kidney Flashcards
what is excretion
the removal of toxic materials and waste products of metabolism
what are the organs of excretion?
- skin
- lungs
- kidney
what does skin excrete?
sweat
what does the water in sweat do?
helps keep the body cool in hot conditions, and it contains salts and urea
what do lungs excrete?
excess carbon dioxide and some water vapour
what do the kidneys excrete?
excess water, salt and urea
why is homeostasis essential?
it keeps the conditions in our body constant
what bodily conditions need to be kept constant?
- water
- salts
- glucose
- CO2 levels in blood
- pH of blood
- body temp
what % of the body does water make up?
60-70%
what is nitrogenous waste?
waste that contains nitrogen
why is glucose reabsorbed?
used in respiration to release ATP
why is water reabsorbed?
maintain concentration in blood
what is osmoregulation?
control of water levels in the body
what is the role of the aorta in the urinary system?
blood supply to the kidneys
straight from the aorta - high pressure
what is the role of the kidneys in the urinary system?
homeostatic organ - controls water and salt concentration
excretory organ - concentrates nitrogenous waste to be removed
what is the role of the ureter in the urinary system?
tube in which urine passes out of the kidneys
what is the role of the vena cava in the urinary system?
removes the blood once filtered by the kidney
what is the role of the bladder in the urinary system?
stores urine before release
what is the role of the urethra in the urinary system?
tube to the outside
the wall contains two ring like muscles - sphincters
what is the role of the nephron?
ultrafiltration/selective reabsorption
what is the role of the renal artery?
brings blood to the kidney
what is the role of the renal vein?
takes blood away from the kidney
what is the role of the ureter?
takes urine from the kidney to the bladder
what is the role of the renal pelvis?
when urine empties into from the tips of the pyramids
connects to the ureter which connects to the bladder
what is the role of the renal pyramid?
parts that make up the medulla
what is the role of the cortex?
contains tiny blood vessels
microscopic tubes -> start of nephrons. filters large molecules from the blood
what is the role of the medulla?
where tubules run into. tubules eventually meet up at the tip of the pyramid. contains loop of Henle
what is filtered in the Bowmans capsule?
blood
what process occurs in the Bowmans capsule?
ultrafiltration
Ultrafiltration:
- blood enters the glomerulus from a high pressure
- the blood vessel which removes blood from the glomerulus has a smaller diameter so the pressure is maintained
- the pressure forces fluid into the Bowman’s capsule - glomerular filtrate
- the blood in the glomerulus and Bowman’s capsule are separated by 2 layers of cells (with spaces between them to make them more permeable) and the basement membrane
- these act as a filter, allowing water, ions and small molecules (glucose) through but not large molecules (proteins) and blood cells
what gets selectively reabsorbed in the kidney?
- glucose
- amino acids
- urea
- sodium ions
- chlorine ions
- water
why does glucose get selectively reabsorbed?
want all glucose back for respiration which releases energy
why do amino acids get selectively reabsorbed?
want all amino acids back to make proteins via protein synthesis
what is the loop of Henle used for
used to concentrate the urine
reabsorption in the loop of Henle:
- water is reabsorbed by osmosis in the descending limb
- sodium and chloride ions are actively transported out of the ascending limb to create a lower water potential in the tissue fluid so water moves out by osmosis in the descending limb
- ascending limb is impermeable to water
why do animals that live in the desert have extremely long loop of Henle’s?
to concentrate their urine and lose as little water as possible
what is the distal convoluted tube used for?
to mop up any remaining reabsorption
what is absorbed in the distal convoluted tube?
- more sodium and chloride ions reabsorbed
- more water reabsorbed
- ammonium ions secreted into the filtrate
what happens in the proximal convoluted tube
reabsorption of glucose, amino acids, sodium and chloride ions, urea
what happens in the collecting duct
selective reabsorption of water happens before the urine is collected in the pelvis and sent to the ureter
what is the amount of water reabsorbed in the collecting duct dependant on?
ADH (anti-diuretic hormone) which controls the water level of the blood
what happens if ADH is not present?
channels not open -> water not reabsorbed -> urine concentration decreases -> volume urine increases
what happens if ADH is present?
open channels in collecting duct -> allows more water to be reabsorbed
-> urine concentration increases -> volume urine decreases
is there more or less ADH if more water is drank?
the more water drank, the less ADH
how does the body know to produce more ADH?
water potential in the blood plasma is detected by hypothalamus, which sends a message to the pituitary gland to produce more or less ADH
what does kidney failure mean?
the water and ion balance cannot be regulated, and the levels of toxic urea build up in the body
what is one method of treatment of kidney failure?
kidney dialysis
what does urine contain
urea, water and ions
