ANAT 1010 Lecture Notes - Referred Pain, Parietal Lobe, Posterior Grey Column
GENERAL (SOMATIC) SENSES (Chapter 21)
A. Sensation
1. Sensation is the conscious or unconscious awareness of external or internal
stimuli.
The nature of the sensation and the type of reaction generated are dependent upon
whether the sensation is translated in the spinal cord, lower brain stem, thalamus,
or cerebral cortex.
2. Perception is the conscious awareness and interpretation of sensations.
3. Modality is the distinct quality that makes one sensation different from others;
in general, a specific sensory neuron transmits only one modality.
B. Classification of receptors:
i. simple receptors are associated with the general senses; the
simplest receptors are free nerve endings
ii. complex receptors are associated with the special senses
iii. receptors can be classified according to two characteristics:
a. by location:
- exteroceptors are located at or near the surface of the body
- interoceptors or visceroceptors are located in blood vessels and
the walls of visceral organs
- proprioceptors are located in muscles, tendons, joints, and the
internal ear
b. by type of stimulus they detect:
- mechanoreceptors detect mechanical pressure or stretching
- thermoreceptors detect changes in temperature
- nociceptors detect pain, i.e., damage to tissues
- photoreceptors detect light
- chemoreceptors detect chemicals
A characteristic of many sensations is adaptation, i.e., a change in sensitivity
(usually a decrease) to a long-lasting stimulus; receptors display one of two
classes of adaptation:
i. rapidly adapting (phasic) receptors play a role in signalling
changes in the intensity of a particular sensation
ii. slowly adapting (tonic) receptors play a role in signalling
information regarding steady states within the body
C. General Senses
1. The general or somatic senses include: i. cutaneous sensations ii. proprioceptive
sensations
2. Cutaneous sensations:
i. Cutaneous sensations include: a. tactile sensations i.e., touch
pressure, vibration (Merkel’s Disc, Meissner’s corpuscle, Hair
Root plexus, Ruffini corpuscle and Pacinian corpuscle),, itch, and
tickle b. thermal sensations, i.e., cold and warmth c. pain (free
nerve endings)
ii. Cutaneous receptors are located in: a. the skin and its underlying
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Document Summary
Sensation is the conscious or unconscious awareness of external or internal stimuli. The nature of the sensation and the type of reaction generated are dependent upon whether the sensation is translated in the spinal cord, lower brain stem, thalamus, or cerebral cortex. Perception is the conscious awareness and interpretation of sensations. Modality is the distinct quality that makes one sensation different from others; in general, a specific sensory neuron transmits only one modality. The general or somatic senses include: i. cutaneous sensations ii. proprioceptive sensations 2. Cutaneous receptors are located in: a. the skin and its underlying shared via c ourse h ero. co m. T his study resource w as https://www. coursehero. com/file/25814044/140-general-senses-study-objectivepdf/ connective tissue b. mucous membranes iii. Nerve impulses initiated by cutaneous receptors are transmitted along somatic afferent neurons in spinal or cranial nerves, through the thalamus, to the somatosensory area of the parietal lobe of the cerebral cortex. vi.
