Urinary System Flashcards
Describe the basic function of the urinary system
- homeostasis
- excrete waste
- water balance
- filter blood
- activate vitamin D
- Regulates blood pressure
- erythropoiesis regulation
List the major components of the urinary system
- Kidneys
- Ureters
- Urinary bladder
- urethra
Define retroperitoneal as it relates to kidney
-external to parietal peritoneum to hold the kidneys in place
List the 3 protective layers of the kidney
- Renal capsule (immediately surrounding kidney)
- adipose capsule
- renal fascia (anchors kidney to abdominal wall)
Describe the Hilus
-External concave area where blood vessels, urters enter/exits kidney
Describe the cortex
-the outer portion of the kidney
Describe the renal medulla
-the inner part of the kidney
Describe the pyramid
- the inner medulla has triangular shaped regions
Describe the renal papillae
- is the apex of each pyramid is a papilla (makes urine)
Describe the renal pelvis
-is the funnel like structure inside the kidney in the region of the hilus collecting urine from the pyramids
Describe the renal calyces
- the extensions into the pyramids
- collecing urine and empty into ureter
- major calyx (8-18)
- minor calyx (2-3)
Describe the blood flow to the kidney
- there is A LOT
- via the renal arteries, about 1/5 of the cardiac output
Name the functional microscopic unit of the kidney and describe its specific parts
Nephron
- glomerulus and glomerular capsules
- renal tubules
- proximal convoluted tubule
- descending limb of the loop of nephron
- loop of nephron
- ascending limb of loop of nephron
- distal convoluted tubule
- collecting ducts
Describe the glomerulus and the renal corpuscles
- glumerulus is a netowrk of permeable blood capillaries
- surrounded by the (bowmans) capsule
- these two structures make the renal corpuscle
- renal= Kidneys
Describe the overall nephron physiology. Define urine
- Nephrons filter blood to make liquid waste (urine)
- control blood pressure, volume, and pH
- remove waste from the bloodstream
- Protein metabolic waste (urea)
Describe glomerular filtration
- Filtration occurs from the glomerulus into the glomerular capsule
- passive process
- influenced by size of the particles and if they can fit through the process of the glomerulus
- not based off of need
- blood pressure in the glomerulus is the driving force
Describe the factors that favor and oppose glomerular filtration.
- glomerular hydrostatic pressure (blood pressure) drives filtration
- the opposing factors are not strong enough to oppose filtration, but include the osmotic pressure in the glomerular as well hydrostatic pressure in the glomerular capsule
Discuss the effects of increased blood pressure and decreased blood pressure (as in hemorrhaging) on glomerular filtration
- Increased pressure increases filtration
- decrease pressure decreases filtration
Describe active and passive tubular reabsorption and give examples
- active reabsorption requires ATP, passive does not
- Glucose is reabsorbed from the proximal convoluted tubule to the bloodstream by active transport
- water flows passively
discuss the significance of an increasingly concentrated intrstitial fluid as you descend from the cortex to the medulla. Describe how this concentration is maintained.
- as you descend into the medulla, the interstitial fluid is very concentrated which offers some great drawing power for pulling water out of the kidney tubules
- the concentration is maintained by having the vasa recta operate in the countercurrent mechanism so that all the solutes are not removed from the interstitial region
- urea adds to the interstitial concentration, as does differential permeability of the different proportions of the nephron
Describe the reabsorption and secretion that occurs in all parts of nephron
- the proximal convoluted tubule
- most reabsorption occurs (water and nutrients)
- descend the limb of the nephron
- permeable to water, water reabsorbed
- the loop
- urea enters the loop from the interstitial region and is recycled back into urine
- Ascending limb is permeable to salt but not h20
- as you ascend into a weakly concentrated interstitial region, the sal will not reabsorb
- Distal convoluted tubule
- ADH and Aldosterone dependent
- If ADH is present, what is reabsorbed
- Aldosterone is present, sodium is reabsorbed and water passively flows
- Collecting duct is also hormone dependent
- ADH present, significant water reabsorption resulting in small amounts of highly concentrated urine
- it gets so concentrated, that neat the bottom of the collecting duct, even urea is reabsorbed into the interstitial region
- secretions of substances such as hydrogen ions, ammonia, and drugs occur primarily in the convoluted tubules
- here substances can pass directly from blood stream into these tubules
Describe juxtaglomerular apparatus. Name the enzyme made here and describe its function.
- juxta=near
- these are the cells of the wall of the distal convoluted tubule that make renin
- Renin is an enzyme that activates angiotensinogen (leads to increased blood pressure)
Describe the function of ADH. Where is it made and stored
- ADH is made by the hypothalamus and stored in the posterior pituitary gland
- it causes water reabsorption in the nephron
Describe the countercurrent multiplication mechanism of the kidneys
- 2 Parallel tubes running in opposite directions benefit each other
- for example if salt is pulled out of one tube, it facilitates pulling water out of the parallel tubes
Describe the change in urine volume and concentration as urine passes through the nephron and collecting tubule.
- There is a vast decrease in volume and increase in concentration upon traveling through the proximal convoluted tubules
- after descending limb the concentration increases and volume decreases
- after ascending the limb, the concentration decreases and volume is unchanged
- after DTC and collecting tubule, if ADH is present, the volume decreases and concentration increases.
Describe the vasa recta and how it is part of the countercurrent mechanism
- Vasa recta serve the limbs of the nephron
- They are parallel tubes of blood flow running in opposite direction
Describe the function of erythropoietin and where its precursor is made
- the precursor is made by the kidneys
- it stimulates RBC production
what is the minimum daily urine volume and why?
-500ml urine per day is the minimum to wash your liquid waste out of your body
Describe the location and function of the ureters and urinary bladder
- Ureters run retroperitoneal from kidney to urinary bladder.
- Function: peristalsis
- Urinary bladder is in the pelvic cavity and functions only to store urine
- the urine is in its final form once it leaves the collecting ducts of the nephron in the kidneys
Urine emptying from the bladder is controlled by what two muscles
- Two sphincters
- internal smooth muscle
- external skeletal muscle
Define micturition. Describe the process. Explain why babies cannot control urination.
- micturition is voiding urine
- as the bladder wall stretches, it reflexively sends message to the sacral region of the spinal cord, which synapses and sends a message back to the bladder wall to contract and the internal sphincter to relax
- at this point you have the urge to urinate, and will do so unless you voluntarily contact the external sphincter
- the pathway from the brain to external sphincter is not yet established in babies
Describe the location and function of the urethra. is it longer in males or females
- Urethra passes from inferior bladder to external urethral orifice.
- empties in the vulva of female and is about 1.5 inches long
- male- passes through the penis in male and is about 8 inches long
Describe the function of aldosterone, where is it made?
- Aldosterone is made by the adrenal cortex
- it causes sodium reabsorption from the nephron and water flows passively
