EXCRETORY SYSTEM NEPHRONS.. DR.NITIN KHARSADE

PHYSIOLOGY and BIOCHEMISTRY
It includes the excretory system🙌

1. Welcome

2. PANCHSHEEL HOMEOPATHIC MEDICAL COLLEGE AND HOSPITAL KHAMGAON D BHMS-1ST PHYSIOLOGY – SEMINAR PRESENTED BY :- 1)AKSA Khan (40) 2) Vrushali kharat (41) 3) NITIN KHARSADE (42) GUIDED BY :- Dr.viplav kavishwar sir 4) BHAKTI KUDALE (43) ( Head of physiology department) DR.Pranshant Kulkarni sir ( Assistant professor)

3. STRUCTURE AND FUNCTION OF NEPHRONS EXCREATORY SYSTEM

4. Introduction Definition :- The nephron is the minute or microscopic structural and functional unit of the kidney. The two kidneys are the chief excretory Organ of The body. Nephrology is the adult and pediatric study of the kidneys and its diseases . Each kidney consists of 1 to 1.3 million NEPHRONS The number of NEPHRONS starts decreasing after the age about 45-50 years at the rate of 0.8-1% per year. They perform excretory and hemeostatic Function. The NEPHRONS ultimately drain into the pelvis of the ureters. From here urine is passes down the ureter and collected in urinary bladder.

5. Part of NEPHRONS Each NEPHRON is fromed by two parts:- Renal corpuscle or malphighian corpuscle – blind end. Renal tubule- a tubular portion.

6. SHAPE – Spheroidal and slightly flattened. DIAMETER - 200 μ . FUNCTION- Filtration of blood which forms first phase of urine formation. SITUATION – Cortex of kidney either CORTICAL NEPHRONS (near periphery) or JUXTAMEDULLARY NEPHRON (near medulla). RENAL CORPUSCLE

7. RENAL TUBLE BOWMAN’S CAPSULES PROXIMAL CONVOLUTED TUBULE LOOP OF HENLE: - Descending limb Hairpin bend Ascending limb DISTAL CONVOLUTED TUBULE

8. Structure of Nephron

9. TYPE OF NEPHRONS Histologically there are two types of nephrons', according to theirs Relative Position in the Cortex:- 1)CORTICAL NEPHRONS or SUPERFICIAL NEPHEONS: Occupy the outer 2/3 of the cortex and make up about 85% of total number Present in outer cortex near the periphery, small in size,fully functional under normal conditions.
It has blood supply of Peritubular capellaries & has function of formation of urine.

10. 2) JUXTAMEDULLARY NEPHEONS : Occupy inner third of cortex and costitute about 15% of total number. Present in inner Cortex near medulla. Large i n size and work Only in under stress conditions

11. The nephron consist of following parts : 1.Renal or malphighian corpuscle
2. Proximal convoluted tubule
3. Loop of Henle
4. Distal convoluted tubule
And proximal & distal straight tubule ▪️The proximal convoluted and distal convoluted tubule are in the cortex
▪️ The loop of Henle extends from the Cortex to variable distance in the medulla according to the position of corpuscle in Cortex Parts of the Nephron :

12. 🔸MALPHIGIAN COURPUSCLE Found only in Cortex Diameter : 200 microns It consist of two parts: 1. GLOMERULUS
2. BOWMAN’S CAPSULE

13. 1) GLOMERULUS Glomerulus is the tuft of capillaries enclosed by bowmen’s capsule.
It consist of glomerular capillaries interposed between afferent and efferent arterioles. Glomerular capillaries arises from afferent arterioles. After entering to bowman’s capsule the afferent arteriole divides into 4 to 5 large capillaries each large capillary subdivided into 20 to 50 small capillaries arranged in irregular loop and forms an anastomosis .
All small capillary reunite to form efferent arteriole which is less in diameter than afferent arteriole .

14. FUNCTIONAL HISTOLOGY :- Capillaries are made from single layer of endothelial cells attached to basement membrane. Endothelial cells has many pore called fenestrae or filtration pore

15. BOWMAN’S CAPSULES :- It is the capsular structure encloses the glomerulus formed by two layers:
# Inner - Visceral # Outer - parietal

16. 1)VISCERAL LAYERS :- Visceral layer covers the glomerular capillaries and it continues as the parietal layer at visceral pole .
Each epithelial cell of visceral layer connected with basement membrane by cytoplasmic extension called pedicle .
This pedicle leaves cleft like space which is called as slit pore . Epithelial cell with pedicle are called as podocytes

17. TUBULAR PORTION OF NEPHRONS 🔸 PROXIMAL CONVOLUTED TUBULE It is the coiled portion arising from bowmen’s capsule .
It is situated in cortex it is continued as descending limb of loop of Henle . Length of proximal convoluted tubule is 14 mm and diameter is 55 μ .

18. FUNCTIONAL HISTOLOGY :- Proximal convoluted tubule is formed by single layer of cuboidal epithelial cells . It has hair like projection directed towards the lumen of tubule because of this projection the epithelial cells are called brush border cells

19. 🔸 LOOP OF HENLE Site for osmoregulation Length is 10 - 15mm and diameter of 30μ . Consist of: 1. Descending limb 2. Hairpin bend 3. Ascending limb

20. 1)DESCENDING LIMB It consist of: A ) Thick descending segment B )Thin descending segment THICK DESCENDING SEGMENT: - It is direct communication of proximal convoluted tubule descend down in medulla. It is of length 6 mm and 55 μ in diameter and form by brush border cuboidal epithelial cell s . THIN DESCENDING SEGMENT :- It is formed by flattened epithelial cel l without brush border . it is continued as hair pin bent of the loop of Henle.

21. 2)HAIRPIN BEND:- Hair pin bend formed by flattened epithelial cells without brush border. It is continues as ascending limb of loop of Henle.

22. ▪️ ASCENDING LIMB:- It has two parts: A)Thin ascending segment B)Thick ascending segment A)THIN ASCENDING SEGMENT:- It is the continuation of hair pin bend . It is also line by flattened epithelial cell without brush border. Thin ascending segment is continues as thick ascending segment.

23. B)THICK ASCENDING SEGMENT I t is about 9 mm long and diameter of 30 μ . It is line by cuboidal epithelial cell without brush border. It is continuous as convoluted tubules . This part of nephron runs between afferent and efferent arterioles forms macula densa. Which is part of JG apparatus .

24. 🔸 DISTAL CONVOLUTED TUBULE: - It is the continuation of thick ascending segment and occupies the cortex of kidney. It is continues as collecting duct . The length of distal convoluted tubule is 14.5 to 15 mm and diameter is 22 to 50μ. FUNCTIONAL HISTOLOGY: Distal convolute tubule are line by single layer of cuboidal epithelial cells without brush border cells. This cell in distal convoluted tubule are called inter-related cells (I cells).

25. 🔸 COLLECTING DUCT OR STRAIGHT TUBULE : - Distal convoluted tubule continuous as initial or arched collecting duct which is in Cortex. The lower part of collecting duct lies in medulla . 7 to 10 initial collecting duct unite to form straight collecting duct, which passes through medulla . Several collecting duct from different nephron joints to form Duct of Bellini. It is 20 mm long and varies in diameter between 40 to 200 μ .

26. RENAL CIRCULATION INTRODUCTION:- Blood vessels of Kidney are highly specialized to facilitate function of formation of urine.
In adults in resting condition both kidneys receive 1300 ml of blood per minute or about 26 percent of cardiac output
Renal arteries supply blood to kidney

27. RENAL BLOOD VESSELS 1- ARTRIL SYSTEM :- 1) RENAL ARTERY :
Arises directly from abdominal arota and enters kidney through hilus
While passing through renal sinus the renal arteries divide into many segment arteries 2)SEGMENTAL ARTERY: Subdivides into interlobular arteries one for each pyramid 3) INTERLOBAR ARTERY: Passes between medullary pyramid. At base of pyramid it turns and run parallel to base of pyramid forming arcuate artery

28. 4)ARCUATE ARTERY: Gives rise to interlobular artery 5) INTERLOBULAR ARTERY: Run through renal cortex perpendicular to arcuate artery From each interlobular artery numerous afferent arterioles arise

29. 6)AFFERENT ARTERIOLE : Enters bowman’s capsule and forms glomerular capillary tuft.
-After entering bowman’s capsule afferent arteriole divides into 4 or 5 large capillaries Short and wide. 7) GLOMERULAR CAPILLARIES: Each large capillary divides into small glomerular capillaries which forms loops. - Capillary loops unite to form efferent arterioles which leaves the bowman’s capsules.

30. 8) EFFERENT ARTERIOLES: Forms a second capillary network called Peritubular capillary. which surrounds tubular portion of nephron Thin and long. Thus renal circulation from a portal system by presence of two sets of capillaries namely a) Glomerular capillaries and b) Peritubular capillary

31. 9)PERITUBULAR CAPILLARIES and VASA RECTA : - Found around the tubular portion of cortical nephron only - Juxtamedullary nephron is supplied by some specialized capillaries and Vasa recta - Vasa recta arises directly from efferent arterioles of juxtamedullary nephron and runs parallel to renal tubule into medulla and ascend towards cortex

32. VENOUS SYSTEM Peritubular capillaries and Vasa recta drain into the venous system. Venous system starts with peritubular venules and continuous as interlobular vein , arcuate vein , interlobular vein, segmental vein and finally the renal vein . Renal vein leaves kidney through hilum and joins inferior vena cava .

33. MEASUREMENT OF RENAL BLOOD FLOW Blood flow of kidney is measured by using plasma clearance of para amino hippuric acid .

34. REGULATION OF RENAL BLOOD FLOW : It is mainly regulated by autoregulation AUTOREGULATION :
is an intrinsic ability of an organ to regulate its own blood flow
It is highly significant and more efficient in kidney
It is important to maintain glomerular filtration rate (GFR)
Blood flow to kidney is normal when mean arterial pressure is between 60-80 mmHg
Two mechanism are involved in renal regulation 1) Myogenic response
2) Tubuloglomerular feedback

35. 1) MYOGENIC RESPONSE Increased blood flow to kidney increases the streches on the elastic walls of afferent arterioles.
Stretching of vessels wall increases flow of calcium ions from extracellular fluids into cells.
Influx of calcium ions lead to contraction of smooth muscles fibers in afferent arterioles which causes contributions of afferent arterioles.
So blood flow decreases.

36. 2) TUBULOGLOMERULAR FEEDBACK Macula densa plays an important role In tubuloglomerular feedback. Which controls renal blood flow and GFR .

37. PECULIARITIES OF RENAL CIRCULATION 1) All blood that passes through kidney has to pass through the glomerular tuft . Renal circulation is a portal system. The blood has to pass through double capillary network at first through glomerular capillaries and then through peritubular capillaries. Two capillary system serve two different functions a) Glomerular tuft filters b) Tubular tuft reabsorbs

38. PECULIARITIES OF RENAL CIRCULATION 2)RENAL BLOOD PRESSURE IS COMPARATIVELY HIGH Reasons: 1)RENAL ARTERY is short and wide and arises directly from aorta it divides into small number of wide branches . > Because of this blood enters kidney at a comparatively high pressure 2)AFFERENT GLOMERULAR VESSELS is wider and shorter than efferent vessel. > Due to this glomerular pressure remains fairly high and is about 3-4 times more than capillary pressure

39. 3) THERE ARE TWO CIRCULATION IN KIDNE a)GREATER CIRCULATION b) LESSER CIRCULATION A) GREATER CIRCULATION: Carriers 85% of blood Blood first passes through peritubular network and finally joins the renal vein PECULIARITIES OF RENAL CIRCULATION

40. 2) LESSER CIRCULATION : Carries 15% of blood and passes through juxtamedullary glomeruli.
Efferent glomerular vessels after a short straight course ,Vasa recta ,joins the renal directly and joins partly the peritubular network.
(Under abnormal conditions it may act as shunt –trueta shunt ) PECULIARITIES OF RENAL CIRCULATION

41. LYMPHATIC SUPPLY Lymph drains vis thoracic ducts into venous circulation in thorax.

42. NERVE SUPPLY Mainly supplies by SYMPATHETIC and PARASYMPATHETIC NERVE FIBERS . SYMPATHETIC comes mainly from 10th to 12 th thoracic segments . PARASYMPATHETIC from vagus . Sympathetic carries vasoconstrictor and afferent fibers . Auto fibers also supply the tubular cells and reabsorption of Sodium is probably influenced by these nerves.

43. JUXTAGLOMERULAR APPARATUS

44. DEFINITION:- Juxtaglomerular apparatus is a Speciliased organ situated near glomerulus of each Nephron. Juxtaglomerular apparatus is formed by three different cells- 1.juxtaglomerular cells 2. Macula densa 3. Extra-glomerular mesangial cells

45. JUXTAGLOMERULAR CELLS Juxtaglomerular cells are granular epithelial cells situated in the Preglomerular portion of afferent and efferent arterioles. These smooth muscle cells are mostly present in tunica media and tunica adventitia of the wall of the afferent arteriole. Also called as granular cell because presence of secretary granules in their cytoplasm..

46. FUNCTIONAL KEY FEATURES OF JUXTAGLOMERULAR APPARATUS : 1.components of GJA Related to control of blood pressure, renal blood flow, salt balance and Erythropoiesis.
2. Renal hypertension is claimed to be cause of secretion of renin from JGA helps in formation of Angiotensin II.
3.granulation in JG cells is related with presence of secretable renin antibodies also localized in JG cells
4.renin secretion is determined by the sodium concentration of macula densa cells..

47. 5.the REF or erythrogenin is known to be secretion of JG cells. It’s production is increase by hypoxia, cobalt salts and androgens.
6.cobalt salts stimulates production of erythropoietin it is known as hormone and it’s having molecular weight of about 25,000-40, 000 causes certain stem cells in bone marrow to be converted to proerythroblast. Blood level of erythropoietin plays imp part in the control of erythropoiesis.

48. Macula densa Macula densa is a modified epithelial cell in portion of DCT lying in contact with affrent glomerular vessels of same Nephron. It does not posses basement membrane..
Macula densa cells possess golgi apparatus which lies in between nucleus of epithelial cell and outer border of cell.
Towards glomerular side this cell are taller and thinner .

49. EXTRA GLOMERULAR Mesangial cells Extracurricular mesangial cells or ‘ lacis cell ‘ is also known as polkisson cell, goormaghtigh’s cells.
It is a cell mass formed by mainly by the agranular or occasional granular cells. These cell lie in close contact with macula densa. Also within the vascular pole formed by afferent and efferent glomerular vessels..

50. APPLIED PHYSIOLOGY or CLINICAL PHYSIOLOGY Renal diseases are classified in two type 1)Acute
2)Chronic *1)Acute* > Low blood volume
>Exposure to kidney toxic, substances
> obstruction of urinary tract *2)Chronic *
>Diabetes mellitus – Glomerular disease. >Hypertension – Vascular disease
>Glomerulonephritis (inflammation of glomeruli)
>Anemia
>Bone disease

51. DIURETIC :- Excretion of large quantity_of water through urine.
such type of osmotic diuresis the diuresis which induced by osmotic effects of solutes like glucose
common in diabetes mellitus. Diuretic therapy * can provide advantageous, effects in many clinical situation such as- - Heart Failure a with Edema - Hypertension APPLIED PHYSIOLOGY or CLINICAL PHYSIOLOGY

52. DIABETES MELLITUS A common cause of renal failure is uncontrolled diabetes mellitus
Diabetes meaning “running through” denotes increased urinary volume excreted by the persons suffering with this disease.
Diabetes can be due to: 1. Deficiency of insulin 2. Decreased responsiveness to insulin This abnormality in carbohydrate metabolism leads to high levels of blood glucose which can lead to considerable damage to many parts of the body.
These include kidneys, heart, eyes and blood vessels.

53. Signs and symptoms of Diabetes mellitus - 1)Frequently urination
- 2)Sudden weight loss
- 3) Always hungry
- 4) Always trusty
- 5) Wounds that won’t heal.
- 6) Blurry Vision
- 7) Numb of Thinning hand or feet
- 8)Woman get diabetes
- 9) Sexual problems.

54. GLOMERULOSCLEROSIS Hardening of the glomerulus of kidney due to Scarring .
Some times diabetic nephropathy is progressive of result in death in 2-3 years after diagnosis. It also leading cause of premature death In young diabetics patient . Important cause of renal failure Also cause of nephritic syndrome in children and adolescents .

55. DIABETES INSIPIDUS Cause due to failure of the posterior pituitary to release the hormone vasopressin or inability of the kidney to respond to vasopressin . In these patients kidneys are unable to conserve water 💦 Large quantity of dilute water is produced. Hence patient consume more water 💧. Also suffer from Dehydration . Also condition is called polyuria- increase urinary outputs.

56. NEPHROGENIC DIABETES MELLITUS Some time ADH secretion is normal but dysfunctioning of renal tubule It doesn’t give the response to ADH hormone lead to excessive Water loss resulting in polyuria like condition occurs.

57. BARTTER SYNDROME It is an genetic disorder cause due to dysfunctioning of Thick ascending segment and Distal convoluted tubule(DCT) . This affect on decrease reabsorption of Na,K,Cl ions . Resulting in loss of large quantity of Na,K,Cl ions through urine. Also large quantity of Ca ions is losses through urine. COMMON SIGNS AND SYMPTOMS :- -Muscle weakness -Cramping -Spasm and Fatigue -Excessive Thirst -Polyuria - Nocturnal urea (may occur)

58. OLIGOURIA Condition in which decreased output of urine. i.e. Less than 500ml/day. COMMON CAUSE Acute renal failure Obstacles in urinary tract Trauma or Infection to RENAL. Heart failure Dehydration Medication (Such as Antibiotics,Imunosuppresent drug and Chemotherapy ).