81047
Description
Flashcards by reynoldslaura, updated more than 1 year ago
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Created by reynoldslaura
over 11 years ago
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| Question | Answer |
| Which part of the haemoglobin molecule does CO₂ bind? | The 'globin' part (as opposed to O₂ which binds to the haeme part) |
| Which is more soluble in the blood HCO₃¯or CO₂ ? | HCO₃¯ |
| What is a 'chloride shift'? | The diffusion of Cl¯ ions into the red blood cell to maintain an electrical balance due to loss of HCO₃¯into the plasma |
| What is the Haldane effect? | It is when the removal of O₂ from Hb increases the ability of Hb to pick up CO₂ and CO₂ generated H⁺ . This further enhances O₂ oxygen release from Hb |
| What is the Haldane effect? | It is when the removal of O₂ from Hb increases the ability of Hb to pick up CO₂ and CO₂ generated H⁺ . This further enhances O₂ oxygen release from Hb |
| How is PCO₂ impacted by pulmonary oedema? | In pulmonary oedema the lungs fill with fluid therefore there will be an increase in PCO₂ as CO₂ can diffuse across fluid 20x more efficiently than O₂ |
| Does hypercapnia or hypoxia lead to increased respiratory acidosis? | Hypercapnia- increased PCO₂ levels |
| When can hypocapnia occur? | In hyperventilation, when the rate of ventilation exceeds the bodies metabolic needs for CO₂ removal. This can be due to asthma, anxiety, fever and aspirin poisoning |
| What causes respiratory alkalosis? | Hypocapnia |
| What is our narrow vital range of pH? | 6.8-7.7 |
| What pH is plasma or ECF maintained at? | 7.4 |
| What is the equation for calculating pH? | -log[H⁺] |
| What is a non-volatile acid? | An acid produced from sources other than CO₂ and is not secreted by the lungs. It is a metabolic acid therefore all the acids produced by the body are non volatile EXCEPT FOR CARBONIC ACID |
| Name the sole volatile acid produced by the body. | Carbonic acid |
| Name two sources of hydrogen loss that will affect acid/base balance. | Loss due to vomit and in the urine |
| Give some examples of ways in which we gain H⁺ ions. | Via generation from CO₂, metabolism that leads to production of phosphoric acid, lactic acid, ketoacids and fatty acids etc and loss of bicarbonate ions via diarrhoea or in the urine |
| What is the ideal composition of acidic and alkaline foods in the diet? | 40% acidic e.g. carbohydrates and protein and 60%alkaline e.g. fruit and veg |
| What are the symptoms of alkalosis? | increased CNS activity presenting as 'pins and needles and dizziness' |
| What are the symptoms of acidosis? | Decreased CNS activity, presenting as lethargy, coma and death |
| What is the difference between respiratory and metabolic acidosis/alkalosis? | Respiratory affects PCO₂ levels whereas metabolic affects HCO₃¯ levels |
| What can cause metabolic acidosis? | Diarrhea, diabetes, alcohol etc |
| What can causes metabolic alkalosis? | Vomiting, excess of anti-acids (e.g. gaviscon) etc |
| How is blood pH kept closely regulated at 7.35-7.45? | By 3 lines of defence. Via buffering (takes seconds), respiratory compensation -for metabolic disorder (takes minutes) and renal excretion- for respiratory disorder (takes hours/days) |
| Define buffer. | A buffer is a mixture of substances in solution that can resist changes in hydrogen ion concentration when strong acids or bases are added |
| Do the three lines of defence act to correct the initial change in pH? | NO but they act to MINIMISE the changes in pH |
| Name an example of a naturally occuring buffer. | HCO₃¯ (transported out from cells in exchange for chloride therefore it results in an increase in H⁺) or plasma proteins (buffering occurs at specific amino acids) or phosphate (especially imp. in the kidney) |
| will doubling the partial pressure of oxygen double the % haemoglobin saturation? | NO because the relationship between the two is not linear! |
| How will a rise in PO₂ from 20-60 mmHg impact Hb saturation? | Although a small change as it is at the bottom of the oxygen dissociation curve it will result in a large increase in Hb saturation |
| What is the main factor that affects % haemoglobin saturation? | PO₂ |
| What are the other factors that affect affinity of O₂ for Hb (therefore haemogolobin % saturation)? | CO₂, acidity, temperature and 2,3-bisphosphoglycerate |
| What effect does CO₂ have on %Hb saturation? | It decreases the affinity of O₂ for Hb by binding to haemoglobin and changing its shape. More O₂ is released from Hb at any specific point as there is a decrease in % Hb saturation therefore more O₂ is released to tissues |
| What affect does acidity have on the haemoglobin dissociation curve? | It shifts it to the right as acid/ H⁺ binds to Hb and reduces the infinity of O₂ for haemoglobin therefore more O₂ is delivered to the tissues |
| What is normal oxygen consumption in ml at rest? | 250ml/min |
| What is the normal amount of CO₂ produced under resting conditions per min? | 200ml/min |
| Explain Fick's law of diffusion. | Diffusion rate of a gas through a sheet of tissue depends on the concentration gradient, the surface area and thickness of the membrane through which it is diffusing |
| What is the Bohr effect? | The influence of CO₂ and acid on the release of O₂ from haemoglobin |
| What effect does an increase in temperature have on % Hb saturation? | It reduces %Hb saturation, again to enhance O₂ release from Hb for use by more active tissues (Heat is often produced in response to exercising muscle or other actively metabolising cells) |
| Where is 2,3- BPG produced from? | Inside red blood cells during active metabolism |
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