Osmos second strike Flashcards
Birds and mammals have adapted to conserve water
Surface coverings to reduce water loss
Amniotic reproduction (membranes protect against desiccation, facilitate gas exchange, hold nitrogenous waste, in developing embryo)
Birds produce uric acid
Both birds and mammals can produce urine more concentrated than their body fluids.
If an animal (like most reptiles) lacks a loop of henle, what happens to their urine?
the liquid urine they produce has about the same osmolarity as body fluids
Bird and mammal kidneys have nephrons with a ______
loop of Henle
In Vertebrates, what Maintains Salt and Water Balance as well as Excretes Nitrogenous and Other Waste?
the kidneys
The kidneys
Dispose of metabolic waste and other unwanted compounds.
regulate volume and composition of body fluids.
What do the kidneys rely on to function?
a system of tubes lined with transport epithelia.
Tubes are in close contact with the circulatory system
Nephrons
The Main Structural And Functional Unit Of The Kidney.
Filter large volumes of blood (180L/day)
Tubules
located in the nephrons found in the kidneys.
responsible for bulk reabsorption and regulated secretion,
and also drive the concentration of urine in the collecting ducts
Urine formation in vertebrate nephrons
Filtration, reabsorption, and secretion
Reabsorption and secretion in the distal tubule is _________
Highly regulated
Glomerular filtration in Bowman’s capsule is followed by______
extensive reabsorption in the tubule
Peritubular capillaries work with the _____, and transport ______
glomerulus.
substances to and from the renal tubules.
anatomy associated with The Vertebrate Nephron
The vertebrate nephron consists of a renal tubule closely associated with two capillary beds, the glomerulus and the peritubular capillaries.
where are Glomeruli located?
in the cortex of the kidney
where are the Proximal convoluted tubules located?
In the cortex of the kidney
Where do the distal convoluted tubules join the collecting duct?
in the cortex of the kidney.
What does Osmotic
loss of water
from renal tubule do?
concentrates the filtrate,
producing urine
Loop of Henle descends and ascends entirely within __________
The Medulla of the kidney
Where are the human kidneys located?
The human kidneys lie against the back wall of the abdominal cavity, in the region of the middle back
The rate of filtration is high due to:
High capillary blood pressure.
High permeability of glomerular capillaries and their podocytes.
glomerulus
a ball of capillaries
Where is blood filtered?
In a glomerulus
Tubular reabsorption
glomerular filtrate flows into the renal tubule, where it is modified by reabsorption of specific ions, nutrients, and water, and useful molecules (e.g. sugars, amino acids) recovered
What filters through the
fenestration in glomerular epithelia and podocyte filtration slits?
Only ions and low molecular weight molecules
The proximal convoluted tubule (PCT)
isosmotic reabsorption of water and solutes
PCT cells have microvilli, and an abundance of mitochondria.
They actively reabsorb Na+, glucose, and amino acids.
water follows the transport of solutes
distal convoluted tubule
fine-tuning of ionic composition .
regulated water absorption
what is the Concentration Of Urine Is Due To?
A Countercurrent Multiplier Mechanism In The Loops Of Henle
Mechanism In The Loops Of Henle
Tubule fluid flows in opposite directions in the ascending and descending limbs.
The loops increase osmolarity of interstitial fluid in a graduated way.
The Loop of Henle Generates and Maintains an ______
Osmotic Gradient
Acending limb in The Loop of Henle
impermeable
to water but highly permeable to
Na+ and Cl–
decending limb in The Loop of Henle
highly
permeable to water but
impermeable to solutes
Where are Aquaporins abundant?
All parts of tubule except Ascending limb.
in DCT and collecting duct: regulated insertion in plasma
membrane.
Thick ascending limb
actively transports Na+ (Cl– follows) and raises their concentration in the interstitial fluid
Thin descending limb
loses water to the neighboring interstitial fluid with high Na+ and Cl– concentration
Thin ascending limb
allows diffusion of Na+ and Cl– into the interstitial fluid
In Collecting Duct, what is The Major Solute In Tubular Fluid?
Urea
Why is water lost to interstitial fluid when fluid flows down the collecting duct?
because of concentration gradient established by loops of Henle.
Whats the outocome of urea diffusing and adding to osmotic force
Some urea also diffuses and adds to osmotic force—recycling this urea contributes to urine concentration.
Extremely long loops of Henle in
desert gerbils, kangaroo rats
and vampire bats.
Why?
Longer limbs: steeper gradients can be generated and maintained
Why do long limbs cause steeper concentration gradients?
. more time and space for water to flow out of the filtrate in the descending limb; so, solutes get more concentrated in longer limbs than in shorter limbs.
Desert animals have long _______
Long Loops Of Henle
In the kidney, what makes up the medualla?
Renal pyramids
The ureter, renal artery, and renal vein enter the kidney on the _______
concave side.
The ureter branches and envelops _____
the renal pyramids.
Nephrons part 2
Regulated reabsorption of water and ions.
Secretion of many solutes (e.g.
excess ions, drugs such as caffeine and aspirin).
Active transport and abundant mitochondria.
What happens to Fluid that leaves the distal convoluted tubule and flows into the collecting duct?
–Has same solute concentration (osmolarity) as blood plasma.
–Has different composition.
