the kidneys and excretion Flashcards
(23 cards)
what is ADH?
ADH stands for anti-diuretic hormone
where is ADH released from?
pituitary glands
what is the role of ADH in the kidneys?
when the bodys water levels drop below usual, ADH is released and directed to the kidneys. this causes the collecting duct to become more permeable to water, allowing more water to be reabsorbed into the body.
what are the excretion products of the lungs?
CO2
what are the excretory products of the kidney?
Urine (urea, salts and water)
what are the excretory products of the skin?
sweat (water, salts and urea)
what is the role of the kidneys?
to regulate the water content of the blood (to maintain blood pressure levels and osmoregulation) and excrete the toxic waste of metabolism and excess substances (urea and salts)
what are waste products that need to be removed from the blood?
urea, creatine, excess water
what is osmoregulation?
the process of maintaining water and salt concentrations across the body
why is osmoregulation important?
to avoid cell lysis or dehydration
how is water lost from the body?
breathing out, sweat and urine. only the water levels of urine can be controlled.
structure of urinary system
vena cava: takes blood to the heart
aorta: takes blood to the body
renal artery: takes blood to the kidneys
renal vein: takes blood from the kidneys back to the heart
ureter: connects kidneys to bladder
bladder: stores urine (shrinks/ dilates with volume)
2 sets sphincter muscles: top set involuntarily open when the bladder is full; second set can be controlled to allow urine out
urethra: carries urine out the body
structure of kidney
renal artery, renal vein. outer layer is cortex; inner layer is medulla, contains nephrons. pelvis in the middle.
how does osmoregulation work?
rise/fall in water levels in blood are detected by osmoreceptors in the hypothalamus, triggering the pituitary gland to stop/start the production of ADH.
increased in ADH in the blood travels to the kidney, causes collecting duct to become less permeable to water, less water absorbed back into blood. (vice versa)
what is a nephron?
a tiny tube that filters the blood (about a million in each kidney)
structure of a nephron
afferent arteriole (a first in alphabet): brings blood into kidney
efferent arteriole: takes blood through this system
glomerulus: network of capillaries, filters the blood
Bowmans capsule: under glomerulus, where ultrafiltration happens
1st coiled tubule: where selective reabsorption happens
loop of Henle
2nd coiled tubule: reabsorption
collecting duct: leads to the ureter
ultrafiltration
happens in Bowmans capsule
small substances forced out of blood under high pressure, forming the glomerular filtrate (water, urea, mineral ions, glucose, salts)
large molecules (RBCs and protein) are left
reabsorption
happens in coiled tubules and collecting duct
useful substances are selectively reabsorbed back into the blood
all sugar is reabsorbed, most minerals are reabsorbed, some salts
anti-diuretic
a substance which reduces urination
diuretic
a substance that increases urination
substances in blood before going through kidneys
proteins, red blood cells, water, glucose, mineral ions, urea, salts
substances in blood in glomerular filtrate
water, urea, mineral ions, urea, sugar, salts
substances in collecting duct
water, (some) mineral ions, urea, salts
