Biology- Excretion in humans 0.0 / 5 ? BiologyExcretion in humansIGCSECIE Created by: KitsuneCreated on: 13-02-17 08:30 What is the need for excretion? Waste materials are toxic 1 of 34 Where is carbon dioxide excreted? In the lungs 2 of 34 How is CO2 toxic? It dissolves in plasma and tissue fluid to form carbonic acid which can denature enzymes and other proteins 3 of 34 How is urea toxic? It can denature enzymes 4 of 34 What harm can salts do? They affect water potential of the blood 5 of 34 What are the two roles of kidneys? To carry out excretion and osmoregulation 6 of 34 How are kidneys adapted to their functions? Each kidney: receives blood from the renal artery, has 1000s of nephrons, has a ureter to take away urine and is close to a feedback system 7 of 34 What is the functional unit of a kidney called? A nephron 8 of 34 What is the ball of capillaries in the nephron called? Glomerulus 9 of 34 What holds the glomerulus? Bowman's capsule 10 of 34 What diffuses through the Bowman's capsule? Waste, blood and water 11 of 34 What happens in the first coiled tubule? Water and useful molecules are selectively reabsorbed 12 of 34 What happens in the Loop of Henle? Salt concentrations in the medulla are altered to aid reabsorption of water from the collecting ducts 13 of 34 What happens in the collecting ducts? Kidneys reabsorb water and return it to the blood under the influence of the antidiuretic hormone 14 of 34 What blood flows in the renal vein? Blood with useful molecules and water but no wastes 15 of 34 What parts of the nephron does the medulla contain? Collecting ducts and loop of Henle 16 of 34 What parts of the nephron does the cortex contain? Coiled tubules and Bowman's capsule 17 of 34 What organ carries out deamination? The liver 18 of 34 What is deamination? Removal of the nitrogen containing part of the amino acid to form urea and excreting it into urine 19 of 34 What does the volume of urine depend on? Water intake, temperature, exercise 20 of 34 What happens to the volume of urine if a person sweats a lot? It decreases greatly 21 of 34 What is osmoregulation? The control of the amount of water in blood taken from the kidneys 22 of 34 How can kidney failure lead to death? The body can't control the amount of urine formed so the content of blood and tissue fluid isn't optimum. 23 of 34 From where does blood leave into the kidney dialysis machine? From the artery 24 of 34 What does a pump do in a dialysis machine? It controls the flow and pressure of blood 25 of 34 What aids diffusion of urea out of blood in a dialysis machine? The countercurrent flow of plasma and the dialysis fluid 26 of 34 Why can only urea diffuse out of blood in a dialysis machine? Because there is a partially permeable membrane and the dialysis fluid has a special composition 27 of 34 What does the chamber in the dialysis machine do? It removes blood clots and rewarms blood 28 of 34 Why does blood need to be rewarmed in a dialysis machine? To avoid shocking the body 29 of 34 Where does blood return to from the dialysis machine? Into the vein where the pressure is low 30 of 34 Why do kidney donors have to be carefully selected? To avoid tissue rejection 31 of 34 What is better- a kidney transplant or kidney dialysis? A transplant 32 of 34 What are the advantages of a kidney transplant? It is much cheaper and the person's life isn't disrupted 33 of 34 How long can kidney dialysis take? 6-8 hours 34 of 34
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