{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}


Juxtaglomerular apparatus region of aerent arteriole

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: eability to sodium, chloride, urea, and water • Blood in the vasa recta capillaries entering the medulla loses water and gains NaCl and urea progressively as it descends. • When blood flow in the vasa recta capillaries reverses direc*on and ascends from the medulla to the cortex, it progressively gains water and loses NaCl and urea, resul*ng in countercurrent exchange • This anatomical arrangement, combined with the rela*vely low blood flow to the medulla, permits sufficient perfusion for nutri*on without destroying the high osmolality of the medulla •  The main reason is to preserves Hyperosmolarity of the Renal Medulla ADH Regula*on of Water Reabsorp*on •  ADH (an*diure*c hormone) –  inser*on of aquaporins into the plasma membrane of tubule cells •  ↑ permeability of distal tubule and collec*ng duct walls to water •  ↑ H2O reabsorp*on = ↓ urine volume, ↑ urine concentra*on –  Secreted by anterior pituitary in response to s*mula*on of osmoreceptors in hypothalamus •  respond to elevated plasma osmolarity Fig 13.12 Renin ­Angiotensin ­Aldosterone System (RAAS) Cue: Decrease in BP or Vol Juxtaglomerular apparatus (JGA) Releases Renin Cleaves Angiotensinogen (released from Liver) Angiotensin I in presence of ACE (enzyme) Produces Angiotensin II (func*on as hormone) Raises the Blood Pressure by constric*ng Arterioles Subsequent decrease in blood flow to kidney Angiotensin IIS*mulates Adrenal Gland Release of Aldosterone (Acts on Nephron’s distal tubules) Reabsorbs more Na+ and H20 Increases BP and Vol Renin ­Angiotensin ­Aldosterone System •  Juxtaglomerular apparatus –  region of afferent arteriole that comes into contact w/ascending limb of Loop of Henle •  Releases renin (enzyme) into blood in response to ↓blood pressure –  Low Na+ levels contribute to low blood pressure •  Renin converts angiotensinogen (plasma protein)→ angiotensin I •  Angiotensin I converted to angiotensin II (fully ac*vated) by angiotensin conver4ng enzyme in lungs •  Angiotensin II s*mulates aldosterone release from adrenal cortex Aldosterone Influences Na+ and Water Reabsorp*on, K+ Secre*on •  Aldosterone s*mulates Na+ reabsorp*on and K+ secre*on by the distal tubule and upper (cor*cal) collec*ng duct) •  Elevated plasma K+ directly s*mulates adrenal cortex to...
View Full Document

{[ snackBarMessage ]}

Ask a homework question - tutors are online