osmoregulation and excretion Flashcards
what does intracellular environment effect
organic molecule formation
what is protein function (e.g enzymes) affected by
ion concentration
when is protein function optimal
within a narrow range of inorganic ion concentration
what are the three compartments water flows between
intracellular, interstitial fluid, blood plasma (inter and blood=extracellular)
what is the make up composition of humans
60% water and 40% bone, protein, lipids
what does osmoregulatory systems regulate
water/solutes in blood, secondarily in intentional fluids
how can cells react to there environment out side
they have some ability to alter their cell volume
how do most cells regulate their intracellular ion compsition
using ATP
most animal cells are…
water permeable
because animal cells are water permeable what does this mean for what they can control
they can control there ionic differences across the cell membrane but not osmotic differences
what are the two main routes of transport epithelial cells use
-transcellular transport
-paracellular transport
what is transcellular transport
movement through the cell across membranes
what is paracellular transport
movement between cells
leaky vs tight epithelia
what is epithelium
layer of cells
what are some types of transporters
-Na+K+ATPase, Ca2+-ATPase
-ion channels (Cl-, K+,Na+,Ca2+)
-electroneutral cotransporters (-paired with+)
-electroneutral exchangers
how does water move
from low solute concentration (high water potential) to high solute concentration (low water potential)–>osmotic graident
what s osmolarity
the measure of solute concentration (number of osmoles per liter)
-1 mol glucose=1 osmole
-1 mol of NaCl=2 osmole
how do most cells respond to swelling or shrinkage
by activating specific membrane transport and/or metabolic processes that serve to return cell volume to its normal resting state
how sensitive are volume sensing mechanisms
can sense and respond to volume changes of 3%
whats RVI
-regulatory volume increase when the cell gains solute if the cell gets too small
what is RVD
regulatory volume decrease when the cell looses solute if cell gets to big
what are the transporters involved with RVI
-Cl-HCO3 exchanger
-Na-H exchanger
-Na-K-Cl cotransporter
what are the transporters involves with RVD
-K-Cl cotransporters
-K+ or Cl- channels
what are the three homestatic processes
-ionic regulation
-volume regulation
-osmotic regulation
what is ionic regulation
concentrations of specific ions
what is volume regulation
total amount of water in a body fluid
what is osmotic regulation
osmotic pressure of body fluids
what is osmoconformers
-strategy animals evolved to deal with osmotic stress
-it means body fluids and cells are equal in osmotic pressure to the environment
-mainly found in ocean where osmolarity averages 1000 mOsm
what are osmoregulators
-strategy animals evolved to deal with osmotic stress
-osmotic pressure of body fluids is homeostatically regulated and usually differrent from the external environment
what are the different stratigies animals have evolved to maintain homeostasis
osmoconformation and osmoregulation
how does osmoregulation in fresh water fish work, what are some consequences of being fresh water and how are they dealt with
-fresh water has a mOsm of <5
-fish has a 300 mOsm
-FW wish lose salt and gain water
-water is absorbed through skin and gills
-salt is lost via facies
-water and some salts are lost via urine
-they obtain salts via chloride cells in gills and with food (using ATP to pump in)
-fish dont need to drink
how does osmoregulation in marine water fish work, what are some consequences of being fresh water and how are they dealt with
-sea water has mOsm of 1000
-fish body has mOsm of 400
-they loose water through gills and skin
-salt loss via facies, salt and little water loss via scant urine
-gain water and salts by swallowing seawater and food
-removes salts via chloride cells in gills
-they drink sea water to obtain water but it also takes up more salt
-retaining water and getting rid of salts in the goal
what is osmoconformers a common strategy in
by marine invertabrates
what takes more energy osmoconforming or osmoregulation
osmoconforming is energetically less expensive then osmoreg
can osmoregulators cope with changes in extracellular osmolarity and ion concentration
no
what maintains a strict extracellular osmotic homeostatasis
osmoregulators
what has a high degree of cellular osmostic tolerance
osmoconformers
in osmoconfromers how can cells cope with extracellular osmolarities
by increasing intracellular osmolarities with compatible osmolytes—>maintaining cell volume
what is the molarity of extra cellular fluid in osmoconformers and what solute is most present
simular to sea water (1000mOsm), dominated by NaCl
in osmo conformers what is the the difference of pressure in ICF and ECF
they have the same osmotic pressure with universal solutes and organic osmolytes
what are some common organic osmolytes
carbohydrates, free amino acids, methylamines, urea, and methylsulfonium solutes
how do organic osmolytes effect macromolecules
they dont disturb then some even stabilize then against denaturing force of others
what are solutes classified based off of
by their effects on macrmolecules
what are perturbing solutes
-they disrupt macromolecular functions
-Na+, K+, Cl-, SO4+, charges amino acids
what are compatible solutes
-little effect on macromolecular function
-polyols (glycerol, glucose, and uncharged amino acids
what are counteracting solutes
-disrupt macromolecular finctions on their own
-counteract disruptive effects of other solutes when employed in combination
what do cartilaginous fish do to increase their tissue osmolarity
-they use urea as an osmolyte
-helps prevent water loss in marine environment
-ureas perturbing effects counteracted by methylamines (e.g TMAO)
what are the two types of osmoconformers
-stenohaline
-euryhaline
what are stenohaline osmoconformers
-they are restricted to a narrow range of salinity
-they cant regulate their osmolytes to compensate
-cant tolerate changes
-stay in the ocean
what are euryhaline osmoconformers
-they are tolerant of changes in salinity
-sucessful in intertdal zones
-regulate organic osmolytes in their cell
in stenohaline bull sharks what happened when they went from salt water to fresh water
-20% reduced Na, Cl
-50% reduced urea
-body fluids still had double osmolarity than fresh water fish
-massive influx of water
-massive urine production (20x more then in salt water)
what else are osmoregulatory organs involves with
nitrogen waste excretion
what is the problem with N waste
-metabolism of proteins and nucleic acids
-produces ammonia (toxic)
-accumulation of NH3 would lead to death (must be excreted)
-NH3 is very soluble–> excretion would require large amounts of water
-animals have developed different strategies depending on water avalibility
what are some N waste strategies and what are they seen in
NH3- seen in teleosts, larval amphibians, aquatic invertebrates
urea- seen in mammals, sharks, rays, turtles, adult amphibians
uric acid- seen in lizards, snakes, birds, insects
what is the most toxic to least toxic and least energy to produce to most energy to produce for N waste in animals
ammonia, urea, uric acid
what are some characteristics of ammonia
-very soluble in water but toxic at low concentrations
-easily permeates membranes
what are ammoniotelic animals
animals that excrete ammonia
how to invertabrates release ammonia
they diffuse it out of the body surface into surrounding water
how do fish release ammonia
excreted out of gills and (to a minor degree) out of kidneys
do all aquatic animals excrete ammonia
no
what is a ureotelic animal
animal that turns NH3 into urea
what are some features of urea
-less toxic than ammonia
-tolerated in more concentrated form
-sacrifice less water
-uses energy to create
what are uricotelic animals
animals that turn NH3 into uric acid
what are some feature of uric acid
-1000x less soluble then NH3
-ppts
-non toxic but requires lots of energy to produce
-storage excretion
what are some features of uricotelic animals
-adapted to limited availability of water
-used for shelled eggs in vertebrates
-excreted by land snails, insects, birds, and many reptiles
what are external osmoregulators
-gills
-skin (e.g amphibians)
what are internal osmoregulators
-gut
salt glands
-specialized internal organs called kidneys
what are the diffrent kinds of specialized internal organs for osmoregulation
-kidney
-protonephrones
-metanephrones
-melpighian tubules
what kind of animals have salt glands
shark, fish, birds and reptiles that live in seawater or desert
what the role of nasal salt glands (what is the nature of it)
-it secretes hyper osmotic NaCl solution
-active transport of NaCl (ATP driven pumps keep the salt in)
-gets rid of salt
-retains water
in a salt gland what happens as you move down the secretory tubule
the concentration becomes higher
what things make up the salt gland
-vein
-artery
-secritory tubule
-which goes to central duct
-capillary
-transory epithelium
-secretory cell
what is the kidney
-internal organ most concerned with osmoregulation
-common architechural and physiological principles
what is the change concentration like in the collecting area
very level
what is the concentration change like in the proximal tubule
-may be reabsorption/secretion of some solutes
-minor changes in osmotic conc
-major ionic chances
what is the concentration change like in the distal tubule
-distal tubule, overall nonisomotic reabsorbtion or secretion
-major changes in osmotic concentration or urine
what are the concentrations changes like in the storage bladder
there is no chane
what is the osmoregulatory and excretory functions of kidney
-regulates water and inorganic solute levels
-removes nitrogenous waste, and other metabolic “waste”
-extensive interaction between blood and tubules
-membrane exchange mechanism are also key
what makes up the kidney
-renal cortex
-renal medulla
-renal pelvis
-renal pyramid
what part of the kidney is the renal cortex and the renal medulla
cortex-outside
medulla-inside
what makes up the kidney system as a whole
-renal vein
-renal artery
-inferior vena cava
-kidney
-aorta
-ureter
-urinary bladder
-urethra
what us the renal medulla divided into
renal pyramids in larger mammals
what is the renal pelvis
drainage area in center of kidney
what is a nephron
the smallest functional unit of the kidney
-1 million in human kidney
what does a nephron consist of
a tubule and associated vascular component
where does the first interaction with blood occur
in the renal corpuscle
what is the nephron
the functional unit of the kidney
what is the nephron responsible for
the formation of urine
what are the three basic nephron processes
-glomerular filtration
-tubular reabsorption
-tubular secrection
resulting fluid is urine
what is glamorous filtration
filtering blood into tubule forming the primary urine
what is tubular reabsorbtion
absorption of substances needed by body form tubule to blood
what is tubular secretion
secretion of substances to be eliminated form the body into the tubule form the blood
how does blood travel through the nephron
-afferent arteriole
-glomerular capillaries
-efferent arterole
-peritubular capillaries and/or vasa recta renis
-renal vein
what occurs in the bowmans capsule
-ultra filtration form the glomerular capillary
-reabsorption into the peritubular capillaries
-secretion back into the bowmans
-urinary excretion
what is excretion
filtration - reabsorption + secretion
what is glamorous filtration
-first step in urine formation
-separation of plasma fraction of the blood
-driven by blood hydrostatic pressure
-when ultrafiltration happens
what is in ultra filtration
-contains small plasma solutes and water
-waste products
-useful molecules (glucose, ions)
no cells enter ultrafiltrate
-very low protein content
how do glomerular capillaries different form other capillaries
they are much more leaky
-400 times more permeable then other capillaries
what forms a filtration structure
podocytes with a foot process
what makes the glomerous filtration good at filtration
-renal corpuscle (glamerulus, glomerular capsule(bowmans capsule)
-glomerulus have large pores fenestrae which is the space between cells
-high permeability (400x greater then other capillaries)
what are the forces involves in matabolism what is the result
-glomerular capillary blood pressure (favours filtration 55mm Hg)
-plasma colloid osmotic pressure (opposes filtration 30mm Hg)
-bowmans capsule hydrostatic pressure (opposes filtration 15mm Hg)
result: net filtration pressure (difference between force favouring and opposing)=favours 55-(30+15)=10mm Hg from capillary to bowmans
what is the glamorous filtration rate
125ml per min
7.5 L per hour
180 L per day
-entire plasma volume filtered every 45 mins
how much of the filtrate is re absorbed by the nephron tubules
approximately 99%
what is the proximal convoluted tubule
-where reabsorption occurs
-and secretion
what happens during the reabsorption of proximal convoluted tubule
-65% of filtered water
-67% of filtered sodium and chloride
-glucose and amino acids
what happens in the secretion of proximal convoluted tubules
-variable proton secretion for acid/base regulation
-organic molecules (organic cat/anions, water soluble toxins)
how is tubular exchange done in the renal system
either transcellular (through cell) or paracellular (between the cells)
what does Na+ do with the electrochemical graidednt
-Na+ goes in the cell from tubular fluid with its electrochemical graident and brings glucose in through cotransport(against its graident)
-forn the tubular fluid Na+ also does counter transport with H+ (Na with the graident, H against)
-to the interstitial fluid 3 Na is transported out and 2K+ in using ATPase
-to the interstitial fluid Na is pumped out agains traident using cotransport and HCO3-
what does glucose do with tubular fluid and interstital fluid
-its transported out of the tubular fluid into the cell using Na+ co trasport against K+ graident
-transported out of cell into interstitial fluid with electrochemical graident
what is interstitial fluid
it interfaces with blood plasma
what does K+ do with tubular fluid and interstital fluid
-K+ is diffused both in and out of the cell with its electrochemical graident
what does Cl- do with tubular fluid and interstital fluid
it diffuses paracellular (between cells)
to the interstitial fluid
what does H+ do with tubular fluid and interstital fluid
it diffuses out of the cell from H2CO3 to the tubular fluid against electrochemical gradient
what does HCO3 do with tubular fluid and interstital fluid
it diffuses out of the cell with its electrochemical graident to the interstitial fluid using cotransport and with Na+
what does the loop of henle do
-it establishes a osmotic graident in the medulla
-reduces the osmotic pressure of the filtrate to ~100mOsm
-reabsorbs 20% of filtered water and sodium
what does the loop of henle crating a osmotic gradient allow for
it allows water reabsorption by collecting duct (produces hypertonic urine)
after the loop of henle how much filtered water and sodium is reabsorbed
-20% from loop of henle
-65% in proximal tubule
-=85% if the ultrafilterate has been reabsorbes by the time it reaches the distal convoluted tubule
in the renal tubule when is the osmotic gradient isotonic
-in the proximal tubule
-the descending limb
in the renal tubule when is the osmotic gradient hyposmotic in the tubule
-in the ascending limb to the distal tubule
in the renal tubule when is the osmotic gradient hypertonic
in the collecting duct
in the loop of henle what is the descending limb permeable and not permeable to
water but not to NaCl
in the loop of henle descending limb where does the filtrate concentrate in
the medulla
in the loop of henle what is the asending limb permeable and not permeable to
-active Na+ and Cl- reabsorption
-impermeable to water
-it dilutes the ultrafiltratre
in the loop of henle ascending limb where does the filtrate concentrate in
the medulla
what is the role of urea
it contributes to the osmotic graident
where does urea accumulate
in the medulla
once fluid reaches the distal convoluted tubule how much of it is the original filtered volume
20% of the original filtered volume
what is the tonicity of the fluid in the distal convoluted tubule relative to the plasma
it is hypotonic relative to plasma
how much of the filtered Na+ is reabsorbed in the distal convoluted tubule (DCT) and collecting duct
7.5%
is the DCT permeable to water
not usually but later nephron segments are
what does the collecting duct do
-concentrates the urine by exploiting the osmotic gradient in the medulla generated by the loop of henle
what is collecting duct permeability regulated by
antidiuretic hormone (ADH)
what kind fo feed back is the antidiuretic hormone regulatory system
negative feedback
how does the ADH regulatory system work
-osmoreceptors in hypothalamus detect an increase in solute concentration in ECF due to water loss
-send signal to hypothalamus
-posterior pituitary gland releases ADH
-which then makes the collecting duct permeable to water
what is the goal of releasing ADH
causes the body to try and retain water
what is nephridia
-the primitive version of osmoregualtion
-the primative kidney
-protonephridia
-metanephridia
what things are protonephridia found in
flat worms, rotifers
what are metanephridia found in
annelids, molluscs, arthropods
what is the structure of protonephridia
-network of closed tubules throughout the body
how does the interstitial fluid filter into the protonephridia
-it filters through membrane where cells interdigitate
-it filters into the lumen at the flame bulb
how do freshwater flat worms work
-they have protonephridia
-mainly osmoregulation
-most waste diffuses out of body or into gastrovascular cavity
-why they are flat: they have high SA:vol
how do parasitic flatworms work
-they have protonephridia
-they are in isotonic environments
-mainly excretion of nitrogenous waste
how does metanephridia work
-filter coelomic fluid
-take small solutes and waste
-tubules reabsorb NaCl and other solutes through active transport
-deals with osmoregulation and nitrogenous waste
what things interact in the metanephridia
-the capillary and the tubule interact
-different form kidney that it doesn’t come into contact wth the circulatory system till later
where are excretory tubules seen
in insects
what are Malpighian tubules
-seen in insects
-acts as a dumping ground
-junction tubules empty out and waste goes into midgut
-all comes out as solid because of uric acid
how do malpighian tubules work
-K+ is secreted into the tubule lumen
-accumulation of K+ draws Cl- ions
-water enters by osmosis
-nitrogenous wastes are secreted in
K+ and Cl- are reabsorbed followed by water
-uric acid ppts as crystals
