Year 4 Excretion in Humans Notes

Excretion: Lesson objectives At the end of the lessons, students should be able to: • Define and explain the importance of excretion. • Identify the component parts of the mammalian urinary system and state the function of each part • Relate the structure of the mammalian kidney to its function • Discuss the role of ADH and collecting duct in osmoregulation • Label the parts of the nephron and relate these structures to the functions of ultra-filtration and selective reabsorption. • Outline the mechanism of dialysis (haemo-dialysis) in the case of kidney failure.

Excretion • is a process by which metabolic waste products and toxic materials are removed from an organism’s body • Urea is a waste product from the deamination of excess amino acids in the liver • Kidney to filter waste products from the blood to prevent the accumulation of the waste products which may be toxic

8.2 Excretion in Humans skin lungs liver kidneys Waste products excreted by: • urea • excess water • excess salts • carbon dioxide • excess water • bile pigments • urea • excess water • excess salts in sweat in expired air in faeces through the intestines in urine

Excretory product Organ Mode of excretion Carbon dioxide Lungs Expired air Urea and excess mineral salts Kidneys Skin Urine Sweat Excess water Kidneys Skin Lungs Urine Sweat Expired air (as water vapour) Bile pigments (from breakdown of haemoglobin) Liver Faeces via the intestines 8.2 Excretion in Humans

Posterior vena cava Renal artery and vein Ureter Aorta Urinary bladder Urethra Structure of the Mammalian Urinary System •Supplied with blood by renal arteries and drained by renal veins •Urine exits each kidney through the ureter •Both ureters drain into a urinary bladder •Urine is expelled through a urethra

Experiment 8A (Pg 89 to 90) Examining the mammalian excretory system Assignment: • Complete drawing of the human urinary system on page 90, Question 2

(b) Kidney structure Section of kidney from a rat 4 mm Renal medulla Renal cortex Renal pelvis Ureter • an outer renal cortex and • an inner renal medulla https://www.youtube.com/watch?v=W0GpIMNTPYg

The Kidney Anatomy (Click link belowfor video) http://www.youtube.com/watch?v=7bpTiqe5R6c&index=2&list=PLzl4lgX_3 RvcgRqo810pAcz9trinh0Irl

blood enters through renal artery blood leaves through renal vein Urine leaves here Hilus CapsuleThe Kidney