Atrial myocytes synthesise, store and release ANP in response to stretch (low P volume sensor).
Major effect is renal vasodilatation. Increased blood flow = increased GFR.
Thus, more Na + reaches macula densa.
More Na + excreted.
May inhibit actions of renin, and generally opposes effects of angiotensin II.
Feedback systems involved in osmolality control
Comparison of systems controlling effective circulating volume and osmolality Water intake Brain: drinking behaviour Thirst Renal water excretion Short term : Blood pressure Long term : Na + excretion What is affected? Kidney Short term : heart, blood vessels Long term : Kidney Effector ADH RAAS, Symp NS, ADH, ANP Efferent Pathways Hypothalamic osmoreceptors Carotid sinus, aortic arch, renal afferent arteriole, atria Sensors Plasma Osmolality Effective Circulating Volume What is sensed?
Remember, these can be either respiratory or metabolic in nature.
Respiratory ones can be chronic or acute; metabolic ones always chronic.
Only chronic ones cause marked change in HCO 3 - .
Renal and respiratory systems work together reflexly to compensate for one another.
Final review of renal integration with respiratory and cardiovascular systems RENAL SYSTEM CARDIOVASCULAR SYSTEM RESPIRATORY SYSTEM Acid-base balance Gas exchange, ACE Effective circulating volume control, ECF osmolality, blood pressure All of these are constantly changing, trying to maintain HOMEOSTASIS!
Problems in one system are often only noticed by appearance of problems in another.
This is because of the integrated nature of these systems – they don’t operate in isolation.
Means we can sometimes compensate for problems in another system via reflexes, but also means that when disease progresses, lots of problems in several systems can begin to appear.
If we understand links between systems, we have more targets for drugs and other therapies to correct problems.
May also target actual cause of problem, rather than just worrying about the symptoms. Scientists think laterally – medics have a tendency just to stay inside their little window of expertise. PY3002 is all about getting you to think independently and laterally.
These three systems are probably the locations of most of the health-related problems you might encounter in whatever career you follow – regardless of whether you are a sports scientist or a physiologist.