Intro to Nephron (CMPP)

How much of lean body water is water

2/3

Total Body Water (TBW)

The total amount of water in the body

Whta are the compartments of TBW

Intracellular Fluid (2/3)

Extracellular Fluid (1/2)

What are the compartments that make up the extracellular fluid

Intravascular Fluid (Plasma)

Interstitial Fluid

What is the predominant ion in ICF

K

What are the predominant ions in ECF

Na

Cl

HCO3

What is normal Na

136-145

What is normal K

3.5 - 5

What is normal Cl

95-105

What is normal HCO3

22-28

What is normal BUN

7-20

What is the normal Creatinine level

0.7 - 1.2

What is normal serum glucose level

70-100

What is normal serum Mg

1.5 -2

What is a good indicator for hydration status

UOP

What is the common order for IV fluids for hydration

Call if UOP < 30mL x 2 hours

What are the main electrolytes we look at for IV fluid

Na and K

What are the IV fluid options

0.9 NS

0.45 NS

Lactated Ringer’s

D5W

3% NS

What is the primary resuscitative fluid

0.9 NS

Lactated Ringer’s

A solution that is slighly less concentrated than 0.9 NS but contains K, HCO3, and Ca

D5W

A IV fluid that contains no Na but does contain glucose

Osmosis

a process that occurs when water moves across a membrane to balance concentrations

Tonicity

the concentration of solutes that cannot pass the membrane

how does water move in osmosis

low solute concentration to high solute concentration

What is the most sensitive tissue to fluid shifts

Brain

Why is maintaining intravascular volume critical

Volume is needed for adequeate perfusion

Filtration

Movement of fluid from the glomerulus into renal tubercules

Reabsorption

Movement of fluid from renal tubules into capillaries

Secretion

= Movement of fluid from the capillaries into renal tubules

Excretion

Movement of fluid out of the body via calcyes and ureters

Fluid

•Liquid in the tubules made of water, electrolytes, glucose, toxins, etc.

Urine

Fluid that has leave the collecting duct and entered the renal calyces

Stretch Receptors

monitor BP through pressure on the walls of the artery

Where are stretch receptors located in

carotid artery, aortic arch, and afferent arterioles (nephrons

What does hypothalamus do in response to low BP

Stimulates thirst mechanism

Stimulates release of ADH

How does the kidney respond to low BP

JGA secrete Renin

What are the steps of RAAS

Low BP  JGA releases Renin

Angiotensinogen (w/ Renin)  Angiotensin I

Angiotensin I (w/ ACE)  Angiotensin II

Angiotensin II induces vasoconstriction and stimulates adrenal cortex

Adrenal Cortex releases Aldosterone

Aldosterone induces Na and H2O reabsorption

Natriuretic Peptides

Hormones that impact Na and H2O handling helping to regular BP

What are the types of natriuretic peptides

Brain Natriuretic Peptide

Atrial Natriuretic Peptide

What is the effects of natriuretic peptidues

Diuretic (Water Excretion)

Natriuretic (Na secretion)

Sympathetic Inhibition

What is the MOA of natriuretic peptides

Inhibits renin, which shuts down RAAS

What is the body’s defense for CHF

Natriuretic Peptides

Where are the kidney

T12-L3

Renal Pyramids

Regions of the renal medulla that contains groups of tubules

What are the regions of the kidney

Cortex

Medulla

Renal Calcyes

Funnel like structures that collect urine from collecting ducts to into renal pelvis

Renal Pelvis

A funnel structure that funnels all urine into the ureter

When does tubular fluid become urine

Once it enters the renal pelvis

What is the functional unit of the kidney

Nephrons

What are the parts of the nephron

•renal corpuscle and renal tubule

What makes up the renal corpuscle

•a glomerulus and Bowman’s capsule

Glomerulus

a network of capillaries consisting of a sandwich of filter

What makes up the layered filter of the glomerulus

Fenestrated Endothelium

Basement membrane

Podocytes

Mesangium

A membrane that holds the layers of the glomerulus together

Bowman’s Space

area around the glomerulus within the Bowman’s capsule

What are the types of nephrons

Cortical

Juxtamedullary

Cortical Nephrons

Nephrons that have their corpuscle closer to the surface of the kidney

•Juxtamedullary nephrons

Nephrons that have their corpuscle closer to the medulla

What are the sections of the renal tubule

Proximal Convoluted Tubule

Loop of Henle

Distal Convoluted Tubule

Collecting ducts

What are the branches of the efferent arteriole

peritubular capillary and vasa recti

•Peritubular capillary

A BV that surronds the PCT and DCT

Vasa Recti

A BV that surronds the LOH and collecting ducts

What is the functions of the kidneys

•Maintained of fluid and electrolyte balance

•Regulation of acid-base balance

•Regulation of blood pressure via RAAS

•Filtration, secretion, and execration of metabolic waste

•Phosphorus filtration and Vitamin D activation for Ca metabolism

•Stimulation of RBC production via EPO

•Reabsorption of glucose, AAs, and vitamins

How does reabsorption occur in the tubule

Electrolytes and Glucose = Active

Water = Passive via Osmosis

Glomerular filtration Rate (GFR)

Quanity of fluid passing through the glomerular capillary into the Bowman’s space in all nephrons

What is the normal GFR

•125mL/min

How much of the fluid is reabsorbed in the tubule

99%

What are the determinants of GFR

•Renal (Glomerular) blood flow (RBF)

•Affterent arteriolar tone

•Efferent arteriolar tone

•Glomerular capillary hydrostatic pressure (Pc) and osmotic pressure (TTc)

•Bowman’s capsule hydrostatic pressure (Pb)

What can cause major GFR increase

•Increased RBF

•Afferent dilation

•Efferent constriction

What can cause major decrease in GFR

•Decrease RBF

•Afferent constriction

•Efferent dilation

Why serum Cr better for evaluating GFR than BUN

•Creatinine is not reabsorbed and minimally secreted into the PCT

What can cause elevated BUN outside of renal

Volume Depletion

GI Bleed

High Protein

What can decrease BUN outside of renal

Liver Disease

Low Protein

What occurs in the PCT

> 70% of Na and water reabsorption

Large protein reabsorption

Creatinine and toxin secretion

How does LOH permeability change

Descending = Water Permeable

Ascending = Salt Permeable

Countercurrent Multipler

A mechanism in which interstitial fluid is kept to higher osmalitiy that tubular fluid

What is the maximum osmolarity of countercurrent

1200 mOsm/L

What is the role of collecting duct

Last water reabsorption (ADH + RAAS)

Carbonic Anhydrase Inhibitors

A medication that Inhibits transport of NaHCO3 from the PCT to interstitial capillary

Result is execration of water and HCO3 (alkaline urine)

Acetazolamide

Carbonic Anhydrase Inhibitors

What is the indication for Carbonic Anhydrase Inhibitors

•Primary Metabolic Alkaloses

•High Altitude Pulmonary Edema

•Glaucoma

•Seizures

Loop Diuretics

Medications that Inhibts active transport of sodium in the ascending LOH

Furosemide (Lasix)

Loop Diuretics

Torsemide (Demadex)

Loop Diuretics

Bumetanide (Bumex

Loop Diuretics

What is the indication for Loop Diuretics

CHF

Thiazide Diuretics

Medications that Inhibits NaCl reabsorption at the DCT results in vasodilation

Hydrochlorothiazide (HCTZ)

Thiazide Diuretics

Chlorothiazide (Diuril

Thiazide Diuretics

What is the indication for Thiazide Diuretics

HTN

Aldosterone Antagonist

A medication that Inhibits Na reabsorption (and K secretion) in the collecting duct

Spironolactone (Aldactone)

Aldosterone Antagonist

Amiloride (Midamor)

Aldosterone Antagonist

Triamterene (Dyrenium)

Aldosterone Antagonist

What is the indication for Aldosterone Antagonist

HTN

CHF

Juxtaglomerular Apparatus (JGA)

A structure that is located on the vascular pole of the corpsucle that allows the kidney to autoregulate using renin and RAAS

What makes up JGA

Macula Densa

Juxtamedullary Cells

Extraglomerular Mesangial Cells

Macula Densa

Special cells in the wall of the DCT that detect GFR changes and relay to JG cells

Juxtamedullary Cells

Special cells in the wall of afferent arteriole that releases renin in low GFR and low BP

Extraglomerular Mesangial Cells

Supportive cells of the JGA that have smooth cell properties