Renal System 4 Flashcards
What are the fluid dynamics like in water?
Rapidly equilibriates throughout ICF and ECF, decreases osmolarity
What is the fluid dynamic like in an isotonic solution?
It will remain in the ECF, and has no effect on plasma osmolarity
Where is the precursor to ADH made and stored?
Made in the hypothalamus and stored in vesicles in the posterior pituitary
What do osmoreceptors in the hypothalamus sense?
Increase in Na+ concentration
Increase in osmolarity
When is ADH released into the bloodstream?
When a signal is sent to the posterior pituitary
What do osmoreceptors have?
Stretch-inhibited cation channels
What can cause cells to shrink?
The hypertonic stimulus action channels opening
What triggers action potentials?
Na+ entering the cells
What has a linear relationship?
Plasma ADH and Plasma osmolarity
Is thirst or ADH more sensitive to regulate?
ADH
What can also increase ADH release?
A decrease in blood pressure/blood volume
Is there negative feedback in ADH release?
Yes, there’s a return to homeostasis when a response brings plasma osmolarity back to normal
What is ADH good at maintaining?
Water balance
What is the renin-angiotensin-aldosterone system important in?
Maintaining sodium balance and blood pressure regulation
What happens in the juxtaglomerular apparatus?
Macula densa cells respond to a decrease in NaCl content by increasing prostaglandins, granular cells in the afferent arteriole release renin and a decrease in pressure in afferent arteriole also acts on the juxtaglomerula cells cause the release of renin
What is the juxtaglomerular apparatus?
Where the distal convoluted tubule touches the glomerulus
What triggers the release of renin from granular (juxtaglomerular) cells?
Low NaCl concentration in the distal tubule (depleted Na)
Decreased perfusion pressure (by granular cells themselves)
Increased sympathetic activity (eg baroreceptors)
Examples of triggers for renin release?
Low blood pressure
Low blood volume
Low Na content
What converts angiotensinogen to angiotensin 1?
Renin (released from JG cells in the kidneys) and is the rate limiting step
What converts angiotensin 1 to angiotensin 2?
Angiotensin converting enzyme (ACE)- in lungs
What are the key properties of angiotensin 2?
Increases aldosterone release
Vasoconstriction
Increases sodium and water reabsorption in proximal and distal convoluted tubules
Stimulates thirst and salt intake, release of ADH
Where/why is aldosterone released?
Released from adrenal cortex in response to angiotensin 2
What does aldosterone do?
It acts on distal tubule and collecting ducts to increase transcription of Na/K+ ATPase pumps thus increasing Na+ reabsorption and K+ excretion, and water reabsorption also increases via osmosis resulting in Na+ and water retention
What does the negative feedback from homeostatic plasma levels of Na and K inhibit?
Adrenal cortex
What does salt increase?
Osmolarity
What do ACE (angiotensin-converting enzyme) inhibitors reduce?
Angiotensin 2
What maintains water and salt balance independent of each other?
ADH maintains water balance, RAA (renin-angiotensin-aldosterone system) maintains salt balance
What is fluid loss/haemorrhage and what does it affect?
Isosmotic, affects renin-angiotensin system and antidiuretic hormone
How are hormones released?
In an hour to hour basis
When is RAAS activated?
After a number of minutes
