Chapter 23 General Senses (by Liz) Flashcards
Sense Organs
Two categories are general and special
Special sense organs are grouped into:
Localized areas (for example, the nasal mucosa or tongue) or into complex organs (such as the eye and ear).
In the presence of continuous stimulus, the rate (frequency) of impulses:
Declines quickly in rapidly adapting receptors of the skin
Visceroceptors (interceptors)
Located internally, often within body organs (viscera)
Examples of exteroceptors include those detect
Pressure, touch, pain, and temperature
Examples of visceroceptors include those that:
Detect pressure, stretch, chemical changes, hunger, and thirst.
Classification of Receptors by Stimulus:
Mechanoreceptors
Are activated when deformed to generate receptor potential
Chemoreceptors:
Are activated by the amount or changing concentration of certain chemicals, such as taste and smell.
Nociceptors
Are activated by intense stimuli that may damage tissue; sensation produced is pain
Osmoreceptors
Are concentrated in the hypothalamus and are activated by changes in the concentration of electrolytes in extra cellular fluids. Stimulates thirst center.
Free nerve endings
Most widely distributed sensory receptor
Called nociceptors: primary receptors for pain
Lamellar (pacini) corpuscles
- Found in deep dermis and joint capsules
- adapt quickly, but sensations they evoke seldom last long
Tactile (Meissen) corpuscle
Large numbers in harmless skin areas, such as nipples, fingertips, and lips
Proprioception
The ability to sense stimuli arising within the body regarding position, motion, and equilibrium
Golgi tendon organs
- When stimulated, they cause muscle to relax
- Type lb sensory neurons are stimulated by excessive contraction
- They are located at the point of junction between muscle tissue and tendon; they are made up of encapsulated neuron endings associated within collagen bundles
