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Histology-World!
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Histology Testbank: Special Senses 1a |
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Instructions: For each histology question, pick the one best answer. This histology test bank is also useful for the histology questions on the USMLE (USMLE step 1). 1. Answer: d The ciliary body is a thickening in the uvea. It contains the ciliary muscle. The site where the optic nerve leaves the eyeball is the optic disc. This region is also called the anatomical blind spot. Since there are no photoreceptors at this spot, it causes a blind spot in the visual field.The fovea centralis is part of the retina. There are only cone cells in the fovea centralis. It is the site for maximal visual acuity. The inner layer of the choroid is the lamina vitrea. The lamina vitrea is also referred to as Bruch's membrane. The lamina cribrosa are small openings within the sclera where the fibers forming the optic nerve travel through. 2. Answer: c The neurons in the retina are bipolar. Neurons can be classified based on the number of axons and dendrites stemming off of the cell body. A unipolar neuron has one process which branches off of it This process then immediately divides into two. Thus, a unipolar neuron is sometimes also called a pseudounipolar neuron. Sensory neurons are unipolar. A bipolar neuron has two process that branch from it: an axon and a dendrite. Bipolar neurons are not very common and are found in some of the organs for special senses. Bipolar neurons are found in the retina, inner ear, and the region of the nose involved with smell. Multipolar neurons have one axon and many (at least two) dendrites that branch off of it. Most neurons are multipolar. Motor neurons and interneurons are multipolar. 3. Answer: e The cornea is transparent. 4. Answer: b The eyeball has three layers. The innermost layer is the retina. The middle layer is the uvea. The outer layer is the sclera and cornea. The retina consists of the rods, cones, bipolar cells, ganglion cells, horizontal cells, and amacrine cells. The receptors for vision are the rods and cones. The rods are located on the periphery, and are not color sensitive. The cones are the receptors for color. 5. Answer: b The vascular pigmented structure of the uvea is the choroid. The ciliary body contains the ciliary muscle. The ciliary muscle is responsible for adjusting the lens. The most anterior portion of the uvea is the iris. The anterior pigmented portion of the retina is called the ora serrata. The sclera is the "white of the eye". 6. Answer: d An os is an opening or mouth. The optic chiasm is the anatomical region shaped like an "X" where the two optic nerves join. The region where the optic nerve exits the eye is the optic disc. The openings within the sclera which allow nerve fibers to exit is the lamina cribrosa. The anterior pigmented portion of the retina is called the ora serrata. 7. Answer: b The retina contains receptor cells, neurons, pigmented epithelium and supporting cells. The nervous element in the retina consists of bipolar cells and ganglion cells. 8. Answer: a The region behind the lens is the vitreal cavity. The chambers anterior to the lens are the anterior chamber and posterior chamber. The iris separates the anterior chamber from the posterior chamber. 9. Answer: d There are five layers to the cornea: epithelium, Bowman's membrane, substantia propria, Descemet's membrane, and endothelium. The surface of the cornea is covered by a non keratinized stratified squamous epithelium. Bowman's membrane and Descemet's membrane are acellular. The majority of the cornea is from the substantia propria. The endothelium is a simple epithelium. 10. Answer: b The ciliary body is a thickening in the uvea. It contains the ciliary muscle. The site where the optic nerve leaves the eyeball is the optic disc. This region is also called the anatomical blind spot. Since there are no photoreceptors at this spot, it causes a blind spot in the visual field. The fovea centralis is part of the retina. There are only cone cells in the fovea centralis. It is the site for maximal visual acuity. The inner layer of the choroid is the lamina vitrea. The lamina vitrea is also referred to as Bruch's membrane. The lamina cribrosa are small openings within the sclera where the fibers forming the optic nerve travel through. |
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