7.2 The Mechnical Senses Flashcards
Vestibular sensation
The system specialized to detect the position and movement of the head
Vestibular Organ
Adjacent to the cochlea monitors each movement and directs compensatory movements of your eyes
Otolith organs
The saccule and utricle
Otoliths
Calcium carbonate particles that line next to the hair cells; when the head tilts in different directions, they push against different sets of hair cells and excite them
Semicircular Canals
Oriented in three different planes, are filled with a jellylike substance and lined with hair cells
The somatosensory system
The sensation of the body and it’s movements
Pacinian corpuscle
Detects sudden displacements or hi-frequency vibrations on the skin
Dermatome
The skin area connected to a single sensory spinal nerve
Mechanical senses
They respond to pressure, bending, or other distortions of her receptor; touch, pain, and other body sensations; vestibular sensation, a system specialized to detect the position and movement of the head
Pain
Depends on certain unmyelinated and thinly myelinated axon’s carrying information to the spinal cord and releasing a neurotransmitter known as substance P
Substance P
A neuromodulator or cotransmitter with glutamate; Released during a strong stimulus
Capsaicin
A chemical that causes neurons containing substance P to release it suddenly; also directly stimulates pain receptors that are sensitive to moderate heat, from about 43°C to 53°C
How is the cingulate cortex involved in pain?
It indicates the emotional context, not the painful sensation itself
Gate theory
Certain areas of the spinal cord receive messages not only from the pain receptors but also from other receptors in the skin and from axons descending from the brain; if these other inputs to the spinal cord are sufficiently active, they close the gates for the pain messages; the brain can increase or decrease its own exposure to pain information
Opioid mechanisms
Systems that are responsive to opiate drugs and similar chemicals
