excretion (week 15) Flashcards
(30 cards)
what is excretion?
removal of metabolic waste from the body
which organs are involved in excretion?
lungs, skin, liver, kidneys
what do the lungs excrete?
carbon dioxide and water vapour
what do sweat glands excrete?
water, salts, urea, uric acid
what does the liver excrete?
urea and bile pigments
what is the most toxic nitrogenous waste?
ammonia
how is ammonia detoxified in the body?
converted into urea by the liver
why is urea less toxic than ammonia?
it is water soluble and much less toxic
what are the three nitrogenous wastes?
ammonia, urea, uric acid
what does uric acid result from?
breakdown of nucleic acids
what are the functions of the kidneys?
excrete urea, regulate water, ions, pH, and blood pressure
what is the functional unit of kidney?
the nephron
what are the three main parts of a nephron?
bowman’s capsule, glomerulus, tubule
what occurs during filtration?
what and solutes are pushed from blood into bowman’s capsule
what substances remain in the blood after filtration?
proteins and red blood cells
where does reabsorption occur?
in the tubules (proximal, loop of henle, distal)
what substances are reabsorbed?
water, glucose, amino acids, some salts
what is secretion in the nephron?
adding substances (e.g., H+, NH4+) into the tubule for excretion
what hormone increases water reabsorption?
antidiuretic hormone (ADH)
where is ADH produced?
in the hypothalamus, stored in the pituitary gland
what does ADH target?
the collecting ducts of the kidney
what does aldosterone do?
increases sodium reabsorption and water retention
where is aldosterone produced?
adrenal cortex
what causes urine to be more concentrated?
increased ADH and water reabsorption
