Renal System YouTube Lecture Handouts

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RENAL SYSTEM

Image of Renal System - 1

Image of Renal System - 1

Image of Renal System - 1

Functions of Kidney

  • Excretion

    • Metabolic waste

    • Foreign sub.-Drugs, etc.

  • Regulation of Fluid & Electrolytes

  • Maintain Acid Base Balance

Functions

Hormonal Functions

  • 1 Renin Angiotensin Aldosterone System

  • 2 Calcitrol

  • 3 Erythropoietin

KIDNEY-ANATOMY

  • Functional anatomy: bean shaped st.

  • Location: retroperitoneal, on post. Abdominal wall. At T12 to L3 Vertebrae

  • Size:

  • Length-----10 cm

  • Width ------5 cm

  • Thickness---2.5 cm

KIDNEYS

  • Weight of kidney is----150gm

  • Rt. Kidney slightly lower

  • On medial side a notch, Hilum is present

  • Through it passes

  • Renal artery and veins

  • Lymphatics and nerves

  • Ureter

Renal Sy

  • Microscopic structure

  • Outer---cortex

  • Inner---medulla

  • NEPHRON: structural and functional unit

  • Each kidney has about 1.2 million nephrons

Image of Renal System - 2

Image of Renal System - 2

Image of Renal System - 2

Renal Sy

  • Nephrons are

  • Cortical

  • Juxtamedullary

Image of Renal System - 3

Image of Renal System - 3

Image of Renal System - 3

NEPHRONS

Differences:

Table of Nephrons Differences - 1
Table of Nephrons Differences - 1

Sn

1

2

Feature

No.

Location of glomerulus

Cortical

85%

Small loc. In cortex

JM

15%

Large at corticomedullary junctions

NEPHRONS

Table of Nephrons Differences - 2
Table of Nephrons Differences - 2

Sn

3

4

Feature

LH

LH

lCortical

Short up to outer medulla

Dl thin seg

Al thick

JM

Long

Deep into medulla

Both have thin seg.

NEPHRONS

Differences

Table of Nephrons Differences - 3
Table of Nephrons Differences - 3

Sn

5

6

Feature

Vascular supply

Filtration rate

Cortical

Vasa recta not present

Slow

JM

Vasa recta present

high

NEPHRONS

Differences

Table of Nephrons Differences - 4
Table of Nephrons Differences - 4

Sn

7

Feature

Main function

cortical

Excretion of waste product

JM

Concentration of urine

NEPHRON

  • Structure of nephron: has two parts

  • Renal or Malpighi and corpuscle

  • Tubules

  • Malpighi and corpuscle has:

  • Glomerulus

  • Bowmans capsule

Image of Nephron

Image of Nephron

Image of Nephron

Malpighi and Corpuscle

Glomerulus (tuft of capillaries) –

  • Size –200 µm

  • Afferent arteriole- short & wide, blood enters through them

  • Efferent arteriole-long & narrow blood leaves, through them

  • Vascular pole- afferent & eff. are close

Malpighi an Corpuscle

Bowman’s capsule –initial dilated part of nephron. It has:

  • Parietal layer—outer layer

  • Visceral layer—Inner, covering the glomerular capillaries

  • Bowman’s space—between two layers

Renal System

Diagram

Diagram of Renal System

Diagram of Renal System

Diagram of Renal System

Glomerular Membrane

Ultrastructure of glomerular membrane

  • Three layers

  • Capillary endothelium: fenestrated pore diameter 70 to 90 nm

Freely permeable to water & solutes

Renal System

2. Basement membrane: matrix of glycoproteins & mucopolysaccharides lamina rara externa lamina dens lamina rara interna has no pores but permeability matches to pore size of about 8nm

Renal System

3. Visceral epithelium of bowman’s cap. Formed by podocytes filtration slits diameter—25 nms slits covered by fine filaments

Renal System

Filtration

Membrane

Image of Filtered Substances Pass Through Endothelial Pores And Filtration Slits

Filtered Substances- through Endothelial Pores, Filtration Slits

Image of Filtered Substances Pass Through Endothelial Pores And Filtration Slits

RS—Tubules

  • Proximal convoluted tubule

  • Loop of Henle

  • Distal convoluted tubule

  • Collecting tubule

Image of RS - Tubules

Image of RS - Tubules

Image of RS - Tubules

Image of Cortical Nephron

Image of Cortical Nephron

Image of Cortical Nephron

RS—Tubules

Characteristics of epi. lining tubules:

  • Cells have special features in different seg. & perform specific functions

  • Cells are mostly cuboidal

  • Apical surfaces have microvilli

  • PCT has brush border on luminal side

RS- JG Apparatus

Also called JG complex: has JG cells macula densa mesangial cells

RS- JG Apparatus

Diagram

Image of RS -JG Apparatus

Image of RS -JG Apparatus

Image of RS -JG Apparatus

Image of Region of Juxtaglomerular Complex In Section

Image of Region of Juxtaglomerular Complex in Section

Image of Region of Juxtaglomerular Complex In Section

RS –JG Apparatus

  • Juxtamedullary cells:

  • Modified my epithelial cells

  • Located in the media of aff. Arteriole

  • Granular cells

  • Densely innervated by sympathetic

  • Secret RENIN

  • Baroreceptor by function

RS—JG Apparatus

Macula Densa Cells:

  • Are in contact with mesangial & JG cells

  • Not well adapted for reabsorption

  • Not innervated

  • Act as chemoreceptor

  • Stimulated by ↓ Nacl

  • ↓ Renin release

RS-JG Apparatus

  • Mesangial cells or Lacis cells

  • Possibly relay signals from macula densa to granular cells

  • Take up immune complexes

  • In extreme hyperactivity show granules containing renin

JG-Apparatus

Functions:

  • Renin secretion

  • Regulation of GFR

  • Mesangial cells mediate signals between Macula Densa & Afferent Arteriole

  • Mesangial cells within the glomerulus communicate with cells outside

  • ↓ surface Area of filtration when BP is V. low

RS-Renal Blood Flow

  • Renal circulation is portal circulation 2 sets of capillaries are present

  • Amount & rate of flow

  • In basal condt. -----1200 ml/min.

  • High flow is related to excretory function.

  • Flow is remarkably constant due to Autoregulation

RS-Renal Blood Flow

Internal distribution of blood flow

  • Cortex--------------90%

  • Outer medulla-----9%

  • Inner medulla------1%

  • Low blood flow through medulla helps in urinary concentration.

Image of RS-Renal Blood Flow - 1

Image of RS-Renal Blood Flow - 1

Image of RS-Renal Blood Flow - 1

Image of RS-Renal Blood Flow - 2

Image of RS-Renal Blood Flow - 2

Image of RS-Renal Blood Flow - 2

RS— Renal Blood Flow

Autoregulation of renal blood flow

  • Feature of cortical blood flow

  • Present in denervated kidney

  • Seen in transplanted kidney.

RS—Renal Blood Flow

Autoregulation of renal blood flow:

  • Myogenic Theory

  • Tubuloglomerular feedback

  • Cell separation Theory

  • Intrarenal tissue pressure

  • Intrarenal reflexes

RS—Renal Blood Flow

Measurement, 2 methods

  • Venous shunt technique

  • Fick principle

Fick principle: substance used

  • Con. In blood can be measured easily

  • Not metabolized, stored or produced

  • Does not affect blood flow

RS—Renal Blood Flow

  • Substances used are

  • PAH (p-amminohippuric acid)

  • Diodrast

  • Usually PAH is used, it has high extraction ratio 90%

RS—RBF

  • Effective Renal plasma flow:

  • ERPF= UPAHxV/PPAH =clearance of PAH e. g. = UPAH =14mg/ml V =0.9ml/min PPAH=0.02mg/ml

  • ERPF = 14x0.9/0.02=630ml.

RS—RBF

ERPF is converted to actual plasma flow Extraction ratio is 0.9

Actual Plasma flow=630/0.9=700ml/min

  • Hematocrit =45%

  • RBF=RPF x 1/1-Hct

  • RBF= 700x1/0.55= 1273ml/min or 1.2L/min

RS— Urine Formation

  • Mechanism: includes

  • Filtration --------- (glomerulus)

  • Reabsorption--(tubules)

  • Secretion---------- (tubules)

Image of Urine Formation

Image of Urine Formation

Image of Urine Formation

RS—Glomerular Filtration

  • Definition: Amount of fluid filtered by all the nephrons of both the kidneys/ min.

  • Normal value=125ml/min.

  • Filtration fraction: Ratio of GFR to renal plasma flow

Filtration Fraction

Is

FF = GFR (ml / min.), RBF (ml/ min) = 125 / 700 Normal range = 16- 20 %

Dynamics of Filtration

NET FILTRATION PRESSURE

Forces Favoring Filtration

1. Gl. Hydro. Press. = 60mmHg

2. Colloid osmotic pressure of Bowman’s capsule = 0

GFR

Forces Opposing Filtration (mm Hg)

1. Capsule Hydrostatic Press. = 18

2. Gl.Cap. Colloid osmotic Pressure =32

NET FILTRATION PRESSURE:

60 - (18 + 32) = +10 mm Hg

GFR

Filtration Coefficient:

  • Rate of filtration / mm Hg Filtration Press

  • 125 / 10 =12.5 ml/min/mm Hg

  • It is GFR at 1mm Hg Effective Filtration Pressure

  • It is product of permeability and filtration area

Filtration Membrane

  • Permeability-

  • Pores in capillary Endo. Cell- 70- 90 nm

  • Podocytes Filtration Slits ----- 25 nm

  • Glomerular Basement Mem. Has no pores but permeability corresponds to pore size of 8 nm.

Image of Glomerular Capillary Entwined By Processes of Three Podocytes

Glomerular Capillary Entwined by Processes of 3 Podocytes

Image of Glomerular Capillary Entwined By Processes of Three Podocytes

Filtration Membrane

  • Molecules less than 4nm—freely filtered

  • Molecules more than 8nm-not filtered

  • Pores are –vely charged due to presence of glycoproteins rich in sialic acid

  • Albumin with mol. Diameter of 7nm is negatively charged so not filtered

Image of Filtration Membrane

Image of Filtration Membrane

Image of Filtration Membrane

Filtration Membrane

  • Area

  • Controlled by mesangial cells

  • COMPOSITION OF FILTRATE:

  • Like plasma except for absence of proteins and cells

Factors Affecting GFR

  • Glomerular capillary hydrostatic press.

  • Glomerular capillary oncotic pressure

  • Hydrostatic press. of fluid in Bow. Cap.

  • Filtration Coefficient

  • Permeability of membrane

  • Filtration Area

GFR Measurement

  • By Clearance method:

  • Salient features of the substance used

  • Not toxic & biologically inert

  • Is freely filtered

  • Has no effect on GFR

  • Not absorbed or secreted by tubules

  • Not stored in kidneys

GFR Measurement

Substances used:

  • Inulin- A polysaccharide Mol. Wt.5200

  • Creatinine

  • Sodium Ferro cyanides

  • Mannitol

  • Radioactive cobalt labelled vit. B12

  • R.A. 51Cr. labelled EDTA

GFR- Inulin Clearance

  • C in = Uin x V / Pin

  • Uin = 35 mg/ml

  • V = 0.9 ml/min

  • Pin = 0.25 mg/ml

  • Cin = 35 x 0.9 /0.25

  • = 126 ml/min is GFR

Creatinine Clearance

  • Endogenous Creatinine Clearance is easy to measure

  • Some reabsorbed & some secreted in tubules

  • Not very exact but convenient

Tubular Reabsorption

  • Filtered Load: Amount of solute transported across the glomerular membrane per unit time.

  • Filtered load = GFR x Plasma concentre of the solute

Glomerulotubular Balance

  • Is percentage of filtered fluid that is reabsorbed in proximal tubule?

  • It is constant i.e. 70 % of fluid filtered.

  • Key element in PT reabsorption is Na+- K+- ATPase

Substances Reabsorbed in PT

Important substances reabs. are

  • Sodium

  • Glucose

  • Aminoacids

  • Bicarbonates

Reabs of Sodium

~ 65% of filtered sodium is reabsorbed

  • In first half by co-transpot along with glucose, aminoacids etc.

  • In second half with chloride

Image of Reabs of Sodium

Image of Reabs of Sodium

Image of Reabs of Sodium

Glucose Reabsorption

  • Essentially all is reabsorbed only few mg. appear in urine

  • Secondary Active transport

  • Filtered at a rate of about 100mg/min.

  • (Plasma concentration--80mg/dL & GFR--125ml/min)

Renal Threshold & Tm

Renal Threshold:

  • Plasma glucose level at which it first appears in urine --- 180mg/dL

  • Transport Maximum is max. Rate at which a substance is transported. Limiting factor is saturation of carrier proteins

TMG

Transport Maximum of Glucose

  • Males----- 375mg/min Corresponding Plasma Level 300mg/dL

  • Females— 300mg/min (Tm and Value)

  • Amino acids 1.5 mg/ min

  • Plasma proteins 30 mg/ min

Bicarbonate Reabsorption

Image of Bicarbonate Reabsorption

Image of Bicarbonate Reabsorption

Image of Bicarbonate Reabsorption

Reabsoption of WATER

  • Total fluid filtered-----180 L/day

  • Urine output----------- 1 L/day

Reabsoption is by Two Ways

  • Obligatory water Reabsoption &

  • Facultative Reabsoption.

Obligatory Reabsoption

  • In proximal tubules

  • Secondary to solute reabs.

  • Osmotic reabs.

  • About 65%

  • Cannot be changed according to need of body

Facultative Water Reabsorb

  • In distal tubule & collecting tubule

  • It changes according to need of body

  • Controlled by ADH

Water Reabs. In Different Parts

  • Approx. values are

  • PT---------60 to 70%

  • LH---------15%

  • DT---------5%

  • CD---C----10

  • ---M---4.7%

Mechanism of Water Reabs

  • By diffusion across cell membrane

  • Diffusion is through protein channels called AQUAPORIN

  • Different types of Aquaporins are in human beings: 1, 2,3,4,5 &9

  • Aquaporin 1&2 play key role in water reabs

Image of Mechanism of Water Reabsorption

Image of Mechanism of Water Reabsorption

Image of Mechanism of Water Reabsorption

Mechanism of Water Reabs

  • Aquaporin-1 is localized in proximal tubules

  • Aquaporin-2 is in collecting ducts

  • Stored in the vesicles in the cytoplasm of Principal Cells

  • Vasopressin causes insertion of these vesicles into the apical mem. of cells

Mechanism of Water Reabs

  • Effect mediated by V2 receptors

  • Cyclic AMP, Protein kinase & a molecular motor (one of dyneins) are also involved

Regulation of Urine Osmolarity and Volume

Body can produce

  • Vol. of urine/ day Osmolarity mOsm/L

  • 500ml ---------------------- 1400

  • 23.3L ----------------------- 30

  • About 87%of filtered Water is always reabs.

Osmolarity

  • Human------1400 mOsm/kg of water

  • Dogs---------2500

  • Rats----------3200

  • Some---------5000

Rodents

It depends on max. Osmolarity present in medulla

Mechanism of Concentration & Dilution of Urine

Principal factors:

  • ANTIDIURETIC HORMONE

  • GRADIENT OF OSMOLARITY IN RENAL MEDULLA

  • SLUGGISH BLOOD FLOW IN MEDULLA

ANTIDIURETIC HORMONE

  • ADH is required for water reabsorption

  • Maximum ADH----99% reabsorbed

  • Absence of ADH---88%

Gradient of Osmolarity in Renal Medulla

  • Gradient generated by Counter Current Multiplier system

  • Maintained by C.C.Exchange system

Image of Gradient of Osmolarity In Renal Medulla

Image of Gradient of Osmolarity in Renal Medulla

Image of Gradient of Osmolarity In Renal Medulla

Counter Current Multiplier System

Image of Counter Current Multiplier System

Image of Counter Current Multiplier System

Image of Counter Current Multiplier System

Counter Current Multiplier System

  • In flow runs parallel to, counter to and in close proximity to outflow.

  • It is active process

  • It generates gradient of osmolarity in renal medulla

  • Key role is played by LOOP of HENLE

LOOP of HENLE

  • DLH is CONCENTRATING SEGMENT

  • Highly permeable to water

  • Relatively impermeable to solutes. Therefore

  • Solute free water moves in interstitium

  • Fluid in DLH becomes concentrated

LOOP of HENLE

  • ALH is DILUTING SEGMENT

  • Thin seg. Impermeable to water & permeable to NaCl and urea

  • Thick seg.

  • Impermeable to water & solutes

  • ACTIVE TRANSPORT of NaCl out of lumen

LOOP of HENLE

  • Sodium transported by

  • Na+-K+-ATPase and

  • Na+-K+-2Cl-

  • In ALH tubular fluid becomes more & more dilute & rich in urea

  • Interstitial fluid becomes hyperosmotic

  • MEDULLARY HYPEROSMOLARITY Gen.

COUNTER CURRENT EXCHANGE SYSTEM

  • Formed by VASA RECTA

  • Cannot generate gradient

  • But maintain gradient of osmolarity in medulla

  • Passive mechanism

CCM

Image of Counter Current Exchange System

Image of Counter Current Exchange System

Image of Counter Current Exchange System

CC Exchange

  • Solutes tend to recirculate in medulla

  • Water tends to bypass it.

  • Medullary HYPEROSMOLARITY is MAINTAINED

Sluggish Blood Flow in Renal Medulla

  • Blood flow of Cortex--------90%

  • Flow of Outer Medulla-------9%

  • Flow of Inner Medulla-------1%

Role of Urea in Concern of Urine

  • DCT & CT- Impermeable to water

  • Urea concern Increases in CT

  • IMCD- Permeable to urea so both water & urea are absorbed in here

  • Outer Medullary interstitial Osmolarity is because of sodium

  • Inner medullary by both Na+ & urea

Image of Osmolality of Different Regions of The Kidney

Image of Osmolality of Different Regions of the Kidney

Image of Osmolality of Different Regions of The Kidney

Image of Cortex

Image of Cortex

Image of Cortex

Formation of Concern Urine

↑ Osmolarity of extracellular fluid

↑ Release of ADH from post. Pituitary

↑ Permeability of DCT & Collecting duct

↑ Increase water reabs.

Formation of Dilute Urine

  • ↓ Osmolarity of ECF (excess of water) ↓

  • ↓ ADH secretion ↓

  • ↓ Permeability f DCT & collecting duct ↓

  • Less water is reabsorbed

Water Diuresis

If large amount of water is taken. Within 45 min. urine output increases. Due to decreased ADH. It continues until osmolarity comes back to normal.

Acidification of Urine

  • pH is negative log of H ion concentration.

  • pH of solutions

Image of Acidification of Urine

Image of Acidification of Urine

Image of Acidification of Urine

Normal pH

  • Plasma pH- 7.4

  • Urine pH--- 6.0

Image of PH Ranges

Image of PH Ranges

Image of PH Ranges

Secretion of H Ions

  • There is always an excess of H ions in body & they must be excreted

  • Hydrogen ions are secreted from tubules

H Ion Secretion in PT

  • In PT secretion depends on sodium reab.

  • It is by Secondary Active Transport Na+-H+ antiport

  • For secretion of every hydrogen ion one Sodium & one Bicarbonate ions are reabsorbed

H Ion Secretion in DT

  • Independent of sodium reab.

  • Mainly by ATP driven PROTON PUMP

  • Aldosterone acts on this pump

  • Active reab.

Iii

Image of H ion Secretion In PT

Image of H Ion Secretion in PT

Image of H ion Secretion In PT

H ION Secretion

  • PCT (rich in CA) -------- 85%

  • DCT---------------------- 10%

  • Collecting tubule------- 5%

Fate of H IONS Secreted

  • LIMITING pH of urine is 4.5 so H IONS must be buffered in tubule

  • BUFFER SYSTEMS IN THE KIDNEY

  • Bicarbonate system

  • Dibasic Phosphate system

  • Ammonia system

Bicarbonate Buffer

  • In PCT

  • No change in tubular fluid pH

  • Large amount of H ions are secreted here

  • H Ions buffered do not add to urinary acidity

Image of Reabsorption of Bicarbonate by Renal Tubular Cells

Image of Reabsorption of Bicarbonate by Renal Tubular Cells

Image of Reabsorption of Bicarbonate by Renal Tubular Cells

Dibasic Phosphate Buffer

  • More important in DCT, as phosphates are concentrated here

  • Dibasic phosphate ions are converted to monobasic phosphate

  • to

  • It adds to urinary acidity

Ii

Image of PH Control In Kidneys

Image of PH Control in Kidneys

Image of PH Control In Kidneys

Ammonia Buffer

  • Ammonia is synthesized & secreted by DCT&CT

  • Sources of Ammonia are

    • 60% by deamination of Glutamine

    • 30% by deamination of Glutamic acid

    • 10% by deamination of other aminoacids like Glycine, Alanine etc.

Ammonia Buffer

Important points

  • Ammonium ion major urine acid

  • Ammonium content increases when urine pH is below 6

  • There is adaptative increase in Ammonia synthesis. In Diabetic ketosis H ion excretion may increase 10 folds.

TITRABLE ACIDITY

Definition: Amount of Alkali that must be added to the urine, so as to bring its pH to 7.4

  • H buffered by Bicarbonate not measured

  • Large contribution is by Phosphate buffers

  • It does not measure H ions that combine with Ammonia

Urinary Acid Excretion

Urinary acid Normal Excretion in mEQ or mmol/ day

  • Titrable Acid (25%) ------- 10-30

  • Ammonium ion (75%) ---- 30-50

  • Total ----------------------- 40-80

PHYSIOLOGY of MICTURITION

  • Includes

  • Structure & Innervation of bladder

  • Physiology of micturition

    • Filling of bladder

    • Micturition Reflex

  • Abnormalities of micturition

Structure of Urinary Bladder

Has

  • Body of urinary bladder

  • Urethra &

  • Sphincters

  • Internal sphincter (smooth muscles)

  • External sphincter (skeletal muscle)

Image of Structure of Urinary Bladder

Image of Structure of Urinary Bladder

Image of Structure of Urinary Bladder

Urinary Bladder

Capacity:

  • At birth---------20-50 ml

  • At one year----200 ml

  • In adult---------600 ml

INNERVATION

Is by

  • Sympathetic nervous System

  • Parasympathetic &

  • Somatic nervous system

Motor Innervation

  • Symp. Is from L1, 2&3

  • Effect of stimulation

    • They relax Detrusor muscles

    • Contraction of Int. Sphincter

    • Retention of urine

    • Prevent reflux of sperms from prostatic urethra to urinary bladder during ejaculation

Motor INNERVATION

  • Parasymp. (Nervi erigentes):

  • From S 2, 3 & 4

  • Effect of stimulation

    • Contraction of Detrusor muscle

    • Relaxation of Internal sphincter

    • Leads to emptying of bladder

  • Somatic innervation: S 2, 3 & 4 (Pudendal Nerve) to Ext. Sphincter

Sensory Inn

  • For

  • Bladder distension &

  • Bladder pain

SENSORY Innervation

Bladder distension:

  • From Detrusor mus. Pelvic Splanchnic Nerves

  • From bladder Neck & Trigone via Hypo gastric plexus

  • Fibres travel in Post. column to reach spinal, pontine& supra pontine M.C.

SENSORY Innervation

  • Bladder pain:

  • In Hypogastric plexus

  • Some in nervi erigentes

  • Run in Lateral Spin thalamic Tract Urethral sensation: Pudendal nerve

Bladder Filling

  • Urine flows from Renal pelvis towards bladder by peristaltic cont. of ureters

  • Renal calyces have inherent Pacemaker activity

  • Peristaltic cont. enhanced by Parasymp.

  • Inhibited by Sympathetic

Cystometry

  • Cystometrogram

  • Shows changes in intravesicular pressure as the bladder fills with urine

  • First urge to pass urine------------150ml

  • Marked fullness & discomfort-----400ml

  • Unbearable---------------------------600ml

  • Anatomical capacity-------------about 1L.

Micturition Reflex

  • Fundamentally a spinal reflex, facilitated & inhibited by higher centres

  • It is a Parasympthetic Reflex

  • Higher Control:

    • Faci.—Post. Hypothalamus & Pontine reg.

    • Inhi.—mid brain

    • Cerebral cortex—in voluntary micturation

Mechanism of exitatory and inhibitory synapses

Exitatory and Inhibitory Synapses

Mechanism of exitatory and inhibitory synapses

Spinal Mic. Reflex

  • Filling of bladder (Afferent nerves) ↓

  • Sacral segment of spinal cord (Mic. Cen) ↓

  • Efferent to motor nerves ↓

  • Emptying of bladder

VOL. MICTURITION

  • Impulses reach to S 234 ↓

  • Dorsal column (travel upwards) ↓

  • Brain (Post Central Gyrus) ↓

  • Motor Cortex ↓

  • Sacral Seg. (Emptying of bladder)

Desire to Hold Urine

  • Cerebral Cortex ↓

  • 1 Inhibit Sacral Parasy. Excitatory activity

  • 2 Stimulate Symp. Activity ↓

  • Desire to Micturate PASSES OFF

  • Only a temporary phase

Accessory Muscles Involved

Muscles Involved during Micturition:

  • Abdominal muscles Contract

  • Perineal muscles Relax

  • Diaphragm descends

  • Breathing is hold with glottis closed

  • Thus Intra-Abdominal Pressure ↑

Applied Aspects

  • DEAFFERENTATION

  • DENERVATION

  • TRANSECTION OF SPINAL CORD

DEAFFERENTATION of URINARY BLADDER

  • Cause: Tabes Dorsalis (Syphlis)

  • Findings:

    • Vol. mict. Is possible

    • Unaware of state of bladder distension

    • Periodical emptying not present

    • Overflow dribbling– AUTOMATIC BLADDER

    • DISTENDED, THIN, HYPOTONIC BLADDER

DENERVATED BLADDER

  • Cause: Tumour or injury to Cauda Equina. Injury to both Afferent & Efferent nerv.

  • Loss of vol. Micturition

  • Bladder is flaccid and distended for a while

  • Bladder is decentralized

  • SHRUNKEN HYPERTROPHIED BLADDER

TRANSECTION of SPINAL CORD

Cause: injury, Syringomyelia, Disseminated Sclerosis

  • Both facilitatory and Inhibitory fibres are damaged

  • Recovery in two stages

    • Early Stage (stage of spinal shock)

    • Late stage

SPINAL TRANSECTION

EARLY STAGE:

  • Vol. Mict. Abolished

  • State of retention with overflow develops

  • Bladder becomes spastic neurogenic

  • Complications like cystitis and ascending urinary tract infections can develop

SPINAL TRANSECTION

LATE STAGE:

  • Voiding reflex returns

  • No voluntary control

  • Micturition can be initiated by mass reflex

Endocrinal Functions

  • Erythropoietin

  • Calcitrol

  • Renin a Proteolytic Enzyme

HORMONES ACTING on KIDNEY

  • Aldosterone

  • Antidiuretic hormone

  • Parathormone

Image of Hormones Acting on Kidney

Image of Hormones Acting on Kidney

Image of Hormones Acting on Kidney

Renal Function Tests

  • Performed to

  • Asses the functional capacity of the kidney

  • To detect the renal impairment in the early stage

Renal Function Tests

Various tests are performed

  • Analysis of urine

  • Analysis of blood

  • Renal Clearance tests

  • Radiology & Renal Imaging

  • Renal Biopsy

  • Other methods

Urine Analysis

Normal Colour----light yellow due to

  • Pigments -Urochrome, urobilin &Uroerythrin

  • Deepens on standing, oxidation of urobilinogen to urobilin

  • Brownish yellow—presence of conjugated Bilirubin

  • Red- Dark brown—porphyria

  • Frothy in Proteinuria

Urine Analysis

Composition

  • Inorganic ---Na, K, Ca & phosphate

  • Organic----

  • Urea----20 to 30g/day

  • Uric Acid-----0.6gm/day

  • Creatinine---1.2gm/day

Urine Analysis

  • Normal vol.—Approx. 1 to 2.5L/day

  • Polyuria----> 2.5L/day (fluid intake not high)

  • Oliguria----< 500ml/day

  • Anuria ---- <50ml/day or no urine formed

  • Obligatory urine vol. ------500ml/day.

  • It is minimum quantity of urine that must be formed to remove waste products.

Urine Analysis

Osmolality & Specific gravity

  • Normal Osmolality---------50 to 1200

  • Normal Specific Gravity---1.003 to 1.030

  • Fixed Osmolarity of 300 mOsm/Kg (sp. gr.-1.010) ----Advanced renal failure

  • Persistently low Osmolality less than 100 (after 8 hr. fluid deprivation) diagnostic of Diabetes Insipidus

Urine Analysis

Approx. correlation between S.G. and osmolality

Table of Urine Analysis
Table of Urine Analysis

S.G.

Osmolality (mOsm/kg)

1001

100

1010

300

1025

1000

1030

1200

1040

1400

Urine Analysis

Reaction

  • Normal range----4.5 to 8, Av.6-7

  • After meals it becomes alkaline (postprandial alkaline tide)

  • Alkaline urine turns red litmus blue

Urine Ana

  • Microscopic

  • normally

    • 1 to 2 WBC or Pus Cells/HPF

    • Hyaline Cast----- occasional

    • They are clear, colourless cast made up of high molecular weight mucoproteins

Urine Analysis

Abnormal constituents

  • RBC

  • Bacteria

  • Granular casts

  • Glucose

  • Albumin

  • Ketone bodies

Applied

  • Isosthenuria – S.G. of urine is fixed at 1010 (Pl. 300 mOsm/L e.g Renal Failure

  • 12 hours water deprivation ↑ S.G. to 1025 failure to do this indicates abnormal Renal functions

  • Albuminuria –Albumin excretion above 150mg/day

Albuminuria

Causes

  • Nephritis

  • TB

  • Carcinoma

Albuminuria

Orthostatic Albuminuria

Albumin appears in urine in standing position

Blood Analysis

Normal

  • Blood Urea-------20 to 40 mg%

  • S. Creatinine-----0.6 to 1.5mg%

  • S. Cholesterol----150 to 240mg%

  • Uric Acid----------2 to 4mg%

  • Protein A/G ratio 1.7: 1

  • Nephrotic Syndrome reversal of A/G ratio

Clearance Tests

  • Tests for Glomerular Functions

    • Inulin Clearance

    • Creatinine Cl.

  • Tests for Tubular Functions

    • PAH Clearance

    • Urea Clearance

    • Phenol Sulphonephthalein (PSP) test

Urea Clearance

  • Standard Urea Cl.- urine flow 2ml/min normally------- 54ml/min (40 to 60)

  • Maximum Urea Cl. ------- flow 2ml/min normally--------75ml/min (60 to 90)

  • It is obsolete & not used clinically

Other Methods

  • Micropuncturing

  • Stop Flow Tech.

  • Microcryoscopic studies

Diuretics

  • Are substances that cause increase in urinary flow

  • They are of various types

Table of Diuretics - 1
Table of Diuretics - 1

1

2

3

4

5

6

Class of Diuretic

Site of act.

Mechanism of action

Effect

K+ depletion

pH

HIGH EFF. LOOP DIURETICS

ν Furosemide

ν Bumetanide

ν Ethacrynic acid

TAL

Inhibition of Na+K+ 2Cl- pump

↑NaCl excret.

↑K+ excret

Yes

Alkal.

Table of Diuretics - 2
Table of Diuretics - 2

1

2

3

4

5

6

MEDIUM EFFICACY THIAZIDE DIURETICS

  • Chlorthiazide

  • Hydrochlorthiazide

Early DT

Inhibition of Na+Cl- symporter

Exc of

↑ K+ ↑ NaCl

Antihypertensive

Yes

Alkal

Table of Diuretics - 3
Table of Diuretics - 3

1

2

3

4

5

6

WEAK DIURETICS

1. C. A. INHIBITORS

Acetazolamide

2. K+ Sparing

  • Spironolactone

  • Triamterene

  • Amiloride

PT

Late DT &CD

Inhibition of Carbonic Anhydrase

Inhibition of Na+ Reabsor & Inhibition of K+ Exc.

HCO- 3 Excretion

Na+ Excret &

K+ Excretio

Yes

No

Acidosis

Acidosis