excretion

• define excretion: the process whereby metabolic waste products such as urea, uricic acid, co2 and creatinine are removed from the body of an organism
• importance of excretion: the accumulation of metabolic waste is toxic or poisonous to the body
• label the urinary system: 1) vena cava 2) aorta 3) renal artery 4) renal vein 5) ureter 6) bladder 7) urethra

  
• function of kidney: organ that removes metabolic waste products, toxic materials, excess water and amino acids from the body
• function of ureter: narrow tube connecting the kidney to the bladder where urine passes through
• function of bladder: stores urine
• function of urethra: duct which removes urine from bladder to external environment
• label the nephron: 1) branch of renal artery 2) afferent arteriole 3) glomerulus 4) efferent arteriole 5) Bowman’s capsule 6) distal convoluted tubule 7) collecting duct 8) Loop of henlé 9) proximal convoluted tubule 10) branch of renal vein

  
• what gets removed during ultrafiltration in Bowman’s capsule: water molecules, small molecules (molecules of glucose, amino acids, mineral salts, nitrogenous waste products). what retains: large molecules such as red blood cell, white blood cell, platelets and molecules of fats and proteins
• why is the afferent arteriole wider than the efferent arteriole: to generate higher hydrostatic pressure of blood
• structure function of glomerulus: structure -> partially permeable basement membrane has small pores . function -> to allow small molecules to pass through
• what gets selectively absorbed in PCT: all glucose and amino acids, most ions and water molecules
• what gets selectively reabsorbed in the loop of henlé: some water molecules
• what gets selectively reabsorbed in DCT: some water molecules and mineral salt ions
• S.F of dialysis fluid: structure: no metabolic waste. function: steep concentration gradient which allows excretory waste products to diffuse into dialysis fluid for removal. structure: direction of blood flow is opposite to that of dialysis fluid. function: maintain a concentration gradient of diffusion of substances to remove metabolic waste products
• S.F of dialysis tubing: structure: partially permeable. function: small molecules like urea and metabolic waste can diffuse but large molecules like blood & proteins remain in blood. structure: long, narrow and coiled. function: increases surface area to volume ratio for faster rate of diffusion