Renal powerpoint-jaime.txt

• Surrounds glomeruli capillaries
• Continuous with first portion of nephron
• Blood is ultrafiltered through this space
• First step in urine formation

What remains of nephron has specialized cells that serve for reabsorption and secretion.

• Nephron
• Each kidney contains approximately 1 million nephrons.
• Consists of glomeruli and renal tubule

Bowmans capsule

• 1. Proximal convoluted tubules
• 2. Proximal straight tubule
• 3. Loop of Henle (thin descending, thin ascending, thick ascending)
• 4. Distal convoluted tubule
• 5. Collecting ducts

• 1. Superficial cortical nephrons
• 2. Juxtamedullary nephrons

• glomeruli in outer cortex
• short loops of Henle
• descend only into outer medulla

• glomeruli near the coritocomedullary border
• Larger
• Higher flow rates
• Long loops of Henle
• Descend deep into inner medulla and papilla- essential for formation of concentration of urine.

• Deliver blood to the glomeruli capillaries.
•  
• BLOOD TO!!

Blood leaves the glomeruli capillaries

blood then delivered to secondary capillary network.

BLOOD AWAY!!!

Outer region of kidney located just under renal capsule

A central region , divided into outer and inner medulla

Outer medulla has outer stripe and inner medulla has inner stripe

The innermost tip of the inner medulla and empties into pouches called minor and major calyces, which are extensions of ureter.

50-70%

3 Kg weight loss = 3 liters loss of total body water.

• 55%
• Cells=45%

7%

The other 93% of plasma volume is plasma water.

• In the ECF
• Cannot cross cell membrane

*choose marker based on where it will go. Mannitol will not cross cell membrane so it stays in the ECF.

• Innulin is same as mannitol, it cannot cross cell membrane.
• It is found in ECF not in the ICF

Solute it contains.

290 mOsm/L

simplicity=300

• ECF= goes down
• ICF= N.C
• Osmolarity=N.C
• Hematocrit= goes up
• Plasma Protein= goes up

• ECF= goes down
• ICF=goes down
• Osmolarity= goes up
• Hematocrit= no change
• Plasma Protein= goes up

• ECF=goes down
• ICF=goes up
• Osmolarity=goes down
• Hematocrit=goes up
• Plasma Protein=goes up

• ecf= goes up
• icf=no change
• osmolarity= no change
• hematocrit= goes down
• plasma protein= goes down

• ECF= goes up
• ICF= goes down
• Osmolarity= goes up
• Hematocrit= goes down
• Plasma Protein= goes down

• ECF= goes up
• ICF= goes up
• Osmolarity= goes down
• Hematocrit= No change
• Plasma protein= goes down

C=U x V/P

• C= clearance (ml/min)
• [U]x= urine concentration (mg/ml)
• V= urine flow per minute (ml/min)
• [P]x=plasma concentration (mg/ml)

Renal clearance is a ration of urinary excretion to plasma concentration.

• C=U x v/p
• C= 100 x 1/2= 50 ml/min

Inulin

Unique properties

Glomerular Marker

25%

1.25 L/min

Vasoconstriction for activation of alpha 1 receptors

Because there are far more alpha receptors on afferent arterioles (taking blood to capillaries) and this increases sympathetic nerve activity- this causes decreased GFR and RBF (renal blood flow) *attempts to raise BP at the expense of kidneys.

RPF( renal plasma flow)

RBF= RPF/1-HCT

The amount of a substance entering the kidney via the artery equals the amount leaving via the vein.

[PAH] in renal blood flow

• [PAH] in renal vein
• PAH- substance used to measure RPF with Ficks principle

effective RPF= [U]pah X V/[P]pah=Cpah

• [U]pah= urine concentration of pah (mg/ml)
• V= urine flow rate (ml/min)
• [P]pah= plasma concentration of PAH (mg/ml)
• Cpah= clearance of PAH (ml/min)
• IN SIMPLIFIED FORM
• EFFECTIVE RPF=CLEARANCE OF PAH

• C= (Urine concentration) [U]x X (urine flow) V/( plasma concentration) [p]x
• or
• GFR= [U]inulin x V/[P]inulin=C inulin

• 150 x 1/1=
• GFR= 150ml /min

• Use renal clearance equation
• GFR  x plasma concentration

• Urine formation
• Bowmans capsule

Amount of substance excreted per unit of time

• V x U
• urine flow rate x urine concentration of X

Filter load - excretion rate

• two hydrostatic pressure- one in capillary blood, and one in interstitial fluid
• two oncotic pressures= one in capillary blood, and one in interstitial fluid
• Oncotic pressure in Bowman's capsule is 0

GFR=Kf= (Pgc-Pbs) - (pie symbol not in parenthesis)gc

• Pgc-Pbs= hydrostatic pressure of glomeruli capsule - hydrostatic pressure of Bowman's capsule
• (Pie)gc= oncotic pressure in glomeruli capsule

Starling Pressures

• RPF=Decreased
• GFR=Decreased
• Pgc=decreased b/c of decreased blood flow
• FF (GFR/RPF)= No change

• RPF= decreased
• GFR- increased  (opposite of afferent end)
• Pgc- increases
• Filtration fraction (GFR/RFP)= increased

• RPF= N.C.
• GFR= Decreases
• FF=Decreases

• RPF= N.C
• GFR= increase
• FF= increase

• RPF= N.C.
• GFR= decreased
• FF= decrease

Creatinine

Slightly overestimates GFR

GFR= [U]creatinine x V/[P] creatinine = C of creatinine

• Vasoconstrictor at both sides- afferent and efferent
• Efferent more sensitive
• Low levels increase GFR (constrict efferent)
• High levels decrease GFR (constrict afferent and efferent)

• Produced in kidneys, causes vasodilation of both
• Protective of RBF (long term vasoconstriction after hemorrhage can cause renal failure)
• Modulated constriction caused by SNS and release of angiotensin II
• NSAIDS- inhibit this synthesis of prostaglandins and therefore interfere with protective effects of prostaglandins on renal function following hemorrhage

amount of substance filtered into Bowman's space per unit of time = filtered load

water and many solutes are reabsorbed from the glomerular filtrate into the peritubular capillary blood

• Few substances are secreted from peritubular capillaries
• Organic acids, organic bases, and potassium
• Mechanism for excreting substances in the urine

GFR/RPF

• In proximal tubule
• 2 steps
• 1.Sodium glucose co-transport- sodium and glucose released into ICF, and potassium moved out -
• 2.facilitated glucose transport across peritubular membrane  (no energy required).

• 300
• 200

all filtered glucose is reabsorbed

All filtered glucose is not reabsorbed.

All carriers are saturated, no reabsorption will take place

• Uncontrolled DM
• Pregnancy
• congenital abnormalities in sodium glucose transport

• Most segments of nephron reabsorb urea
• Urea reabsorbed by simple diffusion and is freely filtered.
• Urea follows the same pattern as water. As water reabsorption increases so does urea reabsorption.

para-aminohippuric acid- the substance used to measure RPF (renal plasma flow) in Ficks principle

filtered across capillary and secreted from peritubular capillary blood into tubular fluid

• maintaining a normal sodium balance
• sodium excretion should equal sodium intake

• Na freely filtered across glomerular capillaries and reabsorbed throughout nephron.
• Excreted 1%
• Reabsorbed 99%

• 67%- Proximal convoluted tubule
• 25%-thick ascending loop of henle
• 8%  distal convoluted tubule and collection ducts

• 67%
• Where sodium goes, water follows

• 67%
• Co-transport with bicarb, organic solutes, amino acids, and glucose
• 100 % of glucose and amino acids reabsorbed
• Na-H exchanger- causes net absorption of bicarb
• 85% bicarb reabsorbed here.

Thick ascending limb of Henle

• Reabsorbs a significant amount of sodium by an active mechanism
• Na-K-2Cl co-transporter= three ion co-transport, energy from sodium gradient, maintained by sodium potassium pump
• Site for loop diuretics, lasix

Early distal convoluted tubule

• 8% of Na reabsorption
• Load dependent= the more you bring to it the more will be absorbed.
• Na-Cl co-transport
• Site for thiazide diuretics

• Principle and alpha cells
• Hormonal regulation: aldosterone, water, reabsorption
• Aldosterone-increase Na reabsorption in principle cells
• Water- without water permeability is low.

• 98% ICF
• 2% ECF
• Freely filtered
• Excretion of potassium must be equal to the intake.

Stimulates potassium uptake in cells.

• alkaline= hydrogen decrease, hydrogen leaves and potassium enters
• academia= k leaves and hydrogen enters

Increase the sodium potassium pump causing a shift of potassium into the cells.

shift of potassium out of cell

take potassium into the cells.

shifts potassium out of the cell

Large amount of potassium is released from ICF

• 67%
• 20%-diffuses to blood
• Fine adjustments of potassium excretion, varies with diet

reabsorb potassium

Excrete potassium

• High potassium diet
• Increase in aldosterone
• Alkalosis
• loop and thiazide diuretics
• presence of large anions in lumen

potassium sparing diuretic

• inhibits actions of aldosterone (increases potassium excretion)
• inhibits potassium excretion

• 40% bound to plasma proteins
• 67% reabsorbed at proximal convoluted tubule
• 25%
• 8% reabsorbed in distal tubule

• 70%
• 15%
• Exhibits tmax

• 20%
• 30%
• 60%

Loop diuretics inhibit magnesium reabsorption strongly.

• 1. water is lost from body (if not replaced increase osmolarity of plasma)
• 2. Increased osmolarity
• 3. stimulation of receptors (stimulates thirst and ADH)
• 4. ADH- increases permeability
• 5. Increased water reabsorption in late distal tubules
• 6. more water returned to body, osmolarity decreases

• function of the loop of henle
• deposits NaCl deep into regions of the kidney
• 1st step- single effect
• thick ascending limb, no water is reabsorbed but NaCl
• 2nd step-descending limb reabsorbs water
• equilibrates with interstitial spaces
• THE TWO BASIC STEPS REPEAT UNTIL FULL GRAIDIENT IS ESTABLISHED. SIZE OF GRADIENT DEPENDS ON LENGHT OF LOOP OF HENLE.

Urea is recycled instead of thrown away in the urine.

• maintains the corticopapillary osmotic gradient.
• passive
• slow flowing blood
• vasa recta

• 1. increases water permeability in the distal tubules and collecting ducts.
• 2. Increases activity of na-k-2cl cotransporter in thick ascending limb
• 3. increases urea permeability in the inner medullary collecting ducts (enhances urea recycling).

• NaCl reabsorbed in thick ascending loop of henle- water reabsorption can not happen here.
• Nacl reabsorbed by NaCl transporter in early distal tubule.
• Principle cells become permeable to water in the presence of ADH
• Urine is produced and osmolarity 1200 mOsm

• Low circulating ADH
• Tubular fluid diluted
• Dilution continues
• (most dramatic if ADH low or absent)
• final urine does not equilibriate with interstitial fluid.
• Final osmolarity= 75 mOsm/L

Changes in Pcg are produced by changes in resistance to afferent and efferent arterioles

Active transport

All three ions are transported into the cell on the co-transporter

Energy from sodium potassium pump

early distal convoluted tubule

Thick ascending limb

Proximal convoluted tubule

• Countercurrent multiplication
• Urea Recycling