Urinary System Part 3 Flashcards
What are the two types of countercurrent mechanisms?
- Countercurrent multiplier (des and asc)
2. Countercurrent exchanger (vasa recta)
What do the countercurrent mechanisms do?
establish and maintain medullary osmotic gradient from renal cortex through medulla
Gradient runs from _____ in cortex to _____ bottom of medulla
300 mOsm
1200 mOsm
Osmolarity is equal to
the concentration of a particular solute in a solution
solvent is water
vasa recta role in osmotic gradient
perserve the gradient
countercurrent exchangers
long nephron loops of juxtamedullary nephrons role in osmotic gradient
they create the gradient
countercurrent multipliers
collecting ducts role in osmotic pressure
use gradient to adjust urine osmolarity
The descending limb is permeable to ____ but not to ___
Water, salt
The ascending limb is_____ to H20, but permeable to_____
impermeable, salt
The amount of salt increases then the intersitial fluid osmolarity ____
Increases
The countercurrent exchanger perserves medullary gradient by
- preventing rapid removal of salt from intersitial space
2. removing reabsorbed water
where does the water in ascending vasa recta come from?
descending vasa recta or reabosrbed from nephron loop and collecting duct
How is the filtrate reaching the DCT dilute and allows the filtrate to be exerted to form dilute urine?
countercurrent mechanism
What releases concentrated urine and causes facultative movement of water?
ADH
Chemicals that enhance urinary output
ADH inhibitors- alcohol
Na+ and H20 reabsorption inhibitors -Drugs for hypertension and edema, caffeine
loop diuretics that inhibit medullary gradient formation
osmotic diruretics
What are osmotic diuretics?
substance not reabsorbed, so water remains in urine
ex. diabetic- high glucose concetrations pulls water from body
What is renal clearance?
vol of plasma kidneys can clear of a particular substance in a given time
Renal clearance tests are used to deteremine GFR to…
help detect glomerular damage
follow progress of renal disease
Renal clearance rate is calculated as
C= UV / P
C = renal clearance rate (ml/min) U = concentration (mg/ml) of substance in urine V = flow rate of urine formation (ml/min) P = concentration of same substance in plasma
What is inulin for ? (plant polysaccharide)
freely filtered and neither reabsorbed nor secreted by kidneys
its renal clearance = GFR 125ml/min
Why is constant GFR important?
allows kidneys to make filtrate and maintain extracellular homeostasis
What is the goal of the local instrinsic controls (renal autoregulation)
to maintain GFR in kidney
what is the goal of extrinsic controls? ( GFR )
maintains systemic blood pressure
What are the three mechanisms that regulate GFR?
- autoregulation: myogenic mechanism and tubuloglomerular feedback mechanism
- hormonal regulation
- neural regulation
Which mechanisms are instrinsic?
autoregulation: myogenic, tubuloglomerular feedback mechanism
Which mechanisms that are extrinsic?
Hormonal and neural regulation
What is the chemical compostion of urine?
95% water 5% solutes, nitrogenous wastes, acidic Ph 6
What are the nitrogenous wastes in urine?
urea (amino acid breakdown) , uric acid(nucleic acid metabolism) , creatinine (metabolic of creatine phosphate)
Why is urine yellow?
from urochrome (pigment from hemoglobin breakdown , yellow deepens with increased concentration)
What kind of diet causes a drop or increase in Ph?
acidic drops and alkaline increases
What is the pathway of urine?
collecting duct –> renal papillae –> minor calyx —> major calyx —> renal pelvis—> ureter —-> urinary bladder —> urethra
Function of ureters
slender tubes that convey urine from kidneys to bladder
As bladder pressure increases, the distal ends of ureters close, preventing….
backflow of urine
ureter wall layers
Mucosa; transitional epithelium (changes shape based on vol) and lamina propria
Muscularis: Longitudinal and circular layer
Adventitia: fibrous connective tissue
What are Renal calculi ?
kidney stones in renal pelvis: crystallized calcium, magnesium, or uric acid salts. block ureters, obstruct urine flow
nephrolithisasis
calculi in kidneys
ureterolithiasis
calculi in ureters
Urinary bladder function
muscular sac that holds urine
Where is the urinary bladder located?
retroperitoneal, on pelvic floor posterior to pubic symphysis
Males: prostate inferior to bladder neck
Females: anterior to vagina and uterus
Three layers of bladder wall
mucosa
smooth muscle
adventia (fibrous connective tissue)
What happens when urinary bladder is empty?
Produces rugae and collapeses
How much does the bladder hold?
Less than 500 ml
The internal urethral sphincter
involantary (smooth muscle) at bladder-urethra junction and has to contract to open
External urethral sphincter
voluntary (skeletal) muscle surrounding the urethra as it passes through pelvic floor
Female urethra: external urethral orfice
anterior to vaginal opening, posterior to clitoris
3 regions of male urethra
Prostatic urethra, intermediate part of the urethra, spongy urethra
Where does the prostatic urethra pass through?
within the prostate gland
Where does the intermediate part of the urethra pass through?
passes through the urogenital diaphragm from prostate to the beginning of the penis
Where does the spongy urethra pass through?
passes through penis, opens via external urethral orifice
Process of urination
- Detrusor muscle contract
- Internal urethral sphincter relaxes
- External urethral sphincter relaxes
