10.11 Environmental and nutritional diseases Flashcards
environmental factors
- clinate
- air
- physical
Climate
- directly by taxing body’s physiological reserves
- indirectly through influence on plants and insects
air pollution, chemicals and radioactive wastes
individual factors
- xenobiotic metabolism: detox or can become more toxic
- dose-response curve: subthreshold, threshold and ceiling effect
- latency period: time between exposure and symptoms
- genetic predisposition
- xeroderma pigmentosa: defective DNA repair >> skin cancer risk from sunlight
- ethnicity, age, gender
cigarette smoking
- particles: polycyclic hydrocarbons and nicotine
- polycyclic hydrocarbons (tar) directly acts as carcinogen on skin, procarcinogens in lung and bladder
- when inhaled, converetd in liver by aryl hydrocarbon hydroxylase >> increased level in smokers with lung cancer
- Nicotine: addictive. can cross brain-blood barrier
cigarette smoking diseases
- chronic bronchitis and emphysema >> COPD
- single largest cause of lung cancer + seven cancers associated.
- increased risk of heart disease, stroke, etc
- increased CO2 level and decreased HDL (which protects from heart dz and arthrosclerosis)
- additive or synergistic effect with other substances
- secondhand smoking also associated with lung cancer and heart dz
blood alcohol concentration (BCA)
type of alcoholic beverage
rate of ingestion, absorption, tissue distribution, metabolism and excretion
alcohol metabolism pathways in liver
excess of NADH over NAD stimulate lipid biosynthesis
oxidation of fatty acids by mito. is decreased.
leads to fatty liver
alcohol and diseases
- liver: fatty change and acute hepatitis
- nerveous, cardio, GI and reproductive dz
- fetal alcohol syndrome: growth and mental retardation and birth defects. Acetaldehyde can pass through placenta
carbon monoxide
- combimes with hemoglobin (carboxyhemoglobin) with 200x more affinity than oxygen >>> hypoxia
- combines with myoglobin (oxygen receptor in muscle) with 60x more affinity than oxygen
- CO binds to the same sites on heme protein as nitric oxide (NO) which is a vasodilator and a signal molecule
- excess NO (or CO) is deleterious to brain cells and other tissues
- headache, nausea, dizziness, other hypoxia symptoms
- cherry-red color of the blood, skin and mucous membranes
Lead poisoning
- from paint dust, battery, automotive exhaust, etc.
- lead deposits in gums,
- disruption of hemoglobin enzyme synthesis,
- contraction of intestinal smooth muscle,
- mental retardaion/encephalopathy in children, nerveous system disorder in adults.
- RBC basophilic stippling: very fine, pinpoint granules dist. evenly in the cytoplasm due to impiared RNA degradation
- treated with dimercaprol
ionizing radiation
- short wavelengths, long frequencies
- directly: hit on vital molecules and alter DNA, RNA and protein synthesis
- indirectly: ionize water to high-energy free radicals
- if systemic: cancer, infertility, nuclear fall out
- localized for therapy: can lead to secondary neoplasms
non-ionizing radiation (UV rays)
- of UVA,B, and C, UVC and most of UVB are absorbed by ozone.
- sunburn and skin cancer (melanoma)
nutritional deficiency
- primary
- secondary
- primary: inadequate food intake
- secondary (conditional): malnutrition in prescence of adequate food consumption
- malabsorption
- increased metabolic demand (folic acid during pregnancy)
- antagonist (folic acid antagonist such as methotrexate used in chemotherapy)
- excess nutrient loss: chronic alcoholism leading to defieincy in vitamins
protein-energy malnutrition (PEM)
energy deficiency
energy deficiency: marasmus and growth retardation
- compensated phase of PEM by catabolism of body’s expandable tissue, adipose and skeletal muscles
- GI digestive enzymes are secreted normally
PEM: protein-deficiency
Kwashiorkor and growth retardation
- decreased serum albumin level result in generalized edema
- decrease in digestive enzyme production in the intestine and atrophy of villi
- hospitalization recommended
nutritional excess - obesity
- diseases
can lead to hypertension, diabetes type II, atherosclerosis, stroke and myocardial infartion
leptin as an anti-obesity factor
obesity and cancer
increased insulin resistance leads to excessive insulin secretion.
hyperinsulinemia
insulin-like growth factor binding protein (IGFBP)-1 and -2 increases cell proliferation and decreases apoptosis
vitamins
- fat soluble
- water soluble
- vitamin B group
- fat soluble: A,D, E, and K
- water soluble: B and C
- B group: B1 (thianim), B2 (riboflavin), B3 (nicotinamide), B6 (pyridoxine), folic acid and B12 (cyanocobalamin)
vitamin A deficiency
- vitamin A
- clinical features
- vit.A: retinol and beta-carotene. can change form to become retinal visual pigment, retinoic acid (affects growth regulation and differentiation)
- clinical features: visual impairment, abnormal maturation of mucus-secreting epithelium
- xerophthalmia (dry eye), keratomalacia
- increased susceptibility to infection due to loss of mucociliary epithelium
- pelvic keratinization and keratin debris >> kidney stones
vitamin D metabolism
- from UV on skin or absorption >> hydroylized in liver into 25-OH-D >> hydroxylized in kidney into 1,24(OH)2-D
- increase Ca and P absorption and promote bone mineralization
- anti-proliferation, pro-differentiation and pro-apoptosis
- by binding with VDR and work as enhancer for transcriptional factor VDRE which codes for many genes including inter-calcium genes for bones and c-myc and c-fos for regulation of cell proliferation and differentiation
vitamin D deficiency
decrease in Ca and P absorption
decrease in Ca and P serum level
mobilization (release) of Ca and P from bones
parathyroid hormone (PTH) increases P release into urine
decrease in Ca and P products and poor bone mineralization
vitamin D deficiency diseases
Rickets: poor bone formation shown as the bowing of legs in young children.
Osteomalacia or osteoporosis: bone pain and muscle weakness in adults
cancer: vit.D increases protection against colorectal and prostate cancer
vitamin K deficiency
- source
- mechanism
- cause
- disease
- source: diets and synthesis from intestinal bacteria
- mechanism: cofactor for synthesis of blood coagulation factors II, VII, IX and X
- cause: poor diet, malabsorption, lack of intestinal bacterial flora (in newborns, GI dz, prolonged anti-biotic therapy), vit.K antagonist
- disease: leads to bleeding disorder
vitamin C deficiency
required for synthesis of collagen and osteroid
result in poor vessel support (bleeding tendency) in gums, joints and skin
impaired wound healing
inadequate synthesis of osteoid (bone marrow tissue before maturation)
vitamin B12 and folic acid deficiency
required for nucleic acid synthesis
leads to megaloblastic anemia (netrophil with hypersegmented nuclei)
iron deficiency
iron-deficient anemia (hypochromic microcytic anemia): smaller RBC
