11.3 The kidney and osmoregulation
All animals excrete nitrogenous waste products and some animals also balance water and solute concentrations.
Mammals have kidney
OSMOREGULATION
EXCRETION
HIGHER IN RENAL ARTERY:
-TOXINS (BETAIN - found in beets)
- N WASTE (UREA)
-GLUCOSE TO SOME EXTENT (used for energy in kidneys)
-DRUGS
REMOVED FROM BLOOD BUT ARE NOT EXCRETORY PRODUCTS:
O2
PLASMA PROTEIN ARE NOT FILTERED BY KIDNEY SO SHOULD BE PRESENT IN ALMOST EQUAL CONCENTRATIONS
Kidneys function to remove waste and in osmoregulation of the blood. So, the blood entering the kidney will be different than the blood that leaves the kidney….
via renal artery
via renal vein
THE NEPHRON
Glomerulus ultrafiltration - 1st stage
FENESTRATIONS
-about 100 nm in diameter - allow fluid to escape but not blood cells
Made of -tive charge glycoproteins - doesn’t let plasma protein through b/c they are -tive
PODOCYTES AND THEY FOOT PROCESSES
Prevent small molecules from being filtered out
Ultrafiltration
Most molecules below the molecular mass of 65 000 atomic mass units pass through
Proteins do not pass
If proteins and glucose are found in the filtrate – what does it indicate?
Selective reabsorption
Moved by active transport
Also, provide enough E for glucose to move through to the outside
Attracted by the gradient set up by Na ions
Water moves out by osmosis b/c of high concentration of solutes now built up on the outside
Kidney animation
Loop of Henle
Loop of Henle
Maintains hypertonic conditions in the medulla
water conservation
Loop of Henle
-vary in length according to water conservation needs (p. 493 DBQ)
NoS
Curiosity about particular phenomena: investigations were carried out to determine how desert animals prevent water loss in their wastes
Very toxic and very soluble in water
Moderately toxic and somewhat soluble in water
Non-toxic in low amounts and is not soluble in water (low solubility)
Osmoconformers keep the osmotic potential of their bodies the same as their seawater environment.
Osmoregulator are organisms that can regulate or keep the solutes or salts of its body fluid at a higher or lower concentration than the concentration of solutes in the external medium
terrestrial animals and marine animal (bony fish)
Insect have the Malphighian tubule system
Review
OSMOREGULATION
at the kidney collecting duct
The Endocrine System
(a hormone called ADH)
Helps Control Blood Osmolarity
START HERE:
Increase in blood osmolarity
This means the blood increases in solute concentration relative to the amount of water; in other words, there’s “not enough” water in the blood relative to the amount of solutes. Maybe due to sweating profusely, eating a real salty meal or not drinking enough water. You are dehydrated.
START HERE:
Increase in blood osmolarity
Osmoreceptors in the hypothalamus trigger release of ADH from the pituitary gland
START HERE:
Increase in blood osmolarity
Osmoreceptors in the hypothalamus trigger release of ADH from the pituitary gland
ADH
ADH: “antidiuretic hormone”
START HERE:
Increase in blood osmolarity
Osmoreceptors in the hypothalamus trigger release of ADH from the pituitary gland
thirst
The ADH
triggers thirst
ADH
START HERE:
Increase in blood osmolarity
Osmoreceptors in the hypothalamus trigger release of ADH from the pituitary gland
Drinking water will reduce blood osmolarity
thirst
Lower blood osmolarity means there is more water in the blood
ADH
START HERE:
Increase in blood osmolarity
Osmoreceptors in the hypothalamus trigger release of ADH from the pituitary gland
Drinking water will reduce blood osmolarity
ADH causes more water reabsorption at the collecting duct
thirst
Reabsorbing more water at the collecting duct will also reduce blood osmolarity.
ADH
ADH is a hormone that travel in the blood from the pituitary to the kidney collecting ducts.
START HERE:
Increase in blood osmolarity
Osmoreceptors in the hypothalamus trigger release of ADH from the pituitary gland
Drinking water will reduce blood osmolarity
Blood osmolarity homeostasis is reached
ADH causes more water reabsorption at the collecting duct
thirst
ADH
When ADH is present, the collecting duct is highly permeable to water. This means that lots of water can leave the urine and return to the body; resulting in a small volume of concentrated urine.
When ADH is not present, the collecting duct is not permeable to water. This means that water will not leave the urine; resulting in a large volume of dilute urine.
DEHYDRATION
OVERHYDRATION
The loss of body fluids, mostly water, exceeds the amount that is taken in.
More water is moving out of our cells and bodies than what we take in through drinking. Due to fever, heat exposure, and too much exercise, vomiting, diarrhea, and extreme burns
Increased thirst, dry mouth, weakness, dizzy, decreased urine, confusion, inability to sweat
When the body takes in more water than it loses.
People who drink excessive water results in too much water and not enough sodium. Drinking large amounts of water usually does not cause overhydration if the pituitary gland, kidneys, liver, and heart are functioning normally.
When overhydration occurs slowly and is mild or moderate, brain cells have time to adapt, so only mild symptoms like distractibility and lethargy may ensue. When overhydration occurs quickly, confusion, seizures, or coma may develop.
DEFINE:
CAUSE:
SYMPTOMS:
remedy for dehydration:
6 tsp of table sugar + ½ tsp of salt + 1 dm3 of water.
Summary:
Not filtered
Reabsorbed: active transport
Reabsorbed: diffusion
Excreted
Kidney Failure
Not Good
Kidney Failure
A condition in which the kidneys lose the ability to remove waste (excrete) and balance fluids (osmoregulation).
Causes of kidney failure
Hemodialysis
In hemodialysis, a machine filters wastes, salts and fluid from the blood when the kidneys are no longer healthy enough to do this work adequately.
DIALYSIS FLUID: Na+ and glucose at correct levels in order to ensure NO diffusion
NO urea → so it diffuses out of the blood
Kidney transplant
A kidney transplant is a surgical procedure to place a kidney from a live or deceased donor into a person whose kidneys no longer function properly.
Ultrasound
Kidney stones can result from chronic dehydration.
Ultrasound is the most common treatment for kidney stones.
Ultrasonic waves from outside the body are
targeted at a kidney stone causing the stone to fragment.
The stones are broken into tiny pieces which can then leave the body.