maintaining water & nitrogen Flashcards
how does water leave the body?
via exhalation and sweat
how are ions, water and urea lost?
in sweat
what is there no control of?
water, ion or urea loss by the lungs or skin
how are excess water, ions and urea removed?
via the kidneys in urine
what can make cells not function efficiently?
if body cells lose or gain too much water by osmosis
how are excess amino acids created?
the digestion of proteins
what is urea?
a metabolite of amino acids
where is urea produced?
in the liver
what ions are formed in the breakdown of amino acids?
ammonium
what are ammonium ions used as/converted to?
some used in biosynthesis of nitrogen compounds, excess converted to urea
describe the process of deamination
when excess proteins are ingested, the excess amino acids are transported to the liver from the small intestine
why are amino acids converted to fats/carbs?
they can’t be stored in natural form
why should ammonia immediately be converted to urea?
it is toxic
how are ions lost?
in sweat, urine
how is the right balance of ions maintained?
by the kidneys through selective reabsorption
what hormone is the concentration of urine controlled by?
ADH
which gland releases ADH?
pituitary gland
how do the kidneys maintain water balance?
they produce urine, they selectively reabsorb the right amount of water
how do the kidneys produce urine?
by filtration of the blood and selective reabsorption of useful substances such as glucose, some ions and water
3 main parts of kidney
cortex, medulla, renal pelvis
what is the effect of ADH on the
permeability of the kidney tubules?
more ADH, mean the kidney tubules are more permeable so more water can be reabsorbed into the blood
describe what happens when there is too little water
- too much water loss e.g sweating
- a receptor in the brain detects that the content is too low
- coordination centre in brain receives and processes information then coordinates a response: releasing more ADH from pituitary
- more water reabsorbed by kidneys
- higher volume of water passes into blood
describe what happens when there is too much water
- too much water gain e.g drinking
- a receptor in the brain detects that the content is too high
- coordination centre in brain receives and processes information then coordinates a response: releasing less ADH from pituitary
- less water reabsorbed by kidneys
- lower volume of water passes into blood
two types of kidney treatment
- dialysis
- transplant
what happens if the kidneys don’t work?
waste substance build up in the blood and water / ion levels can’t be controlled
kidney transplants
healthy kidneys transplanted from recently dead or live donors
pros and cons of transplants
pros - cheaper in long run, can live a normal life after
cons - rejection risk: must take immune-suppressant drugs, shortage of donors, risk from operation
pros and cons of dialysis
pros - no shortage, no need for drugs
cons - expensive, dialysis session must be regular: huge impact on life
describe dialysis
- person’s blood flows between partially permeable membranes surrounded by dialysis fluid
- permeable to ions and waste substances but not big molecules like proteins
what concentration of dissolved ions does the dialysis fluid have in relation to the blood and why?
the same concentration, means that useful ions and glucose won’t be lost
