Revision Flashcards
What are the two main stores of glycogen?
Muscle
Liver
Give an example of a cell type that can only use glucose as an energy source
RBCs
Which glucose transporter is found in the BBB?
GLUT3
The GLUT3 transporter is ________ dependent
concentration
What is the potential risk associated with using protein as an energy source?
How does the body deal with this?
Production of ammonia
Urea cycle- excretes as urea
Where does the bulk of ATP production occur?
The electron transport chain
How does the electron transport chain work to produce ATP?
Using the proton gradient to drive ATP synthase
Glycolysis can be split into which two phases?
Investment (uses glucose)
Payback (2ATP per glucose)
In which situations would we use glycolysis as an energy source?
As a quick energy source (e.g. sprinting)
Anaerobic conditions
Which is the regulator enzyme of glycolysis?
What does it do?
Phosphofructokinase
Catalyses the reaction of fructose-6-phosphate to fructose 1,6 bisphosphate
How does PFK regulate glycolysis at the muscles and in the liver?
Muscles- allosteric (ATP,AMP)
Liver- hormonal (Insulin, glucagon)
The main function of the citric acid cycle is the production of what?
NADH
What drives the electron transport down the ETC?
Reduction of NADH and FADH2
How would a protonophore act on the ETC?
Give an example of such.
Proton gradient dissipated through the protonophore
Energy is released as heat
Dinitrophenoyl
What is the function of the brown adipose tissue in new born babies?
How does it achieve this?
Heat production:
Thermogenin
Uncoupling protein- harnesses the energy in the proton gradient
What is the important enzyme used in fatty acid activation?
Fatty acyl CoA synthase
How are fatty acids tansported into mitochondria?
Carnitine shuttle
How can the transport of FA into mitochondria be inhibited?
What is the function of this inhibition?
Malonyl CoA
Prevents newly synthesised FA from being immediately transported into mitochondira and oxidised
What are the useful products produced by FA oxidation?
NADH and FADH2 (for ETC)
Acetyl CoA (for citric acid cyle)
High levels of ketones in the blood can cause what condition?
Ketoacidosis
What are the two main upstream effects of alcohol oxidation seen in chronic alcohol consumption?
Decrease in NAD+/NADH ratio
Increased Acetyl-CoA
What cellular defences are present to protect against ROS?
Superoxide Dismutase (SOD)
Catalase
Glutathione
In RBCs the only source of NADPH is what?
Pentose phosphate pathway
Ferrous iron is Fe___
Ferric iron is Fe___
Ferrous Fe2+
Ferric Fe3+
Where does iron absorption occur?
Duodenum
Upper jejunum
Which form of iron can we absorb?
Via which transporter?
Fe2+ (ferrous)
DMT1
Conversion of Fe3+ to Fe2+ is aided by what?
Vitamin C
How is iron stored in the body once it has been absorbed?
Ferritin (Fe3+)
How do we transport iron out of the enterocyte?
What protein inhbits this?
Ferroportin
Hepcidin
Via what mechanism relating to iron transport can chronic inflammarion cause anaemia?
Production of Hepcidin which inhibits ferroportin and prevents iron from being released from enterocytes
A 60 year old presents with gradual onset lethargy. His GP arranges for some blood tests.
Hb 83, wcc 3.5, plt 156, MCV 112, retics 10
Signs and symptoms?
Possible causes?
Lethargy, SOB, headache
Palor, tachycardia, tachypnoea, hypotension
B12 deficiency, folate deficiency
Give some specific signs of anaemia
Koilonychia
Glossitis (B12 def.)
Angular stomatitis
What are the three locations of RBCs in which a problem ight occur that may cause anaemia?
Bone marrow
Peripheral RBCs
Removal
In which cases of anaemia are reticulocyte levels more likely to be high?
Problems with: Peripheral RBCs and removal of RBCs
In what conditions might a patient have anaemia with a LOW reticulocyte count?
Macrocytic anaemia (high MCV)
Normocytic anaemia (normal MCV)
Secondary bone marrow failure
In what conditions might a patient have anaemia with a HIGH reticulocyte count?
Microcytic anaemia (Low MCV)
List some causes of microcytic anaemia
Thalassaemia trait
Anaemia of chronic
disease (may be
normocytic)
Iron deficiency
Lead poisoning
Sideroblastic anaemia
“TAILS”
A 40 year old woman presents to A+E with a one week history of shortness of breath and yellow sclera.
She has a FBC taken: Hb 59, wcc 4.1, plt 378, retics 215
What are the possible causes of this presentation?
Bleeding
Increased destruction of RBCs
A 40 year old woman presents to A+E with a one week history of shortness of breath and yellow sclera.
She has a FBC taken: Hb 59, wcc 4.1, plt 378, retics 215
What would you want to ask in the history?
History of trauma
Post-partum haemorrhage
Bleeding history/Past medical history/Family history/Drug history
What is Disseminated Intravascular Coagulation?
Abnormal activation nof coagulation
Small clots form in the small blood vessels and deposit fibrin leading to damage of the RBCs as they pass through = microangiopathies
What is autoimmune haemolytic anaemia?
Autoantibodies bind to RBC membrane proteins
RES cells recognise part of the Ab, attach to it and remove it from the RBC circulation
How can autoimmune haemolytic anaemia be broadly classified?
What differentiates them?
Warm autoimmune haemolytic anaemia (IgG, maximally active at 37◦ C)
Cold autoimmune haemolytic anaemia (IgM, maximally active at 4◦ C)
A 40 year old woman presents to A+E with a one week history of shortness of breath and yellow sclera.
She has a FBC taken: Hb 59, wcc 4.1, plt 378, retics 215
How would you further investigate this patient?
Examination inc palpating for splenomegaly
Check ferritin/look for bleeding (OGD/colonoscopy etc..)
Haemolysis screen – check LDH, bilirubin, blood film, also direct antiglobulin test (you will learn more about this later)
A 65 year old man has a routine FBC as part of a well man check. His past medical history includes COPD.
Hb 194, wcc 6.7, plt 228, haematocrit 0.597
He asks you to explain his blood results…
Haematocrit/Packed cell volume(PCV) = Proportion of blood that is made up of RBC
Haemoglobin = concentration in the blood i.e. amount of Hb mass/plasma volume
Red cell count = Number of RBC in given volume of blood
What is mean cell volume (MCV)?
Mean size of RBC, measured using the amount of light scattered as they pass in a single file past a laser
What is red cell distribution width (RDW)?
Variation in the size of the RBC
What is mean cell haemoglobin (MCH)?
Average measure of the amount of Hb in each RBC (e.g. Hb/RCC)
What is the reticulocyte count?
What units is it measured in?
Measurement of the number of young erythrocytes
Identified using size and RNA content.
x10^9/L
How is vitamin B12 acquired?
What is required in order to absorb B12?
Diet
Intrinsic factor (IF)
Which cells are responsible for the production of intrinsic factor?
Where are they found?
Parietal cells
Stomach
Where in the GI tract is B12 absorbed?
Terminal ileum
List some causes of low vitamin B12
Dietary deficiency
Lack of IF= pericious anaemia
Disease of the ileum (Crohn’s, ileal resection)
Lack of transcobalamin
How might folate deficiency occur?
Dietary deficiency
Increased use (pregnancy, heamolytic anaemia)
Disease of duodenum & jejunum
Lack of methylTHF
Where is folate absorbed?
Duodenum & jejunum
Why do we try and avoid blood transfusion in patients with B12 deficiency?
Can cause fluid overload leading to cardiac failure
Which precursor moleculre is used to synthesise the hormones aldosterone, testosterone and progesterone?
Cholesterol
What effect does insulin have on hormone sensitive lipase?
Decrease in activity
Define the term anaemia?
A Hb concentration below the normal range for that patient dependent on age, sex and ethinicity
How does 2,3 Bisphosphate production aid with anaemia?
Shifts the oxygen dissociation curve to the right so that oxygen is more readily given up at tissues
Under normal conditions, what is the approximate lofiespan of RBCs in the circulatory system?
120 days
What is a sign of intravascular haemolysis?
Haemoglobinaemia (excess Hb in the blood)
Raised MCV (reticulocytes larger than RBCs)
Briefly describe the pathophysiology of heriditary spherocytosis?
Increased RBC rigidity resulting in loss of function
In a pyruvate kinase deficiency what is the net gain of ATP from glycolysis?
0 ATPs
What is measured by a direct Coombs test?
Antibodies bound directly to RBC membrane
Which cellular process is most affected by folic acid deficiency?
DNA synthesis
What are megakaryocytes?
Precursors of platelets
Which neurotransmitter is relased from the primary neurones in the arcuate nucleus of the hypothalamus to stimulate appetite?
Neuropeptide Y
Agouti-related peptide (AgRP)
Which cell plays an imporant fole in recycling iron from old RBCs?
Macrophages
Which biochemical finding would you expect in a patient with acromegaly?
Raised IGF-1 production
Does parathyroid hormone has direct actions on the GI tract to increase the rate of calcium and phosphate absorption from food?
No, acts via the active form of vitamin D (calcitrol)
(outdated- there is some evidence that it does act directly)
What effect would glucagon have on the enzyme glycogen synthase in the liver?
Decrease in activity- don’t want to replenish glycogen stores as we need glucose
What happens to the serum TSH level in hyperthyroidism?
TSH decreases below the normal range
(loss of negative feedback)
At approx. what age does the switch of fetal to adult haemoglobin occur ?
3-6 months
Where is the hormone oxytocin synthesised?
Where is this stored and released from?
Hypothalamus
Posterior pituitary
What term describes abnormally shaped RBCs?
Poikilocytosis
What is the normal range for fasting blood glucose?
3.3-6.0mmol/L
TSH is released from where?
Anterior pituitary
What is the approximate net weight gain in pregnancy?
8kg
The units of MCV are usually stated in femtolitres (fL), how many femtolitres in a litre?
10^15
What is the half life of T4?
What is the half life of T3?
About 5-7 days
About 1 day
Which glucose transporter is the primary of glucose in pancreatic beta cells?
GLUT2
