Opioids And Analgesics Flashcards
What are nociceptors
They are first order neurons.
Sensory ends are located at skin, joints, or where the injury would occur. The dendrites are the sensory end of the nociceptor.
The sense travels up the neuron and transmitted to where the axon terminals are (neuro transmission) which is the second motor neuron
What is the second order neuron
Dorsal horn of the spinal cord, crossed over to the opposite side of the spinal cord and travels up the lateral spinothalamic tract to the thalamus
Third order neuron
Synapse between second and third neurons in the thalamus and that impulse gets distributed to multiple areas of the brain including motor, emotional, somatic area
What includes a family of peptides that are widely distributed in the cns and the peripheral nervous system and they function as neuro modulators, neurotransmitters, and neurohormones?
Endogenous opioids. Endorphins, enkephalins, and dynorphins.
They allow the body to damp down pain sensations
What is the “pain gate”
Descending inhibitory pathways release endorphins that dampen pain response. Occurs at second
What do Presynaptic opioid receptors activate ?
They activate signal transduction pathways that inhibit the n-type voltage-dependent calcium channels which blocks exocytosis and the release of excitatory neurotransmitters (like glutamate and substance p)
What do postsynaptic opioid receptors activate?
They activate Signal transduction pathways that open potassium channels which hyperpolarize membranes and block the formation of action potentials that are essential for transmitting pain sensations
What are mu (u1) (MOR) receptors
Induce analgesia, euphoria, physical dependence
What are mu (u2) (MOR) receptors
Cause sedation, bradycardia, and respiratory depression
What are delta (d)(DOR) receptors ?
Mediate spinal anesthesia and the development of tolerance to opioids
Kappa (k) (KOR) receptors
Mediate spinal anesthesia, miosis, and sedation a
The long term treatment of pain associated with cancer is compromised by the development of tolerance to opioid medications. How could the combined use of delta receptor antagonist and a mu receptor agonist address this problem?
If we block the delta receptors we could block the tolerance while still getting relief by agonizing the mu’s
Tissue injury/pain flow chart
Tissue injury (chemical injury, mechanical injury, inflammation, deprivation of oxygen) - rupture of cellular membranes- 1. release of arachidonic acid- cox makes prostaglandins- sensitize nociceptor- 2. Release of autocloids (self remedy) (histamines, bradykinin) that activate nociceptors- then pain transmission flow neurotransmission by nociceptor (first order)- neurotransmission through spinal cord(second order)- pain impulse transmission through brain (third order) cerebral cortex- perception and emotional response to pain
What are two ways nociceptors are sensitized ?
Prostaglandin e and autocloids(histamine, bradykinin, serotonin)
What are two types of cannabinoids that are found naturally in the resin of the marijuanna (cannabis) plant
Tetrahydrocannabinol (thc) and cannabidiol (cbd)
