Effects of Asphyxiation

Chapter 4: Cellular Biology This chapter explores altered cellular and tissue biology, focusing on cellular adaptation, injury, manifestations of cellular injury, cellular death, aging, and the various types of cell death such as necrosis and apoptosis. Cellular adaptation allows cells to respond to physiological and pathological conditions, but severe or prolonged stressors can lead to cellular injury or death. Common sources of cell injury include lack of oxygen, free radicals, infections, inflammation, and metabolic derangements. Cellular aging also contributes to changes in structure and function. Bullet points Diagnosis of various forms of asphyxiation, including hemorrhages, strangulation, and chemical asphyxiants, can be determined through autopsy findings. Hemorrhages in the eyes and face may indicate asphyxiation. Strangulation can result in impaired cerebral blood flow, leading to injury or death, while chemical asphyxiants, such as carbon monoxide, hinder oxygen delivery to tissues. Bullet points Effects of asphyxiation ● Compression on the neck can cause hemorrhages in the eyes and face ● Impairment of chest expansion can lead to asphyxiation ● Strangulation causes compression of blood vessels and air passages in the neck ● Compression on the neck can result in hypoxia from impaired blood flow to the brain Types of strangulation ● Hanging strangulation occurs when a noose or similar object is placed around the neck and the body falls freely ● Ligature strangulation involves a cord encircling and tightening around the neck ● Manual strangulation involves an assailant's hands compressing the victim's neck Chemical asphyxiants ● Carbon monoxide is the most common chemical asphyxiant ● Carbon monoxide prevents oxygen delivery to tissues and induces CNS depression ● High levels of carboxyhemoglobin (carbon monoxide bound with hemoglobin) can lead to widespread ischemic changes in the CNS ● CO monitors in homes are recommended to detect carbon monoxide exposure Diagnosis CO Poisoning Symptoms and Causes ● CO poisoning may cause cherry red coloration to the skin and mucous membranes ● Symptoms of CO poisoning include headache, giddiness, tinnitus, chest pain, confusion, nausea, weakness, and vomiting ● CO is an environmental air pollutant found in combustion fumes from various sources ● Chronic exposure can occur in confined spaces like underground garages and tunnels ● Individuals most susceptible to CO poisoning are fetuses, infants, and people with chronic heart disease, respiratory problems, and anemia Cyanide Poisoning Symptoms and Causes ● Victims of cyanide poisoning may have cherry red coloration to the skin and mucous membranes ● An odor of bitter almonds may be detected in the presence of cyanide ● Cyanide acts as an asphyxiant by inhibiting the formation of cytochrome oxidase ● As a result, the mitochondria can no longer generate ATP and oxygen cannot bind to the final molecule in the electron transport chain Hydrogen Sulfide Poisoning Symptoms and Causes ● Victims of hydrogen sulfide poisoning may have brown-tinged blood ● Hydrogen sulfide interferes with the body's ability to carry oxygen ● It has a characteristic "rotten egg" odor Methane Poisoning Symptoms and Causes ● Methane causes asphyxiation by displacing oxygen ● It is nontoxic but can lead to suffocation Drowning Mechanism and Factors ● Drowning is death from inhalation and suffocation by a liquid, usually water ● Major mechanism of injury is hypoxemia (low blood oxygen levels) ● Airway obstruction is an important consideration, as little or no water may enter the lungs ● Cerebral hypoxia can lead to unconsciousness in approximately 250 minutes ● Water temperature is an important determinant of survival and irreversible injury ● An incapacitated individual may drown in only a few inches of water Intentional and unintentional asphyxia cases in the United States ● Intentional asphyxia cases: strangulation, suffocation, hanging ● Unintentional asphyxia cases: accidental suffocation, choking on food or objects Common chemical asphyxiants and why they are lethal ● Common chemical asphyxiants: carbon monoxide (CO), hydrogen sulfide (H2S), cyanide ● They are lethal because they interfere with oxygen transport in the body, leading to hypoxia and cell death How carbon monoxide (CO) causes death ● CO binds to hemoglobin in red blood cells, reducing their ability to carry oxygen ● This results in tissue hypoxia and can lead to organ failure and death Major mechanism of injury with drowning ● Drowning occurs when a person is unable to breathe due to submersion in water ● The lack of oxygen causes tissue damage and can lead to brain injury and death Mechanisms of cellular injury ● Genetic: alterations in cell structure, receptors, or transport mechanisms ● Epigenetic: changes in gene expression without altering DNA ● Nutritional: pathological effects due to nutrient deficiency or excess ● Physical agents: temperature extremes, blast injuries, compression waves Types of Radiation Injury ● Decompression sickness (caisson pressure) can cause collapsed thorax, ruptured organs, and widespread hemorrhage ● Ionizing radiation (X-rays, gamma-rays, alpha particles) can remove orbital electrons and cause skin damage, DNA damage, chromosomal aberrations, and cancer ● Mechanical injury can be caused by physical impact or irritation, leading to disorders such as overexertion ● Noise exposure can result in hearing impairment or loss, tinnitus, and various other symptoms Cellular Manifestations of Injury ● Cellular accumulations can occur due to metabolic disturbances or inefficient cell function ● Accumulations can involve normal cellular substances like water, proteins, lipids, and carbohydrates, as well as abnormal substances ● Infiltrations may occur in the cytoplasm or nucleus and can be toxic or harmless ● Intracellular accumulations can result from abnormal metabolism, defects in protein folding or transport, lack of lysosomal enzymes, or ingestion of indigestible materials Intracellular Accumulations: Metabolites and Water ● Metabolites are expelled into the extracellular matrix (ECM) and attacked by phagocytic cells ● Macrophages are the primary phagocytic cells ● Hepatomegaly or splenomegaly may occur due to the swelling of affected tissues ● Cellular swelling is the most common degenerative change and is caused by a shift of extracellular water into cells ● This swelling can result in organ enlargement and oncosis (cytoplasmic swelling) ● In hypoxic injury, movement of fluid and ions into the cell is associated with metabolic failure and the loss of ATP production ● Reduced ATP levels and ATPase enzyme activity lead to the accumulation of sodium within the cell and water moves in, causing swelling Intracellular Accumulations: Lipids and Carbohydrates ● Metabolic disorders can lead to abnormal intracellular accumulation of carbohydrates and lipids ● Lipids accumulate in diseases like Tay-Sachs, Niemann-Pick, and Gaucher ● Carbohydrates accumulate in mucopolysaccharidoses, leading to progressive organ damage ● Intracellular lipid accumulation commonly occurs in the liver, leading to fatty changes and impaired functioning Causes of lipid accumulation in the liver ● Increased movement of free fatty acids into the liver ● Failure to convert fatty acids to phospholipids, resulting in conversion into triglycerides ● Increased synthesis of triglycerides from fatty acids ● Decreased synthesis of apoproteins (lipid-acceptor proteins) ● Failure of lipids to bind with apoproteins to form lipoproteins ● Failure of mechanisms that transport lipoproteins out of the cell ● Direct damage to the endoplasmic reticulum by free radicals Pathologic states with cholesterol accumulation ● Atherosclerosis characterized by plaques containing lipids, cholesterol, calcium, macrophages, and other substances ● Gallbladder deposits leading to obstruction from cholelithiasis (gallstones) ● Niemann-Pick disease characterized by lipid accumulation in the spleen, liver, lungs, bone marrow, and brain due to a genetic lack of sphingomyelinase Glycogen accumulation ● Glycogen is the storage form of glucose, with 90% found in the liver ● Genetic disorders (glycogen storage diseases) and disorders affecting glucose and glycogen metabolism result in intracellular accumulation of glycogen Excess glycogen accumulation seen in 80% of individuals with diabetes