Flashcards in Control of arterial BP part 2 Deck (44)
What percentage of the body weight is water?
Total body fluid equation?
Intracelullar (2/3) + extracellular fluid - normally 1/3 of the total
Extracellular Body fluid volume equation?
ECFV= Plasma volume + Interstitial fluid volume
ECFV= PV + IFV
What is ECFV?
The fluid that bathes the cells and acts as the go between for the blood and the body cells
What happens if plasma falls?
Compensatory mechanisms shift fluid from interstitial compartment to plasma compartment
What else is controlled if ECFV is controlled?
20% of body weight is?
40% of body weight is?
Components of extracellular fluid?
11/14th Interstitial fluid
What 2 main factors affect our bodies extracellular fluid volume ECFV?
Water excess or deficit
Na+ excess or deficit
How do our bodies control the factors that affect our extracellular fluid volume?
Hormones act as effectors to regulate the ECFV by regulating the water and salt balance in our bodies
Healthy= water input=water output
Hormones which regulate the extracellular fluid volume?
The renin-angiotensin - aldosterone system (RAAS)
Natriuretic Peptides (NPs)
Antidiuretic hormone (Arginine Vasopressin) - ADH
Role of RAAS?
Important role in plasma volume regulation and SVR - hence the regulation of MAP
3 components of RAAS?
What is renin?
Renin is released from the kidneys and stimulates formation of angiotensin 1 in the blood from angiotensinogen (produced by liver)
Angiotensin 1 conversion?
Converted to angiotensin 2 by angiotensin converting enzyme- ACE
Where is angiotensin converting enzyme produced?
Mainly by pulmonary vascular endothelium
What does angiotensin 2 do?
-Stimulate the release of aldosterone from the adrenal cortex
- Causes systemic vasoconstriction -which increase SVR
- Also stimulates thirst and ADH release
Contributes to increasing plasma volume mainly by aldosterone
What does aldosterone do?
A steroid hormone which acts on kidneys to increase sodium and water retention- increase plasma volume
What is the rate limiting step for RAAS?
What is the renin angiotensin aldosterone system regulated by?
Mechanisms which stimulate renin release from the juxtaglomerular apparatus in the kidney.
What does the mechanism that regulates RAAS involve?
1)Renal artery hypotension- caused by systemic hypotension (decreases blood pressure)
2)Stimulation of renal sympathetic nerves
3)Decreased [Na+] in renal tubular fluid - sensed by macula densa (specialized cells of kidney tubules)
What are natriuretic peptides?
Peptide hormones synthesized by heart (also brain and other organs)
When are natriuretic peptides released?
In response to cardiac distension or neurohormonal stimuli
What do NPs do?
-They cause excretion of salt and water in the kidneys thereby reducing blood volume and blood pressure.
-Decrease renin release- decrease BP
-Act as vasodilators; decrease SVR and BP
-Provide a counter regulatory system for the RAAS
How many types of natriuretic peptides are released by the heart?
The NPs released by the heart?
1)Atrial natriuretic pepide (ANP)
2)Brian-type natriuretic peptide (BNP)
What is ANP and when is it released?
28 amino acid peptide synthesized and stored by atrial
myocytes (Atrial muscle cells)
-Released in response to atrial distension (Hypervolemic states)
What is Brian-type natriuretic peptide?
32 amino acid peptide synthesized by heart, ventricles, brain and other organs