73: Control of Blood Pressure and Volume Flashcards
…… and ……… intake/excretion determines ECF, blood volume (BV) & blood pressure (BP)
Na+ and H20
When the body contains too much ECF, … and ……..rise
Blood Volume and Blood Pressure
Rise in urinary water (volume) excretion due to raised BP
Pressure diuresis
Rise in Na+ excretion due to raised BP
Pressure natriuresis
Autoregulation occurs when GFR and RBF constant with increases of BP between ……….
80-180 mmHg
Acute rise in blood pressure leads to intrinsic ………. in urinary Na+ excretion.
Increase Na+ Excretion.
no SNS, renin/angiotensin II, antidiuretic hormone activity (ADH
Chronic rise in Blood pressure leads to continued ……
Increase in urinary Na+ output due to hormonal activity (decrease R-A-A system; increase atrial natriuretic peptide (ANP)) excreting Na+/ H2O
……….. maintains fluid balance to keep changes in BV, ECF, CO & BP minimal even with large changes in Na+/ H2O intake
Feedback mechanism
If increase Na+/H2O intake, BP …………
Increases
To compensate renal output of Na+/H20 also increases.
If BP decreases, Na+/H2O intake …….
Decreases
To compensate renal output of Na+/H2O decreases
BV remains constant despite large changes in ………
Fluid Intake
Why does BV remains constant despite large changes in fluid intake?
- Slight change in BV changes cardiac output by changing mean circulatory filling pressure & venous return
- Change in CO changes BP
- Change in BP causes large change in urine output through pressure diuresis and hormonal activity
Only change seen in Blood Volume is when fluid intake is too………to make up for fluid losses (i.e. evaporation
Low
……… ,part of juxtaglomerulus apparatus, sense tubular flow of NaCl and send feedback signals to afferent or efferent arteriole to constrict/dilate to keep RPF and GFR at normal levels
Macula Densa Cells
The juxtaglomerular apparatus (JGA) responds to low blood volume or blood pressure (due to dehydration or loss of blood) stimulates the …………….system
Renin-Angiotensin-Aldosterone System
Protein enzyme released from granular cells of juxtaglomerular apparatus
Renin
The secretion of renin is stimulated by:
- Decreased arterial pressure leading to decreased renal perfusion pressure
- Decrease in NaCl sensed by macula densa cells
- Increased activity of renal sympathetic nerves
Renin catalyzes conversion angiotensinogen to Angiotensin I eventually giving ………….
Angiotensin II
Powerful controller of Na+ reabsorption
Angiotensin II
Angiotensin II secretion is stimulated by…..
- Decreased arterial pressure leading to decreased renal perfusion pressure
- Low Na+ intake
Actions of Angiotensin II:
Actions:
➢ Stimulates aldosterone secretion from adrenal glands ➢ Vasoconstriction (renal arterioles - mainly efferent when low; afferent when high)
➢ Stimulates thirst
➢ Increase NaCl reabsorption in proximal tubule
➢ Increases Na+/H+ exchanger in proximal tubule (therefore also aids in ??? reabsorption)
Angiotensin II causes increased Na+/H20 reabsorption in the ……… which indirectly stimulates Na+ reabsorption in LD/CD via aldosterone.
Proximal Convoluted Tubule
Angiotensin II ……… blood pressure via vasoconstriction and …….. the drive to drink
Increases blood pressure
Increases drive to drink
Angiotensin II ……… Na+/H2O excretion, …………..ECF & arterial pressure
Decreases Na Na+/H2O excretion
Increase ECF & arterial pressure