Excretion
Blood vessel (small artery) bringing blood towards the glomerulus of
the nephron in the kidney.
afferent arteriole
Forming that part of the nephron just after the loop of Henle
through which the glomerular filtrate flows upwards. It is permeable
to salt only.
ascending tubule
A membranous sac filled with fluid. In animals it serves as a reservoir
for fluids, e.g. bile, urine.
bladder
A a double-walled, cup shaped chamber at the expanded end of a
nephron (uriniferous tubule), which encloses a glomerulus.
Bowman's capsule
The space between the membranes forming Bowman’s capsule, of
the nephron in the kidney, into which the filtrate passes.
capsular space
Tubule, in the medulla of the kidney, into which numerous nephrons
discharge their contents (urine) for delivery to the pelvis and hence
to the bladder via the ureter. Water is reabsorbed here during the
formation of urine, which concentrates the urine. The quantity of
water reabsorbed is controlled by the hormone ADH.
Coiled or twisted tubule found in the nephron of the kidney.
Reabsorbs high threshold substances that have been filtered from
the blood.
collecting duct
convoluted tubule
The outermost layer of the kidney.
cortex
Forming that part of the nephron just before the loop of Henle
through which the glomerular filtrate flows downwards. Permeable
to water only.
descending tubule
Excessive production of watery (dilute) urine. It is caused by
insufficient production of ADH (vasopressin) by the pituitary gland.
diabetes insipidus
The use of semi-permeable membranes in a machine for removing
waste products (urea, uric acid, salts) from the blood when the
kidneys fail.
One of two highly coiled tubules in the nephron of the kidney, this
one situated furthest away from the Bowman's capsule and close to
the collecting duct. Water is reabsorbed here during the formation
of urine.
An increase in production of urine by the kidneys, either from
increased fluid intake, alcohol (inhibits ADH production), renal
disease, diabetes insipidus or diuretic therapy.
A drug that increases the amount of urine produced by the kidneys.
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dialysis
distal convoluted
tubule
diuresis
diuretic
Blood vessel (small artery) bringing blood away from the glomerulus
of the nephron in the kidney.
efferent arteriole
The elimination of the waste products of metabolism from a cell,
tissue or organ.
excretion
Collection of organs or structures that function in the elimination of
the waste products of metabolism, e.g. contractile vacuole
(Amoeba), kidney (part of the urinary system), lungs (part of the
respiratory system), etc.
Process which forcibly separates particles in a solution by molecular
size, e.g. in the nephron of the kidney – water, urea, uric acid,
glucose, amino acids, vitamins and mineral salts (all small
molecules), filter from glomerulus into capsular space. Plasma
proteins (albumen, fibrinogen, prothrombin – all large molecules)
and blood cells will not pass through.
Liquid containing dissolved substances that pass from the
glomerulus, in the nephron of the kidney, into Bowman’s capsule.
Similar to blood plasma but without the proteins (albumen,
fibrinogen, prothrombin).
excretory system
pressure filtration
(ultra filtration)
glomerular filtrate
Purifying of the blood using an artificial ‘kidney’ machine. (Dialysis).
haemodialysis
Chemicals that are important or are of use to the body and should
not be lost or excreted.
high threshold
substances
The maintaining of a constant internal environment (i.e.
concentrations of water, salt, turgidity, temperature, etc.) of a cell or
homeostasis
organism or the processes involved with this. Usually achieved by
diffusion and the respiratory and excretory systems.
One of a pair of excretory organs that form and extract urine. Also
involved in osmoregulation.
kidney
Tubule in the kidney. Is the functional unit of the kidney i.e. it makes
urine.
nephron
The U-shaped part of a nephron (uriniferous tubule, renal tubule)
connecting the proximal convoluted tubule and distal convoluted
tubules. Water is reabsorbed here during the formation of urine.
loop of Henle
Central part of kidney (inside the cortex) containing the pyramids.
medulla
Minute finger-like projections on cells, e.g. on the cells of the
proximal convoluted tubule of the nephron and on the cells of the
villi in the small intestine.
Controlling the amount of water in a cell within an organism by
regulating the amounts of salt and water present. It is a function of
the kidneys in humans and the contractile vacuole in Amoeba.
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microvilli
(microvillus)
osmoregulation
One of two highly coiled tubules in the nephron of the kidney, this is
situated nearest to Bowman's capsule. Reabsorption of substances
needed by the body occurs here, i.e. high threshold substances.
proximal
convoluted tubule
Part of the kidney containing collecting ducts.
pyramid
Taking in again, e.g. in the nephron of the kidney - glucose, amino
acids, etc. are taken back into the blood in the proximal convoluted
tubule after being removed from it in the glomerulus.
reabsorption
Of or pertaining or relating to the kidney.
renal
Branch of the aorta bringing blood from the heart to the kidney.
renal artery
Central region of kidney into which urine drains from the collecting
ducts. The urine is brought from here in the ureter to the bladder.
pelvis
Blood vessel bringing blood from the kidney to the inferior vena cava
renal vein
towards the heart.
A nitrogen containing organic compound excreted by most
mammals. Formed in the liver from ammonia, as a result of the
breakdown (deamination) of excess amino acids, and excreted by
the kidneys.
urea
Duct that brings urine from the kidney to the bladder.
ureter
Duct which delivers urine from the bladder to the outside; also, in
the male it deposits sperm in the vagina.
urethra
Group of organs concerned with the production and excretion of
urine, i.e. kidneys, ureters, bladder and urethra.
urinary system
Fluid produced by the kidneys, stored in the bladder (urinary
bladder) and discharged through the urethra. Fluid contains waste
products of metabolism, e.g. water, urea, salts, hormones, etc.
urine
This hormone, produced by the pituitary, encourages the
reabsorption of water in the nephron of the kidney.
vasopressin (ADH)
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