Renal Physl 16 Flashcards
What can cause blood volume and osmolarity to both increase?
Salty food being consumed more than liquid
What is comparable to intake of a hypertonic solution?
Eating salty foods more than water intake
How does a hypertonic solution affect ECF and osmolarity?
ECF volume and osmolarity increase
How is the urine affected by increased ECF and osmolarity?
A hypertonic urine is produced where sodium and water are excreted
What will cause blood volume to increase but plasma osmolarity to remain normal?
The salt and water ingested is the same osmolarity of the plasma so only volume is expanded
What kind of urine is produced if blood volume is increased and plasma osmolarity is normal?
Isotonic urine is produced
What would cause blood volume to increase and osmolarity to decrease?
Ingesting pure water
What would happen to the ECF if blood volume is increased and osmolarity is decreased by ingesting pure water?
ECF is diluted
What kind of urine would be produced if Blood volume is increased and osmolarity decreases?
A large volume of dilute hypotonic urine
What may be stimulated if plasma osmolarity dips to low?
Salt apatite
What may cause blood volume to remain unchanged but plasma osmolarity to increase?
Consuming solutes in the absence of fluid intake
What kind of urine is produced if blood volume is unchanged but plasma osmolarity is increased?
Small volume of concentrated urine
What triggers the thirst mechanism?
When blood volume is unchanged but plasma osmolarity increases
What may cause blood volume to be unchanged but plasma osmolarity to be decreased?
A dehydrated person who only ingests pure water
How do unchanged blood volume and decreased plasma osmolarity affect the ECF?
It causes ECF to be diluted
What was the idea behind gatorade?
When exercising people lose water and salt so gatorade contains fluid and electrolytes to replenish that without diluting ECF
What can cause a reduced blood volume and increased osmolarity?
Diarrhea or excessive sweating where more water is lost than solute
Whos is most susceptible to reduced blood volume and increased osmolarity?
Elderly people and babies
What may cause a reduced blood volume but an unchanged osmolarity?
A hemorrhage
What is the treatment for reduced blood volume and unchanged osmolarity?
Blood transfusion or isotonic saline infusion
What is the goal in response to dehydration?
To restore blood pressure, extracellular fluid volume and plasma osmolarity by conserving fluid and preventing losses
What is the main way to restore BP, ECF volume and plasma osmolarity in dehydration?
Conserving fluid and prevent loss by rapid cardiovascular reflexes and thirst
How are blood volume, pressure and osmolarity affected by dehydration?
Blood volume and blood pressure decrease and plasma osmolarity increases
How does the reduced BP and blood volume seen in dehydration affect carotid and aortic baroreceptors?
Reduced stretch of baroreceptors causes them to relay information to the cardiovascular control centers in the brain
What is the result of the increased cardiovascular input in dehydration?
It increases sympathetic outflow with a decrease in parasympathetic
What does the increased sympathetic activity in dehydration do?
It causes peripheral vasoconstriction increasing resistance which raises BP. It also increases HR and contractility which increases cardiac output
What happens as a result of reduced renal perfusion seen in dehydration?
Increased renal sympathetic activity causes juxtaglomerular cells to release renin which initiates the RAAS system
What are the multiple effects of angiotensin II in dehydration?
- It acts at the cardiovascular system to increase cardiac output
- Powerful vasoconstrictor
- Stimulates the release of vasopressin
- Boosts water intake through thirst
How does low blood volume and pressure due to dehydration affect glomerular capillary hydrostatic pressure and GFR?
It decreases glomerular capillary hydrostatic pressure and GFR
Why is low GFR a good thing in dehydration?
The less fluid filtered, the less that is lost in the urine. This also stimulates juxtaglomerular cells to produce renin
How does sympathetically mediated constriction of the afferent arteriole affect GFR?
It contributes to the volume conservation and RAAS activation by decreasing GFR
Where is information from atrial volume receptors and carotid and aortic baroreceptors integrated?
At the hypothalamus
What does information integrated at the hypothalamus during dehydration stimulate?
The release of vasopressin and thirst
How does dehydration affect hypothalamic osmo receptors?
Because dehydration increases osmolarity, it causes osmoreceptors to shrink triggering vasopressin release
When is Aldosterone released?
- In response to low pressure and volume
* In response to decreased plasma osmolarity (low solutes)
What two signals are found in dehydration?
- Low pressure and volume
* Increased plasma osmolarity
How does the low BP and increased plasma osmolarity affect aldosterone release?
Because low BP stimulates aldosterone and increased plasma osmolarity inhibits aldosterone they cancel each other out and the net effect is suppression of aldosterone
