2. Urinary System (1).pptx by sir waqar ahmed
- 1. Urinary System Jamal Hussain MSN, MsPH, BSN
- 2. Objectives • Analyze the anatomical structure and physiological function of the urinary system • Identifying the role of each component (kidneys, ureters, bladder, and urethra) in maintaining fluid and electrolyte balance. • Evaluate the processes of filtration, reabsorption, secretion, and excretion in the kidneys • Interpret their impact on homeostasis, particularly in regulating blood pressure, acid- base balance, and waste elimination. • Apply knowledge of urinary system pathophysiology to diagnose common urinary disorders
- 3. Urinary System The system which is specialized to filter the blood plasma, excrete waste products , and regulate the body’s water, acid- base, and electrolyte balance.
- 4. • Nephrology: The scientific study of the anatomy, physiology, and pathology of the kidneys. • Urology: The branch of medicine which deals with the male and female urinary systems and the male reproductive system.
- 5. Organ of Urinary System • Kidney-which secrete urine • Ureter- which convey the urine from the kidneys to the urinary bladder • Bladder - where urine collects and is temporarily stored • Urethra - through which the urine passes from the urinary bladder to the exterior
- 6. Structure of Kidney • The paired kidneys are bean-shaped. • Located between the levels of the last thoracic and third lumber vertebrae. • Partially protected by the eleventh and twelfth pairs of ribs. • Lying just above the waist between the peritoneum and the posterior wall of the abdomen, hence they are said to be retroperitoneal (retro= behind) for their position. • The right kidney is slightly lower than the left because the liver occupies considerable space on the right side superior to the kidney.
- 7. Anatomy of kidney • A typical adult kidney is 10—12 cm long, 5—6 cm wide, and 3 cm thick. • It weighs about 135—150 g. • The concave border of each kidney faces the vertebral column. • Near the center of the concave border is a deep vertical fissure called the renal hilum, through which the ureter emerges from the kidney along with blood vessels, lymphatic vessels, and nerves.
- 8. Anatomy There are three areas of tissue that can be distinguished when a longitudinal section of the kidney is viewed with the naked eye. • An Outer fibrous capsule, surrounding the kidney. • The Cortex, a reddish-brown layer of tissue immediately below the capsule and outside the pyramids. • The Medulla, the innermost layer, consisting of pale conical-shaped striations, the renal pyramids.
- 9. • The Hilum is the concave medial border of the kidney where the renal blood and lymph vessels, the ureter and nerves enter. • The Renal pelvis is the funnel-shaped structure that collects urine formed by the kidney • Urine formed in the kidney passes through a renal papilla at the apex of a pyramid into a minor calyx, then into a major calyx before passing through the renal pelvis into the ureter. The walls of the pelvis contain smooth muscle and are lined with transitional epithelium. Peristalsis of the smooth muscle originating in pacemaker cells in the walls of the calyces propels urine through the renal pelvis and ureters to the bladder. This is an intrinsic property of the smooth muscle, and is not under nerve control.
- 10. Microscopic Structures • The kidney is composed of about 1–2 million functional units, the nephrons, and a smaller number of collecting ducts. The collecting ducts transport urine through the pyramids to the calyces and renal pelvis, giving the pyramids their striped appearance. The collecting ducts are supported by a small amount of connective tissue, containing blood vessels, nerves and lymph vessels.
- 11. Nephron • The nephron consists of a tubule closed at one end, the other end opening into a collecting tubule. The closed or blind end is indented to form the cup-shaped glomerular capsule (Bowman’s capsule), which almost completely encloses a network of tiny arterial capillaries, the glomerulus.
- 12. Continuing from the glomerular capsule, the remainder of the nephron is about 3 cm long and is described in three parts: • The Proximal convoluted tubule • The Medullary loop (loop of Henle) • The Distal convoluted tubule, leading into a collecting duct.
- 15. Renal Blood Circulation • The blood vessels of the kidney are supplied by both sympathetic and parasympathetic nerves. The presence of both branches of the autonomic nervous system controls renal blood vessel diameter and renal blood flow independently of autoregulation.
- 16. • The collecting ducts unite, forming larger ducts that empty into the minor calyces. • The kidneys receive about 20% of the cardiac output. After entering the kidney at the hilum the renal artery divides into smaller arteries and arterioles.
- 17. Function of kidney 1. Formation and secretion of urine, which regulates total body water, electrolyte and acid–base balance and enables excretion of waste products production. 1. Selective reabsorption (PCT). 2. Secretion. 3. Filtration This takes place through the semipermeable walls of the glomerulus. The volume of filtrate formed by both kidneys each minute is called the glomerular filtration rate (GFR). In a healthy adult the GFR is about 125 ml/min, i.e. 180 litres of filtrate are formed each day by the two kidneys. Nearly all of the filtrate is later reabsorbed from the kidney tubules with less than 1%, i.e. 1 to 1.5 litres, excreted as urine. Urine composition: Water 96% Urea 2%
- 18. Hormonal influence on reabsorption • Parathyroid hormone This comes from the parathyroid glands and together with calcitonin from the thyroid gland regulates. The reabsorption of calcium and phosphate from the distal collecting tubules. • Antidiuretic hormone Also known as ADH, this is secreted by the posterior lobe of the pituitary gland and increases the permeability of the distal convoluted tubules and collecting tubules, increasing water reabsorption. Secretion of ADH is controlled by a negative feedback system • Aldosterone Secreted by the adrenal cortex, this hormone increases the reabsorption of sodium and water, and the excretion of potassium. Secretion is regulated through a negative feedback system
- 19. • Atrial natriuretic peptide (ANP) this hormone is secreted by the atria of the heart in response to stretching of the atrial wall. It decreases reabsorption of sodium and water from the proximal convoluted tubules and collecting ducts. Secretion of ANP is also regulated by a negative feedback system
- 20. Hormones affecting Renal Function Hormone Target Effects Aldosterone Distal tubule, collecting duct Na reabsorption and K secretion; urine volume Angiotensin II Afferent and efferent arterioles Constricts arterioles, reduces GFR; stimulates ADH and aldosterone secretion; stimulates thirst; H2O intake and urine output ADH Collecting duct H2O reabsorption; urine output, increases concentration ANP Afferent and efferent arterioles, collecting duct Dilates afferent arteriole, constricts efferent arteriole, GFR; inhibits secretion of renin, ADH, and aldosterone; inhibits NaCl reabsorption by collecting duct; urine output Epi and Norepi JG apparatus, affr arteriole Induces renin secretion; constricts afferent arteriole; GFR and urine out PTH Proximal and distal tubules, nephron loop Ca++ reabsorption by loop and distal tubule and Mg++ reabsorption by PCT; inhibits phosphate reabsorption by PCT; promotes calcitriol Synthesis
- 21. Function of kidney 2. Secretion of erythropoietin, the hormone that stimulates formation of red blood cells. 3. Production and secretion of renin, an important enzyme in the control of blood pressure. 4. Electrolyte Balance, Renin–angiotensin–aldosterone system Cells in the afferent arteriole of the nephron release the enzyme renin in response to sympathetic stimulation, low blood volume or by low arterial blood pressure. Renin converts the plasma protein angiotensinogen, produced by the liver, to angiotensin 1. Angiotensin converting enzyme (ACE), formed in small quantities in the lungs, proximal convoluted tubules and other tissues, converts angiotensin 1 into angiotensin 2, which is a very potent vasoconstrictor and increases blood pressure. Renin and raised blood potassium levels also stimulate the adrenal gland to secrete aldosterone.
- 22. • Calcium balance Regulation of calcium levels is achieved by coordinated secretion of parathyroid hormone (PTH) and calcitonin. The distal collecting tubules reabsorb more calcium in response to PTH secretion, and reabsorb less calcium in response to secretion of calcitonin. • pH balance, the cells of the proximal convoluted tubules secrete hydrogen ions. In the filtrate they combine with buffers bicarbonate, forming carbonic acid. Carbonic acid is converted to carbon dioxide (CO2) and water (H2O), and the CO2 is reabsorbed, maintaining the buffering capacity of the blood. Hydrogen ions are excreted in the urine as ammonium salts and hydrogen phosphate. The normal pH of urine varies from 4.5 to 8 depending on diet, time of day and a number of other factors. Individuals whose diet contains a large amount of animal proteins tend to produce more acidic urine (lower pH) than vegetarian
- 23. Ureters • The ureters are the tubes that carry urine from the kidneys to the urinary bladder. They are about 25 to 30 cm long with a diameter of about 3 mm.
- 24. Urinary Bladder • Act as reservoir for urine • The bladder wall is composed of three layers: 1. the outer layer of loose connective tissue, containing blood and lymphatic vessels and nerves, covered on the upper surface by the peritoneum 2. the middle layer, consisting of interlacing smooth muscle fibres and elastic tissue loosely arranged in 3. three layers. This is called the detrusor muscle and when it contracts, it empties the bladder the mucosa, composed of transitional epithelium • The bladder is distensible but when it contains 300 to 400 ml, awareness of the need to pass urine is felt. The total capacity is rarely more than about 600 ml.
- 25. Micturition • When 300 to 400 ml of urine have accumulated in the bladder, afferent autonomic nerve fibres in the bladder wall sensitive to stretch are stimulated. In the infant this initiates a spinal reflex and micturition occurs. Urine passed in the response to parasympathetic stimulation of the bladder, causing contraction of the detrusor muscle and relaxation of the internal urethral sphincter. Urine is expelled from the bladder and passes through the urethra before leaving the body.
- 26. Reflex control of Micturition
- 27. Terminologies Oliguria Urine output less than 400 ml per day Haematuria Presence of blood in the urine Proteinuria Presence of protein in the urine Anuria Absence of urine Dysuria Pain on passing urine Glycosuria Presence of sugar in the urine Ketonuria Presence of ketones in the urine. Nocturia Passing urine during the nigh Polyuria Passing unusually large amounts of urine Frequency of micturition Requiring to pass, often small amounts of, urine frequently Incontinence Involuntary loss of urine
- 28. Disease S/S Glomerulonephritis Hematuria Proteinuria Acute Nephritis oliguria (<400 ml urine/day in adults) hypertension hematuria Uremia Nephrotic syndrome Proteinuria Hypoalbuminaemia Generalized oedema Hyperlipidemia. Renal failure Acute, chronic different. Renal lithiasis Hematuria, flank pain, vomiting UTI, Urethritis
Editor's Notes
- #17: Materials essential to the body are reabsorbed here, including some water, electrolytes and organic nutrients such as glucose. Some reabsorption is passive, but some substances are transported actively. Only 60–70% of filtrate reaches the loop of the nephron. Much of this, especially water, sodium and chloride, is reabsorbed in the loop, so only 15–20% of the original filtrate reaches the distal convoluted tubule, and the composition of the filtrate is now very different from its starting values.