Excretion
The removal of waste products of metabolism
Ureter
Transports urine from the kidney to the bladder
Urethra
Transports urine out of the body
Urea
Produced from the breakdown of excess amino acids in the liver
Urine
A solution of urea + water + salts, stored in the bladder before being released from the body
Nephron
Functional filtering unit of the kidney, also known as kidney tubules
Bowmans capsule
Hollow cup of cells surrounding the glomerulus
Glomerulus
A dense network of capillaries where water, ions, glucose and urea are filtered from the blood into the tubules
Glomerular filtrate
The fluid forced out of the glomerulus under high pressure
What does glomerular filtrate contain?
Glucose, urea, ions
What glomerular filtrate does not contain?
Blood cells, proteins
Proximal convoluted tubule
Site where the majority of glomerular filtrate is reabsorbed
What is reabsorbed back into the blood stream? Which process?
Glicose, active transport
Loop of Henle
A U-shaped loop that runs down into the medulla of the kidney
What is Loop of Henle’s main role
Concentrating the fluid in the tubule to allow more water to be reabsorbed into the blood
Collecting duct
The tubule that receives urine from numerous nephrons.
What controls the permeability of the wall’s of the collecting duct?
ADH hormone
Ultrafiltration
The process where fluid is forced out of the glomerulus under high pressure
Selective reabsorption
The process where the substances we need are absorbed into the blood stream.
Active transport
The transport of substance across a biological membrane against a concentration gradient, which requires energy
Osmoregulation
The hormonal control of water level in the blood
ADH - stands for?
Anti diuretic hormone
ADH
The hormone which increases the permeability of the collecting ducts allowing more water to reabsorbed back into the blood
Hypothalamus
A region of brain which are sensitive to the solute concentration of the blood
Pituitary gland
A small gland in the brain that releases several hormones including ADH
Negative feedback
Any mechanism which reverts a change in a system back to its normal value.
Homeostasis
The maintenance of a constant internal environment
Egestion
Removal of faeces
How does a nephron begin?
With a glomerulus
What follows glomerulus?
Bowman’s capsule
What is the tubule before loop of Henlé called?
Proximal convoluted tubule
What is the tubule after loop of Henlé called?
Distal convoluted tubule
What substances are reabsorbed during selective reabsorption? (3)
1) ALL Glucose 2) SUFFICIENT salt 3) SUFFICIENT water
What process helps selectively reabsorb water?
Osmosis
How are mineral ions reabsorbed into the blood stream?
Active transport
Where does the nephron finally get to?
Collecting duct
Main roles of kidneys (3)
1) Removal or urea 2) Adjustment of salt levels in the water 3) Adjustment of water content of the blood
Where does most of selective reabsorption happen?
Proximal convoluted tubule
What will happen if there is not enough water in the cells?
Reactions in cytoplasm would not occur
What will happen if there is too much water in the cells?
Cells may rapture
What are the 3 main mays of water leaving the body?
1) Sweating 2) Breathing 3) Urinating
What mechanism controlls the process of osmoregulation
Negative feedback
Describe negative feedback in terms of osmoregulation
When water content gets too high or too low a mechanism will be triggered to bring the level back to normal
How does ADH travel through the body?
Blood
Under what conditions less water will be stored? (3)
1) Cold temp 2) No sweating 3) Well hydrated
Under what conditions more water will be stored? (3)
1) Hot temp 2) A lot if sweating 3) Poor hydrated