9.3 2 Osmoregulation in mammals-the kidney Flashcards
(44 cards)
water moves in and out of cells
by osmosis
Osmoregulation definition
the maintenance of a constant osmotic potential in the tissues of living organism by controlling water and salt concentrations
By controlling the water potential of the blood
body can control the water potential of the tissue fluid and protect the cells from osmotic damage
deamination definition
the removal of the amino group from excess amino acids in the ornithine cycle in the liver .
body
cannot store protein or amino acids and without the action of the liver any excess protein you eat would be excreted and wasted
hepatocytes (liver cells)
deaminate excess amino acids
remove amino group (NH2)
convert to ammonia which is very toxic
then very quickly to less toxic urea
ammonia produced in deamination process
converted into urea by a series of enzyme controlled reactions known as ornithine cycle
remainder of amino acid can then be used for celluar respiration or converted into lipid for storage
amino acid +oxygen
keto acid +ammonia (ammonia then goes to ornithine cycle)
Urine produced
is more concentrated (hypertonic to) the body fluids –makes it possible to conserve water
where are kidneys
attached to the back of abdominal cavity
surrounded by a thick layer of fat which helps prevent them from mechanical damage
kidneys purpose
control water potential of the blood removing substances that would affect the water balance as well as getting rid of urea- urea ,excess salts and water is removed
the urine
is stored in the bladder and released from the body in regular intervals
cortex
rich capillary network contains malpighian bodies of all the nephrons
pelvis
central chamber where urine arrives from collecting ducts
two roles of kidney in body
remove urea and osmoregulation
cortical nephrons
found in renal cortex have loop of Henle that only just reaches into medulla (majority)
Juxtamedullary nephrons
have long loops of Henle that penetrate right through the medulla -particularly efficient at producing conctrated urine
Three processes of osmoregulation
ultrafiltration ,selective reabsorption and tubular secretion
why does ultrafiltration occur
high blood pressure in the glomerular capillaries and the structure of Bowmans capsule and glomerulus
Malpighian body
combination of Bowman’s capsule and the glomerulus
how is there a high blood pressure
because diameter of blood vessel coming into glomerulus (afferent arteriole) is greater then blood vessel leaving (efferent arteriole)
the high blood pressure
squeezes blood out through pores in the capillary wall-size of pores mean almost all the contents of the plasma can pass out of the capillary -only blood cells and the largest plasma proteins cannot get through the pores
cells of Bowman’s capsule
act as an additional filter -wall of capsule made up of special cells called podocytes. They have extensions called pedicles that wrap around the capillaries forming slits that ensure any cells platelets or large plasma proteins that have left the capillary do not get into the tubule itself
Filtrate that enters bowmans capsule
contains glucose ,salt ,urea and many other substances in the same concentration as they are in the blood plasma