Week 20 Pathology - Environmental Flashcards
What are the non-malignant effects of smoking?
COPD
Atherosclerosis
Pre-term labour
Gastric ulcers
What are the malignant effects of smoking?
Lung, oesophagus, pancreas, kidney, bladder, cervix
What is the clinical presentation of lead poisoning in children vs adults
Children = intellectual impairment, behavioural problems subclinically, can result in encephalopathy, abdominal pain, tubulointersitial disease, radio dense deposits in epiphyses
Adults = headache, memory loss, peripheral nerve demyelination, (classic wrist drop) as well as the above with children, including anaemia with basophilic stippling (microcytic, hypo chromic) - differential diagnosis for microcytic anaemia
Describe the different pathways of metabolism of alcohol? What is the main one? Where is each located?
Common pathway (3 different mechanisms) metabolises EtOH to acetaldehyde.
- Alcohol dehydrogenase (Main) - Cytosol
- Microethanol-oxidising system (MEOS) - Microsome
- Catalse - Peroxisome
How does ADH work to metabolise EtOH?
Cytosolic ADH catalyses the reduction of NAD to NADH, with the byproduct of acetaldehyde formation.
Within mitochondria, acetaldehyde is acted on by acetaldehyde dehydrogenase to form acetic acid, which is then used in mitochondrial respiratory chain
What are the biggest life threats associated with thermal burns?
- Fluid shift and shock (movement of fluid into interstitial space both locally and systemically due to SIRS, including APO)
- Airway burns
- Infection/sepsis
What is the body’s most sensitive tissue to ionising radiation?
Lymphoid
What are the neurohormones that signal to hypothalamus satiety?
Leptin, Adiponectin, Pyy = satiety
Ghrelin = hunger hormone
What type of hypersensitivity reaction is urticaria?
Type 1
What causes the characteristic wheals in urticaria?
Mast cell degranulation causing dermal microvascular hyper permeability
What is the pathogenesis of urticaria?
Antigen induced release of vasoactive mediators from mast cell granules, IgE antibodies. Also can have IgE independent urticaria from drugs that act directly on mast cells (opioids, contrast, antibiotics)
What hypersensitivity reaction is involved in psoriasis?
Type IV
What is the pathophysiology of psoriasis?
Hyperproliferative disorder resulting from cascade of inflammatory mediators, with increased mitotic activity of basal cells, and increased migration to status corneum. Strong genetic + environmental factors
What are the different types of psoriasis?
Plaque: commonest, raised, inflamed plaques with scaly eruptions
Inverse: occurs in moist areas (axilla, groin, submammary, still well demarcated but not classic scale)
Guttate: children, widespread, fine and scaly often after URTI
Pustular
Psoriatic
What layer of the skin are dermatophytes confined to?
Stratum corneum
What are the mechanisms of spread of osteomyelitis?
- Haematogenous (most common in children, long bones)
- Extension from contiguous site (adults, open fracture, DM wound)
- Direct implantation
What are the common causative organisms in OM?
Staph. aureus 80-90%
E. coli, klebsiella, pseudomonas (concurrent UTI, IVDU)
What is the sequence of events/progression of OM?
Bacteria seeded, proliferate and induce inflammatory reaction - entrapped bone undergoes necrosis and bacteria spread throughout Haversian system to periosteum –> lifting of periosteum and suppurative ischaemic injury
What is the natural progression of rheumatoid arthritis?
Chronic inflammatory disorder producing non-suppurative and proliferative synovitis.
Progressed to destruction of articular cartilage and ankylosis
What is the pathophysiology of RA?
Antibodies directed against self antigen and cytokine mediated inflammation, primarily by CD4 T cells.
Resident synovial macrophages secrete proteases, as well as sensitised plasma cells, which produced autoantibodies for cartilage/connective tissue antigens
What is the pattern of joint pain in RA?
Symmetrical, polyarticular, often MCP joints classically
What increases susceptibility to septic arthritis?
Immunodeficiency
Joint trauma
IVDU
What are the common causative organisms in septic arthritis?
Children < 2 HiB
Aged > 2 Staph aureus
Teens/young adults = gonococcus
What viruses can lead to a reactive arthritis?
Parvovirus
Rubella
EBV
Hep B, C
What are the two endogenous forms of crystal arthritis?
Gout - monosodium urate
CPPD - calcium phosphate
What is the pathogenesis of gout?
Either increased production or decreased excretion of urate.
(Urate = end product of purine catabolism)
Precipitation of monosodium urate crystals into joints, resulting in cytokine mediated recruitment of leukocytes.
What are risk factors for gout?
Genetic predisposition
EtOH
Obesity
Drugs ( thiazides) that reduce urate excretion
