheral and central levels”. Further to this they claim that “agonist-activated cannabinoid receptors, modulate nociceptive thresholds, inhibit the release of pro-inflammatory molecules and display synergistic effects with other systems that influence analgesia.” (**3)
• Every person has an endocannabinoid system which means they have biochemical receptors for both CBD and THC.

• CBD and THC have a very similar chemical structure which allows them both to bind to the same endocannabinoid receptors found in the human body. Used independently or in incorrect ratios with CBD, THC can cause the individual using the cannabinoid to experience feelings of euphoria and other negatively associated side effects of cannabis. This euphoric state can impede judgement and the individual’s ability to function normally.
• CBD however binds to the endocannabinoid receptors and changes their ability to take up THC. Its ability to do this, promotes the positive attributes of cannabis which include a reduction in stress, inflammation or pain without the negative effects experience with THC.
• The debate on the effectiveness of using THC and CBD in combination for medicinal use is ongoing. South African regulation states that when used as a complimentary medicine no more than 0.0001mg of THC and 20mg of CBD may be consumed daily. CBD is a schedule 0, herbal, complimentary medicine. Any solution with a higher THC quantity is scheduled between S4-S7 and requires a prescription from a medical professional for the specific ailment.