3.Which receptors sense pain? What is the structure of a pain receptor? 4. Give examples of mechanoreceptors, chemoreceptors, and photoreceptors. A mechanoreceptor is a sensory receptor that responds to mechanical pressure or distortion. Normally there are four main types in glabrous mammalian skin: Pacinian corpuscles, Meissner's corpuscles, Merkel's discs, and Ruffini endings. Chemoreceptors are: olfactory receptor neurons in the olfactory system: Olfaction involves the ability to detect chemicals in the gaseous state. In vertebrates, the olfactory system detects odorants and pheromones in the nasal cavity.
Photoreceptor proteins are light-sensitive proteins involved in the sensing and response to light in a variety of organisms. 5.Name all the muscles that are associated with eye function, explain what each does and indicate whether it is a skeletal or a smooth muscle. 6.What is the function of tears and which glands produce them? 7. Describe the following structures: optic disc : A small area of the retina containing openings through which the axons of the ganglion cells emerge as the optic (II) nerve. Also, called the blind spot. macula lutea: the yellow spot in the center of the retina. fovea centralis : A depression in the center of the macula lutea of the retina, containing cones only and lacking blood vessels; the area of highest visual acuity (sharpness of vision).