Chapter 10: Mechanisms of cell injury and Aging
What is the correlation between channelopathy and cystic fibrosis?
Channelopathies are disorders caused by dysfunction of a channel protein or one or more of its subunits. In cystic fibrosis, the primary defect is in an abnormal chloride channel, resulting in increased sodium and water resorption that causes respiratory tract secretions to thicken and occlude the airways.
Channelopathies
mutations in proteins that are part of an iron channel and are responsible for a variety of genetic and acquired disorders
A worker in an industrial plant exposed to 50 rem of ionizing radiation will most likely exhibit:
nausea. Rationale: Exposure to 50 rem of ionizing radiation will most likely cause nausea; exposure to 55 rem will cause fatigue; exposure to 70 rem will cause vomiting; exposure to 75 rem will cause hair loss.
Extracellular matrix (ECM)
nonliving material that is secreted by cells
The nurse is working with the parents of a child who has been diagnosed with acute lead poisoning. Which question would be most appropriate for the nurse to ask to obtain more information?
"In what year was your home built?" Lead poisoning develops in many children when they ingest paint chips, which are often found in older houses. Therefore, the nurse would ask how old the family's house is to help determine the source of lead exposure. Carbon monoxide (CO) detectors are useful in preventing CO poisoning, not lead poisoning. Drinking bottled water is not a risk factor for lead poisoning. The degree of supervision during meals does not increase a child's risk for lead poisoning.
After learning the results of a lung biopsy, a patient asks what epithelial dysplasia of the airways means. Which statement should the nurse use to explain the test results?
"The cells are precancerous, but if you stop smoking, they can change back." Epithelial dysplasia of the airways is a precancerous change; it results from cigarette smoking. The changes are reversible if the patient quits smoking. The patient does not have lung cancer and does not require chemotherapy.
The nurse is researching the role of channelopathies in cystic fibrosis. Which statement explains the correlation?
"The channelopathy in cystic fibrosis is an abnormal chloride channel." A person with cystic fibrosis has an abnormality of the chloride channel, leading to increased sodium and water reabsorption that in turn results in thickened airway secretions. Abnormalities in acetylcholine channels are found in myasthenia gravis. Calcium transport channelopathies are noted in asthma. A deficit in the antidiuretic hormone channels is found in people with diabetes insipidus.
Lead
A heavy metal that occurs naturally as part of the earths crust and can be toxic to most organs
Gangrene
A mass of necrotic tissue - gangrenous necrosis is a form of coagulation necrosis
Autophagy
A normal physiologic process in the body that deals with the destruction of cells within the body
The nurse is caring for a patient with cystic fibrosis. Which manifestation of a channelopathy should the nurse expect to see in this person?
A productive cough and secretions Cystic fibrosis results from a chloride channelopathy that leads to sodium and water retention. This in turn results in thickening of respiratory secretions and a productive cough. Smooth muscle cell constriction and airway inflammation with wheezing occur as a result of calcium channelopathies. Progressive diaphragmatic weakness is caused by a channelopathy of acetylcholine in myasthenia gravis.
Metaplasia
A reversible change in which one adult cell type, such as the epithelial or mesenchymal, is replaced by another type of adult cell
Carbon monoxide (CO)
A tasteless, oderless, colorless gas that causes more than half of all deaths from poisoning
The nurse is reviewing the medical record of a patient with dry gangrene of the left foot. Which finding should the nurse expect to find in the physical assessment?
Absence of pedal pulse Dry gangrene results from an impairment of arterial blood flow to the area. Therefore, the nurse would expect to find no pedal pulse in the affected leg. Pitting, weeping edema indicates venous insufficiency. A foul odor is indicative of wet gangrene, and hemolytic anemia occurs in gas gangrene.
The nurse is caring for a patient with a deep leg laceration. Which action should the nurse realize has occurred to help heal the damaged epithelium?
Activation of fibroblasts The location of many epithelial tissues, which are in contact with the external environment, exposes them to a variety of insults. A deep laceration causes the release of factors that activate fibroblasts, which results in the production of collagen and fibronectin to plug the compromised epithelium. Prostaglandins, von Willebrand factor, and tissue plasminogen activator are components in the initial endothelial response.
What are the common structures found in eukaryotic cells?
All eukaryotic cells (those with a true nucleus) have common structures that perform specific, unique functions. The primary components are the nucleus, cytoplasm, and the cell membrane, also known as the plasma membrane.
Hyaline
An alteration within the cells or in the extracellular pace refers to an alteration within the cells or in the extracellular space resulting in protein-containing cell debris that has a pink to red appearance when stained with hematoxylin and eosin
Dysoxia
An imbalance between oxygen supply and oxygen demand
Oxidative stress
An imbalance between the production of reactive oxygen species and the ability of the body to counteract, or detoxify, their harmful effects through neutralization by antioxidants is an imbalance between the production of reactive oxygen species (ROS), such as free radicals, and the ability of the body to counteract, or detoxify, their harmful effects through neutralization by antioxidants
Hypertrophy
An increase in cell size that is coupled with an increase in the amount of functioning tissue mass
Hyperplasia
An increase in the number of cells in an organ or tissue
Which vitamins play an antioxidant role?
Antioxidants are molecules that either inhibit the reactions responsible for production of reactive oxygen species (ROS) or neutralize ROS. Antioxidants include both enzymatic and nonenzymatic compounds. Nonenzymatic antioxidants include vitamins such as A (carotenes), E (tocopherols), and C (ascorbate). Vitamin C is the most important water-soluble antioxidant in the extracellular fluid. It helps to neutralize ROS in the aqueous phase before it can attack the lipids. Vitamin E is the most important lipid-soluble antioxidant, as it can protect the membrane fatty acids from lipid peroxidation.
What role does atrophy play in cellular adaptation?
Atrophy, a decrease in cell size, occurs when there is a decrease in work demands (physiologic atrophy) or as a result of adverse environmental conditions (pathologic atrophy). Most cells revert to a smaller size with a lower and more efficient level of function that is compatible with survival. Atrophied cells decrease their use of oxygen by decreasing the number and size of organelles and other cell structures, including mitochondria, myofilaments, and endoplasmic reticulum structures.
The nurse is caring for a patient with burns over the upper torso. Which process should the nurse realize will help promote cell growth in this patient?
Autophagy Autophagy is the chemical process in which the body replaces cells that have been destroyed but limits cell replication to the exact number of cells that need to be replaced. This occurs in patients who sustain burns. Metaplasia is a reversible change to cells that leaves them able to develop into cancer if chronic inflammation remains. In hypertrophy, cells become larger as a result of needing to work harder. Hyperplasia is the process in which when cells replicate to the point of overgrowth.
Which cellular growth pattern should the nurse expect to occur in a patient who sustained an injury?
Autophagy Autophagy is the process by which cells are replaced in a number equal to that of the cells that have been destroyed by the injury. This maintains homeostasis. Metaplasia is a reversible change in cells. Atrophy is shrinkage of muscles or organs as a result of various mechanisms. Hypertrophy is cell enlargement resulting from excess work.
The nurse is concerned that a patient is experiencing the results of an endothelial cell injury. Which finding caused the nurse to have this concern?
Bacterial infection Endothelial cell injury can be triggered by a number of different mechanisms. These mechanisms include bacterial or viral infection. Lead poisoning is not identified as a mechanism to cause this type of injury. Low blood pressure and muscle cramps do not cause this type of injury.
A patient is brought to the emergency department for the treatment of carbon monoxide poisoning. What should the nurse assess first in this patient?
Capillary oxygen level Carbon monoxide binds to hemoglobin, forming carboxyhemoglobin, which prevents the normal amount of oxygen from binding to hemoglobin. Therefore, the nurse would first assess the patient's capillary oxygen level with a device called a pulse oximeter. Lung sounds, capillary refill, and peripheral pulses would be assessed after oxygenation.
The nurse is teaching a community class on home safety. Which of the following does the nurse teach about carbon monoxide poisoning?
Carbon monoxide has no taste or smell Rationale: Carbon monoxide is a tasteless, odorless, colorless gas, so its presence cannot be directly detected by the person or people affected by it. That is why it is important to have CO detectors in homes and other buildings.
Which disorder is caused by oxidative stress?
Cardiovascular disease oxidative stress causes endothelial changes in the blood vessels over time, leading to cardiovascular disease. Osteoarthritis, macular degeneration, and hyperlipidemia are related to other stressors, not oxidative stress.
Two types of energy metabolism
Catabolism: consists of breaking down stored nutrients and body tissues to produce energy Anabolism: is a constructive process by which complex molecules are formed from simpler ones
Describe the effect of cell injury and aging on the body.
Cell injury, along with aging, affects the entire body. The primary concepts involved in cell injury and aging include cellular regulation along with inflammation and oxidative stress. Cell injury and aging can affect any organ system and therefore impair processes associated with any physiological concept, such as oxygenation, perfusion, immunity, metabolism, neural or endocrine regulation, and elimination.
What part of the cell is a semipermeable structure that serves to separate the intracellular and extracellular environments?
Cell membrane The main function of the cell membrane is to serve as a semipermeable structure that separates the intracellular and extracellular environments. The Golgi complex modifies the substances synthesized in the endoplasmic reticulum and packages them into secretory granules or vesicles. The Golgi complex also receives proteins and other substances from the cell surface by means of a retrograde transport mechanism. Mitochondria supply the energy, in the form of ATP, needed by the cell. Peroxisomes function as part of the cell's digestive system.
Define cellular adaptation.
Cellular adaptation refers to the changes made in the cell in response to these stressors that favor cell survival. The goal of this adaptation is to maintain homeostasis.
Which of the following treatments does the nurse anticipate in a child with acute lead poisoning?
Chelation therapy
Which structure has an increase in destructive enzymes when the lysosomal membrane is injured?
Cytoplasm If oxygen supply is not restored, loss of enzymes, proteins, and ribonucleic acid through the hyperpermeable cell membrane continues. Injury to the lysosomal membrane results in the leakage of destructive lysosomal enzymes into the cytoplasm, resulting in enzymatic digestion of cell components. The mitochondrion supplies the energy, in the form of ATP, needed by the cell. The primary function of the cell membrane is to serve as a semipermeable structure separating the intracellular and extracellular environments. Ribosomes synthesize proteins and other materials needed for cell function.
Which symptom of carbon monoxide poisoning is caused by nitric oxide released from activated neutrophils and platelets?
Headache Carbon monoxide (CO) poisoning causes headaches as a result of nitric oxide (NO) release from activated neutrophils and platelets. Nausea, vomiting, and weakness occur as a result of the buildup of toxins during CO poisoning.
A client is admitted to the hospital with a carboxyhemoglobin level of 15% after inhaling carbon monoxide. Which of the following manifestations is the nurse most likely to assess?
Headache, exertional dyspnea, dizziness Rationale: A carboxyhemoglobin level of 10-30% is associated with headache, exertional dyspnea, dizziness, nausea, and fatigue; a level of 30-50% is associated with confusion, nausea, vomiting, syncope, and tachypnea; a level of 50-60% is associated with severe headache, tachycardia, hypotension, syncope, coma and/or seizures; a level of 60-80% is associated with coma, cardiac and/or respiratory failure, and imminent death.
What is the difference between hypertrophy and hyperplasia?
Hypertrophy is an increase in cell size that is coupled with an increase in the amount of functioning tissue mass. Hyperplasia is an increase in the number of cells in an organ or tissue.
The nurse is caring for a patient with hypoxia resulting from respiratory failure. Which finding should the nurse expect to see during the assessment?
Hypokalemia and edema Hypoxia leads to a reduction in ATP, which can cause acute cell swelling with failure of the energy-dependent sodium-potassium-ATP membrane pump. This leads to fluid volume overload when water and sodium are retained in the cell and hypokalemia as potassium shifts back into the cell. Sodium will be decreased, but the patient will not experience dehydration, hyperchloremia, or hypercalcemia resulting from failure of the sodium-potassium-ATP pump.
A patient arrives at the emergency department with pneumothorax. Which type of hypoxia is the patient experiencing if the PaO2 is less than 80 mmHg?
Hypoxemic Hypoxemic hypoxia occurs when PaO2 falls below 80 mmHg as a result of altitude or lung disease. In ischemic or stagnant hypoxia, the tissue is not receiving enough oxygen because of decreased perfusion caused by a cardiac or vascular disorder. Anemic hypoxia is the condition in which the oxygen-carrying capacity of the blood in the lungs is reduced. It is common in carbon monoxide poisoning, when carbon monoxide binds with hemoglobin and prevents oxygen from binding in the blood. Histoxic hypoxia is seen when the cells have been poisoned, as in exposure to cyanide.
What diseases are associated with impaired endothelial function?
Impaired endothelial function is the initial step in atherogenesis, which leads to ischemic heart disease and thrombolytic strokes. Impaired endothelial function is also associated with hypertension, diabetes mellitus, and heart failure.
Explain the pathologic process by which carbon monoxide poisoning leads to anemic hypoxia.
In anemic hypoxia, the lungs can be in perfect working condition; however, the oxygen-carrying capacity of the blood is reduced. In carbon monoxide poisoning, the carbon monoxide binds with the hemoglobin, preventing oxygen from binding, which reduces the oxygen carrying capacity of the blood.
Describe the characteristics of caseous necrosis
In caseous necrosis, a form of coagulation necrosis, dead cells persist indefinitely as soft, cheeselike debris. Caseous necrosis is commonly found in the center of tuberculosis granulomas and is thought to be the result of immune mechanisms.
Compare and contrast wet and dry gangrene.
In dry gangrene, tissue is dry, wrinkled, and shrinks. The color of the skin changes to dark brown or black. The spread of dry gangrene is slow. The irritation caused by the dead tissue produces a line of inflammatory reaction between the dead and healthy tissue, called the line of demarcation. It often results from interference with the arterial blood supply and is confined almost exclusively to the extremities. In wet gangrene, the area is cold, swollen, and pulseless. Skin is moist and black and appears to be under tension. Blebs, liquefaction, and a foul odor occur if the gangrene is caused by bacterial action. Wet gangrene has no line of demarcation; therefore, the spread of tissue damage is rapid. Systemic symptoms are often severe, and death may occur. Wet gangrene results from interference with venous return and affects extremities and internal organs.
The nurse is caring for a patient with hypoxia. Which complication of hypoxia should the nurse identify that affects cellular metabolism?
Inability to produce ATP Hypoxia results in a reduction in ATP, which can in turn cause acute cell swelling as a result of the failure of the energy-dependent sodium/potassium-ATP membrane pump, which extrudes sodium from, and returns potassium to, the cell. Hypoxia does not trigger an overproduction of glucose. Liver disease results in inability to convert glucose to glycogen, excess fatty acid production, and deposition in the liver, and an inability to break down amino acids.
What neurologic manifestations may be seen in a child with lead poisoning?
Neurologic manifestations of lead poisoning include seizures, movement disorders, delirium, vomiting, coma, and issues with cognition and attention span that result in learning disabilities.
The nurse is caring for a patient who sustained a cardiac arrest lasting 10 minutes. Which long-lasting effects of hypoxia should the nurse expect for this patient?
Memory impairment During hypoxic events, brain tissue has less than 3 minutes before damage occurs; kidney and liver tissue have 15-20 minutes. Therefore, this patient might experience memory impairment. The patient would not experience renal failure, muscle atrophy, or constipation; hypoxia affects the brain before other organ systems begin to show effects.
What are reactive oxygen species (ROS)?
Molecules that include free radicals such as superoxide and hydroxyl Reactive oxygen species (ROS) are oxygen-containing molecules that include free radicals such as superoxide (O2-) and hydroxyl (OH-) radicals and nonradicals such as hydrogen peroxide (H2O2). Channelopathies are disorders caused by dysfunction of a channel protein or one or more of its subunits. Catabolism is the breakdown of stored nutrients and body tissues to produce energy. Dysoxia is an imbalance between oxygen supply and oxygen demand that occurs in the setting of decreased supply of or decreased demand for oxygen.
A patient was found sitting in a closed garage with the car running. Which tool should the nurse use to validate if this patient has carbon monoxide poisoning?
Multiwavelength pulse oximeter To obtain an accurate oxygen saturation reading, a multiwavelength pulse oximeter that measures oxyhemoglobin, deoxyhemoglobin, and carboxyhemoglobin should be used. When assessing oxygenation parameters in a patient with CO poisoning, the saturation of hemoglobin with oxygen in arterial blood (SaO2) measured by standard pulse oximeters will give a falsely elevated level. An arterial blood gas and blood pressure measurement will not provide enough data to determine if carbon monoxide poisoning has occurred.
Antioxidants
Natural and synthetic molecules that either inhibit the reactions responsible for production of reactive oxygen species (ROS) or neutralize ROS
What is the difference between necrosis and apoptosis?
Necrosis is cell death in an organ or tissue that is part of a living organism. It involves unregulated enzymatic digestion of cell components, loss of cell membrane integrity (causing an uncontrolled release of the products into the extracellular space), and initiation of the inflammatory response. Apoptosis, which is often referred to as programmed cell death, is a highly selective process that eliminates injured and aged cells.
Which part of the cell is damaged by oxidative stress?
Nucleic acids Oxidative stress damages not only the cell membrane but also the nucleic acids that make up the DNA. It does not affect the Golgi complex, cytoplasm, or mitochondria.
Describe the role of oxidative stress in the development of respiratory distress syndrome in premature babies.
Oxidative stress is an imbalance between the production of reactive oxygen species (ROS) and the ability of the body to counteract their harmful effects through neutralization by antioxidants. Mature healthy neonates can tolerate the drastic change in oxygen concentration that occurs with the transition from fetal to newborn circulation. An oxidant-antioxidant imbalance in neonates is implicated in the pathogenesis of respiratory distress syndrome. The premature neonate's lungs are particularly susceptible to oxidant stress because there are many sources of ROS production and a general lack of antioxidant defenses. The full-term neonate is armed with sufficient defenses, but the preterm neonate is not.
Reactive oxygen species (ROS)
Oxygen-containing molecules that include free radicals such as superoxide and hydroxyl radicals and nonradicals such as hydrogen peroxide
Describe the protective and harmful effects of ozone on health.
Ozone is a gas produced by a reaction between nitrogen oxides and volatile organic compounds emitted from gasoline vapor, chemical solvents, air conditioners, power plants, and factories in the presence of heat and sunlight. The ozone layer that occurs naturally in the atmosphere high above the earth is protective because it decreases the amount of harmful ultraviolet radiation from the sun that reaches the earth's surface. However, ground-level ozone (smog), is harmful because it causes adverse respiratory and cardiovascular effects.
The nurse reviews the care needs for a group of assigned patients. Which patient should the nurse believe to be at the highest risk for disuse atrophy?
Patient with a leg in a cast for 6 weeks The patient whose leg has been in a cast for 6 weeks has not been able to use the limb, which will have led to muscle disuse atrophy. Protein calorie malnutrition results in muscle weakness and atrophy. Decreased hormone production in menopause can cause ovarian atrophy. Denervation atrophy occurs in the muscles of paralyzed limbs.
The nurse reviews the health problems for a group of assigned patients. For which health problem should the nurse expect the patient to experience dysoxia?
Pneumonia Dysoxia is an imbalance between oxygen supply and oxygen demand in the presence of a decreased supply of or demand for oxygen, which occurs with pneumonia and asthma. Oxidative stress is an imbalance between the production of reactive oxygen species (ROS), such as free radicals, and the body's capacity to counteract or detoxify their harmful effects through neutralization by antioxidants. This occurs in amyotrophic lateral sclerosis, reoxygenation after stroke, and cardiovascular disease.
The nurse is assigned to care for four patients in the pediatric intensive care unit. In which of these patients should the nurse suspect oxidative stress?
Preterm neonate with respiratory distress syndrome Oxidative stress may occur in premature newborns with respiratory distress syndrome due to inadequate surfactant production. Because their lungs are mature, a full-term infant with pneumonia, a 5-year-old with asthma, and an 8-year-old with leukemia can all handle the stress.
What is the purpose of cell metabolism?
Producing and using energy Cell metabolism is mainly involved in the production and utilization of energy for activities such as cell growth and cell or tissue repair. The cells produce energy through metabolism of carbohydrates, amino acids, and lipids. Ribosomes synthesize proteins and other materials needed for cell function. The mitochondria supply energy in the form of ATP needed by the cell. Lysosomes function as part of the cell's digestive system.
Which of the following laboratory values would be elevated in the client with hemochromatosis?
Rationale: Hemochromatosis is an excess accumulation of hemosiderin in the cells caused by iron accumulation.
The nurse is assigned a new patient who has been admitted with carbon monoxide (CO) poisoning. The paramedics report that the patient was exposed to CO for about 70 minutes. Which finding should the nurse expect when assessing the patient?
Respiratory failure A patient exposed to CO for 70 minutes would exhibit respiratory and/or cardiac failure and coma. A patient would experience nausea and confusion with 30-50 minutes of exposure to CO. Seizures occur after 50-60 minutes of exposure.
What is the difference between reversible and nonreversible cell injury?
Reversible cell injury denotes pathologic changes that can revert back to normal when the stimulus is removed and the injury is mild or of short duration. Nonreversible cell injury indicates that pathologic cell changes are permanent, and they may lead to cell death.
Which of the following is the nurse likely to assess in a child with lead poisoning?
Short attention span Rationale: Many of the clinical manifestations of lead toxicity are due to its ability to cause hypoxia and oxidative stress and impair neurotransmitter function in the nervous system. Neurologic manifestations of lead poisoning include seizures, movement disorders, delirium, vomiting, coma, and issues with cognition and attention span that result in learning disabilities.
The nurse prepares to assess a patient with suspected lead poisoning. Which finding should the nurse expect during this assessment?
Signs of calcium deficiency Lead is a positive cation that competes with calcium at binding sites, including the muscles. Therefore, the nurse would assess the patient for signs of calcium deficiency. Abdominal pain, bone pain, dehydration, and polyuria are signs of hypercalcemia. Calcium and lead concentrations do not affect hearing. The other symptoms are not associated with lead poisoning.
The nurse is developing a presentation regarding the carcinogenic effects of ultraviolet (UV-A and UV-B) rays. Which cancer risk should the nurse include in the presentation?
Skin cancer UV-A and UV-B rays are damaging to the skin and can cause skin cancer. Lung and stomach cancer can be caused by radon exposure. Most instances of colorectal cancer are caused by dietary factors or genetics.
Why is use of a pulse oximeter not accurate in measuring oxygen saturation in the patient with carbon monoxide poisoning?
Standard pulse oximeters use two wavelengths of light that measure the ratio between hemoglobin saturated with oxygen (oxyhemoglobin) and desaturated hemoglobin (deoxyhemoglobin). These dual-wavelength pulse oximeters do not detect the presence of carboxyhemoglobin and will give an overestimate of the oxygen saturation. To obtain an accurate oxygen saturation reading, a multiwavelength pulse oximeter that measures oxyhemoglobin, deoxyhemoglobin, and carboxyhemoglobin should be used.
The nurse plans care for a patient with paraplegia caused by a spinal cord injury. Which intervention should the nurse implement to prevent denervation atrophy of the legs?
Stretching exercises The nurse would work with a physical therapist to develop muscle stretching exercises to prevent denervation atrophy of the legs. Swallowing exercises would help prevent aspiration. Adaptive feeding utensils help promote independence in self-care. Group activities help foster socialization.
Describe the possible role of telomere shortening in senescence.
Telemeres are DNA sequences at the ends of the chromosomes. Each time a cell divides, the telomeres shorten until a critical minimal length is attained. Once this occurs, senescence ensues, and further replication of the cell does not occur. Some cells have telomerase that prevent senescence and contribute to the cellular immortality seen in cancer.
Describe the primary function of a cell membrane.
The cell membrane, or plasma membrane, is one of the most important parts of the cell. The primary function of the cell membrane is to act as a semipermeable structure that separates the intracellular and extracellular environments.
How do evolutionary theories explain aging?
The evolutionary theories about the aging process focus on genetic variation and reproductive success. After the reproductive years have passed, it is not clear that continued longevity contributes to the fitness of the species. Therefore, anti-aging genes would not necessarily be selected, preserved, and prevalent in the gene pool.
What are the two levels of response to injury by endothelial cells?
The first level is an initial rapid response; the second is a slower, phenotypic response. The initial rapid response involves changes in levels of nitric oxide, prostaglandins, ET-1, von Willebrand factor, and tissue plasminogen activator. The slower response depends on fundamental changes in the characteristics of the cell surface along with alterations in the underlying basement membrane and the smooth muscle cells that surround the endothelium.
Identify the five categories of general causes of atrophy.
The general causes of atrophy are grouped into five categories: disuse, denervation, loss of endocrine stimulation, inadequate nutrition, and decreased perfusion. Disuse atrophy occurs where there is a reduction of skeletal muscle activity. Denervation atrophy occurs in the muscles of paralyzed limbs. Atrophy may also result from a lack of endocrine stimulation. Atrophy can also occur as a result of malnutrition. When malnutrition is coupled with decreased blood flow, cells decrease in size and require less energy in order to survive.
What factors affect the lifespan of a cell?
The normal lifespan of a cell depends on the type of cell along with the function, location, and overarching purpose of the cell.
The nurse is teaching a community class on disease prevention. The nurse recommends avoiding which of the following types of radiation from the sun to reduce the risk of cataracts?
UV-B
Which vitamin is the most important lipid-soluble antioxidant because of its ability to protect membrane fatty acids from lipid peroxidation?
Vitamin E Vitamin E is the most important lipid-soluble antioxidant because it protects the membrane fatty acids from lipid peroxidation. Vitamin C is the most important water-soluble antioxidant in the extracellular fluid. Vitamin D changes are seen in lead poisoning. Vitamin A is a nonenzymatic antioxidant (carotenes).
What is the role of the basement membrane in controlling epithelial tumors?
When epithelial cells are inappropriately stimulated to divide, tumor formation may result. Cells in epithelial tumors often retain their basic epithelial characteristics, remaining attached to one another and differentiating to form layered structures. As long as the neoplastic cells respect the basement membrane, the tumor will remain localized. However, once cells break through this boundary, they can enter the circulation and metastasize.
A client with dry gangrene of a lower extremity will exhibit which of the following manifestations?
Wrinkled and shrunken tissue Rationale: In dry gangrene, the tissue is dry, appears wrinkled, and shrinks. The color of the skin changes to dark brown or black. The irritation caused by the dead tissue produces a line of inflammatory reaction between the dead gangrenous tissue and the healthy tissue called the line of demarcation. In wet gangrene, the area is cold, swollen, and pulseless. The skin is moist and black and appears to be under tension. Blebs often form on the surface, liquefaction occurs, and a foul odor is noted if the gangrene is caused by bacterial action. Wet gangrene has no line of demarcation between normal and diseased tissue.
Atrophy
a decrease in cell size
Lipofuscin
a granular yellow-brown pigment composed of lipid-containing residues of lysosomal digestion
Melanin
a nonhemoglobin brown-black pigment synthesized in melanocytes
Cell metabolism
a set of chemical processes that help an organism respond to its surroundings
cell membrane
act as a semipermeable structure that separates the intracellular and extracellular environments.
Hemochromatosis
an excess accumulation of hemosiderin in the cells caused by iron excess
Environmental Protection Agency (EPA)
as required by the Clean Air Act, sets national air quality standards for these pollutants. Despite improvements in air quality resulting from these regulations, significant amounts of pollutants continue to be released into the air, and many areas in the United States have air pollution levels that exceed national standards at various times of the year.
Necrosis
cell death in an organ or tissue is still part of a living organism
Eukaryotic cells
cells with true nucleus
Cellular Adaptation
changes that occurs in cell structure or function in responsible to stressors that support cell survival
Hypoxemia
decrease in arterial oxygen level low oxygen in the blood.
Dysplasia
deranged cell growth of specific tissue that results in cells that very in size, shape and organization
Apoptosis
genetically programmed cell death; programmed cell deaths that prevents a cell with abnormal DNA from replicating
Radiation
is a physical environmental hazard and comprises a wide spectrum of wave-propagated energy, including ionizing gamma rays to radiofrequency waves
Hemosiderin
is an endogenous blood-derived golden yellow to brown granular, or crystalline, pigment
Nonionizing radiation
radiation hat has enough energy to cause atoms to vibrate but not enough to eject electrons
Ionizing radiation
radiation that has enough energy to eject electrons that are tightly bound to atoms, producing positively and negatively charged ions has enough energy to eject electrons that are tightly bound to atoms. This produces two types of electrically charged ions; the electrons released are negatively charged, and the molecules from which the electrons are removed are positively charged
Replicative senescence
the limitation in the number of times cells can divide