nucleus cytoplasm extracellular fluid water Na+ K+ Cl- sugars proteins plasma intracellular fluid 7% 26% 67%

The Mammalian Kidney glomerulus Bowman’s capsule Proximal tubule Loop of Henle Distal tubule Collecting duct To bladder Extracellular Na+ conc. Active movement of Na+ Na+ Passive movement of water H2OH2O

Osmotic ImbalanceHypovolemia

Baroreceptors in arteries of the heart Causing an increase in secretion and release of VP VP 2 major effects: 1.Vasoconstriction 2.Water retention in kidney

Collecting Duct Cell glomerulus Bowman’s capsule Proximal tubule Loop of Henle Distal tubule Collecting duct To bladder Passive movement of water H2OH2O The water pore is a protein called: aquaporin 2 (AQP2)

Collecting Duct Cross-Section Cells labeled with fluorescent antibodies made to the water channel

Collecting Duct:

nn to bladder basal aquaporins Aquaporin 2

2 major effects of vasopressin: 1.Vasoconstriction 2.Water retention in kidney: Collecting Duct Cell V2 receptor: localized to the kidney VP Gq PLC IP3 DAG Smooth muscle cell In arteries/capillaries V1a receptor: localized to vascular smooth muscle cells V1a receptor V2 receptor

Control of Aldosterone Secretion Renin Secreted in response to low blood pressure Cells in the capillary walls ANGIOTENSIN I ANGIOTENSIN II angiotensin converting enzyme (ACE: secreted by the lungs) IN THE BLOOD ANGIOTENSINOGEN Made in the liver aldosterone Adrenal gland (cortex)

Osmoreceptors: -Present in cells in the hypothalamus -when dehydrated, cause secretion of VP from PVN and SON VP 2 major effects: 1.Vasoconstriction 2.Water retention in kidney Neural cells in hypothalamus containing osmoreceptors

Vasopressin and Osmolality

Under conditions of high osmolality IN THE BLOOD ANGIOTENSINOGEN LESS ANGIOTENSIN I LESS ANGIOTENSIN II angiotensin converting enzyme (ACE: secreted by the lungs) Made in the liver LESS aldosterone Decreases Na+ absorbtion in the kidney LESS Renin from glomerulus less VP less vasoconstriction less drinking

Neurogenic Diabetes Insipidus VP is made but not transported VP 1. no VP is secreted 2. Very little water is retained in the collecting duct Treatment with VP can alleviate the problem

Nephrogenic Diabetes Insipidus VP Vasopressin is synthesized and secreted normally Collecting Duct Cell But there is a defect in the cellular mechanism that responds to VP