Antidiuretic Hormone

Antidiuretic Hormone: Hyposecretion

*Diabetes Insipidus (NO connection to blood sugar) -Very low levels of ADH leads to water not being reabsorbed by the blood -Causes dehydration VERY quickly—passing large amounts of very dilute urine, increased blood osmolarity follows -Can lead to death if severe and not treated

Antidiuretic Hormone: Hypersecretion

*Syndrome of inappropriate ADH (SIADH) -Common in head trauma patients -Cranial swelling puts pressure on the brain, which puts pressure on the pituitary gland causing hyper secretion of ADH -Large amounts of water reabsorbed into the blood leads to high blood pressure and decreased blood osmolarity. -Cells swell in the brain causing headache, nausea and confusion, even coma or death in severe cases

Negative Charge on the Glomerular Capillary Barrier

-2nd barrier, resist negative charge proteins. -These fixed negative charges are present on the endothelium, on the lamina rara interna and externa of the basement membrane, on the podocytes and foot processes, and on the filtration slits of the epithelium. -solutes such as Na + , K + , Cl − , or HCO 3 − , the effect of charge on filtration of the solute is not important.

Antidiuretic Hormone: Abbreviation and other names

-ADH -Vasopressin

Renal Clearance meaning

-By definition, renal clearance is the volume of plasma completely cleared of a substance by the kidneys per unit time. -Whole-body clearance means the total rate of removal of a substance by all organs, hepatic clearance means the rate of removal by the liver, and renal clearance means the rate of removal by the kidneys.

Antidiuretic Hormone: Inhibition of Release

-Decrease in plasma osmolarity -Increase in blood pressure -Ethanol and caffeine

Antidiuretic Hormone: Stimulation of Release

-Increase in plasma osmolarity (i.e. dehydration) -Decrease in blood pressure -Angiotensin II -Fear, pain or stress -Pituitary tumor

A glomerular marker has the following three characteristics:

-It must be freely filtered across the glomerular capillaries, with no size or charge restrictions. - it cannot be reabsorbed or secreted by the renal tubule. - when infused, it cannot alter the GFR. Thus, the properties of the ideal glomerular marker differ from those of a marker substance used to measure RPF (i.e., PAH).

Antidiuretic Hormone: Where Produced

-Neurohormone -Produced in the hypothalamus -Released by the posterior pituitary

PAH

-Organic acids such as para -aminohippuric acid ( PAH ) have the highest clearances of all substances because they are both filtered and secreted.

Antidiuretic Hormone (ADH): Functions

-Regulates blood osmolarity (most important function) -Causes kidneys to reabsorb water into the blood, < which decreases blood osmolarity -Regulates blood pressure (minor function) -Increases blood volume, which increases blood pressure -Causes vasoconstriction, which increases blood pressure

Other Markers for Glomerular Filtration Rate

-The closest substance is creatinine, which is freely filtered across the glomerular capillaries but also secreted to a small extent. -Accordingly, the amount of creatinine excreted in the urine per minute equals the amount of creatinine filtered across the filtration barrier each minute.

Inulin is freely filtered across the glomerular capillaries

-Used to measure the renal filtration rate (speed) function because it's not reabsorbed. -Inulin has unique properties that make it the only substance whose clearance is exactly equal to the glomerular filtration rate (GFR). is a reference substance called a glomerular marker.

Basement Membrane of the Glomerular Capillary has 3 layers.

-lamina rara interna is fused to the endothelium. -The lamina densa is located in the middle of the basement membrane. -The lamina rara externa is fused to the epithelial cell layer. --The multilayered basement membrane does not permit filtration of plasma proteins and, therefore, constitutes the most significant barrier of the glomerular capillary.

Epithelium of the Glomerular Capillary

-layer consists of specialized cells called podocytes, which are attached to the basement membrane by foot processes. -filtration slits, 25 to 60 nm in diameter.

renal clearance of albumin

-renal clearance of albumin is approximately zero because, normally, albumin is not filtered across the glomerular capillaries. -renal clearance of albumin is C x /C inulin < 1.0

clearance of creatinine

-some is secreted by the tubules thus the clearance of creatinine will be slightly higher than inulin. Use as an index of renal function. -Creatinine is an endogenous substance (inulin is not), and it need not be infused in order to measure GFR.

Countercurrent Multiplication

200 mOsm difference generated by NaCl pumps in ascending LOH is multiplied by countercurrent anatomy of LOH. Ocurrs only in loop of Henle.

Starling Forces Across Glomerular Capillaries

3rd barrier. -Theoretically, there are four Starling pressures: two hydrostatic pressures (one in capillary blood and one in interstitial fluid) and two oncotic pressures (one in capillary blood and one in interstitial fluid).

Where occurs the filtration

Afferent= ultrafiltrate Efferent=

Which substances are C x /C inulin < 1.0

Albumin, Na + , Cl − , HCO 3 − , phosphate, urea, glucose, and amino acids also are less than the clearance of inulin because these substances are filtered and then reabsorbed.

dextran

An artificial plasma-volume expander is

dextran are used for

At any molecular radius, cationic dextran was most filterable, anionic dextran was least filterable, and neutral dextran was in the middle.

Renal Clearance

Cx = Ux V/Px -the volume of plasma from which a given substance is completely cleared by the kidneys per unit of time.

Filtration Fraction

FF = GFR /RPF The 20% percentage of plasma in afferent arterioles that becomes glomerular filtrate is called the _________________.

loop of Henle descending limb

Function is reabsorbs water, no solutes reabsorbed. What tubule is this? Reabsorbs water, secretes NaCl

Clearance of Inulin and GFR

GFR = [U] inulin × V˙[P] Inulin = C inulin

Starling Equation

GFR=Kf [(PGC−PBS) − πG C] Where GFR = Glomerular filtration rate (mL/min) K f = Hydraulic conductance (mL/min • mmHg) or Filtration coefficient (mL/min • mmHg)

glomerular capillary wall

Glomerular capsular space is located between the visceral & parietal layers of the glomerular capsule. As blood flows through the glomerulus, it is filtered by the FILTRATION MEMBRANE which is composed of 3 layers. Name them. Endothelium, Basement Membrane, Epithelium

loop of Henle ascending limb

Impermeable to water and actively transports sodium to kidney. No water absorption in this area. Just absorb Na+ no H2O

countercurrent exchange in Vasa Recta

Minimize the washout effect of osmotic pressure 300 mOsm.

Why Na + , urea, phosphate, and Cl − have clearances that are higher than zero?

Na + , urea, phosphate, and Cl − have clearances that are higher than zero because they are filtered and partially reabsorbed.

Countercurrent Multiplication flow of tubular fluid 2

Repeat flow of tubular fluid but with a higher concentration.

Countercurrent Multiplication single effect 2

Repeat single effect but with a higher concentration.

the lowest renal clearances

Substances with the lowest renal clearances are not removed at all.

Vasa Recta

The capillaries that surround the tubules of the nephron. The vasa recta reclaims reabsorbed substances, such as water and sodium ions. Participate in passive countercurrent exchange.

what substance is the gold standard of GFR?

The clearance of any substance (x) can be compared with the clearance of inulin and is expressed as the clearance ratio. Clearance ratio = Cx /C inulin -If C x /C inulin = 1.0 The clearance of x equals the clearance of inulin. - if C x /C inulin < 1.0 Either the substance is not filtered, or it is filtered and subsequently reabsorbed.

Inulin

The clearance of what substance is the gold standard of GFR?

higher the renal clearance

The higher the renal clearance, the more plasma that is cleared of the substance. may be completely removed on a single pass of blood through the kidneys.

Which substances are C x /C inulin > 1.0

are higher than that of inulin are organic acids and bases, under some conditions, K + .

blood urea nitrogen ( BUN ) and serum creatinine concentration

blood urea nitrogen ( BUN ) and serum creatinine concentration can be used to estimate GFR because both urea and creatinine are filtered across the glomerular capillaries.

UREA Recycling

final mechanism used to establish the counter current multiplier occurs at the deepest part of the medulla. urea increases osmolarity of medulla to ensure that water will follow and leave the Collecting Duct. This is made in 4 stages.

force opposing filtration

glomerular osmotic pressure

Endothelium of the Glomerular Capillary

has pores 70 to 100 nanometers (nm) in diameter. Because these pores are relatively large, fluid, dissolved solutes, and plasma proteins all are filtered across this layer of the glomerular capillary barrier. On the other hand, the pores are not so large that blood cells can be filtered.

glomerular marker is? (Hint. not produced in our body)

inulin, a fructose polymer with a molecular weight of approximately 5000 daltons. : It is neither reabsorbed nor secreted by the renal tubular cells.

Countercurrent Multiplication single effect

loop of Henle, creates an osmotic gradient that facilitates reabsorption of water

renal clearance of glucose

renal clearance of glucose is also zero, although for a different reason: Glucose is filtered and then completely reabsorbed back into the bloodstream.

In certain glomerular diseases, the negative charges on the barrier are removed, what result.

resulting in increased filtration of plasma proteins and proteinuria.

loop of Henle

section of the nephron tubule that is responsible for conserving water and minimizing the volume of the filtrate

Bowman's space

space in which ultrafiltrate goes once leaving the glomerulus.