C5. Controlling Blood Water Potential Flashcards
Regulation of water content
Water is essential to keep the body functioning, so the amount of water in the blood (and so the water potential of the blood) needs to be kept constant. Mammals excrete _____(and other waste products) in solution, which means _____is lost during excretion. Water is also lost in sweat. The ________regulate the water potential of the blood (and urine), so the body has just the right amount of water-this is called _________________:
Water is essential to keep the body functioning, so the amount of water in the blood (and so the water potential of the blood) needs to be kept constant. Mammals excrete urea (and other waste products) in solution, which means water is lost during excretion. Water is also lost in sweat. The kidneys regulate the water potential of the blood (and urine), so the body has just the right amount of water-this is called osmoregulation:
Osmoregulation
If the water potential of the blood is too low(the body is dehydrated), ______water is reabsorbed by __________into the blood from the tubules of the ___________. This means the urine is _____ concentrated, so less water is lost during excretion.
If the water potential of the blood is too low (the body is dehydrated), more water is reabsorbed by osmosis into the blood from the tubules of the nephrons. This means the urine is more concentrated, so less water is lost during excretion.
Osmoregulation
If the water potential of the blood is too high (the body is too hydrated), _____water is reabsorbed by _________into the blood from the _________of the nephrons. This means the urine is _______dilute, so more water is lost during excretion.
If the water potential of the blood is too high (the body is too hydrated), less water is reabsorbed by osmosis into the blood from the tubules of the nephrons. This means the urine is more dilute, so more water is lost during excretion.
Water is reabsorbed into the blood along almost all of the nephron, but regulation of water potential mainly takes place in the loop of ________, ____and _____________ _____. The volume of water reabsorbed by the ____and collecting duct is controlled by ____________
Water is reabsorbed into the blood along almost all of the nephron, but regulation of water potential mainly takes place in the loop of Henle, DCT and collecting duct. The volume of water reabsorbed by the DCT and collecting duct is controlled by hormones
The loop of Henle
The loop of Henle is located in the __________(inner layer) of the kidneys. It’s made up of two limbs’ - the _____________limb and the ____________limb. The limbs control the movement of ____________ions so that water can be _____________by the blood.
The loop of Henle is located in the medulla (inner layer) of the kidneys. It’s made up of two limbs’ - the descending limb and the ascending limb. The limbs control the movement of sodium ions so that water can be reabsorbed by the blood.
Tip: Na’ is a sodium ion. These ions help establish the _________potential that drives the _______________of water from the _______________ __________ back into the blood.
Tip: Na’ is a sodium ion. These ions help establish the water potential that drives the reabsorption of water from the glomerular filtrate back into the blood.
Here’s how the system works:
- Near the top of the ___________ limb, ___ions are ________pumped out into the ___________. The ascending limb is impermeable to water, so the water stays inside the tubule. This creates a low water potential in the medulla, because there’s a high concentration of ions.
- Because there’s a _______water potential in the __________than in the _____________limb, water moves out of the _______________limb (which is permeable to water) into the medulla by __________. This makes the ____________ __________more concentrated (the ions can’t diffuse out-the descending limb isn’t permeable to them). The water in the __________is reabsorbed into the blood through the __________ ___________.
- Near the __________of the _____________limb ____ions diffuse out into the ______, further ______________the water potential in the __________.
(The ascending limb is impermeable to water, so it stays in the tubule.) - Water moves out of the ___________convoluted tubules (_CT) by __________and is _____________into the _______.
- The first three stages massively increase the ___concentration in the ___________, which _______the water potential. This causes ________to move out of the ____________ ______by ___________. As before, the water in the __________is ___________into the blood through the __________network. The volume of water reabsorbed into the _____________is controlled by changing the _______________of the ____and the ______________ _____
- Near the top of the ascending limb, Na+ ions are actively pumped out into the medulla. The ascending limb is impermeable to water, so the water stays inside the tubule. This creates a low water potential in the medulla, because there’s a high concentration of ions.
- Because there’s a lower water potential in the medulla than in the descending limb, water moves out of the descending limb (which is permeable to water) into the medulla by osmosis. This makes the glomerular filtrate more concentrated (the ions can’t diffuse out-the descending limb isn’t permeable to them). The water in the medulla is reabsorbed into the blood through the capillary network.
- Near the bottom of the ascending limb Na+ ions diffuse out into the medulla, further lowering the water potential in the medulla.
(The ascending limb is impermeable to water, so it stays in the tubule.) - Water moves out of the distal convoluted tubules (DCT) by osmosis and is reabsorbed into the blood.
- The first three stages massively increase the ion concentration in the medulla, which lowers the water potential. This causes water to move out of the collecting duct by osmosis. As before, the water in the medulla is reabsorbed into the blood through the capillary network. The volume of water reabsorbed into the capillaries is controlled by changing the permeability of the DCT and the collecting duct
Tip: Different animals have different length loops of Henle. The longer an animal’s loop of Henle, the _____water they can reabsorb from the ____________ __________.
Tip: Different animals have different length loops of Henle. The longer an animal’s loop of Henle, the more water they can reabsorb from the glomerular filtrate.
Antidiuretic hormone (ADH) PT1
The water potential of the blood is monitored by cells called __________________in a part of the brain called the _______________. When the water potential of the blood ____________, water will move out of the osmoreceptor cells by ___________. This causes the cells to decrease in __________. This sends a ________to other cells in the _______________, which send a signal to the ___________ ___________ _______. This causes the _____________ ____________to release a ___________called antidiuretic hormone (ADH) into the blood.
Antidiuretic hormone (ADH) PT1
The water potential of the blood is monitored by cells called osmoreceptors in a part of the brain called the hypothalamus. When the water potential of the blood decreases, water will move out of the osmoreceptor cells by osmosis. This causes the cells to decrease in volume. This sends a signal to other cells in the hypothalamus, which send a signal to the posterior pituitary gland. This causes the posterior pituitary to release a hormone called antidiuretic hormone (ADH) into the blood.
Antidiuretic hormone (ADH) PT2
ADH molecules bind to ___________on the ________ ______________of cells in the ____and the ______________ _____. When this happens, protein channels called _____________are inserted into the plasma —membrane. These channels allow water to pass through via _____________, making the walls of the ____and _____________ ____more _____________to water. This means more water is reabsorbed from these __________into the ___________and into the blood by ____________. A small amount of concentrated urine is produced, which means less water is lost from the body. ADH changes the _________content of the blood when it’s too low or too high:
Antidiuretic hormone (ADH) PT2
ADH molecules bind to receptors on the plasma membranes of cells in the DCT and the collecting duct. When this happens, protein channels called aquaporins are inserted into the plasma membrane. These channels allow water to pass through via osmosis, making the walls of the DCT and collecting duct more permeable to water. This means more water is reabsorbed from these tubules into the medulla and into the blood by osmosis. A small amount of concentrated urine is produced, which means less water is lost from the body. ADH changes the water content of the blood when it’s too low or too high:
Dehydration
- The ________content of the blood drops, so its _______potential drops. ]
- This is detected by _________________in the __________________.
- The ____________ ___________ _______is stimulated to release more ____into the blood.
- More ____means that the ____and _____________ ____are more ______________, so more water is ________________into the blood by ____________
- A small amount of __________concentrated urine is produced and less water is _____.
- The water content of the blood drops, so its water potential drops. ]
- This is detected by osmoreceptors in the hypothalamus.
- The posterior pituitary gland is stimulated to release more ADH into the blood.
- More ADH means that the DCT and collecting duct are more permeable, so more water is reabsorbed into the blood by osmosis.
- A small amount of highly concentrated urine is produced and less water is lost.
Hydration
- The water content of the blood ______, so its water potential ____.
- This is detected by the _______________in the ________________.
- The ____________ ____________ _______releases ____ADH into the blood.
- Less _____means that the _____and ___________ ____are less ____________, so less water is ______________into the blood by ___________
- A _________ amount of dilute urine is produced and _____ water is lost.
- The water content of the blood rises, so its water potential rises.
- This is detected by the osmoreceptors in the hypothalamus.
- The posterior pituitary gland releases less ADH into the blood.
- Less ADH means that the DCT and collecting duct are less permeable, so less water is reabsorbed into the blood by osmosis.
- A large amount of dilute urine is produced and more water is lost.
Loop of Henle in 5 steps
1) Sodium ions actively transported into the medulla reducing its water potential at the top of the ascending limb
2) Water move into the medulla from the filtrate in the descending limb via osmosis
3) Sodium ions diffuse out into the medulla at the bottom of the ascending limb reducing water potential of medulla
4) Water from the distal convoluted tubule and collecting duct move into the medulla via osmosis.
5) All water in the medulla is reabsorbed in the blood via capillary networks
Osmoregulation in 5 steps
1) Low WP is detected by osmoreceptors in the hypothalumus which causes them to lose water via osmosis
2) This send a signal that is picked up by other cells in the hypothalumus which send a signal to the posterior pituritary gland which secretes ADH
3) ADH bind to receptors on the cell membranes of the Distal Convoluted Tubule and the collecting duct and it inserts aquaporins which increase permeability
4) More water is reaborbed from the tubule to the medulla to the blood
5) Small amount of highly concentrated urine is produced so less water is lost
