Lecture 24: Urinary System - Physiology of the Kidneys, Ureters, and Bladder Flashcards
Firstmost function of the urinary system
Maintain homeostasis
Physiology functions of the kidneys
- Regulate interstitial fluid volume
2. Reabsorb required substances
What is osmosis
When water molecules go across a semipermeable membrane and end up with a higher concentration of water molecules. Water in higher concentration puts pressure on the membrane. Membrane lets water pass, but not dissolved solids.
What is in the capsule of Bowman?
The glomerulus and its arteriole.
What does almost everything in the nephron have to go through?
The glomerular filtrate, a pressure that puts fluid and solutes through holes in the glomerular capillaries.
What absorbs important solutes and from where?
The convoluted tubule from the glomerular filtrate.
What makes blood colloid pressure (aka BCOP)?
Pressure of proteins and other solids in blood. Total pressure is 30mm Hg versus the arteriole pressure.
What is the net filtration pressure
A force that gets the filtrate through the kidneys.
Arteriole filters
endothelium, basement membrane, slit membrane
Functions of arteriole filters
to filter out large proteins
How much blood flow does the kidneys receive
20%
How much is filtered a day?
about 200 liters, but 99% is reabsorbed
what regulates glomerular filtration?
three mechanisms - renal autoregulation; neural regulation; hormonal regulation - and five control systems.
Renal autoregulation
At rest, normal processes.
Neural regulation
Increased sympathetic activity; causes the arterioles of the kidney to constrict and to release norepinephrine, and renin
Hormonal regulation
Occurs through hormones: angiotensin II, atrial natriuretic peptide (ANP), and aldosterone.
What is considered abnormal in urine?
An excretion of glucose. This happens when glucose is produced in larger amounts than the tubules can handle
Functions of the descending loop of Henle
Reabsorption of water and large ions and molecules
Functions of aldosterone in the loop of Henle
Increase the reabsorption of sodium and water by the principal cells.
Function of tubular secretion
Getting rid of unwanted materials in the system; mostly occurs in tubules. When pH is too acidic, H+ ions are removed; HCO3- are increased or decreased as needed to maintain pH.
Potassium secretion
Aldosterone increases the secretion by the tubules; increased levels of Na encourage potassium secretion in the DCT. Tubular secretion of K+ increases when there are high serum K+ levels.
