Nephronstuble Wafa

7/31/2019 Nephronstuble Wafa

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Nephrons

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Nephron: Tubular Function

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Each kidney has~1.2 MILLION PER KIDNEY

Functional unit of kidney its microscopic tubules

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Renal corpuscleBowmans or Renal capsuleParietal layer

Visceral layer

Glomerulus

Network of capillaries goes into anothercapillary bed called the peritubularCapillaries

Arterioles

Afferent

Blood to glomerulus

Efferent

Drains not into veinule but anotherarteriole

Tubules

Proximal (convoluted)tubule

Loops of Henle

Descending limb

Ascending limb

Distal (convoluted)tubules

Collecting ducts

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2/Cortical1/Juxta medullary

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composed of:Nephrons

1/Glomerulus2/Tubule

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1/ Glomerulus is a tangled capillary bed.2/ Filters fluid from blood into the Renal

.Tubule

3/ Glomerular Filtration: Fluid movespassively out of Glomerulus

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RENAL CORPUSCLE1/GLOMERULUS PLUS CAPSULE

2/GLOMERULUS ENCLOSED IN TWO-

LAYERED

3/GLOMERULAR CAPSULE

BOWMANS CAPSULE

4/FLUID FILTERS FROM GLOMERULAR

CAPILLARIES

GLOMERULAR FILTRATE

5/FLUID COLLECTS IN CAPSULAR SPACE

6/FLUID FLOWS INTO RENAL TUBULE12


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Blood Supply to the Glomerulus-Afferent ArterioleFeed the Glomerular Capillary Bed

-Efferent ArterioleDrains the Glomerular Capillary Bed13


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Collecting DuctLast part of the collecting tubule in the

Nephron

Glomerularcapsule surrounds theGlomerulus

Funnels filtrate into the Renal TubuleRenal corpuscleName for the Glomerulus and

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1/Renal Tubule is a long tubeProcesses the filtrate from the Glomerulus.2/Tubular Reabsorption: Reabsorbs usefulsubstances .3/Tubular Secretion: Move wastes towards

elimination.

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The Renal Tubule consists of:

1/Proximal Convoluted Tubule (PCT)2/Loop of Henle (Nephron Loop)

3/Distal Convoluted Tubule (DCT)

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PROXIMAL CONVOLUTED TUBULE (PCT)

1/ARISES FROM GLOMERULAR CAPSULE

2/LONGEST, MOST COILED REGION

3/PROMINENT MICROVILLI

((( (((FUNCTION IN ABSORPTION

4/MUCH CONTACT WITH PERITUBULAR

CAPILLARIES

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The Proximal Convoluted Tubule (PCT)

The mechanisms: by which the electrolytes are recovered(reabsorbed) to the blood, most of it, is not under hormonal

control, and referred to as obligatoryrecovery done by :

Passive transport (diffusion or swept along with the water

absorbed by osmosis).

Carrier-mediated transport.

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The PCT initiates the 2nd. Step in the formation of

urine by recovery of constituents of the filtrate that must

be retained within the body:

Nutrients (glucose and amino acids)Electrolytes (sodium, potassium, chloride etc)

Hydrogen carbonate

Water.

The Proximal Convoluted Tubule (PCT)

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Reabsorption in Proximal Nephron

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1/PCT EXTRACELLULAR FLUID

PERITUBULAR CAPILLARIES

2/ROUTES OF REABSORPTION-----TRANSCELLULAR

1-THROUGH EPITHELIAL CELLS OF PCT

-----PARACELLULAR1-BETWEEN EPITHELIAL CELLS OF PCT

2-LEAKY TIGHT JUNCTIONS

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NEPHRON LOOP (LOOP OF HENLE)

1/U SHAPED, DISTAL TO PCT2/DESCENDING AND ASCENDING LIMBS

3/THICK SEGMENTS -ACTIVE TRANSPORT OF SALTS -HIGH METABOLISM, MANY>>>MITOCHONDRIA

4/THIN SEGMENTS -PERMEABLE TO WATER

-LOW METABOLISM

Renal Tubule

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Reabsorption in Loop of Henle

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DISTAL CONVOLUTED TUBULE (DCT)

COILED, DISTAL TO NEPHRON LOOPSHORTER THAN PCTLESS COILED THAN PCT

VERY FEW MICROVILLICONTACTS AFFERENT AND EFFERENT

ARTERIOLES (REGULATION IMPARTED)CONTACT WITH PERITUBULAR CAPILLARIES

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COLLECTING DUCT

DCTs OF SEVERAL NEPHRONS EMPTY

INTO A COLLECTING DUCT

PASSES INTO MEDULLA

SEVERAL MERGE INTO PAPILLARYDUCT (~30 PER PAPILLA)

DRAIN INTO MINOR CALYX

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End of Distal Convoluted Tubule, DCT(composition in lumen of the DCT)

Albumin( 0.2 g/L) 0.0

Glucose (5 g/L) 0.0 (reabsorbed)

Amino acids (2 g/L) 0.0 (reabsorbed)

Sodium (135 mmol/L) 40-135Potassium (4 mmol/L) 4-40

Chloride (115 mmol/L) 35-135

Hydrogen carbonate (25mmol/L) 1-10

Osmotic pressure = 80-300 mOsmol/kgH2O)=

flow rate 5-10 ml/min.

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Kidney Dialysis

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