Ch. 24 & 25 Urinary System Flashcards
What is the primary function of the kidneys?
To produce urine and help regulate blood volume and blood composition
Calyx
Collects urine before it passes further into the urinary tract
Renal artery
Branch of the abdominal aorta that brings freshly oxygenated blood into the kidneys. For kidneys to produce urine, they need plenty of blood flow
Renal vein
Blood is drained after bringing oxygen to the kidneys by the veins into the inferior vena cava.
What is the nephron?
Where the urine is produced and blood volume and composition are regulated in the kidneys. Made of the glomerulus and renal tubule. There are about 3 million nephrons in both kidneys.
What is the Glomerulus?
A porus capillary bed that acts like a strainer, part of the nephron.
What is the Renal Tubule?
A yellow tubular structure surrounds the glomerulus.
What are the components of the Urinary System and what do they do?
2 kidneys- regulates BV and blood composition, produces urine
2 ureters- drains urine from the kidneys to the urinary bladder
1 urinary bladder- collects the drained urine
1 urethra- drains urine from the urinary bladder
What does the Renal Tubule do?
Collects material that goes through the glomeruli, getting filtered out of the blood. It collects this filtrate and transports it.
What are the components of the Renal tubule, listed proximal (surrounding glomerulus) to distal (into collecting dump)?
- Bowman’s capsule that envelops the glomerulus and initially collects filtrate.
- Proximal tubule
- Nephron loop/loop of Henle
- Distal tubule
Where does the filtrate go after the distal tubule (7 things)?
Goes to the collecting duct, papillary duct, urine, renal pelvis, ureter, bladder, and out of the body
What is filtration?
A process in the glomerulus that pushes things out of the bloodstream.
What does our body do with filtrate?
Either let what is in the filtrate stay until it is excreted as urine or get back something that we might have filtered out that we don’t want to pee off.
What do our kidneys allow us to do?
Keep what we need to keep and get rid of what we need to get rid of in specific quantities to maintain homeostasis.
What is the process-free filtration?
It does not matter the quantity, if it is present in the bloodstream and it fits through the pores, it gets filtered.
If someone’s kidneys aren’t working, could they develop anemia?
Yes, this is because there wouldn’t be enough RBC production. The kidneys produce a hormone called erythropoietin that tells bone marrow to produce and release more RBC into the circulation.
What are the 3 steps in urine formation by the kidneys?
- Filtration at Glomerulus- depends on renal blood flow, kidneys need plenty of blood flow
- Tubular Reabsorption
- Tubular Secretion
How much blood flow do the kidneys get?
They have a bunch of blood vessels and blood flow. They get about 25% of all our cardiac output.
What doesn’t normally get filtered?
WBC, RBC, platelets, and any significant amount of proteins don’t because they are too big to fit through the pours.
What are two factors that determine renal blood flow (Q)?
How the heart is working and the BV
How much volume we have circulating dictates what?
How much flow gets to a particular area
How much blood flow to the kidneys drives what?
Drives filtration and we need the heart and blood vessels to be working properly for this to happen.
What is the Glomerular Filtration Rate?
How much filtrate is produced by both kidneys per minute.
What do we do with about 99% of what we filter?
In terms of volume, we reabsorb or just keep what we filter. This is a good thing.
What does Tubular Reabsorption do?
It allows us to keep things that we filtered out that we need to keep.
What is reabsorption?
Moving things from the filtrate in the renal tubule system, back into the bloodstream
What is the difference between absorption vs reabsorption?
Absorption means we are moving something from a particular site into the bloodstream. Reabsorption means it was once in the bloodstream, went out of the bloodstream, and moved back.
What is Tubular Secretion?
Only a few things get secreted and the purpose is to get us to get rid of things that we have too much of. It is the opposite of reabsorption. It moves things from the blood (peritubular capillaries) back into the filtrate so it gets peed off.
What drives the Glomerular Filtration Rate?
-If you are dehydrated, GFR is going to decrease because it reduces blood volume and blood flow until the body tries to compensate.
-If you are bleeding, your GFR is also going to decrease because it reduces blood volume and blood flow.
Can you have a reduction in GFR with a normal BV?
Yes, anything that reduces renal blood flow (Q) would reduce GFR.
If someone had a heart attack, what would happen to their CO, blood flow, and GFR?
They all would decrease but this person would still have normal or high blood volume. When the heart isn’t working well the kidneys have to retain what they have and it takes longer to get rid of it. BV is the same but flow decreases.
What determines blood flow?
-A good heart
-Hydrated
-Not bleeding
What is the purpose of urine production?
To help regulate blood volume and blood composition (the components of the blood)
In Scenario 1, Na+ is at 140
-In normal range (135-145)
-Sodium will be filtered at the glomerulus because it fits and its present
-Sodium reabsorption is normal
If all we did was filter sodium, what would happen?
The levels would decrease
In Scenario 2, Na+ is at 160
-Hypernatremia, too high
-Sodium will be filtered at the glomerulus because it fits and its present
-Sodium reabsorption is decreased
In Scenario 3, Na+ is at 120
-Hyponatremia, too low
-Sodium will be filtered at the glomerulus because it fits and its present
-Sodium reabsorption is increased
If you increase flow to kidneys, what follows?
Increase in GFR and increase in urine output
What happens to make volume overloaded?
An increase in H2O intake because BV increases, GFR increases. Increase in Cardiac output, so increase in Urine Output.
What is TBW?
Total Body Water
The subtotal of all the water in the body
Where is TBW found?
- Inside the cells
-intracellular fluid (TCF)
-2/3 of TBW - Outside the cells
-extracellular fluid (ECF)
-80% of ECF in between cells & 20% in bloodstream
-1/3 of TBW
How did 2/3 of the water in our body get into our cells?
By moving from our bloodstream to interstital compartment to the cells.
Where does water go when you drink it?
- Bloodstream
- Interstital fluid
- Cells
What causes a shift of water from ICF to ECF?
The concentration gradient between the two compartments
What is a solution?
Made of Solvents and solutes (dissolved particules)
Normal Concentration
(280-300), Isotonic, No water shift
ex. Normal water w/ normal koolaid packet
More conentration
(>300), Hypertonic
ex. Less water w/ more koolaid packet
More Diluted
(<280), Hypotonic
ex. More water w/ less koolaid packet
Osmolarity/ Tonicity
The concentration of ECF
What drives the movement of water?
Concentration difference
Which concentration is easier to change more rapidly, outside or inside the cells?
Outside because blood is part of ECF so if you drink water, eat something sweet or salty, you change the amount of water/solute on the outside before the inside (easier access).
What is ADH?
It regulates or reduces the amount of water in our blood and urine, controls how much water our kidneys reabsorb, and helps maintain water and electrolyte balance.
What does Aldosterone affect?
How much sodium is in our blood and influence on the cencentration of ECF
In a Scenario, a student drinks a lot of water. What happens?
Assuming ICF is Isotonic, there is a shift from ECF to ICF because the ECF is more diluted from the water, making it hypotonic. The cells then expand.
TRUE OR FALSE: Water never shifts from more diluted to more concentrated.
FALSE, it always does.
In this Scenario, student eats a lot of salt.
Assuming ICF is Isotonic, there is a shift from ICF to ECF because the ECF is more concentrated from the salt, making it hypertonic. The cells then shrink.
In a scenario, a student has an ADH disorder (No ADH produced)…
-Increase in water loss, pee more water off and pee is almost pure water.
-ECF osmolarity is hypertonic
-Fluid shift because of gradient
-Shift is ICF to ECF
-Blood Volume decreases
-Cellular dehydration
In Scenario, a student has a compulsive water drinker disorder…
-ECF osmolarity is hypotonic
-Fluid shift becuaes there is a gradient
-Water goes from ECF to ICF
-Cells will expand, including all RBCs everywhere
-Could get water toxicitity
In Scenario, IV is placed of Isotonic Saline
-ICF and ECF are at equilibrium
-No shift in water because there isn’t a gradient
-Raise in BV
