Phys lab 5 quiz
aldosterone
"salt-retaining hormone" which promotes the retention of Na+ by the kidneys. na+ retention promotes water retention, which promotes a higher blood volume and pressure. Also promotes K+ excretion.
What occurs to the glucose that is filtered? How is glucose transported by the cells of the nephron?
Glucose is filtered and is then absorbed from the tubule by secondary active transport.
What would be a stimulus for ADH release?
High plasma osmolarity (low water intake-> concentrated plasma) would be a stimulus for ADH release.
What is the driving force for filtration in the nephron?
Hydrostatic pressure is the driving force for filtration
function of Glomerulus and glomerular capsule:
filtration
function of loop of henle
reabsorption of 15% of water and salt (descending limb= water resorption, ascending limb= Na+, Cl- absorption)
reabsorption
return of substances from the nephron tubules back to the blood
How would aldosterone effect potassium levels in the urine?
increased K+ in urine
angiotensin II
increases blood pressure by stimulating kidneys to reabsorb more water and by releasing aldosterone
ADH
increases the water permeability of the renal collecting duct, allowing water reabsorption to conserve fluid.
What is the mechanism of aldosterone's actions and where in the nephron does it operate?
secreted from the adrenal cortex. Primary action site is the distal tubule and the collecting duct. Targets principal cells (P cells).
secretion
selective transfer of certain substances from the blood into the nephron tubules
function of proximal convoluted tubule
-reabsorbs: 65% of Na+,Cl-,H2O Most K+ & HCO3-; Some PO4-,Ca2+,etc -secretes: Drugs, steroids, toxins, etc.
RAAS pathway
1) Low Na inhibits ADH secretion, which causes low blood volume/BP, so Renin is secreted by JGA in response 2) Renin causes conversion of angiotensinogen into angiotensin I 3) AI converted to AII in lungs 4) AII stimulates release of aldosterone in zona glomerulosa. 5) Aldosterone causes retention of sodium and water to raise BP and causes renin secretion to stop.
How does PCO2 or bicarbonate levels in the blood affect pH?
Bicarbonate neutralizes excess acid Increased CO2 means increase in carbonic acid-> acidosis
How does ventilation rate affect pH and how would the respiratory system respond to high or low levels of bicarbonate?
Inadequate ventilation: increased CO2, low plasma HCO3-, lower pH -> lead to hyperventilation to get rid of excess CO2 Excessive ventilation: decreased CO2, high HCO3-, higher pH-> leads to hypoventilation to increase CO2 levels
Where does the bulk of reabsorption take place in the nephron?
Proximal convoluted tubule
How can the urinary system modulate bicarbonate levels in the blood? How would the urinary system respond.
Reabsorption of Bicarbonate can help compensate for changes in pH due to respiration. respiratory acidosis-> increased bicarbonate resorption, more buffer so increase pH respiratory alkalosis-> decreased bicarbonate reabsorption, less buffer so decrease pH
function of distal convoluted tubule
Regulated reabsorption of Na+, H2O Secretion of K+, H+
What is the function of ADH at the nephron and what is the mechanism behind this function?
Stimulates the kidney tubules to reabsorb water from urine. ADH binds to receptors in epithelial cells of collecting ducts. Stimulates cAMP production which starts chain of events that stimulates vesicles with aquaporins in their membranes. These vesicles fuse with plasma membrane which inserts the aquaporins in the membrane.
What size items can be filtered at the nephron? Could you recognize molecules that should not be found in the urine?
Water and non-protein/non-cellular substances are filtered. Cells and proteins are too big to leave the blood. Glucose should also not normally be in the urine.
filtration
certain substances forced out of blood into the glomerular capsule/the process that your kidneys use to filter excess fluid and waste products out of the blood into the urine collecting tubules of the kidney, so they may be eliminated from your body.
