Functional characteristics of nephron

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A male patient, age 60 presents to medical OPD with the complaints of Body Swelling, generalized weakness and anorexia. He is diabetic and hypertensive for the last about 5 years.On examination and investigations, it was found that he was having:1.Edema2.Metabolic acidosis3.Increased levels of Urea, Potassium, creatinine and uric acid4.Anemia5.Osteomalacia 6.Hypertension ©Prof. Dr. Rashid Mahmood 1

What is the probable Cause/ Diagnosis?

2 ©Prof. Dr. Rashid Mahmood 2

Functional characteristics of nephron

3 ©Prof. Dr. Rashid Mahmood3

OBJECTIVES• Goal /Aim

– By the end of this session students should be able to understand the Basic Concepts of Functional characteristics of nephron

• Specific objectives• At the end of the lecture students should be able to

• Describe the Functions of the Kidneys • Outline Physiologic Anatomy of the Kidneys and

Nephron• Describe The nephron as the functional unit of the

kidney• Differentiate between Cortical and juxtamedullary

nephron

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Lesson contents• Multiple Functions of the Kidneys in

Homeostasis– Excretion – Regulation of water and electrolyte balance– Regulation of arterial pressure– Regulation of acid-base balance– Regulation of erythrocyte production

– Regulation of 1,25-Dihydroxyvitamin D2 production

– Glucose synthesis

• Physiologic Anatomy of the Kidneys– General organization of the kidneys and urinary tract– Renal blood supply– The nephron is the functional unit of the kidney– Regional differences in nephron structure: Cortical and

juxtamedullary nephron ©Prof. Dr. Rashid Mahmood

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– By the end of this session students should be able to understand the Basic Concepts Functional characteristics of nephron





nephron


FUNCTIONS OF KIDNEY

• Primary function

• REGULATORY FUNCTIONS

• EXCRETORY FUNCTIONS

• SECRETORY/ENDOCRINE FUNCTIONS

• OTHER FUNCTIONS


Functions of kidney• Primary function

1. Maintenance of the normal volume and composition of body fluids2. To get rid of body waste

materials


Functions of kidney1. REGULATORY FUNCTIONS (Maintenance of Homeostasis)

i. Regulation of water balanceii. Regulation of electrolyte concentrationiii. Regulation of acid-base balanceiv. Regulation of arterial pressure

i. Long-term: salt and water excretionii. Short-term: renin

v. Regulation of blood volume


Functions of kidney2. EXCRETORY FUNCTIONS

i. Excretion of metabolic waste productsUrea, creatinine, uric acid, bilirubin etc

i. Excretion of drugs, hormone metabolites

ii. Excretion of foreign chemicals. ToxinsPesticides, food additives etc

--contd--


Functions of kidney3. SECRETORY/ENDOCRINE

FUNCTIONS (Hormonogenesis)i. Erythropoietinii. Vitamin D-3 (1,25-dihydroxyvitamin

D3; calcitriol)


Functions of kidney3. Other FUNCTIONS

i. Gluconeogenesisii. Detoxification of free radicals and drugs

(Peroxisomes)iii. PROSTAGLANDIN Synthesis and

metabolism i. Dilatation of blood vesselsii. Water and sodium excretioniii. Autoregulation of renal blood flow

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Assessment Question 1

• Name any 4 substances synthesized by kidney

©Prof. Dr. Rashid Mahmood 15








nephron


PHYSIOLOGICAL ANATOMY


Physiological anatomy

• One million nephrons in each kidney

• Cannot be regenerated

• Decrease by 10% every 10 years after the age of 40 years


Pyramids


Nerve supply

• Only Sympathetic nerves


RENAL BLOOD FLOW• 1200 ml/min

• 21% of Cardiac Output

• Weight: 0.4% of total body weight

• Q= P/R

Renal Blood Flow =(Renal Artery Pressure)-(renal vein Pressure)

÷

Total Renal Vascular Resistance


Renal Arterial supply

1

2

3

4

5

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Q. 2

• Calculate the Renal Blood Flow if – Renal Artery Pressure= 1100 mmHg– Renal vein Pressure = 5 mmHg– Total Renal Vascular Resistance= 0.1

» Also write calculations









nephron


100 60

60 18 13


Total length of all

Nephrons in both

kidneys= 100 km

Diameter of nephron=

10-60 microns

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Q. 3

1. Can you identify a portal system in the renal circulation? (Yes/ No)

2. From which Ganglion the renal nerves arise?









nephron


JuxtamedullaryNephron

CorticalNephron

Med

ulla

C

orte

x


Cortex

Medulla

Outer zone

Inner zone

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Summary • The urinary system is well known for eliminating wastes from

the body, but its role in homeostasis goes far beyond that.• Each kidney contains about 1.2 million functional units called

nephrons

• A nephron consists of two principal parts: a renal corpuscle, where the blood plasma is filtered and a long renal tubule that processes this filtrate into urine.

• Nephrons just beneath the renal capsule, close to the kidney surface, are called cortical nephrons

• Nephrons close to the medulla are called juxtamedullary nephrons

• Juxtamedullary nephrons are responsible for maintaining an osmolarity gradient in the medulla that helps the body conserve water.

• About 15% of the nephrons are juxtamedullary39

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Learning Resources

• Guyton and Hall (Text book of physiology), 12th Edition

• Ganong (Text book of physiology), 24th Edition• Berne & Levy Principles of Physiology (Koeppen BM),

6th Edition, 2014 • Human Physiology Stuart Fox, 13th Edition, 2012 • Human Physiology : from cells to system with Power

Lecture DVD Lauralee Sherwood, 8th edition, 2012

• Internet

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Assessment Question 4

1. What is the latest edition of Guyton and Hall (Text book of physiology), and Ganong (Text book of physiology) ?

2. What is the function of Juxtamedullary Nephron?

Functional characteristics of nephron

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