Concise Flashcards Sem 2B
Give the names and functions of the fat-soluble vitamins.
Fat-soluble Vitamins = ADEK
Explain the results of deficiency of each of the vitamins.
Vitamin Deficiencies
Describe the pathogenesis of Wernicke-Korsakoff syndrome.
Describe some features of Wernicke-Korsakoff syndrome.
Wernicke’s Encephalopathy
- Occulomotor abnormalities – nystagmus, opthalmoplegia
- Ataxia of gait (cerebellum) – wide-based stance and slow-uncertian, short-stepped gait
- Derangement of mental function – confusion, apathy, disorientation
Korsakoff’s Psychosis
- Retrograde amnesia – inability to recall events that occurred before the onset of amnesia
- Anterograde amnesia – inability to acquire new information or make new memories
- Confabulation – unconscious creation of facts and experiences to fill gaps in memory
- Peripheral neuropathy, postural hypotension, tachycardia
Briefly list the types of long-term memory.
Types of Long Term Memory
Explicit (Declarative) Memory
- Facts (semantic)
- Events (episodic)
Implicit (Non-Declarative) Memory
- Priming - recognition or recall of words, objects or sounds improved by prior exposure to these stimuli
- Procedural – skills and habits
- Associative learning – classical and operant conditioning
- Non-associative learning – habituation and sensitisation
List the four main metabolic effects of alcohol.
List the 4 major causes of death due to alcohol.
Major causes of death due to alcohol
- Alcoholic liver disease
- Motor vehicle crash injury
- Cancer
- Suicide
List 4 criteria for which one or more needs to be met in a 12- month period to constitute alcoholism.
Alcoholism
- Recurrent substance use resulting in failure to fulfil major role obligations at work, school or home
- Recurrent substance use in situations in which it is physically hazardous (eg driving, using machinery)
- Recurrent substance-related legal problems
- Continued substance use despite having persistent or recurrent social or interpersonal problems caused or exacerbated by the effects of the substance
Describe two medications that can be given to treat alcoholism.
Alcoholism - Pharmacological Treatment
Disulfiram: alcohol dehydrogenase inhibitor
- Requires a motivated patient and a dose supervision carer – begin >48 hours after last drink
- Remains inert unless ethanol is taken
- Within minutes of ethanol intake, the patient experiences headaches, dyspnoea, nausea, blurred vision, vomiting, sweating, weakness
- Reaction is short-lived but can be severe/life threatening
Naltextrone: opiod antagonist
- Blocks alcohol ‘high’ by blocking opoid receptors and → ↑ cravings
- Decreases rate of relapse
List some of the features of simple withdrawal, withdrawal complicated by fits and delirium tremens.
Simple Withdrawal
- Tremor
- Sweating
- Nausea
- Vomiting
- Malaise
- Anxiety
- Agitation
- Depressed mood
- Tachycardia
- ↑ Blood pressure
Withdrawal Complicated by Fits → Grand mal tonic – clonal fits (usually only 1 fit during withdrawal)
Delerium Tremens
- Occurs 24h-7d after cessation
- Tremor & agitation
- Clouding of consciousness
- Disorientation
- Hallucinations
- Paranoid delusions
Give some advantages and disadvantages of MRI and CT.
List some contraindications to MRI.
Contraindications to MRI
- Aneurysm clips placed in the last 6 months
- Surgical clips placed in the last 6 weeks
- Neurostimulator devices
- Pacemaker or implantable defibrillator
- Cochlear implant
- Critical illness
- Claustrophobia
- Metallic ocular foreign body (welding history), metallic shrapnel
- Other metallic implanted devices such as insulin pumps
- Obesity (maximum table allowance is ~160kg)
- Pregnancy
List some general causes of anaemia.
Causes of Anaemia
- Blood loss - acute (trauma), chronic (GIT lesions, gynaecologic disturbances
-
Impaired RBC production
- Defective Hb production - iron deficiency, chronic disease
- Defective DNA synthesis – B12/folate deficiency
- Stem cell failure – aplastic anaemia
- Bone marrow replacement – e.g. infiltration by malignant disease
- Inadequate erythropoietin stimulation – chronic renal failure
- Other nutritional/toxic factors: scurvy, protein malnutrition, chronic liver disease, hypothyroidism
-
Increased haemolysis
- Intrinsic RBC abnormalities – haemoglobinopathies (sickle cell/thalassaemia), membrane defects, enzyme deficiency (G-6-Pase), acquired defects
- Extrinsic causes - autoimmune haemolytic anaemia, haemolytic disease of the newborn, blood transfusion reactions, drug-induced immune haemolytic anaemia, infections (malaria, mycoplasma), snake venom, lead poisoning, physical trauma, hypersplenism
Outline the process of iron absorption.
Process of Iron Absorption
- Cytochrome B on the brush border converts Fe3+ to Fe2+ (vitamin-C dependent)
- Fe2+ is transferred over the brush border by DMT-1
- Some Fe2+ is converted back to Fe3+ and stored as ferritin
- The rest of the Fe2+ is transferred into the interstitium by ferroportin (FP)
- Fe2+ is then converted to Fe3+ by hephaestin (HP) or ceruloplasmin (copper-dependant)
List 7 functions of iron.
Functions of Iron
- Oxygen transport (haemoglobin)
- Cellular respiration (TCA cycle, electron transfer chain etc.)
- DNA synthesis
- Neurotransmitter synthesis
- Hormone synthesis
- Embryogenesis (myelin synthesis)
- Host defence (neutrophil killing)
Outline the regulation of iron metabolism.
Regulation of Iron Metabolism
-
Haemochromatosis Protein (HFE) - reduces cellular uptake of transferrin
- Binds transferrin receptor (TfR) and halves its binding capacity for transferrin
- Also regulates release of Hepcidin by the liver
-
Hepcidin - regulates iron absorption
- Released by the liver in response to ↑transferrin:Fe complexes
- Inhibits ferroportin on entrocytes → buildup of iron in enterocytes → ↓absorption
- Also inhibits DMT-1 and Cytochrome B → ↓uptake of iron into enterocytes
List five general causes of iron deficiency.
Causes of Iron Deficiency
- Blood loss (occult GIT bleeding and menstruation)
- Pregnancy (loss of iron to the foetus)
- Rapid growth (especially 0-2 years)
- Malabsorption
- Dietary insufficiency
List 8 symptoms of iron overload.
Iron Overload Symptoms
- Weakness
- Abdominal pain
- Muscle aches
- Finger joint pain
- Dyspnoea on exertion
- Bronze colour
- Hepatomegaly; cirrhosis
- Pancreatic fibrosis, diabetes mellitus
Summarise α and β- Thalassaemia.
Summarise the pathogenesis of β-Thalassaemia.
Summarise the pathogenesis of sickle cell anaemia.
List some clinical features of homozygotic sickle cell anaemia.
Homozygotic Sickle Cell Anaemia - Clinical Features
- Severe haemolytic anaemia
- Patients present between 6 months – 3 years
- 90% survive to 20 years, 50% survive > 50 years
- Splenomegaly
- Continuous fibrosis → autosplenectomy by adulthood
- Defects in complement pathway → septicaemia/meningitis
- Pain crises – episodes of hypoxic injury and infarction
- General hypoxia → impairment of growth & development
List 8 possible causes of an increase in Prostate Specific Antigen (PSA).
Causes of Increased PSA
- Benign prostatic hyperplasia (BPH)
- Prostate cancer – lower % free PSA than BPH
- Ejaculation – increases PSA for 6-48 hours
- Urinary tract infection
- Urinary retention
- Prostatitis
- Prostatic massage (e.g. DRE – take blood first)
- Prostatic needle biopsy
Comment on the accuracy/quality of PSA testing.
PSA Testing
-
Low specificity (91%)– organ-specific, but not cancer-specific
- Significant overlap with PBH and prostate cancer (but BPH is generally lower)
- Many false positives leading to unnecessary prostatic biopsies
-
Low sensitivity - not all men with prostate disease have elevated PSA
- Many false negatives – many cases missed
- For PSA >4.0 ng/mL, sensitivity is ~91%
- For PSA <4.0 ng/mL, sensitivity is ~56%
Summarise the actions of different tumour supressors.
Tumour Suppressors
- p21
- p16
- p53
- pRB
- p14ARF
For each cyclin, state which cyclin- dependent kinase they bind to and what their function in the cell cycle is.
Cyclins DEAB
- Cyclin D → CDK4 or CDK6
- Cyclin E → CDK2
- Cyclin A → CDK2
- Cyclin B → CDK1
List the 5 pathologic zones of the prostate and state where most hyperplasia and carcinoma occurs.
Zones of the Prostate
-
Peripheral zone (PZ)
- Most carcinomas originate here
-
Central zone (CZ)
- Cancers here (2.5%) are more likely to invade seminal vesicles
-
Transitional zone (TZ)
- Most hyperplasias originate here = BPH
- Periurethral zone
- Fibromuscular stroma (non-glandular)
Outline the pathogenesis of BPH (4 steps).
Pathogenesis of BPH
- Stromal cells produce 5α-reductase
- 5α-reductase converts testosterone to dihydroxytestosterone (DHT)
- DHT is ~10x as potent as testosterone
- DHT stimulates transcription of growth factors by stromal cells (autocrine) and epithelial cells (paracrine)
- Oestrogen also binds androgen receptors, enhancing the response
- Hyperplastic stromal and epithelial tissues compress the prostatic urethra, leading to bladder outflow obstruction
List some symptoms of BPH.
Symptoms of BPH
- Urinary frequency, urgency, hesitancy
- Weak flow of urine, small volume voided
- Nocturia
- Interrupted stream
- Incomplete bladder emptying
- Dribbling