The Excretory System Flashcards

Question

Nephron

Answer 1

Nephron is the functional unit in the kidney Charged with/ responsible for filtration and collection Situated in two parts of the kidney first part is outside area like the shell of the kidney, as a shell we call it the renal cortex a term heard of before like adrenal crotex, just means hte shell! ligther tan part Situated between cortex and medulla (meaning middle) ~1 million nephrons in each kidney Nephron has four regions: 1. Bowman’s capsule surrounding glomerulus 2. Proximal convoluted tubule 3. Loop of Henle 4. Distal convoluted tubule

Answer 2

This means bulk movement of fluid with lots of dissolved ions and nutrients from blood into Bowman's capsule which is the blue lines! Through process of filtration, a lot of material moves through blood stream through glomerulus into nephron which forms the filtrate! blue box filtrate lists what forms filtrate to have it in front of us, ton of water goes into filtrate, salts including NACl, biocarbonates, urea, (part of point to get urea into filtrate) glucose, amino acid, some drugs, ton of stuff The criterion that allows material to pass into bowman's capsule is **really size! Big things stay behind and smaller things go to bowman's capsule,** one example BLOOD CELLS never have blood in urine or something is wrong! Also some really big proteins in blood that are too big to enter the nephron through this process of fitlration, will talk about a bunch called albumin big solid, protein that sits in blood to make sure there is always some SOLUTE IN THE BLOOD! Other function it has is to help transport lipid soluble hormones like last time, aldosterone, esterogen, testosterone can hitch a ride on albumin, big solute doesn't go into filtrate

Answer 3

* filtrate needs to exchange material with the blood so much interplay with the blood capillaries wound all over the place * useful to trace the flow here afferent arteriol from renal artery= arteries branch into smaller vessels called arterioles labeled at top of image is afferent material * then goes into capillary netowk calld glomerulus, hidden inside of ohter structure called bowman's capsule * in terms of the blood--\> blood goes from afferent arteriole to glomerulus which is capillary then into efferent arteriole then more capillaries called vasa recta! * then back out through renal vein * so know how to recite the order of vessels * capillary beds are what connects artery to veins in kidney\* wheich connects the artery adn vein can have O2 flow out and nutrients flow in! peritubular capillaries= collect nutrients that our kidneys will filter vasa recta (O2) efferent arteriole than vasa racta then renal vein\* why it is unusual you have afferent arterial, then clomeruls which is capillary but then have another arterial efferent, then another vasa recta another capillary bed and then goes into vein\*\* goes arteriole capillary arteriole capillary then vein, so that is why it is werid\*

Answer 4

Renal artery\>\>\>Afferent arteriole\>\>\>\>Efferent arteriole\>\>\> Vasa recta\>\>\> Renal vein Glomerulus and Vasa recta are capillaries\*

Answer 5

1. high blood pressure, higher GFR 2. low blood pressure, decrease GFR top page 111 B/c this depends on blood pressure, if somone is hemroagging the kidneys can fail becuase bp crashes when bleed out many systems in trouble but kdiney is one of them specifically that needs a certain minimum blood pressure to keep this system going

Answer 6

* we do not want to lose these nutrients so process of refinign what is actually in the filtrate is very important stuff moving from blood into bowman's capsule, driven by blood pressure\*\*\* * people talk about glomerulra filteration rate, or GFR\*

Answer 7

* glucose reabsorbed bykidney here, still means when see word always means THIGN IS GOING INTO BLOOD so it is going back to the blood ALWAYS\* * can see in figure Hco3-, NaCl, H20, nutrients espeically glucose, K+ all beign reabsorbed * what is red in this image is active transport, purple passive * under normal circumstances, a lot of important things we do not want to get rid of are supposed ot be going back to the blood in the proximal tubule. * Concentration of filtrate is VERY similar to concentration of blood, close connection capillaries not really shown in these images, similar to concentration in proximal tubule * There is an easy exchange between those two compartments\*

Answer 8

* if blood sugar is really high, the rate at which glucose goes into filtrate is very very high * all of that glucose can overwhelm transporter proteins supposed to bring glucose back to the blood * filtrate can flow all the way through proximal tubular and still some glucose will not be absorbed properly becuase there is just so much of it * tha tis why sign someone has diabetes they have glucose in their urine\*\* real explanation blood glucose high and the filtrate glucose will be very high, concentration of glucose in filtrate exceeds capacity of glucose transporters tha are supposed to reabsorb the glucose to the blood

Answer 9

* the area surrounding the nephron becomes MUCH MORE COCNENTRATED with solute, including salt and urea, environmen taround nephron is changing * also walls of descending limb are permeable to water, which means as fitlrate flows down and there is all this saltiness right outside in medulla, water naturally flows out of nephron into interstitial area (word for area not inside cell/ not inside blood stream just like an open area in body with fluid * purple arrow passive flow of water out of loop of henle out of nephron into surrounding for descending loop, filtrate gets darker blue at bottom meant to represent filtrate getting much mroe concentrated because a lot of water is being lost on the way down * on the way up, ascending limb is permeable to salt BUT NOT TO WATER\*\*\* * as go up up toward cortex area around nephron becomes less salty, less concentrated so in order for the nephron to stay isotonic same concentration with its surroundings, now it is salt that moves, as filtrate flows up salt is lost makes filtrate less concentrated on the way up! * toward distal convoluted tubule have to use energy to pump some out, the rest will take care of it on its own, stuff remains salty * once ascending limb, sodium left due to passive transport water will follow it, then when water left even saltier solution there in filtrate more sodium going to leave, so how we can get inc and inc saltier the deeper we go down * whole thing is that once sodium leaves water follows it, since salt cannot leave until enters into ascending limb how we pull all water/salt out if tube! -also bed of capillaries surrounding loop of henle, water will be picked up and go right to blood

Answer 10

proximal tubule refines, called reabsorption which always means stuff going from filtrate to blood reabsorbed back ot blood back to body, not going out in urine!

Answer 11

* b/c active transport implies proteins in membrane pushing back stuff into blood, also implies can be a maximum rate for process because can run out of active sites on transporters if have a huge concentration of glucose * also connects to situation where all those transporters become saturated, if glucose concnetration is really really high as filtrate moving through proximal tubule siutation where glucose transporters working as fast as they can but they get saturated, very analogous to transport maximum very much like vmax here * so a lot of kinetics learned in context of enzymes they like to somehow ask about it a bit here--\> so can be a vmax or transport maximum for glucose one thign to say is affinity of glucose for transporters just as can talk abotu affinity of substrate for enzymes if more transporters present or working faster has no impact on Km of individual transporter for glucose, more transportesr have transport maximum for Vmaxx but same Km which is exactly how it si with enzymes\* Km doesn't change bc affinity has to do with how well substrate adn transporter bind to each other. has to do with what kind of chemical bonds are involved, what is the mechanism of transport. so whether there is one transporter doing that mechanism or 1000 affinity is an individual level thing. * creates an upper limit how fast it can go, only so many transporters all busy binding glucose but there are only so many of them so the transporter binding sites get saturated gives you a transport maximum * if you suddenly put in twice as many transporters can double transport max, doubel vmax like if you double amount of enzyme can double vmas

Answer 12

Each substrate enters filtrate at a certain rate Each substrate returns to blood at a certain rate 3. **Key fact is filtration rate is greater than reasborption rate then a substance will appear in urine SO we can say if GFR (glomerulr filtration rate is greater than the Tm (reabsorption transport maximum)** than the substance will appear in urine, biggest context they like to ask about this is in diabetes Maximum tubular reabsorption rate (Tm) varies for each substance Maximum tubular reabsorption rate (Tm) reflects saturation of carrier proteins **If filtration rate \> reabsorption rate, excess substance appears in urine** Example: glucose in urine in diabetes mellitus

Answer 13

1. NaCl purple arrow passive transport leaving 2. then pumped out active transport as move up keeps medula salty, want medulla ot be more concentrated then teh cortex so it is this pumpign of NaCl that helps that happen WANT MEDULLA TO BE SALTIER, want gradient!!! maintaing a gradient where medulla is more salty than cortex is really important and we will get to why, this pumping of sodium chloride is part of maintaining that gradient

Answer 14

**this is a moment at top of loop of henle, filtrate much less concentrated then immediate surroundings, much less concentrated than blood, HYPOTONIC TO BLOOD** **ONLY PLACE NOT ISOTONIC** -overall priority is to not get dehydrated, its adaptive for us to be able to conserve water/ most of this nephron stuff is set up to conserve water, but may be some situations, but it is possible and bad for organisms to have too much water, you can actually drink too much water, so the idea that it is possible to make a filtrate less concentrated then blood if priority is to get rid of water this is a mechanism that allows us to do that, mostly geared toward making filtrate more concentrated then blood, this is a key moment want less concentrated then blood, incase that is what the body actually needs, this is when you can do it, if have 5 liters of water and decided not to go running

Answer 15

1. active transport reabsorption of bicarbonate, passive of H2O, NaCl active **2. K+ and H+ adding to filtrate there,** **another process called secretion\*** secretion means that material is being added late in game to filtrate because anything that is going into filtrate through secretion will be excreted from body 3. can see H+ is secreted a little bit in proximal tubule but more significant in distal, can see that if there is excess acidity or H+ good way to pump more into distal tubule and get rid of it, kind of like last chance to get rid of excess by the end should be isotonic with blood again, last part collecting duct now!

Answer 16

filtration= make filtrate originally reabsorpriton= goes back to blood secretetion= last chance to add more stuff into filtrate

Answer 17

Renal artery brings blood to kidney Renal artery branches into afferent arterioles Afferent arteriole branches into capillary network Capillary network coalesces in ball-like glomerulus Cup-like Bowman’s capsule surrounds glomerulus and receives filtrate from blood Bowman’s capsule feeds into proximal convoluted tubule Glomerulus is the first part of nephron - artery branches off to arteriole, called afferant meaning going towards arteriole - gives same arteriole as one single vessel but called this that goes off of it efferent, meanign left glomerulus\*

Answer 18

Proximal convoluted tubule feeds into hairpin-shaped loop of Henle Loop of Henle feeds into distal convoluted tubule Distal convoluted tubule feeds into collecting duct Collecting ducts collect filtrate into renal pelvis Renal pelvis filters into ureter Filtered blood leaves glomerulus via efferent arteriole Efferent arteriole branches to form capillary network (vasa recta) in medulla Vasa recta surrounds nephron and reabsorbs material from interstitial fluid

Answer 19

Fraction of blood plasma (~10%) is pushed into Bowman’s capsule = FILTRATION Pores in glomerular capillaries act like a sieve Fluid and small molecules in blood pass through Cells and most proteins cannot pass through Filtrate contains water, salts, urea, amino acids, and glucose In Bowman’s capsule, filtrate has roughly equivalent osmolarity to blood ~ 180 L is filtered each day through kidneys 1% excreted as urine = 1.5 L each day 99% is reabsorbed in nephron system

Answer 20

High blood pressure → increased glomerular filtration rate Low blood pressure → decreased glomerular filtration rate If glomerular filtration rate is too low, kidney can fail

Answer 21

Most reabsorption occurs in the proximal convoluted tubule Proximal tubule has villi/microvilli, “brush border” to maximize surface area Reabsorbs water, glucose, amino acids, vitamins from filtrate → back to blood Active and passive transport important for reabsorption **Reabsorption of Na+ by active transport** **H2O follows Na+ passively via osmosis**

Answer 22

Loop of Henle has descending limb and ascending limb Loop of Henle passes through a Na+ gradient: countercurrent system of absorption [Na+] is low in cortex, high in medulla Filtrate is concentrated on way down, diluted on way back up Active Na+ transport contributes to salt gradient Longer loop of Henle → more concentrated urine can be made (e.g., desert animals)

Answer 23

Descending limb is permeable to H2O, but not Na+ Descending limb: H2O moves osmotically out of tubule, concentrating filtrate

Answer 24

Ascending limb is permeable to Na+ but not H2O Ascending limb: Na+ diffuses out from concentrated filtrate, diluting filtrate At top of ascending limb, Na+ is actively pumped out

Answer 25

Actively moves blood H+ and K+ ions into filtrate

Answer 26

Actively moves blood H+ and K+ ions into filtrate = SECRETION Actively pumps out Na+ from filtrate Relatively impermeable to water Osmolarity at beginning of distal convoluted tubule is less than blood Site of aldosterone action Aldosterone promotes Na+ reabsorption, water follows More aldosterone → more H2O reabsorption to blood → increase blood pressure, volume Less aldosterone → less H2O reabsorption to blood → decrease blood pressure, volume

Answer 27

Renal tubules from several nephrons drain into a collecting duct Collecting ducts descend from cortex through medulla Colleting duct moves through salt gradient Site of ADH action If ADH present, collecting duct is permeable to H2O (leaves filtrate by osmosis) If ADH is absent, collecting duct is impermeable to H2O More ADH → more H2O reabsorption to blood → increase blood pressure, volume Less ADH → less H2O reabsorption to blood → decrease blood pressure, volume

Answer 28

- filtrate goes down and becomes much more concentrated again, a little NaCl pumping out but main thing/net change going down through collecting duct filtrate becomes much more concentrated much saltier, **we can conserve water by sending water back to the blood** - filtrate at bottom of collecting duct is about 4x as concentrated as blood - units that people use for this are called miliosmo per liter, blood like 300 miliosmos per liter\* and the urine is about like 12000 miliosmos per liter in terms of solute concentration Loop of henle set up pumping of sodium chloride happens to keep medulla salty, but when you really really take advantage of that is when coming down through collecting duct at the end, gets very concentrated and how get water and urine much more concentrated then blood, otherwise losing so much water all the time and we would have to drink about 4x as much water if we didn't have this mechanism, key is to help keep medulla salty, works for us and sets us up for collecting duct

Answer 29

acts on DISTAL TUBULE 1. stimulus low blood volume/low blood presssure, sensed by the kidney itself 2. kidney releases Renin 3. angiotensinogen from liver, cleaved by renin 4. angiotensin I is cleaved by ACE to angiotensin II, which tells adrenal gland to create aldoesterone! **5. aldoesterone acts on distal tubule causes more NA+ absorption, and then water follows, raises blood volume and blood pressure,** restoring homeostatis, original simtulus blood volume too low blood pressure too low kidney senses that and then we go through this whole pathway and then we end up with mechanism that raises blood pressure

Answer 30

aldosterone

Answer 31

ppl with high blood pressure= inhibits angiotensin I conversion to angiotensin II puts block in pathway, so lower down get less aldoesterone so medication that would keep blood pressure lower\* a lot of medication to lower blood pressure act on kidney, sometimes ppl with high blood pressure taking 3, 4, 5 different medications very challenging to lower someone's blood pressure without screwing up ion balances, in a way if you just give someone a diereatic and pee out a lot of water, lowers blood pressure but really messes with concentration of ions, all these other drugs have to get around it in differenet ways, so many ppl have high blood pressure

Answer 32

Antidiretic hormone-reabsorb water in collecting duct - ADH secreted: low BP or dehydrated ADH NOT secreted: High BP (blood pressure) or hydrated

Answer 33

......collecting duct is permeable to H2O (leaves filtrate by osmosis) If ADH is absent, collecting duct is impermeable to H2O

Answer 34

More ADH → more H2O reabsorption to blood → increase blood pressure, volume

Answer 35

Less ADH → less H2O reabsorption to blood → decrease blood pressure, volume

Answer 36

**-antidieretic hormone -made in hypothalumus and secerted from posterior pituitary** -hypothalamus senses high blood osmolarity meaning that lots of solute less solvent! so that would also imply low blood volume and low blood pressure, a very similar trigger to what we just said for aldosterone Pathway= ADH acts on collecting duct **-inc water reabsorption, more aquaporin channels/water channels are inserted into the wall of the collecting duct,** so get more watery absorption, more water going back to the blood to raise blood volume and raise blood pressure\*\* blood volume inc blood pressure inc so adh and aldosterone both redundant both raise blood vol and blood pressure, just act in different ways

Answer 37

**-inhibits release of ADH**, which means its a dieretic, inhibits antidieretic - have to really really go to bathroom an hour or two later, everything drinking will pee out peeing everything out you would be taking in even if you need it "don't break the seal"- no such thing, not releasing ADH and peeing everything out

Answer 38

**In the Liver** part of what goes out through urine is urea, last bullet point mentioning that insects, reptiles and birds excrete uric acid, which is an even less toxic form of nitrogenous waste, and normally wouldn't get into anything with animals, how do birds get rid of nitrogenous waste, answer is uric acid\*\*\*\*\*

Answer 39

CO2 in blood combines with H2O to form carbonic acid Carbonic acid gives rise to H+ and bicarbonate Reaction catalyzed by carbonic anhydrase: CO2 + H2O ← → H2CO3 ← → H+ + HCO3– Must maintain blood and interstitial pH **H+ secreted into filtrate at distal convoluted tubule → into urine** **K+ critical for muscle contraction** K+ excess in blood and interstitial fluid decreases strength of muscle contraction Heart can fail at high K+ levels K+ secreted into filtrate at distal convoluted tubule → into urine

Answer 40

H+ secreted into filtrate at distal convoluted tubule → into urine very important for pH regulation

Answer 41

K+ critical for muscle contraction K+ excess in blood and interstitial fluid decreases strength of muscle contraction Heart can fail at high K+ levels K+ secreted into filtrate at distal convoluted tubule → into urine

Answer 42

Sterile mixture of water, salts, urea, and minor metabolic products Hypertonic to blood and interstitial fluid Roughly 4× as concentrated as blood

Answer 43

Negative feedback controls blood pressure homeostasis **When blood pressure is high, ADH and aldosterone are inhibited** **When blood pressure is low, ADH and aldosterone are secreted** ADH and aldosterone increases H2O reabsorption → increases blood volume & pressure ADH regulated by blood osmolarity, sensed in hypothalmus Aldosterone is regulated by renin-angiotensin pathway (minor role for ACTH) Renin cleaves angiotensinogen to angiotensin I Angiotensin converting enzyme (ACE) cleaves angiotensin I to angiotensin II Angiotensin II stimulates aldosterone secretion, vasoconstriction, and thirst Some anti-hypertensive drugs inhibit ACE

Answer 44

Diuretics interfere with ADH action (e.g., caffeine) Diuretics → dehydration (more H2O excreted in urine)

Answer 45

Ammonia (NH3) is converted to less toxic urea in the liver Insects, reptiles, birds excrete uric acid = conserves (contains little) water

Answer 46

sodium ions, smaller proteins subunits like amino acids and also glucose can leak out\* they get from arteriole into bowman's space, made up of cells and the cells that line our vessels are called endothelial cells endothelial cells have nucleus and other organelles, eukarotyoic cells they are fenestrated

Answer 47

- sets up concentration gradient in medulla - pumps sodium Na+ out of tube, against its concentration gradient this is costing us ATP in order to do so so this is active transport in proximal tube - descending limb- permeable to water -if pump Na+ out to surrounding area and we have our filtrate passing by, we now have a very salty area, water inside tube will want to exit tube! less of me out there I need to go towards that particular substance, water needs to follow it becomes saltier there, once water exists in descending limb everything that remains wil be very very salty but cant have any salts pass durign descending limb because impermeable, so v salty then finally in asending limb green light saying we now have if want to mvoe down cocnentration gradient you can, what will happen, if salt given opportunity to leave it will nwo do so! only at this moment mvoes down concentration gradient, no atp is used so that is passive transport

Answer 48

- most reabsorption and secretion takes place in proximal convoluted tubule, relatively unregulated 1. where secretion and most reabsorption takes place reabsorbs sodium and chloride, also amino acids and glucose\* 2. when absorb things like this especially sodium take water with it as well, absorbed with proximal convoluted tubule reabsorbs about 65% of these important nutrients, the most of anywhere else in the nephron\*

Answer 49

water absorption! 1. last ditch effort do we want any more of this water or not, and so we talked about fact distal convoluted tubule entered control of Aldosterone. The collecting duct under control of ADH\*\*\* 2. release ADH when low blood pressure, or dehydrated, if pour more water in container/blood raise blood pressure, if dehydrated do no want to pee out precious water you have, want to get rid of it 3. means that when we are not releasing ADH then we are not going to get any water reabsorption! means water will not be reabsorbed stays in collecting duct form our urine, if high blood pressure or really hydrated then don't release ADH so pee out additional fluids you have, getting rid of additional fluids means less stuff in container will lower blood pressure, in fact one medication will put ppl on if have high blood pressure is a dieratic, get rid of fluids in body can lower blood pressure!

Answer 50

- blood comes into kidneys entering through the renal artery, have 2 renal arteries - have filtration of our blood from that filtrate we process it and reabsorb some ions adn water, as we reasborb what is important we collect it in our renal veins\*\* - renal veins take returned or reabsorbed nutrients into our blood and moves it on its way\*

Answer 51

**filtration= take blood and filtrate it out so have all our waste products and important amino acids pass to kidneys, want to get rid of waste we do not need, so another important function of our kidneys is collection** -so kidney takes our blood and puts out urine, single functional unit\*\* single smallest functional unit of the kidney= THE NEPHRON * -filter blood release urine, collection of waste products urine will hang out in bladder until appropriate time to go to the bathroom * each kidney has oxygenated blood vessels can be nutrients like electrolytes, sodium ions, proteins and amino acids, even glucose that build carbohydrates what body uses as building blocks to help other structures of your body work, also with nutrients oxygen with arterial blood and waste products, things cell made with respiration, urea and other toxic compounds **we dont want to build up also can include extra electrolytes like Na+ if hold onto a lot of sodium inc blood pressure\*** if have too much nutrients become waste products, so kidneys help to make sure you balance, not too much of each

Answer 52

**-screening out blood cells and large proteins, preventing them from entering Bowman's capsule** - vessels have lots of holes, very holy= endoltheial - allows amino acids and glucose to slip through, some of these holes can allow bigger proteins to come through but they still do not because another layer sits between endothelial cells and tubular

Answer 53

= filtrate or primary urine\* -the retained blood cells and proteins circulate through the pertiubular capillary beds

Answer 54

FILTERS BLOOD to produce URINE to maintain homeostasis maintaing homeostasis (pH, blood pressure, osmolarity etc. ) of body fluid volume and thereby regulating blood pressure maintaing homesotasis of plasma solute composition and helping control plasma pH excreting waste products, such as urea, uric acid, ammonia, and phosphate

Answer 55

ball like structure in middle is the glomerulus, main site of filtration\*\* takes blood coming in from renal artery pushes out fluid, taking out ion, waste where we take blood and turn it into filtrate and let the rest of the blood flow on leaks out fluid, which is caught in the capsule, containes onto the rest of our nephron and its capsule has a name called Bowman's capsule

Answer 56

- for afferant= inc diameter, more space, and more runners inc filtration - for efferent- if inc diameter allow ppl to leave will not stay around here for a long period of time, so filration rate will decrease\*\* blood moving away from place it would be filtered - if dec diameter of afferant, if dec amount of blood will be decreasing filtration - if dec diameter of efferent arteriole hard to let ions and amino acid, glucose hanging around adn around these holes, so blood will back up and so will these guys so there will be filtered through these holes and collecte dinto bowman's space so filtration will inc\*\*\*

Answer 57

filtrate is isotonic to its immediate surroundings\*\* so when going through the proximal tubule it is in very close proximity to blood so isotonic to blood, down loop fo henley immediate surroundings are interstitial fluid saltier or saltier so that is what it is trying to say isotonic too\*\*\* filtrate is always isotonic to its immediate otherwise to immediate surroundings

The Excretory System Flashcards

(81 cards)