The urinary system and Renal physiology (chapter 25) Flashcards
how much fluid filtered from blood by kidneys every single day?
200 liters
Maintaning the composition of the body’s extracellular fluids by filtering the blood. This involves
* regulating total body water volume and concentration of solutes in water
* regulate concentration of ions in ECF
* acid-base balance
* remove toxins, metabolic wastes and foreign substances
* hormone production -EPO(RBCs) and Renin(blood pressure)
kidneys
true or flase:
Kidneys are retroperitoneal organs
True
ureters, renal blood vessels, lymphatics, and renal nerve supply enter here
renal hilum
sits immediatley superior to each kidney
adrenal gland
- dense connective tissue
- anchors kidneys to surrondings structures, prevents spread of infection
renal fascia
- fat mass surrounding kidneys
- cushions kidneys from physical trauma, layer of adipose tissue that surrounds each of the kidneys. Kidneys are vulnerable to physical trauma since they are not near bone so adipose tissue helps in absorbing shock
perirenal fat capsule
- thin, transparent capsule
- prevents disease from spreading to kidneys from other parts of body
Fibrous capsule
- provides area for glomerular capillaries and blood vessel passage, EPO produced here
- glomerular capillaries are responsible for filtrate which is the first step in urine formation
- EPO stimulates rbc production
Renal cortex
- contains renal pyramids–> packed with capillaries and urine collecting tubules
- seven renal pyramids separated by renal columns
- renal pyramids + surrounding columns=kidney lobe
Renal Medulla
- open space in center of each kindey
- Branches to form Major/Minor calyces
Renal pelvis
- urine collection from renal medulla
- pathway to get urine from renal pyramid out of kidneys towards the bladder
Major/Minor calyces
- deliver to kidneys, divde into smaller blood vessels to serve major regions of kidneys
renal arteries
deliver blood to higher and lower secretions of kidneys
segmental arteries
travel between kidney lobes
interlobar arteries
arch over bases of pyramids
arcuate arteries
supply cortical tissue
cortical radiate arteries
True or false
veins trace arterial supply but in reverse
true
autonomic nerve fibers and ganglia
renal plexus
has control over blood vessels
sympathetic division
adjusts diameter of renal arterioles to adjust blood flow to glomeruli
sympathetic vasomotor fibers
- functional unit of the kidney
- responsible for forming filtrate and eventually urine in the kidneys
Nephron
each nephron contains a
renal corpuscle and renal tubule
- filters blood to form filtrate
- located in the renal cortex
renal corpuscle
reabsorbs what is needed for the body from the filtrate and secretes more substances into the filtrate
renal tubule
cluster of blood vessels
glomerulus
blood enters glomerules via…..and leaves via…..
- afferent arterioles
- efferent arterioles
True or false
capillaries are very porous
true
double layered structure that completely surronds glomerular capillaries
glomerular capsule
The glomerular capsule inner layer has 2 structures
Podocytes and foot processes
(There is not a lot of open space between processes it prevent large size substances from entering the filtrate)
begins in the renal cortex and extends into renal meduall, then returns to renal cortex
-the hairpain structure helps increase surface area which is more affective
renal tubules and collecting ducts
- leads immediatley off from glomerulus
- located in renal cortex
- large cuboidal epithelia cells with dense microvilli
- microvilli increases absorption and secretion
Proximal convoluted tubule (PCT)
- travels between renal cortex and renal medulla
- allows the kidney to vary the concentration of urine according to how much water is reabsorbed
nephron loop
- portions continuous with PCT
- high permeability to H20, low permeability to solutes
- water can cross wall of descending limb but solutes cannot
descending limb
- continuous with DCT
- high permeability to solutes, low permeability to H2O
- solutes can cross wall of ascending limb, but water cannot
Ascending limb
- located in cortex, composed of small cuboidal epithelia
- smaller diamter than PCT, contain no microvilli
Distal convoluted tubule (DCT)
- pass through cortex and medulla
- waste goes through
- receives filtrate from tubules of multiple nephrons
collecting ducts (collecting ducts fuse together, dump urine into minor calyces)
2 important cell types in collecting duct
Principal cells and intercalated cells
- maintain Na+ balance in body
- influence absorption of water
Principal cells
Helps maintain acid-base balance
Intercalated cells
- located almost entirely in the cortex
- small portion of nephron loop found in renal medulla
Cortical Nephrons
- Nephron loops deeply invade renal medulla
- have a longer nephron loop so its more useful to form highly concentration urine
- better ar reabsorbing water
Juxtamedullary Nephrons
- maintains high pressure to increase filtrate production
- Fed and drain by arterioles to keep high pressure
Glomerulus
- low pressure capillaries arising from efferent arteriole (want low pressure since it allows as much reabsorption as possible)
- cling to proximal and distal tubules of cortical nephrons (reabsorbs water and solutes from tubule cells)
- empty in venules–> filtered blood returns to circulation
Peritubular capillaries
- found only on juxtamedullary nephrons
- run parallel to long nephron loop
- forms more concentrated urine
vasa recta
(The more the vasa recta reabsorbs water from nephron loop= the more concentration the urine/filtrate will be)
- portion of nephron where distal ascending limb lies against arterioles
- regulate blood pressure and filtration rate of the glomerulus
Juxtaglomerular complex
- chemoreceptor cells
- monitor NaCl content of filtrate entering distal convoluted tubule
macula densa
- specialized smooth muscle cells
- found in arteriolar walls of afferent arteriole
- can sense blood pressure in afferent arteriole
- have baroreceptors
- secrete renin
granular cells
low NaCl concentration…
increases renin release
- packed between tubule and arterioles
extraglomerular mesangial cells
allows passage of water, small solutes into glomerular capsule
Filtration membrane
pores in capillary walls allow all but large proteins and cells to pass through (allows fluid to squeeze through, but pores are small enough to not let large proteins in)
fenestrated endothelium of capillaries
negatively charged layer that allows only passage of small molecules and electrically repels other macromolecular anions
basement membrane
- foot processes create filtration slits
- slits prevent passage of macromolecules/large sized materials into filtrate
Foot processes of podocytes
pressure that force fluid into or out of glomerulus
filtration pressure
- promotes filtrate formation
- fluid moves from capillary into glomerular capsule
outward pressure
blood pressure of the glomerular capillaries that forces fluid into the surrounding space
Hydrostatic pressure in glomerular capillaries
- oppose filtrate formation
- fluid moves from glomerular capsule and into glomerular capillary
inward pressure
pressure exerted by filtrate that is already in the glomerular capsule
hydrostatic pressure in capsular space
- proteins that are still in capillaries will “pull” water back in
- always have a net pressure on 10 mmHg
Colloid osmotic pressure in glomerular capillaries
the total volume of filtrate formed per minute for all nephrons in the kidney-125 mm filtrate per minute
Glomerular Filtration rate
Increase of decrease the 10 mm HG then you either forming more or less filtrate
Net filtration pressure
adjust surface area of capillaries
-contraction will cause less surface area–>decreasn filtration formation
Glomerular mesangial cells
kidneys adjust resistance to blood flow
renal autoregulation
smooth muslce contracts when stetched
Myogenic mechanism
controlled by Macula densa of juxtaglomerular complex (JGC)
Tubuloglomerular Feedback Mechanism
The sympathetic nervous system will override renal autoregulation
Neural Mechanisms (extrinsic)
- overall affect is to increase blood pressure
- granular cells of JGC stimulated to release renin
renin Angiotensin Aldosterone mechanism (hormonal Mechanism)
substances move in between kidney tubule cells
paracellular
substances move through kidney tubule cells
transcellular
collecting ducts have no aquaporins until…. is present
ADH (antiduretic hormone)
Any pathway using a transport potein has a
transport maximum (Tm)
- inhibits urine formation by increasing water reabsorption to blood
- directly proportional to number of aquaporins inserted
Antidiuretic hormone (ADH)
- promotes Na+ reabsorption by principal cells of collecting ducts
Aldosterone
inhibits Na+ reabsorption in collecting ducts
Atrial Natriuretic peptide (ANP)
Increase reabsorption of calcium in the DCT
Parathyroid hormone (PTH)
- selectively moving substances from the blood and back in the filtrate
- main site is PCT
secretion
the normal solute concentration of body fluids and ICF is…
300 Mosm
movement of fluids in the opposite direction through the nephron loop allows exchange of material
countercurrent exchange mechanism
- occurs in ascending and descending limb of juxtamedullary nephron loops
- movement of solutes and water out of nephron loop allows for formation of concentrated urine
countercurrent multiplier
- flow of blood through the ascending and decending limb of the vasa recta
- vasa recta reabsorbs water to maintain gradient of multiplier
countercurrent exchange
- countercurrent exchange mechanism establishes a …..
- kidneys can vary urine concentration
Meduallary Osmotic Gradient
- GFR of <60 ml/min for 3+ months
- filtrate formation decreases–> wastes build up, blood pH decreases
- caused by: diabetes mellitus, hypertension, pyelonephritis, physical trauma
Chronic renal disease
- “urine in the blood” (nausea,muslce cramps, mental changes, fatigue etc)
uremia
patients blood passed through selectively permeable membrane tubing
Hemodialysis
color of urine comes from presence of…
urochrome
the ratio of mass of a substance to the mass of an equal volume of distilled H20
Specific gravity
Tubes that allow urine to pass from the kidneys to be stored in the bladder
Ureters
what are the 3 layers of the ureter?
- Mucosa
- Muscularis
- Adventitia
- Build up calcium, magnesium salts and uric acid in kidneys
- severe abdominal pain, nausea and vomiting, cloudy/foul-smelling urine
Renal Calculi (Kidney stone)
Stones can remain lodged in the renal pelvis
Nephrolithiasis
Stones can become lodged in the ureter
Ureterolithiasis
- found in abdominopelvic area
- stores urine temporarily
- …. has three openings
- Bladder
- Trigone
Human bladder normally holds up to…
400-500 ml of urine
critical capacity of urine
1000ml urine
- Extends from bladder, leads out of body
urethra
- thickening of detrusor muslce
- closes urethra when urine is not being passed
Internal urethral sphincter
- closes urethra when urine is not being passes
internal urethral sphincter
….also helps close off urethra (contracts with more force when your legs are closer tg)
Levator ani muscle
the act of empyting the bladder
micturition
Control of micturition:
pons has
Potine micturition center and Pontine Storage center
- Anything that enhances urine output
Diuretics