Osmotic Regulation Flashcards
What are osmoconformers?
organisms whose body fluid is the same osmolarity as their environment
What type of organisms are osmoconformers typically?
most marine invertebrates
What exactly is osmolarity?
total number of solute particles in a solution
What are osmoregulators?
organisms whose body fluid is not the same as their environment
What type of organisms are osmoregulators?
most marine vertebrates and everyone else
Why is it hard to maintain osmolarity?
because our cells are constantly breaking down amino acids, so ammonia is formed (which is toxic)
What do organisms that live in the water do to get rid of the ammonia?
they use gills and do diffusion to get the ammonia out of the body
What do mammals, fish, and amphibians do to the ammonia?
ammonia is converted to urea in the liver and is excereted via the kidneys
What is a disadvantage to converting ammonia to urea?
it requires a lot of water
What do reptiles, birds, and insects do to the ammonia?
they convert ammonia to uric acid in order to save water
What is a disadvantage to converting ammonia to uric acid?
high energy cost
What is the purpose of bird and mammal kidney?
to produce urine more concentrated than body fluids
What transports the blood to the kidney?
renal artery
What are the three levels of the kidney (start from the top)?
- renal cortex
- renal medulla
- renal pelvis
What part of the kidney conducts the filtration?
nephron
What are the two types of nephron?
juxtamedullary and cortical
What kind of urine do freshwater fish make and why?
they make dilute urine because they use the kidney to excrete excess water not waste (they remove waste by passive diffusion)
What kind of urine do marine fish make and why?
they make concentrated urine because they use the kidney to excrete ions
What does the juxtamedullary nephron do?
it is used to increase concentration of urine (which is why it is longer)
What does the cortical nephron do?
i is used for reabsorption and secretion (which is why it’s smaller)
What is the path of the blood to urine?
renal artery
kidney
glomerulus
collecting duct
ureter
bladder
urethra
Through which arteriole is blood coming in through?
afferent arteriole
What is the glomerulus?
a ball of capillaries used for filtration
How does filtration occur in the glomerulus?
pressure in the capillaries releases the blood and big stuff into the efferent arteriole while the filtrate is released into the bowman’s capsule
How does the filtrate leave the bowman’s capsule?
through the renal tubule
Why are blood and renal tubes still intertwined?
this helps diffusion of particles out of the loop of henle and beyond
Walk through the path of the filtrate?
- filtrate goes from the renal tube to the proximal tube
- filtrate goes down the descending loop of henle
- then, it does up the acceding loop of henle
- then the filtrate travels to the distal tubule
- and then the filtrate travels down the collecting duct to get excreted
In what parts of the nephron is water reabsorbed into the capillaries?
proximal tubule, descending loop of henle, distal tubule (if you have to), and collecting duct
Why does water leave the nephron at various places?
this is because in these places, there is more solute outside the nephron, so water follows the solute
Where does reabsorption of molecules happen and what molecules are reabsorbed?
it happens in the proxminal tubule and glucose and amino acids are reabsorbed by the body (capillaries)
How does secretion occur?
- unwanted molecules are actively transported from blood to nephron and this occurs in the distal convoluted tubule
What is excretion?
when the filtrate goes through the collecting duct and is concentrated into the urine
What organisms have the loop of henle?
mammals and birds
What is the point of the loop of henle?
it is to create a gradient to up the concentration of urine
Why doesn’t the loop of henle actually achieve its point?
the solution coming out of the loop is actually more dilute than the solution going into the loop
What is the countercurrent exchange in the loop of henle?
- as the filtrate goes through the descending loop of henle, water moves out of the loop and into the environment
- as the filtrate goes through the ascending loop of henle, sodium and chlorine ions move out of the loop of henle using active transport
What happens as we go deeper through the environment of the loop of henle?
the osmolarity increases (more concentration of stuff)
How does filtrate turn into urine?
as the filtrate move through the collecting duct, more water is reabsorbed into the blood and filtrate becomes urine as concentration increases
Why is urine acidic?
-bicarbonate is naturally needed in the blood to maintain pH, so it gets reabsorbed in the proximal convoluted tubule
-but H+ is also naturally secreted from the body to the distal tubule in order to maintain pH
-so, we took away the buffer and added acid, so urine is acidic
What dies ADH regulate?
blood osmolarity, blood pressure, and volume
What does your body do when it recognizes there isn’t enough water in your blood?
- hypothalamus triggers thirst
- hypothalamus releases ADH
- ADH causes kidneys to reabsorb more water
How does ADH cause kidneys to reabsorb more water?
ADH adds aquaporins in the distal tubules and collecting ducts
What happens when ADH levels are high?
blood pressure increases and blood volume increases, because theres more water going through the arteries so its thicker
