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A&P Chapter 11
Sense Organs (Q&A)
Question | Answer |
---|---|
What is an example of stimulus? | Cold receptors respond only to cold; light receptors respond only to light |
What is location of stimulus? | Responds to stimuli in a certain area; Sensitive areas contain many receptors |
Describe the intensity of stimulus? | The stronger the stimulus, the more nerve fibers fire; this allows the brain to interpret the intensity of a sensation. When the stimulus is continuous, the firing frequency of the nerve slows, causing sensation to diminish (adaptation) |
What are the classifications of receptors? | Chemoreceptors, Mechanoreceptors, Thermoreceptors, Nociceptors, Photoreceptors, & Proprioceptors |
Define Chemoreceptors | React to chemicals, including odors & tastes |
Define Mechanoreceptors | Respond to change factors such as pressure, stretch, & vibration that change the position of a receptor |
Define Thermoreceptors | Activated by a change in temperature |
Define Nociceptors | Respond to tissue damage from trauma as well as from heat, chemicals, pressure, or a lack of oxygen |
Define Photoreceptors | Respond to light; found only in the eyes |
Define Proprioceptors | Provide information about body movement, muscle stretch, and the general orientation of the body |
What is the 6th step in the pain pathway? | Impulse bypasses the thalamus and travels to the hypothalamus and limb is system (these areas trigger emotional and behavioral responses to pain (ex: fear & nausea) |
What is referred pain? | Pain originating in a deep organ, may be sensed as if it is originating from another area on the body's surface |
What is taste? | Taste results when chemicals come in contact with taste buds, most of which are located in protrusions called papillae |
What does gustatory refere to? | Taste |
What do the taste buds do and what are the three cranial nerves that are involved? | Taste buds send impulses to the brain using the facial nerve (#7), glossopharyngeal nerve (#9) & vagus nerve (#10) |
What is smell? | Incoming odor molecules bind to cilia projecting from the ends of olfactory receptor cells |
How does hearing occur? | The ripples in the perilymph travel to the organ of Corti: hairs of the organ of Corti are stimulated & send nerve impulses along the cochlear nerve to the brain where is is interpreted as sound |
What is responsible for balance? | The vestibule & semicircular canals |
What does conjunctiva consist of? | Transparent mucous membrane that lines the inner surface of they eyelid & cover the anterior surface of the eyeball; secretes a thin mucous film to keep the eyeball moist |
What cranial nerves are associated with eye movement? | Oculomotor (#3), Trochlear (#4), and Abducen (#6) |
What are the tissue layers of the eye? | Sclera, Cornea, Iris, Ciliary body, Choroid, Retina, and Optic nerve |
What is the Sclera? | Outermost layer |
What is the Cornea? | Transparent extension of the sclera in the anterior part of the eye; sits over the iris and admits light |
What is the Iris? | Ring of colored muscle that adjust the diameter of the pupil to control the amount of light entering the eye |
What is the Ciliary Body? | Forms a collar around the lens; secretes a fluid called aqueous humor |
What is the Choroid? | Highly vascular layer of tissue that supplies oxygen and nutrients to the retina and sclera |
What is the Retina? | Thin layer of light-sensitive cells |
What is the Optic Nerve? | Transmits signals to the brain |
What are the eye chambers and fluids? | Anterior cavity, Posterior cavity, Lens, Vitreous humor, Ciliary body, Canal of Schlemm |
Where does the Anterior cavity lie? | Between the lens and cornea |
Where dos the Posterior cavity lie? | Behind the lens; large cavity filled with vitreous humor |
What is the Lens? | Transparent disc just behind the pupil; changes shape for near & far sighted |
What is the Vitreous humor? | A jelly like substance that fills the posterior cavity |
What does the Ciliary body do? | Secretes aqueous humor |
What does the Canal of Schlemm do? | Drains aqueous humor from the anterior cavity; if becomes obstructed, pressure in anterior cavity would rise |
What is refraction? | Bending of light rays; light rays that enter the eye have to be bent so they focuse precisely on the retina |
What is accommodation of the lens? | Curvature of the lens that changes to allow the eye to focus on a near object |