Homestatis Flashcards
(26 cards)
What are the three main roles of the kidney
1) Removal of urea from the blood
2) adjustment of salt levels in the blood
3) adjustment of water content in the blood
How do they carry out these three main roles
By filtering stuff out of the blood under high pressure and then reabsorbing the useful things
What is the end product from the kidneys called
urine
What are Nephrons
The filtration units within the Kidneys
What is the first thing that happens to blood when it passes the thousands of nephrons
Ultrafiltration
What is the first stage of ultrafiltration
Blood from the renal artery flows through the glomerulus - a bundle of capillaries at the start of the nephron
What is the second stage of ultrafiltration
A high pressure is built up which squeezes water, urea, salts and glucose out of the blood and into the Bowmans capsule
What is the the third stage of ultrafiltration
The membranes between the blood vessels in the glomerulus and the Bowmans capsule act like filters so big molecules such like proteins and blood cells are not squeezed out and stay in the blood.
The filtered liquid is called the the Glomerular Filtrate.
What is the the second thing that the blood goes through in the kidneys
Reabsorption
What happens during Reabsorption
As the filtrate flows along the nephrons useful substances are selectively reabsorbed back into the blood
What is the first step of Reabsorption
All the glucose is reabsorbed from the proximal convoluted tubule. This involves the process of active transport against the concentration gradient
What is the second stage of Reabsorption
Sufficient salt is reabsorbed. Excess salt is not
What is the final stage of Reabsorption
Sufficient water is reabsorbed from the collecting duct into the blood stream.
How is the waste released
The remaining substance in the filtrate (water, salts and urea) form urine. This continues out of the nephron through the ureter and down the bladder where is stored before being released via the urethra.
What type of organs are Kidneys
Excretion organs
What else do Kidneys do apart from the filtering of blood
Adjust the bodies water content
What are the three main ways in which water is lost from the body
Sweating, breathing and urinating
What is the name given when the body has to constantly balance the water coming in against the water coming out
Osmoregulation
Give one example of osmoregulation
Adjusting the amount of water that is excreted by the kidneys in the urine
How does the body control the amount of urine in the body
If a person is sweating a lot or has not drunk enough water the kidneys then reabsorb mor water from the blood so less is lost in the urine and the water balance is maintained
What hormone controls the amount of water reabsorbed in the nephrons
ADH
What does ADH stand for
Anti - diuretic hormone
What does ADH do
ADH makes the nephrons more permeable so more water is reabsorbed back into the blood
What does the Brian do in water regulation
The Brian monitors the water content and instructs the pituitary gland to release ADH into the blood according to how much is needed.
