9 - excretory system Flashcards
organs of excretion
- lungs: get rid of carbon dioxide and water
- skin: get rid of water, salt, small amounts of urea
- waste: get rid of ammonia
- waste: get rid of urine
the role liver plays in excretion
the liver transforms material into removable wastes
deamination
- the removal of nitrogen containing amino groups in proteins forming ammonia.
- the ammonia combines with the carbon dioxide in the liver forming urea
uric acid is formed by
the breakdown of amino acids
Primary functions of the urinary system
- removes salts and nitrogenous wastes from the blood
- maintains water balance,
- maintains PH
- controls red blood cell production and blood pressure
the kidneys
- kidneys filter blood
- blood is carried to the kidney by the renal artery and carried back to the heart by the renal vein
kidney - capsule
an outer layer of connective tissue that surrounds the kidney
kidney - renal medulla
the inner layer of the kidney, found beneath the cortex
kidney - renal pelvis
the centre chamber of each kidney, that connects to the ureters
kidney - renal vein
veins that branch from the kidney to the inferior vena cava they carry deoxygenated blood to the heart
kidney - renal artery
arteries that branch into the kidney from the aorta they carry oxygenated blood from the heart
kidney - nephrons
the site of blood filtration
nephron - afferent arteriole
branches from the renal artery and carries blood to the glomerulus
nephron - efferent arteriole
carries blood away from the glomerulus
nephron - glomerulus
a tuft of capillaries that is surrounded by the Bowmans capsule
- the site of filtration
nephron - Bowmans capsule
- a cup like structure that surrounds the glomerulus
- receives the filtered fluids from the glomerulus
nephron - proximal tubule
joins the Bowman’s capsule with the loop of Henle
- the site of reabsorption from the nephron back to the blood
nephron - distal tubule
the last segment of the nephron
- connects the loop of Henle to the collecting duct
- reabsorption can occur here
nephron - loop of Henle
takes urine from the proximal tubule to the distal tubule
- descending part is permeable to water and ions and is the site of some reabsorption
- ascending part is impermeable to water so sodium ions are actively transported out
nephron - collecting duct
collects urine from many nephrons and carries the urine to the renal pelvis
stage 1 - Filtration
- the pores in the glomerulus are large enough to allow some substances in the blood plasma to pass easily into the Bowmans capsule to form the filtrate
- force filtration relies on blood pressure
stage 2 - reabsorption
proximal tubules: water, amino acids, sodium, glucose descending loop of henle: water ascending loop of henle: salt distal tubules: salt and water collecting duct: water
stage 3 - secretion
- opposite of reabsorption (gets rid of)
proximal convoluted tubules: hydrogen, urea, uric acid, creatin
loop of henle: urea
distal convoluted tubules: Hydrogen, potassium, ammonium
maintaining blood PH at 7.4
if blood is too acidic, kidneys will excrete hydrogen ions and bicarbonate is reabsorbed
if blood is too basic, kidneys will not excrete hydrogen ions and bicarbonate is not reabsorbed
water balance
when blood plasma becomes too concentrated (deydration) osmotic pressure increases
what do osmorecpetors do
they send an signal to the pituitary gland to release ADH (antidiuretic hormone)
Balance of salt - adolsterone
- the kidneys regulate salt balance
- adolsterone stimulates the distal tubule and collecting ducts to reabsorb sodium into the blood
