Changes

==Control of Blood Pressure==

==Control of Blood Pressure==

If a sudden change in [[Vascular System - Anatomy & Physiology|blood pressure]] occurs it is controlled in the short term by the sympathetic nervous system which alters three things:

If a sudden change in [[:Category:Blood Pressure|blood pressure]] occurs it is controlled in the short term by the sympathetic nervous system which alters three things:

* Total peripheral resistance

* Total peripheral resistance

* Capacitance

* Capacitance

* If more sodium is excreted less water is reabsorbed therefore the ECF volume decreases and blood pressure decreases.

* If more sodium is excreted less water is reabsorbed therefore the ECF volume decreases and blood pressure decreases.

* The actual mechanism is not clear but it is thought to involve a direct effect of the pressure on the renal interstitium.

* The actual mechanism is not clear but it is thought to involve a direct effect of the pressure on the renal interstitium.

=====[[Important Hormonal Regulators of the Kidney - Anatomy & Physiology#The Renin Angiotensin Aldosterone System (RAAS)| Renin-Angiotensin-Aldosterone System]]=====

=====[[Renin Angiotensin Aldosterone System| Renin-Angiotensin-Aldosterone System]]=====

* Specialized cells in the distal tubule called the macula densa sense the concentration of sodium and chloride.

* Specialized cells in the distal tubule called the macula densa sense the concentration of sodium and chloride.

* If blood pressure falls there is a reduction in concentration of sodium and chloride in the distal tubule which is sensed by the macula densa.

* If blood pressure falls there is a reduction in concentration of sodium and chloride in the distal tubule which is sensed by the macula densa.

* The macula densa releases prostaglandins which act on the juxtaglomerular apparatus which releases renin into the bloodstream.

* The macula densa releases prostaglandins which act on the juxtaglomerular apparatus which releases renin into the bloodstream.

* The drop in blood pressure is also detected by baroreceptors in the aortic arch, carotid sinus and the afferent renal arteriole which stimulates renin release by the juxtaglomerular apparatus.

* The drop in blood pressure is also detected by baroreceptors in the aortic arch, carotid sinus and the afferent renal arteriole which stimulates renin release by the juxtaglomerular apparatus.

* Renin cleaves angiotensinogen into angiotensin 1 which in turn is cleaved by [[Angiotensin Converting Enzyme(ACE) - Renal Anatomy & Physiology|'''Angiotensin Converting Enzyme''' (ACE)]]  into angiotensin 2.

* Renin cleaves angiotensinogen into angiotensin 1 which in turn is cleaved by [[Angiotensin Converting Enzyme|'''Angiotensin Converting Enzyme''' (ACE)]]  into angiotensin 2.

* Angiotensin 2 is a potent vasoconstrictor and also stimulates the adrenal cortex to release [[Important Hormonal Regulators of the Kidney - Anatomy & Physiology#Aldosterone|aldosterone]].

* Angiotensin 2 is a potent vasoconstrictor and also stimulates the adrenal cortex to release [[Aldosterone|aldosterone]].

* [[Important Hormonal Regulators of the Kidney - Anatomy & Physiology#Aldosterone|Aldosterone]] acts on the distal tubules and collecting ducts in the kidney causing retention of sodium and water.

* [[Aldosterone|Aldosterone]] acts on the distal tubules and collecting ducts in the kidney causing retention of sodium and water.

* Blood pressure increases.

* Blood pressure increases.

==Regulation of Renal Blood Flow==

==Regulation of Renal Blood Flow==

It is essential that renal blood flow is maintained to ensure that adequate filtration of toxins from the blood takes place. Changes in pressure affect renal blood flow.  Important auto-regulatory processes are responsible for this and are covered in detail [[The Formation of the Filtrate by the Glomerular Apparatus- Anatomy & Physiology#Regulation of the GFR|here]].

It is essential that renal blood flow is maintained to ensure that adequate filtration of toxins from the blood takes place. Changes in pressure affect renal blood flow.  Important auto-regulatory processes are responsible for this and are covered in detail [[Glomerular Apparatus and Filtration - Anatomy & Physiology#Regulation of the GFR|here]].

==The Role of Salt==

==The Role of Salt==

Increasing the salt intake of an animal increases blood pressure in the short term.  It increases the osmolarity of the blood which therefore increases water movement from tissues to the blood causing an increased circulating volume.  As a result of this increased osmolarity more ADH is released as the osmoreceptors in the hypothalamus are triggered.  This results in increased water retention in the kidneys further increasing the circulating volume.  Secondary to the increase in salt the thirst centre is stimulated to increase fluid intake to try and counter act the increased osmolarity.  This would increase blood volume and therefore pressure temporarily until this was corrected by the compensatory mechanisms detailed above.

Increasing the salt intake of an animal increases blood pressure in the short term.  It increases the osmolarity of the blood which therefore increases water movement from tissues to the blood causing an increased circulating volume.  As a result of this increased osmolarity more ADH is released as the osmoreceptors in the hypothalamus are triggered.  This results in increased water retention in the kidneys further increasing the circulating volume.  Secondary to the increase in salt the thirst centre is stimulated to increase fluid intake to try and counter act the increased osmolarity.  This would increase blood volume and therefore pressure temporarily until this was corrected by the compensatory mechanisms detailed above.

==Revision==

 

|flashcards = [[Renal Blood Pressure - Renal Flash Cards - Anatomy & Physiology|Renal Blood Pressure Flashcards]]  

Use the [[Renal Blood Pressure - Renal Flash Cards - Anatomy & Physiology|flash card revision resource]] for this section to test yourself.

[[Category:Urinary System]]

[[Category:Kidney - Anatomy & Physiology]][[Category:Blood Pressure]]

[[Category:Cardiology Section]]