RENAL 08: HORMONAL REGULATION OF BODY SALTS Flashcards
diuretics that block thick ascending limb of loop of henle lead to what effect on water?
Water wasting
What are the conditions for Na balance?
Na intake must exactly equal Na excretion
What is a positive sodium balance indicating
you have etra sodium retained in volume, so you epand ECF because body holds onto water (hyperosmotic), this expands the blood volume and increases arterial pressure as well as leads to an increase in body weight due to edema
What is a negative sodium balance indicating
You have a decrease of sodium intake, and therefore a reduction in ECF (hyposmotic), so you have a volume contraction. Because blood volume is decreasing, this decreases arterial pressure and body weight
What is ECV
Effective circulating volume; potion of ECF that is in the vascular system and effectively perfusing tisues
Volume receptors on afferent side of circulation
Cardiac atria (will release ANP); intrathoracic veins
This is because of the relationship of salt and volume
Afferent pressure sensors
Aortic and carotid baroreceptors (will communicate to brain if shit is going down); afferent arteriole also has an internal baroreceptor
Afferent receptors in kidney specifically
Pressure sensors in macula densa will determine if you’ve got too much tubular fluid
Efferent sensors - neurohumoral
RAAS
SNS/Catecholamines
ANP/BNP
Prostaglandins
Efferent hemodynamic forces effect on kidney salt excretion
GFR effects, peritubular forces will either increase or decrease based on what is required
Renal SnS activity leads to what?
Vasoconstrition of afferent arterioles - increased proximal tubule Na reabsorption.
Therefore-decrease GFR but what does go through you absorb more Na from.
Tubuloglomerular feedback
Macula densa senses flow and salt content in lumen - this is going to feed back to glomerulus to tell it what to do. if flow and Na are high, this causes contraction of afferent arteriole to decrease GFR. If there is low flow and low salt, prostaglandins and NO will be released to increase filration in the glomerulus.
Reinin is produced by what
Cells in the juxtaglomerular apparatus
When is renin secreted?
In situations of low sodium
If you have a high salt diet what does your renin secretion look like?
It’s low
How do we control renin production (3)
- SNS nerve activation (NE) - innervate afferent arterioles - activates b1 receptors and produce renin in juxtaglomerular cells
- Low pressure on afferent arteriole - intrarenal baroreeptors within juxtaglomerular cells will sense this and produce renin so we hold onto more water
- Macula densa - release of ATP causes reduced renin secretionof JG cells - prostaglaindins cause increased renin release from JG cells
RAAS system
Renin –> Ang I –> ACE makes Ang II-
ANG II and ang III will stimulate aldosterone release from adrenal cortex (under ACTH presence), leaing to a dcrease of Na and H20 secretion. Ang II will also cause for ADH to be released from posterior pituitary
ADH affects (salt/water) Aldosterone affects (salt/water)
Water
salt
What does aldosterone do
Affects late distalt ubule and collecting duct, inserts more NKA and also increases activity
Is aldosterone potassium saving or wasting
wasting
Is aldosterone sodium wasting or saving
Saving
ANP is released from where
Atria (as well as ventricles but mostly atria)
ANP is released when
when you have a volume overload and stretch is sensed
What is the job of ANP
Salt wasting
How does ANP affect the kidney
Affects vasculature similar to ang II , but also affects tubules. Unlike ang II however it has a dual effect:
- DILATION of afferent arteriole (causes a net increase in GFR
- Suppress renin, aldosterone, and decrese sodium reabsorption
Other natriuretic proteins
BNP
Urodilatin
What is a major cause of edema
increase in capillary hydrostatic pressure and decrease in oncotic pressure
how do we treat edema
diuretics
