Physiology Of Pain Flashcards
The sensory aspect of pain
Nociception
Nociceptor that responds to extremes of temperature
Thermoreceptors
Nociceptors that respond to extremes of pressues including incisions
Mechanoreceptors
Nocicrptors that respond to chemicals
Chemoreceptors
Nociceptors that only respond to one set of stimuli
Unimodal
Nociceptors that only respond to more than one type of stimuli
Polymodal
Pain that is created from a stimulus that does not normally cause pain
Allodynia
A normamly painful stimulus causes more pain than usual
Hyperalgesia
Inflamatory mediators released when tissue is damaged
Prostglandins & Leukotrienes
How can inflamatory mediators affect nociceptors
Lower the firing threshold and cause them to respond to less intense stimuli
Pain which arises from the skin or muscle
Somatic pain
Pain which arises from the internal organs
Visceral pain
In comparison to nociceptors in the skin, visceral nociceptors are:
Sparse in their distribution
Why is visceral pain harder to localise?
The noiciceptors are sparce and cause a diffuese sensation
Why type of stimuli will visceral nociceptors be more reactice to?
Stretching and distension
A sharp incision will be more painful in which area?
Skin
The conversion of noxious stimulus into an electrical stimulus
Transduction
Aδ
Delta
Types of nerves
Aδ (delta) & C fibres
Electrical stimuli travel up the nerves to the spinal chord
Transmission
Part of the spinal chord where stimuli enters during transmission
the dorsal horn
Fast conducting, small fibres which are myelinated for sharp, mechanical pain
Aδ fibres
Slow conducting, unmyelinated fibred from longer lasting, or dull, burning pain
C fibres
Happens in the dorsal horn to make the motor nerves move the muslce to remove the part of the budy away from the noxious stimulus
A reflex arc
Other than the relex arc what happens at the doral horn in response to noxious stimulus?
Decision on whether the nociceptive input is sufficient enought to be passsed up to the brain or not.
The decision making in the dorsal horn about whether to sent a signal to the brain about a nociceptive input,
Modulation
What happens if modulation takes place the the dorsal horn send the signal to the brain.
The signal arrives at the cerebral cortex and the animal becomes aware of the pain
Where does a signal from the dorsal horn arrive for perception of pain to occur?
The cerebral cortex
Sudden onset of pain usually the result of a clearly defined cause such as an injury or surgery
Acute
Pain resolved with the healing of its underlying cause and can be alleviated by analgesic drugs
Acute pain
Considered a disease state.
Chronic pain
Pain thast outlasts the normal time of healing, if associated with disease or injury.
Chronic
Pain from tissue injury
Nociceotive pain
Pain from nuerve injury
Neuropathic pain
Pain from sensitised nervous system
Nociplastic
Physolohical consequences of leaving a patient in pain
- Increased sympathetic tone
- Increased systemic vascular resistance and preload
- Increased stroke volume
- Increased myocardial work
- Increased metabolic rate
- Altered clotting function
- Decreased gastrointestinal and urinary tone
- Increased ACTH, cortisol, ADH, renin and angiotensin
- Hyperglycaemia
- Increased protein muscle metabolism
- Retention of sodium and water
- Hypoventilation
