Packet 26 Flashcards
Increases water permeability of principal cells so regulates facultative water reabsorption
Stimulates the insertion of aquaporin-2 channels into the membrane
–water molecules move more rapidly
Antidiuretic Hormone
When osmolarity of plasma & interstitial fluid decreases, more ADH is secreted and
facultative water reabsorption increases.
cells do not reabsorb water if ADH is low
principal
-having fewer solutes than plasma (300 mOsm/liter).
Water reabsorbed in thin limb, but ions reabsorbed in thick limb of loop of Henle create a filtrate more dilute than plasma
- –can be 4x as dilute as plasma
- –as low as 65 mOsm/liter
Dilute
can be up to 4 times greater osmolarity than plasma
urine
It is possible for principal cells & ADH to remove water from urine to that extent
–Long loop juxtamedullary nephrons make that possible
–Na+/K+/Cl- symporters reabsorb Na+ and Cl- from tubular fluid to create osmotic gradient in the renal medulla
Urea recycling causes a buildup of urea in the renal medulla
dilute and concentrated urine
Substances that slow renal reabsorption of water & cause diuresis (increased urine flow rate)
- -caffeine
- -alcohol
- -prescription medicines
diuretics
which inhibits Na+ reabsorption
caffeine
which inhibits secretion of ADH
alcohol
can act on the PCT, loop of Henle or DCT
prescriptive medicines
can act on the PCT, loop of Henle or DCT
–Kidney function is so impaired the blood must be cleansed artificially
dialysis therapy
directly filters blood because blood flows through tubing surrounded by dialysis solution
cleansed blood flows back into the body
–performed by artificial kidney machine
hemodialysis
10 to 12 in long Varies in diameter from 1-10 mm Extends from renal pelvis to bladder Retroperitoneal Enters posterior wall of bladder Physiological valve only --bladder wall compresses arterial opening as it expands during filling --flow results from peristalsis, gravity & hydrostatic pressure
ureters (anatomy)
Hollow, distensible muscular organ with capacity of 700 - 800 mL
Trigone
urinary bladder
smooth flat area bordered by 2 ureteral openings and one urethral opening
trigone
- Posterior to pubic symphysis
- anterior to vagina & inferior to uterus
- lies anterior to rectum
Both
Females
Males
signal spinal cord and brain
when volume exceeds 200-400 mL in urination
stretch receptors
Impulses sent to ____ in sacral spinal cord (S2 and S3) & reflex is triggered
parasympathetic fibers cause detrusor muscle to contract, external & internal sphincter muscles to relax
micturition center
Filling causes a sensation of fullness that initiates a desire to urinate before the reflex actually occurs
- -conscious control of external sphincter
- -cerebral cortex can initiate micturition or delay its occurrence for a limited period of time
Micturition reflex
length of 1.5 in., orifice between clitoris & vagina
Histology - transitional changing to nonkeratinized stratified squamous epithelium, lamina propria with elastic fibers & circular smooth muscle
female urethra
Variable length…
tube passes through prostate, UG diaphragm & penis
3 regions of urethra
-circular smooth muscle forms internal urethral sphincter & UG diaphragm forms external urethral sphincter
male urethra
three regions of the urethra in males
-prostatic urethra, -membranous urethra -spongy urethra
Lack of voluntary control over micturition
normal in 2 or 3 year olds because neurons to sphincter muscle is not developed
urinary incontinence
caused by increases in abdominal pressure that result in leaking of urine from the bladder
-coughing, sneezing, laughing, exercising, walking
injury to the nerves, loss of bladder flexibility, or damage to the sphincter
Stress incontinence in adults
