Somatosensory System Flashcards
What is the somatosensory system?
Parts of the body innverated by the somatic NS
Voluntary control via skeletal muscle
Which nerve fibres are involved in the somatosensory system?
Afferent or sensory
Efferent or motor
What is the difference between a primary and secondary sensory cell?
Primary are attached to muscle spindle fibres
Secondary release neurotransmitter into synapse with a primary sensory cell. NO AXONS
Which is the only sense which contains primary sensory cells?
Olfaction
What are the differences between rapid and slow sensory cells?
Rapid- myelinated, tactile hair
Slow - unmyelinated, continue to trigger impulses e.g. cutaneous mechanoreceptors
What are the 4 modalities (forms of perception) of the somatosensory nervous system?
Proprioception (perception of where body parts are)
Pain
Tactile (touch)
Thermal
What is the difference between acute and chronic pain?
Acute - surface of body, immediate, myelinated axons
Chronic - deep, increase in intensity, unmyelinated
What are pacinian corpuscles?
deep pain receptors
Rapid adapting
Lamellae distorted onto dendrite
What causes itching
Local inflammation - chemicals
Stimulate free nerve endings
In thermal sensations, where are cold and warm free nerve endings located? (Extremes result in nociceptors being stimulated)
Cold - epidermis
Warm - dermis
What is nociceptive pain?
Strong mechano/thermo/chemical stimulation on free nerve endings
What is neurogenic pain?
Impulses WITHOUT free nerve endings
What are examples of neurogenic pain?
Sciatica - slipped disc - dachshunds, Great Danes
Phantom pain in amputated limb
Pain stimuli initiate nerve impulses and produce prostaglandins which intensify perceived pain. What are prostaglandins?
Hormones produced in injured/inflamed tissue
What are analgesics?
Drugs that reduce pain
