Excretion is one of the characteristics of all

Excretion is one of the characteristics of all living things www. juniorscience. ie

Excretion is the removal of toxic chemical substances Toxic substances are poisonous and can harm the cells of the body if not removed www. juniorscience. ie

Excretory Organs • We have 3 excretory organs • Kidneys • Lungs and Skin www. juniorscience. ie

Kidneys • The kidneys remove urea and salts they clean our blood • If your kidneys are damaged you may need to go on a dialysis machine www. juniorscience. ie

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Kidneys renal artery renal vein y e n kid ureter bladder urethra www. juniorscience. ie

renal artery carries blood to kidney renal vein carries blood from kidney filters blood to remove urea ureter transports urine to bladder urethra www. juniorscience. ie bladder stores urine urethra releases urine

• urea, which is toxic, is produced in the liver from excess protein Toxic urea is removed by and carried by blood to the kidney excess protein from our food is carried from the gut by blood www. juniorscience. ie

water salt urea 1 blood containing water, salts and urea enters the kidney 2 urea, some salts and water are removed from bloodstream by kidney and form urine 3 the urine leaves the kidney in the ureter www. juniorscience. ie

urine is stored in the bladder before being released from the body urethra www. juniorscience. ie

Lets dissect our own kidneys in the lab! www. juniorscience. ie

• carbon dioxide and water are waste products of the process of respiration in all the cells of the body www. juniorscience. ie

• the carbon dioxide and some of the water is carried to the lungs by the blood to be excreted H o H www. juniorscience. ie oc H o o oc H o

Can you remember how we can prove there is water and Carbon dioxide in our breath? ? • Test for Carbon dioxide = Limewater • Test for water = Cobalt Chloride paper www. juniorscience. ie

• Human skin has sweat glands which lead to pores at the surface – water, salt and a tiny amount of urea is excreted as sweat through these pores section of skin pore sweat gland blood capillaries www. juniorscience. ie

In Summary • We have 3 excretory organs Organ Lungs Skin www. juniorscience. ie Kidneys Product excreted Carbon dioxide + water Sweat which is water and salt Urea and

Questions www. juniorscience. ie

One or Two? How many of each of the following are in the human urinary system? • Kidney • Bladder • Renal artery • Renal vein • Ureter • Urethra blad der urethr www. juniorscience. ie HINT

Bladder structure and function Why is the bladder shaped like a plastic bag? Why is the bladder situated below the kidneys? There is a small circular muscle at the exit to the bladder. Why? www. juniorscience. ie blad der urethr

Kidney location Which answer places the kidney in the correct area of the body? A B C D www. juniorscience. ie A C BC B D D

Kidney The kidney is usually covered in a layer of hard fat. Can you suggest a reason for this? www. juniorscience. ie

Kidney All the blood in the body is filtered by the kidney, but when it is cut open there is almost no blood visible. Can you think of a reason for this? www. juniorscience. ie

Water - where and when? Water is released from the body by the lungs, the skin and the kidney at different rates under different conditions. How do you think each of the three excretory organs would react on a very hot day? ? www. juniorscience. ie

Excretion OB 2 -OB 23 OB 20 understand the structure and function of the urinary system: bladder, renal artery, renal vein, ureter, urethra and kidney OB 21 name the products of excretion: CO 2, water and urea OB 22 understand the function of the skin in the excretion of waste products made in the body OB 23 recall that waste products are removed from the bloodstream by filtration in the kidneys in the form of urine, which contains urea, water and salts, and that urine is stored in the bladder before being released from the body www. juniorscience. ie