Urinary System Flashcards
What are the three things the kidneys are responsible for regulating and keeping in homeostatic conditions?
Regulate
1. total body water and osmolarity
2. Ion concentrations in the ECF
(Na+, K+, Ca2+)
3. Acid-base balnce (pH)
What do the kidneys do with vitamin D?
Convert to its active form calcitrol
What can the kidneys do during fasting or starvation?
Gluconeogenesis via taking other types of molecules (proteins, fatty acids, amino acids) and converting them to glucose.
What hormone and what enzyme do the kidneys produce?
- Enzyme: Renin
- Hormone: Erythropoietin
What does it mean to say that the kidney is in the retroperitoneal position?
Behind the peritoneal membrane that lones the digestive cavity
What does the kidney bean visually resemble?
A kidney bean with a hilum
What sits ontop of each kidney?
Adrenal gland
What are the three supportive layers in order from superficial to deep of the kidney?
- Renal Fascia
- Perirenal fat Capsule
- Fibrous capsule
What is the role of the renal fascia?
Hold the kidneys in roughly the same place
Describe the perirenal fat capsule
A big heavy-duty layer of fat that is protective.
Describe the fibrous capsule of the kidney and its role
It is very tighly bound to the surface of the kidney that is designed to sort of suran wrap the kidney with heavy duty layer of protective tissue.
Is the fibrous capsule of the kidney ment for friction free movement?
No
What are the prenchymal (functional) structures of the kidney?
Cortex - All Corpuscles
-Outer Layer = PCT
-Renal Columns = DCT
Medullary Pyramids = Nephron Loops
What are the collecting structures of the kidney?
-Minor Calyx
-Major Calyx
-Renal Pelvis
-Ureter
-Bladder
-Urethra
-Out
What is meant by a “lobe” in the kidney?
1 medullary pyramid and the renal cortex that overrises it
What is the correct order of arteries in the kidney starting at the Aorta and ending at the efferent arteriole?
Aorta
Renal a.
Segmental a.
Interlobar a.
Arcuate a.
Cortical radiate a.
Afferent arteriole
Glomerulus
Efferent arteriole
What is the order of veins returning to the heart from the kidneys starting at the efferent arteriole?
Efferent Arteriole
Peritubular capillaries & Vasa recta
Cortical radiate v.
Arcuate v. (Vasa recta also flows into here)
Interlobar v.
Renal v.
Inferior Vena Cava
What is the functional and structural unit of the kidney?
Nephron
How many nephrons does each kidney have?
1 million
What does each nephron consist of
A renal corpuscle and a renal tubule?
Does only one nephron or do many nephrons feed into a single collecting duct?
Many
What comprises the renal corpuscle?
-Glomerulus
-Glomerular corpuscle
Describe the capillaries of the glomerulus
They are a ball of fenestrated capillaries that allow for filtration of everything except blood cells to occur more rapidly.
What doesn’t the glomerulus filter?
Everything but cells and proteins to pass from blood to the filtrate.
What is filtrate?
Whatever is filtered out of the blood
Describe the glomerular capsule
it surrounds the glomerulus and is continuous with the tubule.
What are the layers of the glomerular capsule and what are the comprised of?
Parietal layer - simple squamous epithelium
Visceral layer - podocytes that wrap around the capillaries
How long is the renal tubule and how many regions does it have?
-3cm
-3 regions
What are the three regions of the renal tubule?
-Proximal Convoluted Tubule (PCT)
-Nephron Loop
-Distal Convoluted Tubule (DCT)
Describe the PCT
It is comprised of simple cuboidal epithelium with many mitochondria and microvilli
Why would the PCT have a lot of mitochondria and microvilli?
The large amount of mitochondria indicate a large amount of energy being utilized and the large amount of microvilli increase the surface area for reabsorption.
What kind of transport would be occurring at the PCT?
Active Transport
About what percentage of your bodies ATP is utilized by the PCT)?
6%
Describe a generic nephron loop
A long tube with descending and ascending limbs that have thick and thin segments.
Describe the thick segments of the nephron loop
Simple cuboidal epithelium that is not permeable to H2O
Describe the thin segments of the nephron loop
Simple squamous epithelium that is permeable to H2O
What does the ascending limb of the nephron loop connect to?
DCT
Describe the DCT
Comprised of simple cuboidal epithelium with no microvilli or mitochondria
Describe the collecting duct
It is comprised of cuboidal cells (2 types) and drains into the minor calyx.
What is obligatory reabsorption?
The things we must reabsorb.
What are the two classes of nephrons and what are the percentage of each in the kidneys?
Cortical Type - 85%
Juxtamedullary Type - 15%
Describe the cortical type of nephron
-They are almost entirely in the cortex
-They have short nephron loops
-They filter blood and form urine
-Are associated with the peritubular capillaries
Describe the juxtamedullary type of nephron?
-Originate near the cortex/medullary border
-Very long nephron loops
-Filter blood, make urine, and maintain a salinity gradient in the medulla so urine can be concentrated
-Associated with the vasa recta
What is the salinity gradient in the medulla so important?
It allows urine to be concentrated and for H2O to be conserved which allows us to live on land.
Should reabsorption occur in the glomerulus?
No
What about the A&P of the glomerulus specializes it for filtration?
It is fed and drained by the arterioles which keeps the pressure high and forces filtration.
Describe the peritubular capillaries
They wrap around the tubule and readily reabsorb water and solutes that we need to get back after filtration and are associated with the cortical type of nephron loop.
Describe the vasa recta
Very long, straight vessels that play a role in concentrating urine and are associated with the juxtamedullary type of nephron loop.
Where is the juxtamedullary complex at?
Point of contact where the distal ascending loop lies against the afferent and efferent arteriole
What is the role of the juxtamedullary complex?
To regulate the rate of filtration and systemic blood pressure.
What do the macula densa cells do?
They monitor the NaCl content of the filtrate to find out how fast the filtrate is still moving and to make an estimate of systemic blood pressure based on the speed of the filtrate.
What determines filtration?
BP
How can the macula densa cells determine BP based on the speed of the filtrate?
The faster the filtrate moves the less NaCl is reabsorbed into the body (so the higher the BP)