73: Control of Blood Pressure and Volume Flashcards

1
Q

…… and ……… intake/excretion determines ECF, blood volume (BV) & blood pressure (BP)

A

Na+ and H20

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2
Q

When the body contains too much ECF, … and ……..rise

A

Blood Volume and Blood Pressure

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3
Q

Rise in urinary water (volume) excretion due to raised BP

A

Pressure diuresis

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4
Q

Rise in Na+ excretion due to raised BP

A

Pressure natriuresis

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5
Q

Autoregulation occurs when GFR and RBF constant with increases of BP between ……….

A

80-180 mmHg

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6
Q

Acute rise in blood pressure leads to intrinsic ………. in urinary Na+ excretion.

A

Increase Na+ Excretion.

no SNS, renin/angiotensin II, antidiuretic hormone activity (ADH

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7
Q

Chronic rise in Blood pressure leads to continued ……

A

Increase in urinary Na+ output due to hormonal activity (decrease R-A-A system; increase atrial natriuretic peptide (ANP)) excreting Na+/ H2O

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8
Q

……….. maintains fluid balance to keep changes in BV, ECF, CO & BP minimal even with large changes in Na+/ H2O intake

A

Feedback mechanism

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9
Q

If increase Na+/H2O intake, BP …………

A

Increases

To compensate renal output of Na+/H20 also increases.

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10
Q

If BP decreases, Na+/H2O intake …….

A

Decreases

To compensate renal output of Na+/H2O decreases

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11
Q

BV remains constant despite large changes in ………

A

Fluid Intake

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12
Q

Why does BV remains constant despite large changes in fluid intake?

A
  1. Slight change in BV changes cardiac output by changing mean circulatory filling pressure & venous return
  2. Change in CO changes BP
  3. Change in BP causes large change in urine output through pressure diuresis and hormonal activity
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13
Q

Only change seen in Blood Volume is when fluid intake is too………to make up for fluid losses (i.e. evaporation

A

Low

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14
Q

……… ,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

A

Macula Densa Cells

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15
Q

The juxtaglomerular apparatus (JGA) responds to low blood volume or blood pressure (due to dehydration or loss of blood) stimulates the …………….system

A

Renin-Angiotensin-Aldosterone System

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16
Q

Protein enzyme released from granular cells of juxtaglomerular apparatus

A

Renin

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17
Q

The secretion of renin is stimulated by:

A
  1. Decreased arterial pressure leading to decreased renal perfusion pressure
  2. Decrease in NaCl sensed by macula densa cells
  3. Increased activity of renal sympathetic nerves
18
Q

Renin catalyzes conversion angiotensinogen to Angiotensin I eventually giving ………….

A

Angiotensin II

19
Q

Powerful controller of Na+ reabsorption

A

Angiotensin II

20
Q

Angiotensin II secretion is stimulated by…..

A
  1. Decreased arterial pressure leading to decreased renal perfusion pressure
  2. Low Na+ intake
21
Q

Actions of Angiotensin II:

A

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)

22
Q

Angiotensin II causes increased Na+/H20 reabsorption in the ……… which indirectly stimulates Na+ reabsorption in LD/CD via aldosterone.

A

Proximal Convoluted Tubule

23
Q

Angiotensin II ……… blood pressure via vasoconstriction and …….. the drive to drink

A

Increases blood pressure

Increases drive to drink

24
Q

Angiotensin II ……… Na+/H2O excretion, …………..ECF & arterial pressure

A

Decreases Na Na+/H2O excretion

Increase ECF & arterial pressure

25
➢ Secreted by glomerulosa cells of adrenal cortex ➢ Binds to basolateral receptors on principals cells of LD/CD ➢ Directs synthesis of proteins involved in Na+ reabsorption (luminal membrane Na+ channel, Na+/K+-ATPase)
Aldosterone
26
Aldosterone secretion is stimulated by:
1. Angiotensin II 2. Hyperkalemia (high plasma [K+]) 3. Hyponatremia (low plasma [Na+])
27
Actions of Aldosterone:
Actions: ➢ Increase Na+/H2O reabsorption by principal cell in LD/CD ➢ Increase K+ secretion ➢ Increase H+ secretion from a-intercalated cells
28
The overall effect of the Renin-Angiotensin-Aldosterone System:
Low blood pressure (BP) stimulates renin secretion from the kidney. Renin stimulates the production of Angiotensin II, which stimulates aldosterone secretion from the adrenal cortex. Aldosterone increase Na+ and water reabsorption in the kidney.
29
Increases in ECF volume dilute OncoticPC and ......... PCT reabsorption
Decrease
30
.......... in ECF volume concentrates OncoticPC and stimulates PCT reabsorption
Decreases
31
Nerves reduces Na+ excretion in 3 ways:
1. Decreases GFR and RBF leads decreased filtered Na+ load and PT cap hydrostatic pressure for excretion 2. Direct stimulatory effect on Na+ reabsorption by renal tubules 3. Causes renin release leads to increases angiotensin II and aldosterone levels for reabsorption
32
* Peptide hormone secreted by posterior pituitary * Involved in the regulation of body water content * Also called vasopressin
Anti-Diuretic Hormone (ADH)
33
The secretion of Anti-Diuretic Hormone (ADH) is stimulated by:
1. Increased plasma osmolarity of 1 mOsm/L (most important physiologic stimulus) 2. Hypovolemic loss of >8% ECF (MOST POTENT stimulus)
34
Large volume changes evoke ADH secretion regardless of ............
Osmolarity/Tonicity
35
Actions of Anti-Diuretic Hormone (ADH):
Allows formation of water channels in the late distal and collecting duct increasing reabsorption of water  increases urine osmolarity and decreases urine flow volume ➢ Increases H2O permeability (V2 receptors) ➢ Increases contraction of vascular smooth muscle (V1 receptors)
36
Actions of......... on renal tubule : ➢ Increases H2O permeability ➢ Increases 2Cl-/Na+/K+ co-transporter effectiveness ➢ Increases urea permeability
Anti-Diuretic Hormone (ADH)
37
➢ADH binds to .........receptor ➢................ that increases cAMP ➢ Increases in cAMP cause the insertion of ............(H2O channels) to facilitate H2O reabsorption
V2 G-protein coupled receptors Aquaporins
38
➢ Released by cardiac atrial myocytes ➢ Receptors found in adrenal cortex, vascular endothelium, collecting duct, distal tubule but NOT proximal tubule AND several areas in brain (i.e. thirst center)
Atrial Natriuretic Peptide (ANP)
39
The secretion of Atrial Natriuretic Peptide (ANP) is stimulated by:
Atrial stretch from excess BV (ECF)
40
Actions of Atrial Natriuretic Peptide (ANP):
Actions: ➢ Vasodilation (afferent arterioles - also constricts efferent arterioles) ➢ Inhibits Na+ reabsorption at medullary CD ➢ Inhibits norepinephrine & angiotensin II induced vasoconstriction ➢ Inhibits renin and aldosterone secretion ➢ Inhibits ADH secretion ➢ Inhibits adenylate cyclase in target tissues