Excretory System Flashcards
why is excretion important ?
allows waste products to be removed, also helps to maintain a constant internal environment
what does the excretory system consist of ?
kidneys, bladder, ureters, urethra
purpose of the excretory system
filter the blood to remove waste products which would be toxic if they built up
excretory system of a mammal
- ureters are 2 tubes which carry urine from kidneys to the bladder
- the bladder stores the urine before it is removed from the body
- the urethra allows the passing of urine from the bladder and out of the body
excretory system of a bird
- the ureters are 2 tubes which carry urine from kidneys to the cloaca
- the cloaca allows urine and other waste products to be cleared from the body
nitrogenous waste removal
the excretory system removes nitrogenous waste products such as ammonia, salt and water that come from the breakdown of proteins
how do mammals remove nitrogenous waste products
remove ammonia in the form of urea that requires water to allow it to be excreted from the body as urine
how do birds remove nitrogenous waste products
remove ammonia in the form of uric acid this does not require water and is an insoluble substance
describe the kidney and what takes place there.
are the core organ involved in waste removal, contain millions of nephrons where ultrafiltration of the blood takes place producing urine.
what is the glomerulus
a knot of capillaries
what’s the renal bowman capsule
collects the filtrate from the glomerulus
what’s the tubules
allow transportation of filtrate to and from the loop of henle
what’s the collecting duct
collects urine and passes to the ureter
what’s the countercurrent multiplier mechanism (CCMM)
allows concentrated urine to be produced
longer henle = can produce more concentrated urine
what 3 processes are in the kidneys
- ultrafiltration - removing substances from the blood
- selective reabsorption - reabsorbing the substances the body needs
- urine formation - substances which are not reabsorbed travel as urine along the nephron to the collecting duct where waste travels to bladder
what’s the body water content controlled by
kindeyse via osmoregulation
ultrafiltration
occurs in the renal capsule. blood enters via renal artery and flows through the capillaries under high pressure. small molecules and ions are squeezed out of the blood by pressure into the nephron, larger molecules stay in the blood
selective reabsorption
Mostly occurs in the proximal convoluted tubule where simple ions amino acids and glucose diffuse into the blood via channel proteins. some larger molecules may be reabsorbed by endocytosis. loop of henle reabsorbs water and salts
anti-diuretic hormone increases amount of water reabsorbed into the kidneys, released from the pituitary gland to maintain homeostasis
CCMM in the loop of henle
- descending limb - permeable to water, water leaves nephron by osmosis and is reabsorbed, as much as body needs is absorbed
- ascending limb - permeable to ions because tissue has high conc of water, sodium and chloride ions diffuse out the nephron. conc of salt in A limb decreases further up the limb where at the top some sodium chloride ions are actively pumped out
- where final reabsorption of ions and water occurs to adjust the water balance. ADH has an effect on the amount of water reabsorbed here
what’s osmoregulation
maintaining balance of salt and water concentration in the body to keep a constant osmotic pressure
high water content
causes body to be hydrated, detected by the osmoreceptors in the hypothalamus which send a response to the pituitary gland to secrete less ADH. less water is reabsorbed into kidneys resulting in more urine being produced so more water is lost
what detects changes in water content
hypothalamus via osmoreceptors and controls regulation of water levels in the body
what process is osmoregulation
physiological process
low water content
causes the body to become dehydrated, detected by osmoreceptors in the hypothalamus which sends a response to the pituitary gland secrete ADH which increases permeability of the walls of the collecting duct which causes more water to be reabsorbed into kidneys via osmosis resulting in less urine being produced so less water is lost
how does osmoregulation keep cells working
if conc to solutions surrounding cells are too high (hypertonic) the cells shrivel
if they become too low (hypotonic) the cell will take too much water in and burst
ornithine cycle
takes place in the liver converting ammonia to urea. urea is much less toxic and doesn’t need so much water during excretion
uric acid
converts nitrogenous waste to insoluble uric acid which is nearly non toxic. uses more energy to make than urea it requires less water to produce meaning birds require less water in their body and are lighter for flight
amino acids and deamination
some animals diets contain a lot of protein that can be used for repair, growth and energy production. however, they are made of amino acids and when being broken down the amino group (NH2) is removed (deamination) and converted to ammonia (highly toxic and needs a lot of water to dilute)
liver damage (cirrhosis)
where scar tissue affects normal liver function, cannot be reversed and stops liver function. affects ornithine cycle leaving toxic chemicals to build up
causes - damage to liver from disease, meds or toxins, infection of hepatitis C, excess fat build up in liver
treatments/cure - no cure, preventions are exercise and healthy diet and treatment of underlying conditions
symptoms - loss of appetite, weight loss, vomiting of diarrhoea, lack of energy and increased urination
whats nephritis
inflammation of the kidneys which leads to problems with filtering blood effectively
caused by disease, meds, disorders
symptoms - weight loss, protein in urine, increased thirst, increased urination and vomiting
