Chapter 16: Sensory, Motor and Integrative Systems Flashcards
What is sensation?
Conscious or subconscious awareness of changes in the internal or external environment.
What is perception?
Conscious interpretation of sensations.
Sensory modality.
Each type of sensation.
A given sensory neuron carries information for how many sensory modalities?
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General senses.
Somatic senses and visceral senses.
Special senses.
Smell, taste, vision, hearing, equilibrium.
Somatic senses.
Tactile, thermal, pain, proprioception.
Visceral senses.
Pressure, stretch, chemicals, nausea, hunger, temperature of internal organs.
Does a sensory receptor respond to stimuli of other sensory modalities?
Weakly or not at all.
Where are conscious sensations or perceptions integrated?
Cerebral cortex.
Free nerve endings of first-order sensory neurons.
Bare dendrites, not encapsulated, lack any structural specializations. Attached to small diameter unmyelinated C-fibres.
What sensations are sensed by free nerve endings?
Pain, temperature, tickle, itch, touch.
Encapsulated nerve endings of first-order sensory neurons.
Dendrites are enclosed in a connective tissue capsule, distinctive microscopic structure, different types of capsules enhance the sensitivity or specificity of the receptor. Attached to large diameter myelinated A-fibres.
What sensations are sensed by encapsulated nerve endings?
Pressure, vibration, touch.
Separate cells that synapse with first-order sensory neurons.
Hair cells for hearing and equilibrium. Gustatory receptors on tastebuds. Photoreceptors in retina. Receptor potential triggers release of NT –> PSP in sensory neuron –> triggers nerve impulses if threshold is reached.
Exteroceptors.
At or near the external surface of the body. Sensitive to stimuli originating outside the body. Provide information about external environment.
What sensations are sensed by exteroceptors?
Hearing, vision, smell, taste, touch, pressure, vibration, temperature, pain.
Interoceptors.
Visceroceptors in blood vessels, visceral organs, muscles and nervous system. Provide information about internal environment. Not consciously perceived. Activation by strong stimuli may be felt as pain or pressure.
Proprioceptors.
In muscles, tendons, joints and inner ear. Provide information about body position, muscle length, muscle tension, and position and movement of joints.
Mechanoreceptors.
Detect stretching and bending of cells, as well as touch, pressure, vibration, proprioception, hearing, equilibrium.
Chemoreceptors.
Detect chemicals in mouth, nose and body fluids.
Osmoreceptors.
Detect osmotic pressure of body fluids.
Describe adaptation in sensory receptors.
Receptor potential decreases in amplitude during a maintained constant stimulus which causes the frequency of the nerve impulse to decrease. This causes the perception of a sensation to fade or disappear even though the stimulus persists.
Rapidly adapting receptors.
Adapt very quickly as they are specialized for signalling changes in a stimulus.