CH 44 Sensory Systems
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provide information from our internal and external environments that is crucial for survival and success
______ sense external stimuli
_______ sense internal stimuli; usually simple
3 classes of receptors
- Mechanoreceptors- stimulated by mechanical forces such as pressure
- Chemoreceptors-detect chemicals or chemical changes
- Energy-detecting receptors-react to electromagnetic and thermal energy ex: infrared heat
Sensory information is conveyed to the _ _ _ and perceived in a ____ step process
CNS (central nervous system) ; four
4 step process of perception
Sensory cells respond to stimuli via _____-_____ ____ _____ in their membranes
stimulus gated ion channels
describe how sensory cells respond via stimulus gated ion channels
- In most cases, a depolarization of the receptor cell occurs, which is analogous to the excitatory postsynaptic potential.
- Referred to as "receptor potential"
respond to stimuli in between external and internal environments
transmit impulses perceived as pain. Most consist of free nerve endings located throughout the body.
- naked dendritic endings of sensory neurons that are sensitive to changes in temperature.
- contain TRP ion channels that are responsive to hot and cold
________ ______ are located higher in the skin and are much more numerous then their counterpart.
cold receptors vs. hot receptors
Several types of _____ in the skin detect the sense of touch
two types of mechanoreceptors
- Phasic- intermittently activated
- Tonic- continuously activated
- detect blood pressure
- highly branched network located in the carotid sinus and the aortic arch
- detect tension or stretch in the walls of these blood vessels
can bind to particular chemicals in the extracellular fluid. Used in the senses of taste and smell. They are also important in monitoring the chemical composition of blood
_____ begins with the capture of light energy by ______
vision ; photoreceptors
four phyla with well developed image forming eyes
- annelids, mollusks, arthropods, chordates
- they all evolved eye structure independently- convergent evolution
white portion of the eye formed of tough connective tissue
Transparent portion through which light enters; begins to focus light
Colored portion of the eye. contraction of iris muscles in bright light decreases the size of its opening, the pupil
a transparent structure that completes focusing of light onto the retina
the lens is attached to the _____ muscles by the _____ _____
ciliary; suspensory ligament
- responsible fore black and white vision
- most nermerous
- Responsible for color vision and high visual activity
- trichromatic vision
most rods and cones are located in the central region of the retina known as the ____
structure of rods and cones
- inner segment rich in mitochondria and vesicles filled with neurotransmitter molecules.
- connected by a narrow stalk, cilium, to the outer segments
- this is packed with hundreds of disks which contain photopigments
The elasmobranchs have electroreceptors call the _____ ___ L_______
- ampullae of Lorenzi
- can sense electrical currents.
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