Excretion Flashcards
What is excretion?
The removal of metabolic waste from the body
What is metabolic waste?
Consists of waste substances that may be toxic it are produced in excess by reactions inside the cells
What are the main substances that need to be excreted?
Almost any cell product that is formed by chemical processes inside the cell, in particular carbon dioxide from respiration and nitrogen contains compounds such as urea
Where are these substances produced?
Co2 produced by every living cell in respiration
Urea produced in liver from excess amino acids
Where is co2 excreted?
Passes from cells of respiring today’s into bloodstream, transported in blood mostly as HCo3 ions to the lungs. Diffuses into alveoli and excreted as we breathe out
Where is urea excreted?
Made by breaking down excess amino acids in liver, deamination, passes into bloodstream to be transported to kidneys in solution in plasma. In kidneys unread is removed from blood to become part of urine, and excreted
What are the effects of a high level of carbon dioxide?
Carried as hydrogen carbonate, also forms hydrogen ions in red blood cells by carbonic anhydrase. Hydrogen ions combine with haemoglobin and compete with oxygen
Carbon dioxide firms carbaminohaemoglobin Lowe affinity for oxygen
Respiratory acidosis
What is respiratory acidosis?
Co2 dissolves in plasma, combine with water to carbonic acid, dissociates to release hydrogen, lowers pH, more acidic, proteins in blood are buffers resist change, small change detected, increase breathing rate to remove. If drops below 7.35 results in slow or difficult breathing c, headache, can also cause change in blood pressure and heart rotate
What causes trout story acidosis?
Diseases in lungs, blocked airways
Why do nitrogen compounds have to be excreted?
Proteins cannot be stored, but high energy, deaminated in liver, toxic amino group removed. Initially forms ammonia, very toxic, converted to less toxic urea, transported to kidneys for excretion. Keto acid also made used in respiration.
What is formula for deamination?
2NH3 + CO2 > CO(NH2)2 + H2O
