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Question |
Answer |
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What the effects of varying sodium concentration within the body? |
- Too low
- Water and ECF volumes fall
- Sodium dependant transporters are disturbed
- Too High
- Water and ECF volume increases
- Sodium dependant transporters are disturbed
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Why is sodium not regulated on the basis of plasma concentration? |
- Water follows sodium. Therefore volume notconcentration alter
- The hormonal controllers affect sodium concentration and ECF concentration
- ADH and the thirst response dilute any increase in sodium by increasing ECF volume
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What is "salt hunger"? |
It's where an animal with low body salt concentrations actually craves salt |
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What are the three major sources of potassium? |
- Diffusion from the small intestine
- Active transport from the colon
- Recovered from cellular breakdown
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By which three methods is potassium homeostasis managed? Which of these make up the chronic and which the acute response |
- Cellular translocation - Acute
- Renal excretion - 90% of chronic
- GI excretion - 10% of chronic
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Which two things control the acute response and how do they do it? |
- Insulin
- Activation of beta2 adrenoreceptors
- Work by increasing the activity of Na+ / K+ ATPases causing sodium efflux and potassium influx
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Which hormone is the main regulator of potassium?? |
Aldosterone |
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In which two regions of the nephron is H+ secreted? |
- Proximal tubule
- Collecting duct
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What role do buffers play with regard to excreting hydrogen ions? |
Once all bicarbonate has been reabsorbed they combine with residual excess hydrogen allowing it to be excreted without the loss of bicarbonate and without making the urine very acidic. |
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In ruminants fed low nitrogen diets more urea is reabsorbed. Why? |
It is transported to the rumen and converted to microbial protein |
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