Histo Lecture 12


What are the three areas of reabsorption in the nephron?


Proximal tubuleLoop of HenleDistal tubule


Water follows what in the capillaries?


NaCl


What is the proximal tubule in charge of?


Reabsorbing most nutrients


What is transcellular transport?


Movement through the cytoplasm


What is paracellular transport?


Movement through "tight junctions" between cells


Most humeral control of kidney reabsorption involves what?


Alteration in NaCl reabsorption


What are some some hormones affecting NaCl reabsorption?


Angiotensin II, aldosterone, atrial natriuretic peptide (ANP), brain netriuretic peptide (BNP), catebholeamines


What does Renin do?


Catalyzes conversion of angiotensin I to angiotensin IIOccurs in the lungs


Renin is released from kidney cells in response to


Decreased perfusion pressure in the kidney (decreased BP)Decreased filtered load of NaCl (decreased GFR)Inreased sympathetic nerve activity


Where does Angiotensin II act?


Stimulates NaCl reabsorption in the proximal tubule


What is aldosterone secreted in response to?


Plasma concentration of angiotensin II


What is epinephrine/norepinephrine released in response to?


Low ECFStimulates reabsorption of NaCl in all parts of nephron


What stimulates sympathetic input to the kidney?


Low ECF volume or low BP


What is dopamine released in response to?


Increased ECF


What is the function of dopamine on the kidney?


Inhibits NaCl/H2O reabsorption in the proximal tubule


What stimulates secretion of ANP and BNP?


Increase in BP and ECF


What are the functions of ANP and BNP?


Decrase total peripheral resistanceInhibit Nacl/H2O reabsorption in the collecting ductReduce ADH secretion from posterior pituitary


Natriuretic peptides are secreted by what?


By the heart in response to increased ECF or BP


How do ANP and BNP perform their functions?


Stimulate vasodilationIncrease H2O/NaCl excretionInhibits secretion of renin, aldosterone and ADH


Where is Urodilatin secreted?


By distal tubule and collecting duct


What stimulates secretion of urodilatin?


Increase in BP and ECF


What does urodilatin inhibit?


NaCl and H2O reabsorption in the collecting duct


What is the definition of dehydration?


Increased plasma osmolarity and more concentrated urine


What is definition of over-hydration?


Decreased plasma osmolarity and more dilute urine


What is the normal range in adults for osmolarity?


280-295mOsm


Where is ADH synthesized?


hypothalamus


Where is ADH stored and secreted from?


posterior pituitary


What is ADH released in response to?


Low BP and high Osmolarity


Where are the baroreceptors that monitor arterial pressre?


aortic archcarotid sinus


Where are the baroreceptors that monitor venous blood pressure?


Atriapulmonary vessles


What is the osmolarity range for urine?


50-1200mOsm


Ascending LOH absorbs what and not what?


NaClNOT WATER


Decreased filling of pulmonary system/atria results in:


Increased sympathetic activity to generate BPIncrease ADH secretion - increases ECF


What is the systemic response to increased ECF?


Decreased renal sympathetic signalingIncreased release of ANP/BNP and urodilatinInhibition of ADH secretion and activityDecreased renin secretion resulting in decreased angiotensin and aldosterone


What is the systemic response to decreased ECF?


Incrased renal sympathetic signalingInhibition of ANP/BNP and urodilatin secretionIncreased ADH secretionIncreased renin secretion resulting in increased angiotensin and aldosterone