Nociception/Pain

What is receptor adaptation?

Most receptors adapt to constant stimulation, some slowly and some fast

What are tonic receptors?

Receptors that adapt slowly or not at all, constantly responding to stimuli (e.g nociceptors)

What are phasic receptors?

Receptors that adapt quickly and respond to changes in stimuli (e.g pressure receptors)

What is the labelled line?

The stimulus type depends on the labelled line and the area of the cortex at the end ie for mechanoreceptors can be first orer in the PNS, second order in the brainstem or thalamus, third order thalamus to cerebral cortex

What is the receptor field?

A region of skin surrounding the sensory neuron

How does the receptor field work?

The more the receptors, the smaller the area of monitoring and the greater discriminative ability i.e on the face

What is a tactile receptor?

mechanoreceptor for touch, pressure, vibration

What are barocreptors?

mechanoreceptors for pressure e.g blood vessels

What are proprioceptors?

Mechanoreceptors for position of joints and muscles

What are thermoreceptors?

Receptors for temperature there are cold and warm thermoreceptors

How are temperature extremes detected?

thermal nociceptors

What do mechanical nociceptors detect?

cutting, crushing, pinching

What do high-threshold cutaneous nociceptors detect?

Mechanical injury, they send A fibres (myelinated) to detect fast-sharp pain

What do polymodal receptors detect?

Mechinal, thermal and chemical stimuli, they send C fibres (unmyelinated axons) to transmit slow-burning pain

How does the nervous system determine stimulus type?

From the specific receptor activated and the pathway it takes

How does the nervous system determine the intensity of a stimulus?

By the rate of neurons firing and the number of neurons activated

How does the nervous system determine the location of a stimulus?

The sensory neuron from the relevant receptor field is activated which is delivered to the thalamus and then sensory homonculus

What are the two types of pain fibres? What types of stimulus cause the two types of pain?

A fibers send high-threshold, fast-sharp pain, detecting mechanical injury of the skin

C fibers send polymodal slow-burning pain, detecting mechanical, thermal and chemical stimuli

How is the intensity of a stimulus determined?

Number of action potentials, number of receptors activated

How is the location of the stimulus identified?

From the relative receptor field