Central Nervous System Test - Assignment Example

Question 3 A 68 year old-man presents for repair of an abdominal aortic aneurysm. Severe, complicated atherosclerosis is d at surgery, promptingconcern for embolism of atheromatous material to the kidneys. If the patient were to develop renal cortical infarct as a result of surgery, which of the following would be the most likely outcome? A. Fibrosis: correct answer B. Granuloma formation C. Liquefaction D. Metastatic calcification E. Regeneration: My answer Answer A: Fibrosis: Kidneys are common sites of infarcts because of their extensive blood flow and being end organs to their arterial blood supply. Most of the infarcts are due to embolism. Also, the infarcts are of "anemic type" and become sharply demarcated within 24 hours following the insult. The ischemic necrosis of kidneys gradually heals by undergoing progressive fibrous scarring (Alpers, pg. 1012). Destruction of extracellular matrix occurs. The regenerative capacity of renal tissue is maximal in cortical tubules, less in medullary tubules, and nonexistent in glomeruli. Hence this is the correct answer. B: Granuloma formation: Granulomas are formed following chronic inflammation and are encountered in some immunological mediated reactions, infections and some non-infections conditions. Some of the common conditions in which granulomatous inflammation occurs are tuberculosis, sarcoidosis, cat-scratch disease, leprosy and syphilis. The granuloma consists macrophages mainly (Kumar, pg.83-84). Hence this is not the correct answer. C: Liquefaction: Liquefaction or liquefactive necrosis is a condition in which the affected cell is completely digested due to powerful hydrolytic enzymes. It usually occurs in fungal and bacterial infections and causes formation of abscess. Also, ischemic injury in brain causes liquefaction (Mitchell, 138). Hence this is not the correct answer. D: Metastatic calcification: Deposition of calcium salts in otherwise normal tissue is known as metastatic calcification. It occurs due to elevated calcium levels. It is commonly seen in the kidneys and lungs. Hence this is not the correct answer. E: Regeneration: This commonly occurs in the liver and not in the kidneys. Hence this is not the correct answer. References Alpers, Charles. "The Kidney." Robbins and Cotran Pathologic Basis of Disease. 7th ed. Philadelphia: Saunders Publishers, 2007, pg. 1012. Kumar, Vinay, Abbas, Abul and Fausto, Nelson. Robbins and Cotran Pathologic Basis of Disease. 7th ed. Philadelphia: Saunders Publishers, 2007, pg 83-84. Mitchell, Richard. "Hemodynamic disorders, thromboembolic disease and shock.” Robbins and Cotran Pathologic Basis of Disease. 7th ed. Philadelphia: Saunders Publishers, 2007, Pg. 138. Question 7 A 25 year old-woman sustains a deep laceration over the right forearm in a motorcycle accident. The wound is cleaned and sutured. During the next 3 months, the wound heals with formation of a linear scar. Which of the following nutritional factors is required for proper collagen assembly in the scar tissue of the patient? A. Folic acid B. Thiamine C. Vitamin A D. Vitamin C: correct answer E. Vitamin E Answer A. Folic acid: Folate, the useful form of folic acid is an essential nutrient for the production and maintenance of new cells because it is needed for the replication of DNA. It is not useful for collagen production. Hence this is not the correct answer. B. Thiamine: Thiamine is mainly necessary for metabolism of carbohydrates and fats like dehydrogenation of alphaketoacids. It is important for growth and development and has an important role in the functioning of the heart and the nervous system. It does not have any role in the regeneration of cells or collagen fibres. Hence this is not the correct answer. C. Vit.A: The forms of Vitamin A which are useful in the body are retinol, retinal and retinoic acid. Vitamin A is useful for proper perception of light. Some forms of it act like hormones and affect various gene functions which influence many physiological processes. It is also required for normal functioning of the immune system, growth and development and red cell production. It has no role in collagen formation. Hence this is not the correct answer (Vitamin A, Micronutrient Information Center). D. Vitamin C: Vitamin C has an essential role in the formation of collagen in our body. It is useful in collagen hydroxylation where it donates electrons. It activates prolyl and lysyl hydroxylases from inactive precursors, providing for hydroxylation of procollagen (Kane, pg.458-459). Infact, Vitamin C deficiency leads to improper collagen formations which does not have any tensile strength. Hence this is the correct answer. Other than this function, Vitamin C also acts as an anti-oxidant and is necessary for appropriate functioning of various other enzymes like dopamine beta hydroxylase. E: Vitamin E has a main role in the body as an antioxidant. It encourages skin healing and actually reduces scarring after injuries. Hence this is not an appropriate answer. References Kane, Agnes. “Environmental and Nutritional Pathology.” Robbins and Cotran Pathologic Basis of Disease. 7th ed. Philadelphia: Saunders Publishers, 2007, Pg.458-459. “Vitamin A.” Micronutrient Information Center. Linus Pauling Institute. 7th November, 2007 Question 10 A 10 year old boy trips at school and scrapes the palms of his hands. The wounds are cleaned and covered with sterile gauze. These superficial abrasions will heal primarily through which of the following pathways? A. Fibrosis B. Granulation tissue C. Primary intention D. Regeneration: correct answer E. Secondary intention A. Fibrosis: Fibrosis is the process of formation of excess fibrous tissue in a tissue as a reaction to inflammation. It is mainly associated with chronic inflammation and seen in conditions like tuberculosis, lung fibrosis and hepatic cirrhosis (Kumar, pg. 115).Hence this is not the correct answer. B. Granulation tissue: Granulation tissue is seen in granulomas which are formed following chronic inflammation and are encountered in some immunological mediated reactions, infections and some non-infections conditions. Some of the common conditions in which granulomatous inflammation occurs are tuberculosis, sarcoidosis, cat-scratch disease, leprosy and syphilis (Kumar, pg.83-84). Hence this is not the correct answer. C. Primary intention: This method of healing occurs within hours during repair of full thickness surgical incision. The surgical insult involves destruction of only a minimal amount of cell constituents (Mercandetti, eMedicine). Hence this is not the correct answer. D. Regeneration: Regeneration refers to growth of cells and tissues to replace lost structures. It requires an intact connective tissue scaffold which is seen in abrasion wounds (Kumar, pg.89). Hence this is the correct answer. Tissue of the skin (epithelia) has high regenerative capacity and it can renew continuously as long as the original stem cells are intact. E. Secondary intention: Secondary healing or healing by secondary intention is a type of healing in which a full-thickness wound is allowed to close and heal. It results in an inflammatory response that is more intense than with primary wound healing. There is a larger quantity of granulomatous tissue. It results in pronounced contraction of wounds (Mercandetti, eMedicine). Hence this is not the correct answer. The wound contraction is contributed by fibroblastic differentiation into myofibroblasts, which resemble contractile smooth muscle References Kumar, Vinay, Abbas, Abul and Fausto, Nelson. Robbins and Cotran Pathologic Basis of Disease. 7th ed. Philadelphia: Saunders Publishers, 2007,pgs. 83-84, 89, 115. Mercandetti, Michael. “Wound Healing, Healing and Repair.” eMedicine from WebMD, 2005. 7th November, 2007 < http://www.emedicine.com/plastic/topic411.htm> Question 12 A 10 year old boy trips at school and scrapes the palms of his hands. The wounds are cleaned and covered with sterile gauze. Which of the following cellular processes in involved in the restoration of normal epithelial structure and function in the patient? A. Axonal regeneration B. Contact inhibition of growth: correct answer C. Deposition of collagen-rich extracellular matrix D. Myofibroblast contraction: Proliferation of capillary endothelial cells Answer A: Axonal degeneration: This is a process by which the distal part of the nerve will degenerate following cut to a nerve fiber. Hence this is not the correct answer. B: Contact inhibition of growth: Contact inhibition is the natural process of arresting cell growth when two or more cells come into contact with each other. By application of gauze, the inhibition is not allowed because cells do not come in contact with each other and this enables growth and regeneration to occur. Hence this is the correct answer. C: Deposition of collagen-rich extracellular matrix: The extracellular matrix is a complex structural and functional network of proteins and proteoglycans that can interact simultaneously with multiple cell surface receptors. The adhesion of cells to each other or to the extracellular matrix is responsible for a wide range of normal and aberrant cellular activity. This includes migration of immune cells to sites of infection, invasion and metastasis of tumor cells, and angiogenesis (the formation of new blood vessels) during wound healing ("Adhesion and Structure"). The role of matrix is seen when deeper tissues are involved not in superficial abrasions. Hence this is not the correct answer. D: Myofibroblast contraction: This method of healing occurs in secondary intention healing. Secondary healing or healing by secondary intention is a type of healing in which a full-thickness wound is allowed to close and heal. This method of healing results in an inflammatory response that is more intense than with primary wound healing. There is a larger quantity of granulomatous tissue. It results in pronounced contraction of wounds (Mercandetti, eMedicine). Hence this is not the correct answer. References “Adhesion and Structure.” Millipore. 8th November, 2007. Mercandetti, Michael. “Wound Healing, Healing and Repair.” eMedicine from WebMD, 2005. 7th November, 2007 < http://www.emedicine.com/plastic/topic411.htm> Question 16 A 69 year old woman with a history of hypertension is hospitalized after suffering a mild stroke. Which of the following cells is the principal mediator of tissue repair in the brain of this patient? A. Ependymal cells B. Fibroblasts C. Glial cells: correct answer D. Neurons E. Schwann cells A: Ependymal cells: Ependymal cells are the cells which line the ventricles of the brain and are typically cuboidal and often have cilia. They are affected in infections and tumor formation. They are similar to the epithelial cells which line other parts of the body. They form a relatively permeable barrier between the cerebrospinal fluid that fills those cavities and the tissue fluid that surrounds the cells of the CNS (“Cells of the Nervous System”). They are not affected in ischemic injury to the brain and have no role in repair. Hence this is not the correct answer. B. Fibroblasts: Fibroblasts are cells which synthesize and maintain the extracellular matrix of the tissues of our body. They play a critical role in wound healing maintain the structural integrity of connective tissue by continuously secreting precursors of the extracellular matrix. But they do not have a role in the repair of ischemic brain injury. Hence this is not the correct answer. C. Glial cells: Glial cells or neuroglia are actually non-neuronal cells in the brain which provide support and nutrition, maintain homeostasis, form myelin, and participate in signal transmission in the nervous system. They have a wide role in inflammation and repair (Frosch, pg.1349) of brain tissue. This is the correct answer. D: Neurons: Neurons are electrically excitable cells in the nervous system that process and transmit information. They are highly specialized for the processing and transmission of cellular signals. They actually are amitotic (although neurogenesis is proven these days). Hence this is not the correct answer. E: Schwann cell is a type of glial cell that mainly provides myelin insulation to axons in the peripheral nervous system. The nervous system of the humans relies on this myelin sheath for insulation and as a method of decreasing membrane capacitance in the axon. There are some of these cells which are not involved in myelination. They are involved in maintenance of axons and are crucial for neuronal survival. References “Cells of the Nervous System.” 1999. 7th November, 2007 Frosch, Mathew, et al. "The Central Nervous System." Robbins and Cotran Pathologic Basis of Disease. 7th ed. Philadelphia: Saunders Publishers, 2007, pg.1349 Read More