Data

Copy and paste the text below. It is read-only. Select All

11.3.1 - Define excretion excretion is the removal from the body of the waste products of metabolic pathways 11.3.2 - Draw and label a diagram of the kidney include the cortex (ultrafiltration and selective reabsorption of blood contents), medulla (reabsorption of water), pelvis (collecting ducts deliver urine to the pelvis to be passed to the ureter) ureter (carries urine to the bladder) and renal blood vessels (renal vein = balanced blood, renal artery = unbalanced blood) 11.2.3 - Annotate a diagram of a glomerulus and associated nephron to show the function of each part glumerulus - delivers blood renal capsule - ultrafiltration proximal convoluted tubule - selective reabsorption distal convoluted tubule - secretion of toxins into urine collection duct - delivers urine to pelvis loop of henle - osmoregulation 11.3.4 - explain the process of ultrafiltration, including blood pressure, fenestrated blood capillaries and basement membrane *occurs in the renal capsule in the cortex of the kidney *blood enters the afferent arteriole and leaves the efferent arteriole *the afferent arteriole is larger than the efferent arteriole causing high pressure in the renal capsule *Water, glucose, amino acids and solutes are forced out of blood (including metabolic wastes) through fenestrated capillaries and basement membrane *podocyte cells act as a filter, plasma proteins, platelets and cells are large so they remain in the blood *glomerular filtrate is carried through the nephron where selective reabsorption takes place in the proximal convoluted tubule. 11.3.5 - define osmoregulation the control of the water balance of the blood, tissue or cytoplasm of a living organism 11.3.6 - Explain the reabsorption of glucose, water and salts in the proximal convoluted tubule, including the roles of microvilli, osmosis and active transport *occurs in the proximal convoluted tubule *water salts amino acids and glucose in glomerular filtrate need to be reabsorbed *selective reabsorption occurs in proximal convoluted tubule of nephron *convolutions and microvilli increase surface area for reabsorption *large numbers of mitochondria present in PTC cells generate ATP *Active transport pumps Na+ ions from PTC cells into capillaries generating concentration gradient between PTC cells by facilitated diffusion *Glucose and amino acids follow by cotransport *solute concentration increases in PTC cells leading to osmosis of water from lumen into PTC cells *facilitated diffusion carries glucose and amino acids into blood, flow of blood maintains concentration gradient * 65-80% of water is recovered, 100% glucose and amino acids recovered *some urea also diffuses back into the blood. 11.3.7 - Explain the roles of the loop of Henle, medulla, collecting duct and ADH (vasopressin) in maintaining the water balance of the blood *The loop of henle generates a high concentration of solutes in the cells and fluid of the medulla, output of urine in more dilute than input, removes a large amount of salts *Na+ is pumped into the medulla by active transport, solute concentration in filtrate decreases as loop ascends *The collecting duct balances the water concentration of the blood, through hormonal control *If a person is dehydrated ADH (a hormone) acts on the walls of the collecting duct, producing aquaporins (channels) making it more permeable to water 11.3.8 - explain the differences in the concentration of proteins, glucose and urea between blood plasma, glomerular filtrate and urea *Glucose, is in blood *proteins are in blood *urea are in blood (small), glomerular filtrate and urea *only glucose and amino acids are 100% reabsorbed *happens in selective reabsorption in the PCT 11.3.9 - explain the presence of glucose in the urine of untreated diabetic patients *presence of glucose in the urine can be generally indicative of diabetes *characterized by lack of or diminished production of insulin by the pancreas *when blood glucose levels are abnormally high, the filtrate still forms a balanced concentration gradient with the blood and ends up having too much glucose present for it to be comprehensively removed during selective reabsorption *when this occurs it is said that the glucose levels have passed the renal threshold *result is glucose in the filtrate that eventually becomes urine, which in healthy people, does not occur because of the near 100% absorption rate of glucose during selective reabsorption