the conscious or subconscious awareness of changes in the external or internal environment
the conscious awareness and interpretation of sensations, is primarily a function of the cerebral cortex
Each unique type of sensation—such as touch, pain, vision, or hearing
what kinds of sensory modality ?
The different sensory modalities can be grouped into two classes: general senses and special senses.
The general senses
somatic senses and visceral senses
The types of Somatic senses?
tactile sensations (touch, pressure, vibration, itch, and tickle), thermal sensations (warm and cold),
and proprioceptive sensations
Function of visceral sense ?
Visceral senses provide information about conditions within internal organs.
The special senses
the sensory modalities of smell, taste, vision, hearing, and equilibrium or balance.
The Process of Sensation
1. Stimulation of the sensory receptor
2. Transduction of the stimulus
3. Generation of nerve impulses
4. Integration of sensory input
first-order neurons ?
Sensory neurons that conduct impulses from the peripheral nervous system (PNS) into the CNS
Distinguish between general senses and special senses?
general senses are somatic senses and visceral senses, whereas special senses are smell, taste, vision, hearing, and equilibrium
What is receptor selectivity?
the ability of a receptor to select one modality over all others
What is transduction?
conversion of energy from a stimulus into a graded potential
Sensory receptors classification ?
structurally, functionally, or by the type of stimulus detected
Types of Sensory Receptors
1. Free nerve endings
2. Encapsulated nerve endings
Function of sensory receptors ?
Free and encapsulated nerve endings trigger nerve impulses in the same first-order neurons.
-Separate sensory receptors release a neurotransmitter that triggers nerve impulses in a first-order neuron.
group sensory receptors is based on the location of the receptors and the origin of the stimuli that activate them.
group sensory receptors is according to the type of stimulus they detect
detects mechanical deformation of the receptor or adjacent cells; detecting touch, pressure, vibration, proprioception, hearing, equilibrium, and blood pressure.
detects changes in temperature.
respond to painful stimuli resulting from physical or chemical damage to tissue.
detect light that strikes the retina of the eye.
detect chemicals in the mouth (taste), nose (smell), and body fluids.
detect the osmotic pressure of body fluids.
How do sensory receptors differ structurally?
free nerve endings are bare dendrites; encapsulated nerve endings have dendrites enclosed within a connective tissue capsule; separate cells
What is adaptation? How does it occur?
the generator potential or receptor potential decreases in amplitude during a maintained, constant stimulus resulting in the sensation fading or disappearing even though the stimulus persists
What is the difference between rapidly adapting and slowly adapting receptors?
rapidly adapting receptors adapt very quickly and are specialized for signaling changes in a stimulus; slowly adapting receptors adapt slowly and continue to trigger nerve impulses as long as the stimulus persists
the state of awareness of external and internal condition of the body
a free nerve ending that detects painful stimuli