Osmoregulation and Routine Urinalysis

1. Peachy Mae A. Pineda Osmoregulation and Routine Urinalysis

2. Urinary System • The urinary system(also called excretory system) is the organ system that produces, stores, and eliminates urine. • It consist of the kidneys,ureters, urinary bladder, and urethra.

3. Urinary System Renal artery Kidneys Renal vein re Aorta Ureters Inferior vena cava Urinary bladder Urethra

4. Kidney • is a compact, bean-shaped organ attached to the dorsal body wall outside the peritoneum. • its main roles are to regulate volume and composition of the body fluids. • the structure of the kidney consists of the cortex, medulla (inner and outer zones of outer medulla and papilla or inner medulla), pyramids,renal calyxes and pelvis, and ureters. 

5. Kidneys CORTEX MEDULLA RENAL PYRAMID MINOR CALYXES MAJOR CALYXES RENAL PELVIS URETER

6. General Functions of the Kidney • Blood Filtering • Excretion of Waste • Homeostasis • Acid-base balance • Blood pressure • Plasma volume • Hormone Secretion

7. General Functions of the Kidney *Blood Filtering • Takes place in the nephron. • Blood pathway in the kidney (entering) • renal artery in the renal sinus • branches into segmental arteries • further divide into interlobar arteries • then supply blood to the arcuate arteries • supply a variety of additional interlobar arteries • afferent arterioles to be filteredthrough.

8. General Functions of the Kidney *Blood Filtering • Blood pathway in the kidney (exiting) • blood moves through a small network of venulesthat converge into interlobar veins • the interlobar provide blood to the arcuate veins • back to the interlobar veins • form the renal vein exiting the kidney for transfusion for blood

9. General Functions of the Kidney *Excretion of Waste Products • The excreted product came from the waste produced by metabolism. • Mostly nitrogenous waste: UREA and URIC ACID,and Water. • It is excreted through urine.

10. General Functions of the Kidney *Homeostasis • The kidney is one of the major organs involved in whole-body homeostasis. • Among its homeostatic functions are acid-base balance, regulation of electrolyte concentrations, control of blood volume, and regulation of blood pressure.

11. General Functions of the Kidney *Homeostasis • Acid-base balance • The kidneys regulate the pH of blood by adjusting H+ ion levels, referred as augmentation of mineral ion concentration, as well as water composition of the blood. • Blood pressure • Sodium ions are controlled in a homeostatic process involving aldosterone which increases sodium ion reabsorption in the distal convoluted tubules.

12. General Functions of the Kidney *Homeostasis • Plasma volume • Controlled by hypothalamus. • (together with posterior pituitary gland) hypothalamus secretes antidiuretic hormone. • resulting in water reabsorptionby the kidney and an increase in urine concentration. • The two factors work together to return the plasma osmolarity to its normal levels

13. General Functions of the Kidney *Hormone Secretions • The kidneys secrete a variety of hormones. • Erythropoietin is released in response to low levels of O2 in the renal circulation. It stimulates erythrocyte production in red bone marrow. • Renin is involved in the regulation of aldosterone secretion. • Calcitriol, the activated form of vitamin D, promotes the absorption of Ca2+ from the blood and the excretion of PO32-. They both help to increase Ca2+ levels.

14. Kidneys *Nephrons • Nephrons are microscopic tube-likestructures in the kidneys which mainly facilitates the functions of the kidney. • They are the most basic structural and functional unit of the kidney, and are an integral part of the urinary system. • Each kidney contains approximately one million of them.

15. Kidney *Nephrons • Glomerulus • Proximal convoluted tubule • Loop of Henle • Distal Convoluted tubule • Collecting ducts

16. Kidney *Glomerulus • A capillary network enclosed by the a cup-shaped tructure called the Bowman's capsule. • Together with the Bowman’s capsule, glomerulus is called the Renal corpuscle. • The renal corpuscle (or Malpighian corpuscle) is the beginning of the nephron.

17. Kidney *Glomerulus • It is the nephron's initial filtering component. • It regulates the concentration of essential substances, and removes substances not produced by the body. • Blood enters the glomerulus, it is filtered out to the space made by the Bowman’s capsule. • The blood then enters the convoluted tubules through the interstitial space, combines with efferent venules of other glomerulus then rejoins the main blood stream.

18. Kidney *Renal Tubule • Renal tubule or the convoluted tubules is composed of proximal convoluted tubule, (2) loop of Henle, and (3) distal convoluted tubule.

19. Renal tubule *Proximal Convoluted tubule • Can be divided into an initial convoluted portion and a following straight (descending) portion. • Fluid entering the proximal convoluted tubule is reabsorbed into the peritubular capillaries, including filtered salt and water and all filtered organic solutes.

20. Renal Tubule *Loop of Henle • Also called the nephron loop, is a U-shaped tube that extends from the proximal tubule. • The primary role of the loop of Henle is to concentrate the salt in the interstitium, the tissue surrounding the loop. • It consists of a descending limb and ascending limb.

21. Renal Tubule *Loop of Henle • It begins in the cortex, receiving filtrate from the proximal tubule, extends into the medulla as the descending limb, and then returns to the cortex as the ascending limb (hairpin turn)to empty into the distal convoluted tubule. • The descending limb is permeable to water but completely impermeable to salt, and thus making the interstitiumhypertonic. • The ascending limb is impermeable to water, a critical feature of the countercurrent mechanism. It actively pumps sodium outof the filtrate, because of this the fluid became more hypotonic.

22. Renal Tubule *Distal Convoluted Tubule • Cells lining the tubule have numerous mitochondria to produce enough energy (ATP) for active transport to take place. • Regulated by the endocrine system.

23. Renal Tubule *Distal Convoluted Tubule • In the presence of parathyroid hormone, the distal convoluted tubule reabsorbs more calcium and excretes more phosphate. • Aldosterone promotes more sodium to be reabsorbed and more potassium to be excreted. • Atrialnatriuretic peptide causes the distal convoluted tubule to excrete more sodium. • In addition, the tubule also secretes hydrogen and ammonium to regulate pH.

24. Collecting Ducts • The distal convoluted tubules of several nephrons empty into a single collecting duct. • Collecting ducts then unite and converge to form papillary ducts.

25. Collecting Ducts • As the filtrate moves through the renal tubule, the osmolarity of the filtrate changes.  • As it moves deeper into the medulla, it increases, and when it ascends the loop of Henle, it decreases only to increase again while going down the collecting duct.  • It is this hyperosmotic condition in the medulla that allows passive transport to occur.  • Collecting duct is normally impermeable to water, it becomes permeable in the presence of antidiuretic hormone (ADH). Lower portions of the collecting duct are also permeable to urea..

26. Urine Formation *What is Urine? • The waste product secreted by the kidneys that in mammals is a yellow to amber-colored, slightly acid fluid discharged from the body through the urethra. • An aqueous solution of organic and inorganic substances, mostly waste products of metabolism. • It consists of water, carrying in solution the body's waste products such as urea, uric acid, creatinine, organic acids, and also other solutes such as Na+, K+, Ca2+, Mg2+, Cl-, the body fluid concentrations of which are regulated by the kidneys.

27. Urine formation • The production of urine is vital to the health of the body. • “Cleaning" of the blood takes place in the kidneys and, in particular, in the nephrons, where the blood is filtered to produce the urine. • The kidneys' 2 million or more nephrons form urine by three precisely regulated processes.

28. Urine Formation • The three processes are the following: A. Glomerulus Filtration B. Tubular Reabsorption C. Tubular Secretion Expressed mathematically as: Urinary excretion rate = Filtration rate – Reabsorption rate + Secretion rate

29. Urine Formation *1.Glomerular Filtration • Urine formation begins with the process of filtration, which goes on continually in the renal corpuscles (glomerulus and Bowman’s capsule). • As blood courses through the glomeruli, much of its fluid soaks out of the blood through the membranes (by osmosis and diffusion) where it is filtered and then flows into the Bowman's capsule. • The water, waste products, salt, glucose, and other chemicals that have been filtered out of the blood are known collectively as glomerular filtrate

30. Urine Formation *1.Glomerular Filtration • The glomerular filtrate consists primarily of water, excess salts (primarily Na+ and K+), glucose, and a waste product of the body called urea. • The total rate of glomerular filtration (glomerular filtration rate or GFR) for the whole body is normally about 125 ml per minute. That is, about 125 ml of water and dissolved substances are filtered out of the blood per minute.

31. Urine Formation *GlomerularFiltration • The GFR per hour is: • 125 ml/min X 60min/hr= 7500 ml/hr. • The GFR per day is: • 7500 ml/hr X 24 hr/day = 180,000 ml/day or 180 litres/day.

32. Urine Formation *2.Tubular Reabsorption • Reabsorptionis the movement of substances out of the renal tubules and collecting ducts back into the blood capillaries located around the tubules (called the peritubularcopillaries). • Substances reabsorbed are water, glucose and other nutrients, and sodium (Na+) and other ions. • Reabsorption begins in the proximal convoluted tubules and continues in the loop of Henle, distal convoluted tubules, and collecting tubules.

33. Urine formation *2.Tubular Reabsorption • Large amounts of water about 99% of the 180 liters of water that leave the blood each day by glomerular filtration returns to the blood from the proximal tubule through the process of passive reabsorption. • The nutrient glucose (blood sugar) is entirely reabsorbed back into the blood from the proximal tubules. In fact, it is actively transportedout of the tubules and into the peritubular capillary blood.

34. Urine Formation *2.Tubular Reabsorption • Sodium ions (Na+) and other ions are only partially reabsorbed from the renal tubules back into the blood. • Sodium ions are actively transportedback into blood from the tubular fluid. • The amount of sodium reabsorbed varies from time to time; it depends largely on how much salt we take in from the foods that we eat.

35. Urine Formation *3.Tubular Secretion • Secretion is the process by which substances move into the distal and collecting tubules from blood in the capillaries around these tubules. • Secretion is reabsorption in reverse. • Whereas reabsorption moves substances out of the tubules and into the blood, secretion moves substances out of the blood and into the tubules where they mix with the water and other wastes and are converted into urine.

36. Urine Formation *3.Tubular Secretion • These substances are secreted through either an active transportmechanism or as a result of diffusion across the membrane. • Substances secreted are hydrogen ions (H+), potassium ions (K+), ammonia (NH3), and certain drugs. • Kidney tubule secretion plays a crucial role in maintaining the body's acid-base balance

37. Summary of Urine Formation

38. Characteristics of Normal Urine

39. Abnormal Constituents in Urine

40. Osmoregulation

41. Osmoregulation • Regulation of the concentration of dissolved substances in the cells and body fluids (e.g. blood) of an animal. • Importance: Maintains homeostasis • cells being bathed in tissue fluid which has the correct amount of water, mineral salts, glucose and temperature.

42. Osmoregulation • the physiological processes that an organism uses to maintain water balance; that is, to compensate for water loss, avoid excess water gain, and maintain the proper osmotic concentration (osmolarity) of the body fluids • Most humans are about 55 to 60 percent water by weight (45 percent in elderly and obese people and up to 75 percent in newborn infants).

43. Procedure

44. Results and Discussions Volume of Urine Produced

45. Results and Discussions

46. Results and Discussions Total Volume of Urine Produced

47. Results and Discussions • Diuretics • Increase urine output by the kidney • Promote diuresis

48. Results and Discussions • Caffeine is a natural diuretic. • It makes you secrete more urine. • It is found in coffee, tea, soft drinks, and chocolate.

49. Results and Discussions • If caffeine promotes diuresis, then why does coffee and soft drinks which contain caffeine only ranked fourth and third respectively in volume of urine excreted?

50. Results and Discussions • Subsequent studies have further shown that the mechanism of caffeine diuresis is dubious in nature, as caffeine containing beverages did not impact urinary output any differently, when compared to other beverages that do not contain caffeine. However, this does not mean that caffeine does not increase your need or urge to urinate.