Page 227 - Concise Pathology for Exam Preparation ( PDFDrive )

212 SECTION I General Pathology

2. Chronic effects: Chronic alcohol intake has deleterious effects on specific organs as
described:
(a) Liver: Fatty change, hepatitis, cirrhosis, portal hypertension or hepatocellular car-
cinoma are possible effects (alcohol oxidation by ADH causes reduction in nicotin-
amide adenine dinucleotide or NAD levels as ADH reduces NAD to NADH. NAD
is required for fatty acid oxidation in liver and conversion of lactate into pyruvate.
Its deficiency, therefore, causes accumulation of fat in the liver of alcoholics).
(b) Nervous system: Thiamine deficiency is common in alcoholics and is known to
induce degeneration of nerve cells, reactive gliosis and atrophy of cerebellum
and peripheral nerves. Two syndromes are closely associated with chronic alcohol
intake, namely, Wernicke syndrome, which presents with ataxia, disturbed
cognition, ophthalmoplegia, nystagmus and Korsakoff syndrome, which is
believed to result from a combination of alcohol toxicity, poor nutrition and
thiamine deficiency, and manifests with severe memory loss.
(c) CVS: Chronic alcohol intake causes injury to myocardium leading to dilated conges-
tive cardiomyopathy, which is thought to be due to direct toxicity rather than thia-
mine deficiency. High blood alcohol levels have a vasopressor effect due to release
of catecholamines, which may induce hypertension. Heavy consumption of alcohol
also leads to decreased levels of high-density lipoproteins (HDL) and contributes
to coronary artery disease.
(d) GIT: Alcohol can cause massive bleeding from gastritis/gastric ulcer or oesophageal
varices and acute or chronic pancreatitis. It is also associated with increased risk of
cancer of the oral cavity, and oesophagus. Ethanol is not a direct-acting carcinogen;
but one of its metabolites, acetaldehyde, may act as a tumour promoter. Ethanol
inhibits detoxification of chemical carcinogens such as nitrosamines, which have
been associated with tumours of the upper gastrointestinal tract.
(e) Reproductive system: Heavy long-term consumption of alcohol is known to cause
testicular atrophy in men and reduced fertility and spontaneous abortions in
women.
(f) Skeletal muscle: Alcohol causes rhabdomyolysis, which, in turn, leads to muscle
weakness and pain.
(g) Ethanol is a substantial source of energy; therefore, chronic alcoholism commonly
leads to malnutrition and deficiencies.
(h) Alcohol intake during pregnancy can induce fetal alcohol syndrome, which
manifests in infants as microcephaly, growth retardation and facial abnormalities;
older children may show a reduction in mental functions.

Smoking
Tobacco is the most frequent exogenous cause of human cancer. Main contributor is ciga-
rette smoking, but pipes, snuff and tobacco chewing are also harmful. Smoking associated
cancers include cancer of the larynx, lung, oesophagus, pancreas, urinary bladder and oral
cavity. The important toxic chemicals present in tobacco smoke are enlisted in Table 9.1.

TABLE 9.1. Toxic chemicals in tobacco smoke
Chemicals Effects
• Tar
• Polycyclic aromatic Carcinogenesis
hydrocarbons
• Nitrosamines
• Nicotine Ganglionic stimulation and depression and tumour promotion
• Phenol Tumour promotion
• Formaldehyde Irritation and toxicity to respiratory mucosa
• Nitrogen oxide
• Carbon monoxide Reduced oxygen transport

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