Clinical Conditions Flashcards
How can a supraepicondylar fracture of the humerus occur?
A supraepicondylar fracture occurs by falling on a flexed elbow.
How can familial male precocious puberty be caused?
Gain-of-function mutation (Receptor active without ligand) to the luteinising hormone (LH) receptor
How can retinitis pigmentosa be caused?
Loss-of-function mutation to Rhodopsin
How do you treat Kwashiorkor?
Make alterations to the diet to ensure correct amount of protein intake. However, be aware of refeeding syndrome!
How does a nitrogen embolism occur?
Nitrogen bubbles formi in the blood with rapid decompression. (The Bends)
How does muscular dystrophy occur?
Genetic faults cause the absence or reduced synthesis of specific proteins which anchor actin filaments to the sarcolemma (cell wall) to such a degree that muscle fibres may tear themselves apart during contraction
How does denervation atrophy occur?
The muscle no longer receives contractile signals that are required to maintain normal size and muscle fibres are replaced with fibrous and fatty tissue
How does the cholera toxin interfere with the G protein cycle?
-Eliminates the GTPase activity of the alpha subunit of Gs -Gsα becomes irreversibly activated
How does the pertussus toxin interfere with the G protein cycle?
-Interferes with the GDP/GTP exchange on the alpha subunit of Gi. -This leads to the alpha subunit of Gi becoming irreversibly inactivated.
How is an anterior dislocation of the shoulder caused?
Trauma to a fully abducted arm, usually from a posterior direction.
How do you treat Marasmus?
Changes to the diet - avoid REFEEDING SYNDROME!
How is I-cell disease caused?
Deficiency of the N-acetylglucosamine phosphotranferase enzyme which results in mannose-6-phosphate not being added to proteins so they can’t be targeted to lysosomes and end up in the blood/urine
How is myasthenia gravis caused?
It is caused by antibodies directed against NAchR’s, on the postsynaptic membrane of skeletal muscle. Endplate potentials are reduced in amplitude, leading to muscle weakness and fatigue.
How is neuromuscular transmission disrupted in organophosphate poisoning? What is the main consequence?
Irreversibly inhibits the actions of acetylcholinesterase meaning the receptors are constantly activated - permanent muscle contraction
How is phenylketonuria treated?
Diet low in phenylalanine.
How is neuromuscular transmission disrupted in Botulism?
Toxins block the release of acetylcholine
How is sickle cell disease caused?
Autosomal recessive condition resulting in a mutation of A which turns to T resulting in a an amino acid change from glutamate to valine. This forms a sticky hydrophobic pocket, classic sickle shape and aggregation of these cells.
How is Volkmann’s ischaemic contracture caused?
Brachial artery damage leads to ischaemia/necrosis of the muscle fibres of the flexor group of muscles of the forearm, which becomes fibrotic and short.
How might the axillary nerve be damaged?
-Damage due to lesions/trauma in the quadrangular space -Anterior dislocation of the humerus at the glenohumeral joint -Surgical neck fracture of the humerus
How might the musculocutaneous nerve be damaged? What will this result in?
Stabbing in the axilla leading to weakened flexion at the shoulder and elbow, aswell as weakened supination.
How do the symptoms of malignant hyperthermia occur?
-Exposure to the volatile anesthetic agents and the neuromuscular blocking agent, succinylcholine -Excessive calcium release -High amounts of ATP needed to put calcium back
How might the radial nerve be damaged?
-Dislocation/fracture of the proximal humerus (damage in the axilla) -Midshaft fracture (damage in the radial grove) -Posterior dislocation of radius at elbow
How would you treat myasthenia gravis?
Acetylcholine esterase inhibitors
If paracetamol overdose is not treated what will occur?
-Hepatocyte necrosis -Liver Failure -Death
If there is a defective CFTR protein what happens to the secretions of epithelial cells?
Becomes more viscous
In children what other condition is homocystinuria often misdiagnosed as?
Marfan’s syndrome
In cystic fibrosis which protein channel is affected? What does it transport?
Cystic fibrosis transmembrane conductance regulator (CFTR) channel transports chloride ions across epithelial membranes
List two problems, for molecules, of too much circulating glucose in persistent hyperglycaemia
-Aldose reductase converts glucose to sorbitol which depletes NADPH -Non-enzymatic glycosylation os plasma protein alters its structure and therefore function.
Name other things that can be causes of hyperthyroidism?
-Ectopic thyroid -Over secretion of TSH and T3/T4 by adenomas -Excessive therapy of hypothyroidism -Excessive treatment of other conditions with drugs - amiodarone
Suggest some of the possible causes of a deep vein thrombosis?
-Immobility/bed rest -Post-operative -Pregnancy and post-partum -Oral contraceptives -Severe burns -Cardiac failure -Disseminated cancer
Suggest some physiological and pathological causes of atrophy?
-Physiological - Ovarian atrophy in post menopausal women -Pathological - Muscle Atrophy (denervation) Cerebral atrophy (Alzheimer’s disease)
Suggest some things that ischaemic heart disease can result in
-Sudden Death -MI -Angina pectoris -Arrhythmias -Cardiac Failure
What are amyloidoses?
Incorrect folding of proteins which results in production of amyloid fibres infiltrating organs
What are the 6 main features of diabetic ketoacidosis?
-Prostration -Nausea -Vomiting -Dehydration -Abdominal pain -Hyperventilation
What are the common signs/symptoms of a major pulmonary embolism?
-Shortness of breath -Cough -Blood stained sputum
What are skin blisters caused by?
-Heat -Sunlight -Chemicals
What are the four main fractures of the humerus?
-Surgical neck fracture -Mid shaft fracture -Supraepicondylar fracture -Medial epicondyle frature
What are the 5 main risk factors for osteoporosis?
-Age -Post-menopausal women (reduced oestrogen) -Smoking -Poor diet (not enough ions) -Exercise
What are the long term complications of bacterial meningitis?
-Brain damage -Hearing loss -Learning disabilities
What are the macrovascular clinical complications of diabetes mellitus?
-Increased risk of MI -Increased risk of stroke -Poor peripheral circulation
What are the main management steps for multiple sclerosis?
-Steroids (treatment for relapses of MS symptoms) -Beta interferons to modify the disease course
What are the main symptoms of achondroplasia?
-Short limbs -Increased spinal curvature
What are the main symptoms of hyperammonaemia?
-Blurred vision -Tremors -Slurred speech -Coma
What are the main symptoms of hypothyroidism?
-Weight gain -Tiredness -Cold intolerance -Alopecia -Decreased BMR
What are the main symptoms of lactose intolerance?
-Flatulence -Diarrhoea -Nausea
What are the main symptoms of malignant hyperthermia?
- Uncontrolled increase in skeletal muscle oxidative metabolism -Sharp CO2 increase, O2 decrease -Circulatory collapse
What are the main symptoms of Marfan syndrome?
-Tall height + long arms and legs -Large elastic arteries (e.g. aorta) rupture high blood pressure due to size of wall -Streched lung tissue - pneumothorax
What are the main symptoms of multiple sclerosis?
-Numbness and tingling -Blurring of vision -Problems with mobility and balance -Muscle weakness and tightness
What are the main symptoms of osteogenesis imperfecta?
-Blue sclera -Fragility of bones (leads to fractures) -Hypermobility of joints -Hearing loss
What are the main symptoms of paracetamol overdose?
-Hepatic damage then necrosis -Liver damage -Kidney failure
What are the main symptoms of scurvy?
-.Periodontal ligament (high collagen turnover) is affected -Loss of teeth and bleeding gums
What are the main symptoms of type 1 diabetes mellitus?
-Polyuria -Polydipsia -Weight loss
What are the main symptoms of type 2 diabetes mellitus?
-Triad of symptoms -Lack of energy -Persistent infection -Visual problems
What are the main treatments for defects in the urea cycle?
Low protein diet and replacing the essential amino acids with keto acids that use up NH4+ when converted to amino acids, therefore lowering NH4+ concentration.
What are the management steps for sickle cell disease?
-Manage underlying symptoms -Prevent sickle cell crisis
What are the microvascular clinical complications of diabetes mellitus?
-Eye (glaucoma due to osmotic effects of glucose and blindness due to damaged blood vessels which is diabetic retinopathy) -Kidney (nephropathy poor blood supply and damaged glomeruli) -Neuropathy (damaged nerves leading to loss of sensation) -Feet (low peripheral blood vessels and nerves - might lose feet)
What are the signs and symptoms of glucose 6-phoshate dehydrogenase deficiency? How are they caused?
-Fatigue (heinz body formation) -Dark urine/Jaundice (bilirubin formation from haemolysis)
What are the symptoms of hypercalcaemia?
Stoans, moans and groans: -Kidney stones (renal calculi) -Depression and tiredness -Constipation and dehydration
What are the symptoms of hypercholesterolaemia (hyperlipoproteinaemias Type IIa)?
-Corneal Arcus -Tendonal Xanthoma (fatty deposits on tendons) -Xanthelasma - fatty deposits under skin (around eyes) -Absence or deficiency of LDL receptors
What are the symptoms of hypocalcaemia? How are they caused?
-Convulsions -Arrythmia -Tetany (involuntary muscle contraction) -Paraesthesia (tingling) Due to low calcium at neuromuscular junctions which leads to easier depolarisation
What are the symptoms of hypocalcaemia? How are they caused?
-Arrythmia -Tetany (involuntary muscle contraction) -Paraesthesia (tingling) Due to low calcium at neuromuscular junctions which leads to easier depolarisation
What are the symptoms of Marasmus?
-Muscle wasting -Loss of body mass -Thin and dry hair -No oedema -Diarrhoea
What are the symptoms of myasthenia gravis?
-Ptosis (drooping eyelid) -Profound weakness (increases with exercise) -
What are the symptoms of Kwashiorkor?
-Abdominal distension due to enlarged liver (hepatomegaly) and odema (ascites) -Anaemia (low serum albumin) -Lethargy/apathy
What are the symptoms of type I hyperlipoproteinaemias?
-Eruptive xanthomata -Abdominal colic
What are the three main causes of atrophy?
-Disuse -Age -Denervation
What are the two main autoimmune causes of Hashimoto’s disease (primary hypothyroidism)?
-Antibody blocks a TSH receptor -Destruction of follicles
What are the two main reasons for the creation of large amounts of ketone bodies in type 1 diabetes mellitus?
-High rate of Beta oxidation of fatty acids in liver -Low amount of insulin
What are the two main treatments for Duchenne’s Muscular Dystrophy (DMD)?
-Ataluren - makes dystrophin -Steroids - prednisolone
What are the two main types of osteoporosis and how are they caused?
Type 1 - Menopause Type 2 - Age
What are the symptoms of Ethlers-Danlos disease?
-Unstable joints -Bruise easily -Flat feet
What are the two most common fractures of the wrist?
-Smith’s -Colles’
What are type I hyperlipoproteinaemias?
A defective lipoprotein lipase enzyme which means core TAGs cannot be removed from the chylomicrons - can’t break down fatty acids
What builds up when phenylalanine hydroxylase isn’t functioning correctly?
Phenylalanine accumulates in tissues and blood and is metabolised by other pathways to produce various products (phenylpyruvate) that are excreted in the urine.
What can be other causes of hypothyroidism?
-Adenoma preventing secretion of TSH -Iodine deficiency
What can cause hypotonia?
-Damage to cerebellum (lesions) -Cerebral/spinal shock -Breakdown of muscle tissue (myopathies) -Lesions of lower motor neurons
What can cause the hypocalcaemia in Osteomalacia?
Lack of Vitamin D as it helps the absorption of calcium in the small intestine
What can recurrent pulmonary embolisms lead to?
Pulmonary hypertension
What are the symptoms of Galactosaemia?
-Cataracts -Glaucoma -Damage to the kidney, liver and brain possible by galactose-1-phosphate
What can reduced liver function can result in?
-Reduced uptake of conjugate bilirubin → Hyperbilirubinaemia → Jaundice - Decreased Urea production → Hyperammonaemia and increased Glutamine -Reduced Protein synthesis → reduced albumin, clotting factors and lipoproteins -Reduced Serum Albumin may produce oedema
What causes Galactosaemia?
The lack of the galactose kinase or galactose 1-phosphate uridyl transferase enzyme causes build up of galactose or galactose 1-phosphate and galactose respectively.
What causes Kwashiorkor?
A complete deficiency of protein, however, a small amount of carbohydrate remains in the diet
What causes Marasmus?
Marasmus is caused by a diet lacking in all types of food, it is not only a protein deficiency
What are the main symptoms of hyperthyroidism disease?
-Exopthalmos -Osteoporosis (due to excessive bone turnover) -Weight Loss -Heat intolerance -Intestinal hypermotility
What causes waiter’s tip?
Damage to the suprascapular and axillary nerves means the lateral rotators of the shoulder are no longer innervated. As the deltoid, infraspinatus and teres minor are no longer functioning there is unopposed medial rotation.
What are the main symptoms of Duchenne’s Muscular Dystrophy (DMD)?
-Gower’s sign (use of hands/knees for strength) -Contractures (shortened muscles, don’t stretch) -Pseudohypertrophy (enlarged calf/deltoid muscles before fat/CT show up) -Difficulty standing/weakness
What clotting factor is deficient in haemophilia type A?
Factor VIII (8)
What are the main presenting symptoms of myasthenia gravis?
-Ptosis (drooping eyelid) -Fatigue and sudden falling -Double vision