excretion in humans Flashcards
lungs
- breathing out
- carbon dioxide, water
kidneys
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- urinating
- urea, excess water, excess salts
skin
- sweating
- water, salts, urea
urinary system
bladder stores urine
urethra excretes urine from bladder
ureter transports urine from kidneys to bladder
renal vein flows blood into kidneys
renal arteries flows blood away from kidneys into vena cava
nephron structure
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1- branch from renal artery 2- glomerulus 3- Bowman's capsule 4- proximal convoluted tubule 5- loop of Henle 6- blood capillaries around loop 7- distal convoluted tubule 8- back to renal vein 9- to collecting duct
ultrafiltration in Bowmans capsule
short definition-
filters the big molecules from the blood and lets smaller one into the Bowman’s capsule, high pressure in the glomerulus squeezes small molecules into the nephron
1- blood from renal artery flows through a glomerulus
2- the walls of the capillaries and Bowman’s capsule have small gaps in them
3- the high pressure in the Glomerulus squeezes out small molecules from the blood into the nephron
4- the high pressure that builds up in the Glomerulus squeezes out water, urea, salts, amino acids and glucose into the Bowman’s capsule.
5- this filtered liquid in the Bowman’s capsule is known as the GLOMERULAR FILTRATE
6- big molecules like PROTEINS and BLOOD CELLS are not squeezed out, they stay in the blood.
how water is reabsorbed into blood from collecting duct
reabsorbed from the LOOP OF HENLE and COLLECTING DUCT
- water could move to your capillaries by osmosis
- with lots of salts in the water, the concentration gradient is bigger so can move into LOOP OF HENLE by OSMOSIS easier
selective reabsorption
short definition-
selecting molecules that have been absorbed in the nephron back into the blood because we want them in the body eg glucose (leaving the nephron)
- substances needed by the body have to be reabsorbed from the NEPHRON
- glucose is reabsorbed from the fluid in the PROXIMAL CONVOLUTED TUBULE by ACTIVE TRANSPORT
- it passes into BLOOD CAPILLARIES that surround the proximal convoluted tubule
- any water and salts that the body needs are reabsorbed from the fluid in the LOOP OF HENLE and COLLECTING DUCT
- they pass into the BLOOD CAPILLARIES that surround these parts of the nephron
ADH when you’re overhydrated
1- the gain of water means the concentration of the blood starts to decrease
2- detected by special cells in the HYPOTHALAMUS
3- these cells cause the PITUITARY GLAND to release less ADH
4- ADH travels in the BLOOD to the kidneys
5- at the KIDNEY TUBULES, it causes the COLLECTING DUCTS to become LESS PERMEABLE to water
6- this means LESS WATER IS REABSORBED back into the blood
7- this makes the URINE MORE DILUTE, and the blood becomes more concentrated
formation/ contents of urine
1- substances that remain in the nephron make up the urine
2- urea, excess salts and water stay in the nephron and become the urine
3- urine flows down the collecting ducts in each kidney into the ureters
4- it travels down the 2 ureter tubes into the bladder where its stored
5- urine passes out of the body through the urethra
6- this is controlled by a ring of muscle.
-the concentrations of urea and salts are higher in the urine than in the blood because there is less water in the urine than in the blood.
water
urea
salts
osmoregulation-
keeping a constant amount of water in the body
-important because if there’s too much
(a HYPOTONIC solution)
it will move into the cells by osmosis
which will make them LYSE
(as there is a CONCENTRATION GRADIENT) and eventually pop.
if there’s too little water (HYPERTONIC solution),
water will leave the cells by osmosis
causing them to shrivel and slow down chemical reactions.
(in an ISOTONIC solution the cells have a perfect amount of water)
osmoregulation-
keeping a constant amount of water in the body
-important because if there’s too much
(a HYPOTONIC solution)
it will move into the cells by osmosis
which will make them LYSE
(as there is a CONCENTRATION GRADIENT) and eventually pop.
if there’s too little water (HYPERTONIC solution),
water will leave the cells by osmosis
causing them to shrivel and slow down chemical reactions.
(in an ISOTONIC solution the cells have a perfect amount of water)
body gains water by-
drinking
eating
respiration
body loses water by- sweating urinating breathing out egesting
ADH when youre dehydrated
1- the loss of water means the concentration of the blood starts to increase
2- this is detected by special cells in the HYPOTHALAMUS
3-
ADH when youre dehydrated
1- the loss of water means the concentration of the blood starts to increase
2- this is detected by special cells in the HYPOTHALAMUS
3- these cells cause the PITUITARY GLANDS to release MORE ADH
4- ADH travels in the BLOOD to the kidneys
5- at the kidney tubules, it causes the COLLECTING DUCTS to become MORE PERMEABLE to water
6- this means MORE WATER IS REABSORBED back into the blood
7- this makes the URINE MORE CONCENTRATED, and the blood becomes more DILUTE
